Description:FIELD OF THE INVENTION
[0001] The present disclosure relates generally to the field of chemical engineering. More specifically, the disclosure is directed to a process for silica separation from biomass using non-thermal source and controlling electromagnetic radiation from microwave to give controlled microwave. The present disclosure also provides a system for silica separation from biomass using controlled microwave.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Silica is one of the most significant inorganic compounds which are present in a number of plant species. The amount of silica in different plant species varies significantly. Biomass is extensively utilized as animal fodder or as biofuel but the presence of silica in it leads to a multitude of problems. For example, its usage as fodder for animal consumption causes serious diseases such as silicosis, lung cancer and chronic obstructive pulmonary disease (COPD) in animals. Silica contributes as high as 85-100% in ash content generated from burning of biomass with high silica content, such as rice stubble. Thus, separation of silica from biomass is essential to make use of it as animal fodder or biofuel.
[0004] Several processes are known in the art for removal of silica from biomass. Conventionally, thermal processes or processes using thermal energies are used to catalyze removal of silica, but they have some challenges. In thermal processes, elevating the temperature requires time hence, the throughput of the machine used is quite less. For large amounts of biomass, the reactor requirements increase which eventually increases the cost of the overall machine. These processes also result in undesired fermentation which in-turn makes the processed biomass unsuitable for its usage as fodder. Additionally, use of thermal energies result in imbalance of C, H and O ratio in the resultant processed biomass. Hence, the generated biofuels are found to be less efficient.
[0005] Accordingly, there is a need in the art to provide an advanced process and system which is non-thermal and produces processed biomass that is suitable for various applications.

OBJECTS OF THE INVENTION
[0006] An object of the present disclosure is to provide a process and system that overcomes one or more deficiencies of prior arts.
[0007] An object of the present disclosure is to provide a process for separation of silica from biomass using microwave.
[0008] An object of the present disclosure is to provide a process for separation of silica from biomass using controlled microwave by adjusting E to H ratio of microwave.
[0009] Another object of the present disclosure is to provide a system for separation of silica from biomass using controlled microwave.

SUMMARY OF THE INVENTION
[0010] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in Detailed Description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
[0011] Aspects of the present disclosure provide a process and system that use non-thermal energy for separation of silica from biomass. The source of non-thermal energy used is microwave.
[0012] In an aspect, the present disclosure provides a process for separation of silica from biomass using controlled microwave, wherein the process comprises the steps of: (a) sprinkling the biomass with sodium hydroxide; (b) subjecting the biomass of step (a) to treatment with the controlled microwave; and (c) sieving the biomass obtained from step (b) to give processed biomass; wherein ratio of electric field (E) to magnetic field (H) of the controlled microwave is in a range of 17:1 to 10:1.
[0013] In an embodiment, the biomass is crop stubble or crop straw. In a preferred embodiment, the biomass is rice stubble or rice straw.
[0014] In a preferred embodiment, the sodium hydroxide is an aqueous solution having a concentration of 10% w/v. In an embodiment, the controlled microwave has an intensity in the range of 1 kW to 5 kW.
[0015] The biomass obtained after subjecting to microwave treatment in step (b) gives crystallized biomass with silica separated onto the surface as sodium silicate that can be sieved as in step (c) to give the processed biomass.
[0016] In an aspect, the present disclosure provides a system for separation of silica from biomass using controlled microwave, wherein the system comprises: (a) a biomass input valve configured to insert the biomass; (b) a batch reactor connected to the biomass input valve operable to treat the biomass; (c) a sprinkler connected overhead of the batch reactor configured to sprinkle sodium hydroxide on the biomass in the batch reactor; (d) a microwave launcher operatively connected to the batch reactor and configured to introduce the controlled microwave for treatment of biomass in the reactor; and (e) an output valve connected to the bottom of the batch reactor configured to remove the processed biomass from the batch reactor; wherein ratio of electric field (E) to magnetic field (H) of the controlled microwave is in range of 17:1 to 10:1.
