FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
TITLE OF THE INVENTION
"Fe304 NANOPARTICLES EMBEDDED ZnO ASSEMBLIES"
APPLICANT
Indian Institute of Technology, Bombay of Powai, Mumbai-400076, Maharastra,
India; Indian
INVENTORS
Prof. Dhirendra Bahadur, Sarika Singh and Kanhu Charan Barick all Indian Nationals of Indian Institute of Technology, Bombay Powai, Mumbai 400 076, Maharashtra, India
The following specification particularly describes the invention and the manner in which it is to be performed

FIELD OF THE INVENTION:
The present invention relates to Fe304-ZnO magnetic semiconductor nanocomposites (MSN) and a process of production thereof and their subsequent structural analyses by XRD, XPS, TGA, TEM-EDS and magnetic measurements. Particularly, it has been observed that these nanocomposites of the present invention have strong affinity for the simultaneous removal of toxic metal ions such as Ni2+, Cd2+, Co2+, Cu2+, Pb2+, Hg2+, and As3+ from waste-water due to their porous network structure, surface polarity and high surface area. The synthesized novel nanocomposites of the instant invention also exhibit good photocatalytic decomposition of organic dye (methylene blue) under UV irradiation, and is found efficient for easy and rapid capturing of bacterial pathogens (Escherichia coli).
BACKGROUND OF THE INVENTION:
Today's world is facing alarming challenges in meeting the rising demands of clean drinking water and conditions are very severe particularly in developing nations. Non-biodegradable effluents such as organic dyes and heavy metal ions produced from textiles, chemicals, mining and metallurgical industries cause severe environmental pollution, especially by releasing toxic and carcinogenic materials into water. The clean water (free from contaminants such as bacterial pathogens, toxic chemicals and metal ions) is essential to human health. Thus, there is an immediate requirement for the development of better techniques for purification of water from various contaminants.
There are several techniques to perform this such as adsorption, ion exchange, chemical precipitation, membrane based filtration and photodegradation. Among these, adsorption and photodegradation are conventional but efficient techniques to remove toxic contaminants from water. Numerous adsorbents/catalysts have been developed for the purification of waste-water. In most cases, these are highly porous nanomaterials, providing ample surface area for adsorption. However, the existence of intraparticie diffusion may lead to a decrease in available space and adsorption capacity. Thus, the development of efficient biocompatible adsorbent having large surface area, active surface sites and low intraparticie diffusion rate is of great

significance. Among various porous nanomaterials, the functional oxides such as semiconducting ZnO and magnetic Fe304 are two important classes of adsorbents for purification of water from organic and inorganic contaminants.
Recently, ZnO nanoparticles have been used as an alternative to T1O2 for photocatalytic degradation of organic contaminants due to its higher absorption capacity, better quantum efficiency, wide band gap and non-toxic nature with good sensing behavior. ZnO nanoparticles with high surface area and porosity exhibit higher photocatalytic activity than their bulk counterparts, through minimizing the distance between the site of photon absorption and electron (e") - hole (h+) redox reactions. In addition, these ZnO catalyzed reactions can be performed in nearly neutral solution, which is an added advantage of ZnO over its competitors and makes ZnO, a significant candidate for detoxification of water from organic contaminants by photocatalysis. Further, ZnO also has potential applications in removal of toxic metal ions in comparison to sorbent beds and for killing bacterial pathogens such as Escherichia coli (E. coli) and Staphylococcus aureus (S .aureus).
Superparamagnetic Fe304 nanoparticles on the other hand, in addition to high surface area also possess optimal magnetic properties, which lead to high adsorption efficiency, high removal rate of contaminants and easy and rapid separation of adsorbent from solution via magnetic field. It has been recently reported that surface engineered Fe304 nanoparticles are excellent nanoadsorbents for simultaneous removal of toxic metal ions and capturing of bacterial pathogens from waste-water. Amongst several attributes mentioned above, these superparamagnetic Fe304 nanoparticles are one of the most effective heating materials for the local hyperthermia in an AC magnetic field. Though magnetic hyperthermia using Fe304 nanoparticles is well studied in heat activated cancer therapy, only a very few reports are available on killing/inactivation of bacterial pathogens by using magnetic hyperthermia. Tomas et al "Carboxylic acid-stabilised iron oxide nanoparticles for use in magnetic hyperthermia", J. Mater. Chem. 19 (2009) 6529-6535 reported the use of carboxylic acid coated iron oxide nanoparticles for killing of S. aureus bacteria by magnetic fluid hyperthermia. Recently, Park et al. "Inactivation of Psuedonomas aeruginosa PA01 biofilms by hyperthermia using superparamagnetic nanoparticles", J. Micro. Methods 84 (2011) 41-45 investigated the thermal

inactivation of Pseudomonas aeruginosa PA01 biofilms by hyperthermia. Thus, the heat activated killing of microbial organisms by magnetic nanoparticles under AC magnetic field could form the basis of a new approach to the treatment of a variety of infectious diseases.
In view of the above, it is apparent that there are numerous ways of detoxifying and decontaminating water, however, it is also apparent that each of these methods has certain technical drawbacks that prevent implementing them. Therefore, a need was felt to provide for novel nanocomposites which will materially alleviate the difficulties associated with the known methods mentioned above. In view of the aforesaid problems, the inventors of the present invention have developed nanocomposites having both magnetic and semiconducting properties, which would be an efficient adsorbent/catalyst for removal/degradation of toxic contaminants and bacterial pathogens from water as well as for their easy and rapid separation. Furthermore, the magnetic and optical properties of magnetic semiconductor nanocomposite could be optimistically tuned for many other applications and alleviating most of the limitations coupled to conventional methods.
Thereby, the present invention is directed to a composite of semiconducting ZnO with superparamagnetic Fe3C4 that enhances the efficacy of killing bacterial pathogens due to the combined effect of reactive oxygen species and magnetic hyperthermia.
Accordingly, the inventors of the present invention have endeavored to develop Fe3O4-ZnO magnetic semiconductor nanocomposites (MSN) by embedding Fe304 nanoparticles into porous ZnO assemblies by a facile soft-chemical approach for detoxification of contaminants from water. Specifically, the present invention explores their efficiency for photocatalytic degradation of organic dye (methylene blue), removal of multiple toxic metal ions (Co2+ , Ni 2+ , Cu2+ , Cd 2+ ,

Pb2+ , Hg2+ and As3+ ) and for capturing of pathogenic bacteria (E. coli). Furthermore, heat activated killing of bacterial pathogens is investigated under external AC magnetic field. Inventors believe that the developed nanocomposites are much more cost-effective and eco-friendly as compared to the noble metal based water purification processes.
OBJECT OF THE INVENTION

In accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention provides nanocomposites having both magnetic and semiconducting properties to act as an adsorbent/catalyst for removal or degradation of toxic contaminants and bacterial pathogens.
Another object of the present invention is related to a method of synthesizing the nanocomposites which comprises (i) preparing glycine functionalized Fe304 nanoparticles, (ii) refluxing zinc acetate dihydrate in diethylene glycol (DEG) medium in presence of Fe304 nanoparticles, (iii) obtaining brown colored Fe304-ZnO nanocomposites shortly after reaching the reflux temperature.
Another aspect of the invention is directed to investigation of efficiency of photocatalytic decomposition of organic dye (methylene blue) under UV irradiation, removal of toxic metal ions and capture of bacterial pathogens by the Fe304-ZnO magnetic semiconductor nanocomposites (MSN) of the present invention.
Other features and advantages of the present invention will become apparent as the following detailed description proceeds or may be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.
DESCRIPTION OF FIGURES
The foregoing summary, as well as the following detailed description of preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:
Figure 1. XRD patterns of the Fe304, ZnO, and Fe304-ZnO MSN. Inset shows the expanded XRD
pattern of Fe304-ZnO MSN revealing (400) and (422) planes of Fe304.
Figure 2. XPS spectra of (a) Zn 2p, (b) Fe 2p, and (c) 0 Is region of Fe304-ZnO MSN.

Figure 3. TGA plots of Fe3O4,ZnO and Fe304-ZnO MSN.
Figure 4. (a) HR-SEM micrographs of ZnO (inset shows TEM micrograph of Fe304) and (b) SEM
micrograph of Fe304-ZnO MSN (inset shows HR-SEM micrograph of a Fe3O4-Zn0 MSN).
Figure 5. (a) TEM-EDS spectrum of Fe304-ZnO MSN (inset shows the TEM image indicating the
path of line scan) and the corresponding Ka spectral profile and x-ray mapping of Zn and Fe are
shown in (b) and (c), respectively.
Figure 6. Field dependence of magnetization (M vs. H) plot of Fe304-ZnO MSN at 5 and 300 K
(inset 'a' shows expanded M vs. H plot of Fe304-ZnO MSN at the in low-field region showing
coercivity and inset 'b' shows the M vs. H plot of Fe304).
Figure 7. (a) N2 adsorption-desorption isotherm and (b) dV/dD pore volume vs. pore diameter curves
of ZnO and Fe304-ZnO MSN.
Figure 8. Photodegradation of methylene blue (MB) under UV irradiation in the presence and
absence of catalysts (inset shows time dependent absorption spectra of MB degradation over Fe304-
ZnO nanocomposites under UV irradiation).
Figure 9.Removal efficiency of foxic means loans by (a) 50mg or different nanoadsorbents at PH 6
and (b) different amounts of Fe304-ZnO MSN at pH 6.
Figure 10. Capture efficiency of E. coli by different concentrations of Fe304, ZnO and Fe304-Zn0
MSN after 12 h inoculation (inset shows the capture efficiency of E. coli by 0.4 mg/ml of Fe304-ZnO
MSN after 6 and 12 h inoculation).
Figure 11. SEM images of (a) E. coli (control) and (b) E.coli obtained after incubating these
bacteria with Fe304-ZnO MSN for 12 h.
Figure 12. TEM images of (a) E. coli (control), and E. coli obtained after incubating these bacteria
with 0.8 mg/ml of (b) Fe3045 (c) ZnO and (d) Fe304-ZnO MSN for 12 h.
Figure 13. (a) Viability of bacterial pathogens (E-coli) after 1 h incubation in presence and absence
of Fe304 and Fe304-ZnO MSN nanoadsorbents under AC magnetic field (inset shows its temperature
vs. time plot under AC magnetic field), and photographs showing viability of bacterial cells after
treating under AC magnetic field (b) in absence of nanoadsorbents (control), (c) in presence of Fe304
and (d) in presence of Fe304-ZnO MSN.

DETAILED DESCRIPTION OF THE INVENTION
The terms used in this specification generally have their ordinary meanings in the art, within the context of the invention, and in the specific context where each term is used. Certain terms that are used to describe the invention are discussed below, or elsewhere in the specification, to provide additional guidance to the practitioner regarding the description of the invention.
The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and in no way limits the scope and rneaning of the invention or of any exemplified term. Likewise, the invention is not limited to various embodiments given in this specification.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the case of conflict, the present document, including definitions will control.
As used herein, "around", "about" or "approximately" shall generally mean within 20 percent, preferably within 10 percent, and more preferably within 5 percent of a given value or range. Numerical quantities given herein are approximate, meaning that the term "around", "about" or "approximately" can be inferred if not expressly stated.
As used herein, "plurality" means two or more. As used herein, the terms "comprising" "including," "carrying," "having," "containing," "involving," and the like are to be understood to be open-ended, i.e., to mean including but not limited to.
The multifunctional nanocomposite of the present invention comprises at least two components
(a) a superparamagnetic component of Fe304 nanoparticles
(b) a semiconducting component of ZnO;
Wherein, the superparamagnetic component (a) comprising Fe304 nanoparticles are embedded into the porous network of semiconducting component (b) comprising ZnO nanoassembly thereby forming Fe304-ZnO magnetic semiconductor nanocomjiosites (MSN).