[0017] Other aspects of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learnt by the practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The following drawings form part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
[0019] Figure 1 illustrates an exemplary layout of a system for separation of silica from rice stubble or rice straw, as per an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
[0020] The following is a detailed description of embodiments of the disclosure. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0021] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0022] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0023] In some embodiments, numbers have been used for quantifying weights, percentages, ratios, and so forth, to describe and claim certain embodiments of the invention and are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0024] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0025] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0026] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0027] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[0028] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0029] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified.
[0030] The description that follows, and the embodiments described therein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles and aspects of the present disclosure. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the disclosure.
[0031] It should also be appreciated that the present disclosure can be implemented in numerous ways, including as a system, a method or a device. In this specification, these implementations, or any other form that the invention may take, may be referred to as processes. In general, the order of the steps of the disclosed processes may be altered within the scope of the invention.
[0032] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0033] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
[0034] As used herein, the term ‘controlled microwave’ refers to a non-thermal, controlled electromagnetic energy from a microwave source that is tuned to a particular E to H ratio.
[0035] As used herein, the term ‘processed biomass’ refers to biomass that has been subjected to the process recited in the present disclosure and is free of silica.
[0036] Aspects of the present disclosure provide a process and system that use non-thermal energy, i.e. microwave, for separation of silica from biomass.
[0037] In an embodiment, the present disclosure provides a process for separation of silica from biomass using controlled microwave, wherein the process comprises the steps of: (a) sprinkling the biomass with sodium hydroxide; (b) subjecting the biomass of step (a) to treatment with the controlled microwave; and (c) sieving the biomass obtained from step (b) to give processed biomass; wherein ratio of electric field (E) to magnetic field (H) of the controlled microwave is in range of 17:1 to 10:1.
[0038] In an embodiment, the biomass is crop stubble or crop straw. In a preferred embodiment, the biomass is rice stubble or rice straw.
[0039] In an embodiment, sodium hydroxide is an aqueous solution having a concentration in the range of about 8% w/v to about 20% w/v. In a preferred embodiment, sodium hydroxide is an aqueous solution having a concentration of 10% w/v.
[0040] In an embodiment, the microwave is a continuous wave with intensity in the range of about 1 kW to about 5 kW. In a preferred embodiment, the microwave has an intensity of 1 kW. In an embodiment, the biomass is treated with the microwave in step (b) for a time period ranging from about 15 minutes to about 25 minutes.
[0041] Microwave comprises of high frequency electromagnetic waves with two components which are electric field (E) and magnetic field (H). The electric and magnetic fields propagate perpendicular to each other. The electric field component produces heat while the magnetic field component helps in propagating ahead. In the process, without being bound to theory, it is believed that the electric field variations produce variation in enhanced amount of magnetic field which in-turn generates a number of non-thermal effects. The magnetic field component generated with the controlled microwave at the specific electric field (E): magnetic field (H) ratio catalyses the endothermal chemical reaction of silica shown below.

[0042] It was surprisingly noted that by decreasing the ratio, kinetics of the process increases. Silica can thus be precipitated out quickly in the form of sodium silicate.
[0043] The biomass obtained after subjecting to controlled microwave treatment in step (b) gives crystallized biomass with silica separated onto the surface of biomass as sodium silicate that can be sieved as in step (c) to give the processed biomass.
[0044] In an embodiment, in the step (c) of sieving, the sodium silicate is sieved out while the processed biomass which is silica free remains on the sieve. In an embodiment, the sieve may have a pore size in the range of about 50 microns to about 200 microns.
[0045] In an embodiment, the process is economical.
[0046] In an embodiment, the kinetics of the process is high. Thus, the production costs of processed biomass decreases.
[0047] In an embodiment, the processed biomass obtained from the process may be used for a number of applications including, but not limited to, biofuel or fodder for animals. The processed biomass is devoid of silica and has balanced ratio of carbon, hydrogen and oxygen such that it serves as an efficient fuel.
[0048] In an embodiment, the process does not result in undesired fermentation, making the processed biomass suitable for use as fodder.