In accordance to the present invention, a nanocomposite is as a multiphase solid material where one of the phases has one, two or three dimensions of less than 100 nanometers (nm), or structures having nano-scale repeat distances between the different phases that make up the material. They combine one or more separate components in order to obtain the best properties of each component (composite). The nanocomposite of the present invention has a particle size of about 1-100 nm, more preferably 1-50 nm and most preferably about 23-30 nm.
Nanocomposite materials are materials that comprise at least one component phase with nanometer-sized dimension (0.1 to 100 nm), the nanoscale material phase, or nanophase. The nano scale material phase may comprise any one or more of components including metal or alloy, semiconductors, metal oxides, metal hydroxides, metal oxyhydroxide, metal salts, polymer, organics, and the like.
These nanocomposite materials also comprise at least a secondary phase. The secondary phase can be one or more bulk material phases, either continuous or discontinuous, or can be made up of one or more types of nanoscale materials. The nanoscale phase is dispersed, mixed, embedded or otherwise combined with the secondary phase. The nanocomposite can include more than one secondary phase.
"Precursor" refers to a compound or entity at least a portion of which is a component of the eventual nanocomposite which is formed.
Nanocomposites of the present invention can have an average width or diameter from approximately 1 nm to approximately 100 nm. In certain embodiments, the nanoparticles have an average diameter, less than approximately 100 nm, less than approximately 75 nm, less than approximately 50 nm, less than approximately 20 nm, less than approximately 10 nm, less than approximately 5 nm. In some embodiments, the average width or diameter of the nanoparticles can range from approximately 1 nm to approximately 25 nm, from approximately 25 nm to approximately 50 nm, from approximately 50 nm to approximately 75 nm, from approximately 75 nm to approximately 100 nm, from approximately 1 nm to approximately 10 nm, or from approximately 1 nm to approximately 50 nm.

In some embodiments, nanocomposites are prepared by forming a secondary phase in-situ with the nanoparticles. In another embodiment, the instant invention features the method of producing the magnetic semiconductor nanocomposites (MSN) by a facile soft-chemical approach. The method includes the following steps (a) Preparing a homogenous colloidal suspension of functionalized nanoparticles in a suitable solvent (b) Adding the precursor component to the suspension of step (a) and obtaining a mixture which is slowly heated to reflux at a temperature of about 160-170°C (c) recovering the nanocomposite.
The nanocomposite of the present invention comprises at least two components. The nanocomposites can be bi- or multifunctional. The functionality can be provided or determined by the different components of the nanocomposite. For example, the secondary (e.g., inorganic) phase can provide a physical functionality such as, for instance, susceptibility to magnetization or chemical functionality such as ability to participate in ion-exchange. Thus, the functionality imparted on the nanocomposite can be physical or chemical functionality (e.g., can include chemi- or physisorption, ion-exchange, photocatalysis, light absorption, porosity, antimicrobial and the like. It comprises an inorganic phase that can be chosen to provide a first functionality to the nanocomposite. It also comprises a nanoparticle that can provide a second functionality to the nanocomposite. In some embodiments, the functionality provided by each component can be the same or a different functionality to the nanocomposite. The functionality provided by each component may be same or different. The nanocomposite is thus multifunctional. The functionalities rendered are also synergistic or complementary determined by the components of the nanocomposite. The multifunctionality can be further increased by incorporation of multiple types of nanoparticles.
Combinations of the properties for each component of the nanocomposite can be useful for specific applications. A multifunctional magnetic semiconductor nanocomposites (MSN) prepared in accordance to the present invention can afford photocatalytic decomposition of organic dyes under UV irradiation, efficient and easy capturing of bacterial pathogens and the like.

The nanocomposites can have a large surface area and/ or can be highly porous. The high porosity and high surface area allow for the appropriate reactions, associations and other useful interactions associated with the use of nanocomposite material. According to one aspect, the surface area of the nanocomposite is between about 1 to 100 m2 /g.
According to a significant aspect of the present invention, the magnetic semiconductor nanocomposites (MSN) produced by the present invention are subjected to detailed structural analysis and characterization by various techniques such as XRD, XPS, TGA, TEM-EDS and magnetic measurements.
As used herein, the term "X-ray diffraction (XRD)" refers to one of X-ray scattering techniques that are a family of non-destructive analytical techniques which reveal information about the phase formed, crystallographic structure and crystallite size of nanoparticles. These techniques are based on observing the scattered intensity of an X-ray beam hitting a sample as a function of incident and scattered angle, polarization, and wavelength or energy. In particular, X-ray diffraction finds the geometry or shape of a molecule, compound, or material using X-rays. X-ray diffraction techniques are based on the elastic scattering of X-rays from structures that have long range order. The most comprehensive description of scattering from crystals is given by the dynamical theory of diffraction.
As used herein, if any, the term "transmission electron microscopy (TEM)" refers to a microscopy technique whereby a beam of electrons is transmitted through an ultra thin specimen, interacting with the specimen as it passes through it. An image is formed from the electrons transmitted through the specimen, magnified and focused by an objective lens and appears on an imaging screen, a fluorescent screen in most TEMs, plus a monitor, or on a layer of photographic film, or to be detected by a sensor such as a CCD camera.
As used herein, if any, the term "energy dispersive X-ray spectroscopy (EDS or EDX)" refers to an analytical technique used for the elemental analysis or chemical characterization of a sample. It is one of the variants of X-ray fluorescence spectroscopy which analyzes X-rays emitted by the matter in response to being hit with charged particles such as electrons or protons, or a beam of

X-rays. Its characterization capabilities are due in large part to the fundamental principle that each element has a unique atomic structure allowing X-rays that are characteristic of an element's atomic structure to be identified uniquely from one another.
EXAMPLES
The following examples are provided to better illustrate the claimed invention and are not to be interpreted in any way as limiting the scope of the invention. All specific compositions, materials, and methods described below, in whole or in part, fall within the scope of the invention. These specific compositions, materials, and methods are not intended to limit the invention, but merely to illustrate specific embodiments falling within the scope of the invention. One skilled in the art may develop equivalent compositions, materials, and methods without the exercise of inventive capacity and without departing from the scope of the invention. It will be understood that many variations can be made in the procedures herein described while still remaining within the bounds of the invention. It is the intention of the inventors that such variations are included within the scope of the invention.
EXAMPLE 1:
Preparation of glycine functionalized Fe304 nanoparticles
In a typical synthesis of glycine functionalized Fe3O4 magnetic nanoparticles, 5.406 g of FeCl3. 6H2O and 1.988 g of FeCl2. 4H20 were dissolved in 80 ml of water in a round bottom flask and temperature was slowly increased to 70°C in refluxing condition under nitrogen atmosphere with constant mechanical stirring at 1000 rpm. The temperature was maintained at 70°C for 30 min and then 30 ml of 25% ammonia solution was added instantaneously to the reaction mixture, and kept for another 30 min at 70oC. Then, 4 ml aqueous solution (0.3 gm/ml) of glycine was added and temperature was slowly raised up to 90°C under reflux and reacted for 60 min with continuous stirring. The obtained black coloured precipitates were then thoroughly rinsed with water and separated from the supernatant using a permanent magnet.
EXAMPLE 2:
Preparation of Fe304-ZnO magnetic semiconductor nanocomposites (Fe304-ZnO MSN)

The Fe3O4-ZnO MSN were prepared by refluxing zinc acetate dihydrate in diethylene glycol (DEG) medium in presence of Fe304 nanoparticles. Briefly, 0.01 mole of zinc precursor was added into a homogeneous colloidal suspension of glycine functionalized Fe304 nanoparticles (0.1 mg/ml of Fe) in 100 ml of DEG and the mixture was slowly heated to reflux (160-170°C). The brown coloured Fe3O4-ZnO nanocomposites were obtained shortly after reaching the refluxing temperature. The reaction mixture was kept under stirring for another 1/2 h at the refluxing temperature. The samples were then dried at 80°C for further characterizations. Pure ZnO were prepared through a similar method by refluxing zinc acetate dihydrate in DEG medium.
EXAMPLE 3 Characterization techniques
X-ray diffraction (XRD) patterns were recorded on a PANalytical's X'Pert PRO diffractometer with Cu Ka radiation. The crystallite size is estimated from the X-ray line broadening using the Scherrer formula. The infrared spectra were recorded in the range 4000-400 cm"1 on a Fourier transform infrared spectrometer (FTIR, Magna 550, Nicolet Instruments Corp.). The X-ray photoelectron spectroscopy (XPS) analysis was performed on a Multilab 2000 (Thermo VG Scientific) using Mg Ka (hu = 1253.6 eV) as the exciting source for identification of the elements and chemical status with the electronic database. The binding energies obtained in the XPS analysis were standardized for specimen charging using carbon (Cls) as the reference at 285 eV. The thermal analyses were performed by TA Instruments SDT Q600 analyzer under N2 atmosphere from room temperature to 600°C with a heating rate of 10°C/min. The scanning electron micrographs (SEM) and transmission electron micrographs (TEM) were taken by JSM-7600F FEG SEM and JEOL JEM-2100F FEG TEM, respectively. The surface area and porosity measurements were performed by Micromeritics ASAP 2020 surface area and porosity analyzer. These samples were degassed at 90°C for 2 hours and then at 200°C for 4 hours by surface area and porosity analyzer prior to surface area, pore volume and pore size measurements. The magnetic properties of the samples were measured by physical property measurement system (PPMS, Quantum Design).
EXAMPLE 4

Photodegradation of organic dye (methylene blue)
Methylene blue (MB) was used as a model dye to evaluate the photocatalytic activity of Fe304-ZnO nanocomposites. In a typical experiment, 24 mg Fe3O4-ZnO MSN (catalyst) was dispersed in 80 ml of 10 ppm MB aqueous solution. The above reaction mixture was mixed in dark in an ultrasonic water bath for 15 min and then magnetically stirred for 30 min to obtain a colloidal solution. The photocatalytic experiment was conducted at room temperature under a UV tube light (Philips TUV 25W/G25T8, λ = 365 nm) positioned horizontally above the liquid surface (solution was magnetically stirred throughout the experiment to ensure full suspension of particles). During the photocatalytic experiment, 2 ml of sample aliquots were extracted at an interval of 10 min and subsequently centrifuged at 1200 rpm for 10 min. The decomposition of MB was monitored by measuring the absorbance of supernatant at 665 nm by UV-Vis spectrophotometer (Cecil, Model No. CE3021).
EXAMPLE 5
Removal efficiency of toxic metal ions (Ni2+, Cd2+, Co2+, Cu2+, Pb2+, Hg2+ and As3+) In order to investigate the simultaneous removal of toxic metal ions, adsorption experiments were conducted by mixing 40 ml of waste-water containing different toxic metal ions (15.81 mg/L Ni2+, 40.11 mg/L Cd2+, 15.75 mg/L Co2+, 23.83 mg/L Cu2+, 36.22 mg/L Pb2+, 45.06 Hg2+ and 22.55 mg/L As3+) with 50 mg of Fe304, ZnO and Fe304-ZnO MSN at pH 6. The original pH of ZnO and Fe304-ZnO MSN waste-water solution mixture was 6 whereas pH of Fe304 wastewater was adjusted to 6 for comparative studies. The above mixture was kept under continuous water shaker for 24 h at room temperature (30°C). Further, the adsorption experiments were carried out at pH 6 with varying concentration of nanoadsorbent (50, 5 and 0.5 mg of Fe304-ZnO MSN in 40 ml of waste-water keeping all other parameters constant, i.e. solid/liquid (S/L) ratio in the range of 10-3 to 10-5 g/ml) to investigate the effect of S/L ratio on adsorption efficiency of metal ions. The nanoadsorbents with adsorbed metal ions were separated from the mixture by a permanent magnet. The concentrations of metal ions were measured by inductively coupled plasma-atomic emission spectrometer (ICP-AES, 8440 Plasma lab, Labtam). The removal efficiency (%) and equilibrium adsorbed concentration, q (mg/g) of metal ions were calculated as follows:


where, C0 and C1 are the initial and residual concentration of metal ions (mg/L) in aqueous solution, V is the total volume of solution (L) and M is the adsorbent mass (g). The adsorption experiments were performed in triplicates and the averaged values are reported here.
EXAMPLE 6:
Capturing of bacterial pathogens (Escherichia coif)
The ability of Fe3O4,ZnO and MSN to capture bacterial pathogens was examined using E. coli DHa as a model microorganism. E. coli pathogens were thawed on ice for 15 min before being plated on an agar plate. The plate was dried before incubation for 16 h in a standard cell culture environment (5% CO2, 37°C). A single colony of E. coli was selected using a loop and inoculated into test tubes containing 5 ml of Luria Broth (LB). Bacteria in tubes were then incubated in cell culture environment under agitation at 200 rpm for another 16 h. At that point, 100 (j.1 of bacterial solution was diluted in 4 ml LB to obtained the desired optical density (0.05) at 600 nm (OD600) using a UV-visible spectroscopy. The different concentration of nanoadsorbents suspended in 0.1M PBS (2.0, 4.0, and 8.0 mg/ml) were then added into the tubes containing bacterial solution (pH 7.0, OD600 ~ 0.05), and the solution volume was fixed to 5 ml for maintaining the final concentration of 0.4, 0.8 and 1.6 mg/ml of nanoadsorbents. A tube of bacteria without nanoadsorbents served as a control. The suspension of nanoadsorbents were also added to tubes containing only LB at the same concentration as above and this served as a particle control. The solutions were incubated by a rotary shaker at 200 rpm for a specific period (6 and 12 h), then an external magnet was used for magnetic separation. The supernatant was used to measure its OD600- The capture efficiency of bacteria by nanoadsorbents was calculated from the decrease of turbidity relative to the reference samples. The bacterial capture experiments were performed in triplicates and the averaged values are reported here. For safety considerations, all of the bacterial samples were placed in an autoclave at 120°C for 20 min to kill bacteria before disposal and all glassware in contact with bacteria were sterilized before and after use.