[0049] In an embodiment, the present disclosure provides a system for separation of silica from biomass using controlled microwave, wherein the system comprises: (a) a biomass input valve configured to insert the biomass; (b) a batch reactor connected to the biomass input valve operable to treat the biomass; (c) a sprinkler connected overhead of the batch reactor configured to sprinkle sodium hydroxide on the biomass in the batch reactor; (d) a microwave launcher operatively connected to the batch reactor and configured to introduce controlled microwave for treatment of biomass in the reactor; and (e) an output valve connected to the bottom of the batch reactor and configured to remove the processed biomass from the batch reactor; wherein ratio of electric field (E) to magnetic field (H) of the controlled microwave is in range of 17:1 to 10:1.
[0050] In an embodiment, the biomass is crop stubble or crop straw. In a preferred embodiment, the biomass is rice stubble or rice straw.
[0051] In an embodiment, the microwave launcher may be connected to a microwave unit. The microwave unit may comprise an array of components that tune the microwave to the desired E to H ratio.
[0052] In an embodiment, the microwave unit comprises one or more of a power source(s), a safety and control unit, a microwave source, a stub tuner, a mode controller, a directional coupler, a tunable H-plane tee junction, and a tunable E-plane tee junction.
[0053] In an embodiment, the system further comprises a central control unit for controlling operation of the system. In an embodiment, the central control unit may be operatively connected to the sprinkler, the microwave launcher, the output valve, the biomass input valve, the safety and control unit, the tunable H-plane tee junction, the tunable E-plane tee junction or combinations thereof. The central control unit may be used to adjust the desired E to H ratio, the amount of biomass that enters the reactor, the amount of sodium hydroxide, or the amount and time at which the processed biomass is removed from the reactor.
[0054] In an embodiment, the central control unit may comprise a Wi-Fi device, a Central Processing Unit, a positioning system, a monitor, a screen, or combinations thereof.
[0055] The system is designed to first introduce the biomass into the batch reactor through the biomass input valve. Thereafter, sodium hydroxide of the desired concentration is sprinkled by the sprinkler. The sodium hydroxide sprinkled biomass is then exposed to the specified non-thermal energy i.e., the controlled microwave. The microwave converts the silica to sodium silicate which crystallizes on the biomass. Upon sieving the crystallized biomass, the sodium silicate separates out to leave the processed biomass on the sieve. In comparison to conventional thermal processes, the non-thermal process of the present disclosure is both time and energy efficient.
[0056] In an embodiment, the system may treat a bulk of biomass. In an embodiment, the system is capable of treating biomass with weight in the range of about 100kg to about 1000kg per hour.
[0057] In an embodiment, the efficiency of separation of silica by the system may be in the range of about 40% to about 85%.
[0058] In an embodiment, the system is small and concise and may be used at the point-of-use i.e., at farms or fields without the need to bring the biomass to large processing plants as in conventional systems.
[0059] Figure 1 depicts an exemplary layout of a system for separation of silica from rice stubble or rice straw, as per an embodiment of the present disclosure. The system (100) comprises: (a) a biomass input valve (102) configured to introduce the biomass; (b) a batch reactor (104) connected to the biomass input valve (102) and configured to treat the biomass; (c) a sprinkler (106) connected overhead of the batch reactor (104) and configured to sprinkle sodium hydroxide on the biomass in the batch reactor (104); (d) a microwave launcher (108) operatively connected to the batch reactor (104) and configured to introduce controlled microwave for treatment of biomass in the reactor; and (e) an output valve (110) connected to the bottom of the batch reactor(104) and configured to remove the processed biomass from the batch reactor (104); wherein ratio of E to H of the controlled microwave is in range of 17:1 to 10:1.
[0060] In the system (100), the microwave launcher (108) is connected to a microwave unit comprising a power source (202), a safety and control unit (204), a microwave source (206), a stub tuner (208), a mode controller (210), a directional coupler (212), a tunable H-plane tee junction (214), and a tunable E-plane tee junction (216). These units are linked in a chain to give the desired E to H ratio through the microwave launcher (108) into the batch reactor. The system (100) further comprises a central control unit (112) for controlling the operation of the system. The central control unit (112) is operatively connected to the sprinkler (106), the microwave launcher (108), the output valve (110), the biomass input valve (102), the safety and control unit (202), the tunable H-plane tee junction (216), and the tunable E-plane tee junction (214).
[0061] While the foregoing describes various embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
EXAMPLES
[0062] The disclosure will now be illustrated with working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs.