Furthermore, the viable count of E. coli was studied under AC magnetic field in the presence and absence of Fe304 and Fe304-ZnO MSN nanoadsorbents. 1 ml suspension of Fe304 and Fe304-ZnO MSN (10 mg/ml) in PBS (0.1 M solution) was added into test tube containing 4 ml of overnight culture broth (-2.8 xlO7 CFU/ml) to maintain a final concentration of 2 mg/ml. The bacterial solutions were kept in the center of the coil in AC magnetic field of 425 Oe at a frequency of 250 kHz for 1 h, and then an external magnet was used for separation of bacterial solution. The suspended bacteria cells were spread on the LB agar plate and incubated at 37°C for 18 h, and then the number of colonies were counted to evaluate the viable cell number. A control experiment was carried out in similar condition in absence of Fe3O4 and Fe3O4-ZnO MSN for comparative purpose.
EXAMPLE 7:
Structural/microstructural studies - XRD analysis
Figure 1 shows the XRD patterns of the Fe304, ZnO, and Fe304-ZnO MSN. XRD patterns of Fe304 and ZnO reveal the formation of crystalline single-phase inverse spinel magnetite Fe304 and hexagonal wurtzite ZnO, respectively. The average crystallite sizes of Fe304 and ZnO were found to be about 10 and 20 nm (a = ± 10 %), respectively. Further, the lattice constants determined for Fe304, a = -8.378 A (JCPDS Card No. 88-0315, a = 8.375 A), and for ZnO, a = 3.248 A and c = 5.205 A (JCPDS Card No. 36-1451, a = 3.249 A and c = 5.206 A) are very close to reported values. The appearance of peaks of both Fe304 and ZnO in Fe304-ZnO MSN (Figure 1 and its inset) indicate the formation of crystalline nanocomposite phase. In addition, apparent broadening and shifting of ZnO peaks (towards higher angle) in nanocomposites are observed because the lattice fringes are close to those of Fe304. Further, the lattice strain generated in MSN as a result of entrapment of Fe304 nanoparticles in ZnO assemblies may also affect the broadening and shifting of ZnO peaks.
EXAMPLE 8: XPS analysis
XPS analysis shows the presence of Zn, Fe, and O in Fe304-ZnO MSN. Except for adventitious carbon (C Is), no other impurity phase was observed in the XPS analysis. Figure 2 shows the XPS spectra of (a) Zn 2p, (b) Fe 2p, and (c) O Is region of Fe3O4-ZnO MSN. The sharp and high symmetric peaks of Zn 2p3/2 and Zn 2pm core levels centered at 1022.02 and 1045.12 eV, respectively, with a spin-orbit splitting (A) of 23.1 eV confirms that Zn in MSN is present as Zn2+

Due to spin-orbit coupling, the Fe2P core levels also split into Fe 2p3/2 and Fe 2p1/2 components with spin-orbital-splitting (A) of 13.6 eV, situated at 711 eV and 724.5 eV, respectively. The broadening of the Fe 2p3/2 and Fe 2p1/2 peaks indicates the presence of Fe2+ with Fe3+ ions. The absence of the
satellite line located at ~719 eV, which is characteristic of Fe3+ in y-Fe203, suggests that y-Fe203 does
not exist in the composite- The O Is spectrum exhibits an asymmetric feature revealing the presence of multicomponent oxygen species onto the surface of the sample. The 0 Is core level peak was resolved into two components positioned at 529.8 and 531.05 eV by Gaussian function. The component at the lower binding energy can be ascribed to the crystal oxygen. However, the higher binding energy peak corresponds to absorbed H20 or O2 of the surface. Thus, the XPS analysis suggests that both Fe304 and ZnO are present in the Fe304-Zn0 MSN.
EXAMPLE 9: TGA Analysis
Furthermore, TGA analysis (Figure 3) also supports the presence of both Fe304 and ZnO in the Fe304-ZnO MSN. A total weight loss of about 4.75% and 6.35% are observed up to 600°C in Fe304 and ZnO, whereas about 8.9% weight loss is observed in Fe304-Zn0 MSN (due to the desorption/decompositiofi of physically/chemically absorbed organic moieties, entrapped reaction by products/solvents etc.). The overall weight loss in case of MSN is less than the sum of the weight loss for Fe3O4 and ZnO and this could be due to the filling of pores with Fe304 nanoparticles (i.e., decrease in weight loss from entrapped reaction byproducts/solvent),
EXAMPLE 10: HR-SEM micrographs
Figure 4 shows the HR-SEM micrographs of (a) ZnO (inset shows TEM micrograph of Fe304) and (b) SEM micrograph showing size distribution of Fe304-ZnO MSN. SEM micrograph at high magnification shown in the inset of Figure 4b clearly suggests that numerous nanocrystals (10-30 nm) are three-dimensionally (3D) spatially connected to form a well-defined porous spherical shaped cluster (self-aggregated) assembly of ZnO and Fe304-Zn0 MSN. From TEM micrograph, it is evident that Fe304 nanoparticles are almost spherical in shape with an average size of ~10 nm (cr < 10%).

EXAMPLE 11: TEM-EDS Spectrum
In order to confirm the presence of Zn and Fe, and their distributions in samples, Ka spectral profile was performed by collecting TEM-EDS spectrum at each point while the fine electron probe was scanned across the nanoparticles. Figure 5 shows (a) TEM-EDS spectrum of Fe3O4-ZnO MSN (inset shows the TEM image indicating the path of line scan) and the corresponding Ka spectral profile and X-ray mapping of Zn and Fe are shown in (b) and (c), respectively. The hemispherical shaped Ka spectral profile of Zn Kocand its corresponding X-ray mapping suggest that Zn2+ ions are almost uniformly distributed in the samples. However, the Fe Ka spectral profile and its inhomogeneous distribution in X-ray mapping suggests that glycine functionalized Fe3O4 nanoparticles are randomly (non-uniformly) embedded into the ZnO nanoassembly. Though TEM-EDS analysis shows the incorporation of Fe304 into ZnO nanoassemblies, we could not completely rule out the possibility of freely existing Fe3O4 nanoparticles along with the formation of Fe3O4-ZnO nanocomposites.
EXAMPLE 12
Magnetic, surface area and porosity studies
Magnetization measurements were mainly performed to investigate the use of these novel nanocomposites as a magnetic nanoadsorbent in the magnetic separation. Figure 6 shows the field dependence of magnetization (M vs. H) plot of FejCVZnO MSN at 5 and 300 K (inset 'a' shows expanded M vs. H plot of Fe304-ZnO MSN at the low-field region showing coercivity and inset 'b' shows the M vs. H plot of FesCU). The MSN exhibit superparamagnetic behavior without magnetic hysteresis and remanence at 300 K, whereas ferromagnetic like behavior with a coercivity of about 220 Oe is observed at 5 K (inset 'a' of Figure. 6). This transition from superparamagnetic behavior at room temperature to ferro or ferrimagnetic behavior below the so-called blocking temperature is typically observed in MNPs. The maximum magnetizations at 20 kOe of Fe304-ZnO MSN are found to be 11.5 and 10.6 emu/g at 5 and 300 K., respectively. Even though the magnetization of MSN is about 6 times less than that of Fe304 (superparamagnetic behaviour at 300 K with maximum magnetization of 65.2 emu/g at 20 kOe as shown in inset of'b' of Figure 6), still it retains sufficient magnetic field responsivity and can be separated easily from the solution with the help of an external magnetic force. Furthermore, the magnetization of nanocomposite can be tailored by varying the amount of Fe^ nanoparticles added during synthesis.

To determine the capacity of porous ZnO and Fe3O4-Zn0 MSN for the uptake of gases, the gaseous N2 adsorption-desorption isotherm was measured. The N2 gas adsorption-desorption isotherms (Figure 7a) display the typical type IV curve accompanied by a type H3 hysteresis loop, according to IUPAC classification which is usually attributed to the predominance of mesopores. However, due to the presence of large mesopores, the capillary condensation takes place at very high relative pressures and adsorption saturation is not significantly visible. Both the adsorption (ascending) and desorption (descending) boundary curves are sloping in ZnO as well as Fe304-Zn0 MSN. The desorption branch of Fe304-Zn0 MSN include steep region at which the remaining condensate comes suddenly out of the pores as a consequence of so-called tensile strength effect (TSE).
The specific Brunauer-Emmett-Teller (BET) surface areas of ZnO, Fe304 and Fe304-Zn0 MSN were found to be 20.6, 105 and 43 m2/g, respectively. The pore size calculation of ZnO and Fe304-Zn0 nanocomposites for determination of the mesopores size distribution were performed on desorption branch of N2 adsorption-desorption isotherm (since capillary condensation occurs at relatively higher pressure) by Barrett-Joiner-Halenda (BJH) method. The dV/dD pore volume vs. pore diameter curve (Figure 7b) of ZnO shows broad distribution of mesopores with a peak at about 28 nm, whereas Fe304-ZnO MSN shows bimodal distribution of mesopores with peaks at around 6 and 25 nm, Furthermore, the BJH desorption pore size distribution curve of MSN confirmed the significant decrease in mesopores size as compared to ZnO. This decrease in pore size distribution clearly indicates that Fe304 nanoparticles are embedded into the porous network of ZnO nanoassembly. Further, the sharp peak around 3 nm in Fe304-Zn0 MSN arises from the tensile strength effect (TSE) and is not the indication of mesoporosity. As compared to ZnO and Fe304-ZnO MSN, no significant intraparticle porosity was observed in Fe3O4 nanoparticles from BJH method.
EXAMPLE 13
Photodegradation of organic dye (methylene blue)
Figure 8 shows the (a) photodegradation of methylene blue (MB) under UV irradiation in the presence and absence of catalysts (inset shows time dependent absorption spectra of MB degradation over Fe304-Zn0 nanocomposites under UV irradiation). In Figure 8, C0 and C were the initial concentrations after the equilibrium adsorption of catalyst and the reaction concentration of methylene blue at time t, respectively. The degradation of MB was negligible under the UV irradiation in absence of catalysts as well as in presence of Fe304, whereas the concentration of MB

decreased rapidly with exposure time in presence of ZnO and Fe304-ZnO MSN, indicating the photocatalytic degradation of the organic dye. Furthermore, their In (Co/C) shows a linear relationship with the irradiation time, which indicates that photogradation of the dye over ZnO and MSN proceeds through a pseudo first order kinetic reaction i.e., In (Co/C) = kt, where, k is the photodegradation rate constant (k = 0.035 min'5 and 0.015 min"1 for ZnO and Fe304-ZnO MSN, respectively).
The native point defects such as oxygen vacancies are very common on the surface of ZnO nanoparticles, which can work as electron acceptors and trap the photogenerated electrons temporarily to reduce the surface recombination of electrons (e") and holes (h4). In addition to the oxygen vacancies, Barick et al. "Porosity and photocatalytic studies of transition metal doped ZnO nanoclusters", Micro. Mesopor. Mater. 134 (2010) 195-202 reported the appearance of various planer defects (stacking faults, dislocations and deformation of lattice planes) in ZnO, relating to the formation of spherical assemblies by oriented attachment of nanocrystals which can also trap the photogenerated electrons. Thus, the e" and h+ may migrate to the catalyst surface (porous nanostructures having defects) where they participate in redox reactions with adsorbed organic molecule and thus enhanced the photocatalytic activity by decomposing organic dye. The presence of Fe304 nanoparticles in ZnO assembly may act as the trapping or recombination centers for electrons and holes similar to transition metal ion substituted in ZnO and hence, the photodegradation efficiency of nanocomposite is slightly decreased even though it has no overall affect on photodegradation. Furthermore, the photocatalytic activity of ZnO and Fe304-Zn0 MSN was observed to be strongly dependent on the amount of catalyst as well as initial concentration of dye. Also, both ZnO and its nanocomposite are found to be highly stable against photo corrosion (no significant loss of photocatalytic activity upon recycling up to three generation).
EXAMPLE 14
Removal efficiency of toxic metal ions (Ni2+, Cd2+, Co2+, Cu2+, Pb2+, Hg2+ and As3+)
Figure 9 shows the removal efficiency of toxic metal ions by (a) 50 mg of different nanoadsorbents at
pH 6 and (b) different amounts of Fe304-ZnO MSN at pH 6. It has been observed that the removal
efficiency of metal ions (Mn+ = Ni2+, Cd2+, Co2+, Cu2+, Pb2+, Hg2+ and As3+) at room temperature
(30°C) with contact time of 24 h is strongly dependent on the types of nanoadsorbent. The Fe304-
ZnO MSN showed much better removal efficiency for metal ions than Fe304 and ZnO individually.