[0063] Example 1:
[0064] 1kg of rice stubble was processed in the system of Figure 1. The rice stubble was added via the biomass input valve and 100mL of 10% aqueous solution of sodium hydroxide was sprinkled over it using the sprinkler controlled by the central control unit. After sprinkling sodium hydroxide the biomass was subjected to treatment for 17 minutes with microwave of power 1kW from the microwave launcher. The E: H ratio for the microwave was maintained at 10:1 using the tunable E-plane and H-plane TEE tuned with the stub tuner from the microwave unit. After treatment with the microwave, crystallized biomass was obtained from the output valve. This crystallized mass was then sieved through 200 microns sieve to give the processed biomass on the sieve. The amount of processed biomass obtained was 710 gm. The amount of sodium silicate obtained was 140 gm. The efficiency of silica separation was found to be 71%.
[0065] Example 2:
[0066] 2kg of rice stubble was processed in the system of Figure 1. The rice stubble was sprinkled with 200 mL of 10% aqueous solution of sodium hydroxide and then subjected to treatment for 22 minutes with the controlled microwave of 2 kW power. The E: H ratio for the microwave was 17:1. After treatment with the controlled microwave the obtained crystallized biomass was sieved through 200 microns sieve to give the processed biomass on the sieve. The amount of processed biomass obtained was 1.4 kg. The amount of sodium silicate obtained was 290 gm. The efficiency of silica separation was found to be 74%.
[0067] As can be seen from the two examples, the efficiency of the process and system of the present disclosure in separating silica with controlled microwave with E:H ratio of 17:1 and 10:1 was over 70%. Further the time required for the present process was also low.
[0068] From the foregoing, it will be appreciated that, although specific embodiments of the invention have been described herein merely for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention and should not be construed so as to limit the scope of the invention or the appended claims in any way.

ADVANTAGES OF THE INVENTION
[0069] The present disclosure provides a process and system for separation of silica from biomass using non-thermal energy i.e., microwave.
[0070] The present disclosure provides a process and system for separation of silica from biomass that provides processed biomass suitable for use as biofuel and fodder.
[0071] The present disclosure provides a process and system for separation of silica from biomass that is fast and economical.

We Claims:

1. A process for separation of silica from biomass using controlled microwave, wherein the process comprises the steps of: (a) sprinkling the biomass with sodium hydroxide; (b) subjecting the biomass of step (a) to treatment with the controlled microwave; and (c) sieving the biomass obtained from step (b) to give processed biomass; wherein ratio of electric field (E) to magnetic field (H) of the controlled microwave is in range of 17:1 to 10:1.
2. The process as claimed in claim 1, wherein the biomass is rice stubble or rice straw.
3. The process as claimed in claim 1, wherein the sodium hydroxide is an aqueous solution having a concentration in the range of 8% w/v to 20% w/v.
4. The process as claimed in claim 1, wherein the controlled microwave is a continuous wave with intensity in the range of 1 kW to 5 kW.
5. The process as claimed in claim 1, wherein the biomass is treated with the microwave in step (b) for a time period ranging from 15 minutes to 25 minutes.
6. A system for separation of silica from biomass using controlled microwave, wherein the system comprises: (a) a biomass input valve configured to insert the biomass; (b) a batch reactor connected to the biomass input valve operable to treat the biomass; (c) a sprinkler connected overhead of the batch reactor configured to sprinkle sodium hydroxide on the biomass in the batch reactor; (d) a microwave launcher operatively connected to the batch reactor and configured to introduce the controlled microwave for treatment of the biomass in the reactor; and (e) an output valve connected to the bottom of the batch reactor and configured to remove the processed biomass from the batch reactor; wherein ratio of electric field (E) to magnetic field (H) of the controlled microwave is in range of 17:1 to 10:1.
7. The system as claimed in claim 6, wherein the microwave launcher is connected to a microwave unit.
8. The system as claimed in claim 7, wherein the microwave unit comprises one or more of a power source(s), a safety and control unit, a microwave source, a stub tuner, a mode controller, a directional coupler, a tunable H-plane tee junction, and a tunable E-plane tee junction.
9. The system as claimed in claim 6, wherein the system further comprises a central control unit for controlling operation of the system.