Almost 100% removal efficiency was achieved for Cu2+, Pb2+, Hg2+ and As3+ ions by Fe304-ZnO MSN from waste-water. Further, the adsorption experiments carried out with varying concentration of Fe3O-4ZnO MSN (50, 5 and 0.5 mg in 40 ml of waste-water, i.e. S/L ratio in the range of 10"3 to 10"5 g/ml) revealed that removal efficiency increases with increasing concentration of Fe3O4-VZnO MSN. This is obvious as the availability of active surface sites for adsorption of metal ions increases with increasing the concentration of nanoadsorbents. It is interesting to note that complete removal of highly toxic metal ions, Pb2+, Hg2+ and As3+ can be achieved by the developed magnetic semiconductor nanocomposites. Furthermore, the successful removal of other metal ions can also be realized by varying the pH of the medium.
The efficiency of simultaneous adsorption of metal ions can be explained on the basis of surface functionality, competitive affinity of metal ions, surface charge, polarity and availability of active surface sites. From zeta-potential (ζ ) measurements, it has been observed that the pH of zero point charge (pHpzc) of glycine functionalized Fe3O4 nanoparticles is around 5.3 and they have negative surface charge above pHpzc. It was evident from FTIR analysis that glycine is chemisorbed onto the surface of Fe304 nanoparticles through carboxylate ions (COO") thereby leaving free amine (NH2) groups on the surface. Recently, Singh et al. "Surface engineered magnetic nanoparticles for removal of toxic metal ions and bacterial pathogens", J. Hazard. Mater. 192, 2011, 1539-1547 reported that the appearance of negative charge on surface of amine functionalized Fe304 nanoparticles above pHpzC is possibly due to the formation of -NH2OH-. On one hand this could reduce the adsorption of metal ions through surface complexation (NH2Mn+), but on the other hand it might increase the adsorption of metal ions through the electrostatic attraction between the -NH2OH~
and metal ions (NH2OH_ Mn+). Thus, these glycine functionalized Fe304 nanoparticles having
free amine groups capture the toxic metal ions from waste-water through the electrostatic interaction at pH 6. However in case of ZnO, inventors believe that the polar nature (positively charged Zn2+ ion terminated-(OOOl) plane and negatively charged O2' ion terminated-(OOOl) plane) of ZnO surfaces as well as their porous structure may play a crucial role in adsorption of metal ions. The porous network provides sufficient active surface sites for the adsorption of metal ions whereas the presence of uncompensated charged crystalline surfaces promotes the adsorption of metal ions through electrostatic interaction. In general, the preference of common hydrous solids for metals has been related to the metal electronegativity. The electronegativity values of Co2+, Cd2+, Ni2+, Cu2+, Hg2+, Pb2+ and As3+ are 1.88, 1.69, 1.91, 1.90, 2.00, 2.33 and 2.18, respectively. Due to high

electronegativity, Pb2+, Hg2+ and As3+ have stronger attraction towards the ZnO nanoassemblies and hence exhibited better removal efficiency. However, the better performances of Fe304-Zn0 MSN could be attributed to the combined effect of ZnO and Fe304 owing to their porous network structure, polar nature, surface functionality and high surface area.
EXAMPLE 15
Capturing of bacterial pathogens (Escherichia coli)
The antimicrobial activity of the Fe304, ZnO and Fe304-Zn0 nanocomposites has been examined on gram negative bacterium E. coli. Figure 10 shows the capture efficiency of E. coli by different concentrations of Fe304, ZnO and Fe304-ZnO MSN after 12 h inoculation (inset shows the capture efficiency of E. coli by 0.4 mg/ml of Fe304-ZnO MSN after 6 and 12 h inoculation). It has been observed that the capture efficiency increases significantly with increasing the concentration of nanoadsorbents as well as inoculation time. The ZnO nanoassemblies exhibit the highest bactericidal activity and almost completely eradicated bacterial species after 12 h, whereas the inhibition zone (bactericidal activity) of Fe304-Zn0 MSN lies between those of Fe304 and ZnO. More specifically, these results indicate that ZnO and Fe304-ZnO MSN nanoadsorbents possessed excellent capture performance to bacterial pathogens and well matched with the earlier reports on concentration and time dependent bacterial inhibition by nanoparticles.
The typical SEM micrographs of E. coli (control) and Fe304-ZnO treated E. coli are shown in Figure 11. The Fe304-ZnO nanocomposites are clearly observed in SEM micrographs of Fe304- ZnO treated (E. coli obtained after incubating these bacteria with nanoadsorbents for 12 h) E. coli. Further, the SEM-EDS elemental analysis and corresponding Ka spectral mapping of treated E. coli show the presence of Fe. These results indicate that nanoadsorbents were successfully adsorbed/ incorporated to the bacterial cells.
In order to investigate the cause of nanoadsorbents to be bactericidal, inventors further studied the TEM analysis of E. coli (control) and nanoadsorbents (Fe304, ZnO and MSN) treated E. coli. From the TEM images (Figure 12), it has been observed that bacterial pathogens are successfully trapped by Fe304 (particles bind to the surface of E. coli). The cell wall of the bacteria trapped by the nanoadsorbent is almost damaged (nanoparticles contact with lipid bilayer component of the cell membrane and disrupts its structural integrity) whereas that of control bacteria (i.e. without

nanoadsorbent) is intact. Thus, the capture/killing of bacteria pathogen may be due the contact of nanoadsorbents with cell wall of the bacteria. Furthermore, the observed higher inhibition of bacterial pathogens in presence of ZnO and Fe304-ZnO MSN is possibly due to the formation of reactive oxygen species (ROS) such as superoxide radicals (O2), bydroxyl radicals (*OH), hydrogen peroxide (H2O2), and singlet oxygen (O2) via oxidative stress in association with the capture/killing of bacteria by contact of nanoadsorbents with cell wall. Interestingly, the use of Fe304 nanoparticles with ZnO as a nanocomposite helps reduction of bacteria as well as their easy and rapid separation via external magnetic field. It is envisaged that the composition of these novel nanocomposite materials can be easily tailored to suit desired requirements.
The viability assay of bacterial pathogen was explored under AC magnetic field in presence of nanoadsorbents to examine the effect of hyperthermia (heat activated killing of bacterial pathogens). Figure 13a shows the viability of bacterial pathogens (E-coli) after 1 h incubation in presence and absence of Fe304 and Fe304-ZnO MSN nanoadsorbents under AC magnetic field (inset shows temperature vs. time plots of Fe304 and Fe304-ZnO MSN under AC magnetic field). The photographs in Figurel3 show viability of bacterial cells after treating under AC magnetic field (b) in absence of nanoadsorbents (control), (c) in presence of Fe304 and (d) in presence of Fe304-ZnO MSN. The control experiment (absence of nanoadsorbents) hardly shows any killing of bacteria. However, about 85% and 70% bacteria killing was observed for Fe304-ZnO MSN (temperature raise: 55-60°C) and Fe304 (temperature raise: 70-75°C) nanoadsorbents, respectively under AC magnetic field. The photographs (Figure 13b-d) of bacterial cells spread on LB agar plate clearly show their killing after treating with nanoadsorbents under AC magnetic field. These results indicate that the presence of the Fe304 and Fe304-ZnO MSN in bacterial solution inhibited their growth after nucleation.
Thomas et al. "Carboxylic acid-stabilised iron oxide nanoparticles for use in magnetic hyperthermia", J. Mater. Chem. 19 (2009) 6529-6535 reported that the rate of killing is dependent on the temperature achieved under AC magnetic field. They have observed complete bacterial killing (107 CFU/ml) at a concentration of 50 mg/ml and above with carboxyl acid stabilized iron oxide nanoparticles with raise in temperature up to 100°C. Interestingly, our Fe304-ZnO MSN shows much better killing efficiency (85%) of bacterial pathogen even at very low concentration (final concentration: 2 mg/ml) and temperature (55-60°C). This may be due to the combined effect of hyperthermia (heating effect is potentially able to denature bacteria) and reactive oxygen species (ROS) generated during heating, which in turn enhanced their killing efficacy. The killing efficiency

of bacteria under the exposure of AC magnetic field for 1 h is much higher than the capture efficiency observed in absence of magnetic field for 12 h (Fig. 10). Furthermore, the complete bacterial killing of bacteria can be achieved either by increasing the concentration of Fe3O4-Zn0 MSN or the exposure time of AC magnetic field. The novelty of this method for killing bacteria could lead to a potential application to the treatment of a variety of infectious diseases.
A person skilled in the art will be able to practice the present invention in view of the description presented in this document, which is to be taken as a whole. Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, one of skill in the art will appreciate that certain changes and modifications may be practiced within the scope of the appended claims. Numerous details and examples have been set forth in order to provide a more thorough understanding of the invention. While the invention has been disclosed in its preferred form, the specific embodiments and examples thereof as disclosed and illustrated herein are not to be considered in a limiting sense. It should be readily apparent to those skilled in the art in view of the present description that the invention tan be modified in numerous ways. The inventor regards the subject matter of the invention to include all combinations and subcombinations of the various elements, features, functions and/or properties disclosed herein.

We claim,
1. A multifunctional nanocomposite comprising at least two components
(a) a superparamagnetic component of Fe304 nanoparticles
(b) a semiconducting component of ZnO;
Wherein, the superparamagnetic component (a) comprising Fe304 nanoparticles are embedded into the porous network of semiconducting component (b) comprising ZnO nanoassembly thereby forming Fe304-Zn0 magnetic semiconductor nanocomposites (MSN).
2. The multifunctional nanocomposite as claimed in claim 1, wherein the nanocomposite is between about 1 nm to 100 nm in particle size.
3. The multifunctional nanocomposite as claimed in claim 1, wherein the component (a) is dispersed randomly throughout the porous network of component (b).
4. The multifunctional nanocomposite as claimed in claim 1, wherein the surface area of the nanocomposite is between about 1 to 100 m /g.
5. The multifunctional nanocomposite as claimed in claim 1, wherein the nanocomposite is an antimicrobial agent capable of capturing microbial agents, a photocatalyst capable of degrading organic substances and a detoxifying agent capable of removing multiple toxic metal ions from a particular source.
6. A method of synthesizing the Fe3O4-ZnO magnetic semiconductor nanocomposites (MSN) comprising the steps of
(i) Preparing glycine functionalized Fe3O4 nanoparticles
(ii) Refluxing zinc acetate dihydrate in diethylene glycol (DEG) medium in presence of
Fe3O4 nanoparticles (iii) Obtaining brown colored Fe304-ZnO nanocomposites shortly after reaching the reflux
temperature.
7. The method as claimed in claim 6, wherein the glycine functionalized Fe304 are prepared by

(i) dissolving FeCl3, 6H20 and FeCl2. 4H20 in a suitable aqueous solvent with temperature slowly increased to about 70°C in refluxing condition under nitrogen atmosphere
(ii) 25% ammonia solution was added instantaneously to the reaction mixture of step (i)
(iii) glycine was added to the resultant solution of step (ii) and temperature was slowly raised up to 90°C under reflux
(iv) obtained black coloured precipitates were thoroughly rinsed and separated from the supernatant using a permanent magnet.
8. The method as claimed in claim 7 wherein Fe3O4 nanoparticles are spherical in shape with an average size of about 10 nm.
9. A multifunctional nanocomposite as claimed in any of the preceding claims possessing both magnetic and semiconducting properties to act as an adsorbent/catalyst for removal or degradation of toxic contaminants and bacterial pathogens.