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Compounds, Process Of Preparation And A Method For Fluoride Removal From Wastewater
Abstract: The present invention relates to an aluminium based inorganic polymeric compound [i.e. compound of formula I] useful for removal of fluoride from coke oven wastewater in steel industry. The present disclosure provides a simple, scalable and economical and an efficient method for the preparation of said inorganic polymeric compound and a method for removal of fluoride from coke oven wastewater in steel industry.
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Notices, Deadlines & Correspondence
Notices, Deadlines & Correspondence
Patent Information
Application #
Filing Date
30 March 2022
Publication Number
40/2023
Publication Type
INA
Invention Field
CHEMICAL
Status
Email
Parent Application
Patent Number
Legal Status
Grant Date
2025-06-09
Renewal Date
Applicants
TATA STEEL LIMITED
Jamshedpur-831001, Jharkhand, India
Inventors
1. TINA CHAKRABARTY
C/o Tata Steel Limited, Jamshedpur – 831001, Jharkhand, India
2. PINAKPANI BISWAS
C/o Tata Steel Limited, Jamshedpur – 831001, Jharkhand, India
3. SAROJ KUMAR BANERJEE
C/o Tata Steel Limited, Jamshedpur – 831001, Jharkhand, India
4. AMAR BOUNTRA
C/o Tata Steel Limited, Jamshedpur – 831001, Jharkhand, India
5. MAITREYEE DEB
C/o Tata Steel Limited, Jamshedpur – 831001, Jharkhand, India
Specification
Claims:We claim:
1. An aluminum based inorganic polymeric compound of formula I
Compound of formula I
wherein ‘X’ is a halide;
‘n’ represents the degree of polymerization wherein 1 95% fluoride removal at a very minimum dose. With increasing doses of the compound, fluoride removal capacity of up to 2 mg/L increases by more than 99%.
In an embodiment, the foregoing descriptive matter is illustrative of the disclosure and not a limitation. While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. Those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
EXAMPLES
EXAMPLE 1:
MATERIALS AND METHODS
Preparation of coagulants
AAS, AS1, AS2, IPC, and PVA were ground into powder form and stored in airtight containers. Without any further treatment, all coagulants were used for fluoride removal experiments.
Composition/Compound/Coagulant of the present disclosure
Composition for preparing compound of formula I of the present disclosure: 30wt% IPC+ 68% AS1+1% PVA+1% AlCl3. The mechanistic route for fluoride removal is depicted in Scheme 2.
Mechanism A
Mechanism B
Scheme 2. Probable Mechanisms for fluoride removal reaction
Floc formation and fluoride concentration measurement
All coagulants (AAS, AS1, AS2, IPC, and compound of formula I) were ground finely into powder and used without further treatment or purification. Whenever required, stock solution was prepared first as per desired concentration. All laboratory tests were carried out using Multiple Stirring Device (Jar Tester) equipped with stirring paddles and provision for controlled mixing. Experiments were carried out using all individual coagulants, which were added directly to the wastewater sample in varying concentrations: 0.5 gm/L, 1 gm/L, 1.5 gm/L, and 2 gm/L with continuous stirring. The floc size and its settleability were observed in each case with the illuminating device. As time progressed, changes in floc size with time were also noted for all experiments.
Using a 1000 ml beaker, the measured volume of sample solution was flocculated using the Jar test apparatus. After placing the beaker in the jar tester, the motor of the stirrer paddles was started. AAS, AS1, AS2, IPC, and compound of formula I were added, maintaining a speed of around 90-100 ppm, followed by slow mixing. Time and floc formation progress were noted continuously to check reaction kinetics. The experimentation lasted up to 2 hours. The fluoride concentration of treated water was measured using an ion selective method using a Fluoride electrode and an Advanced Electrochemistry metre from Thermo Scientific as the reaction progressed. All analytical detections were carried out following the standard method. The colour changes after treatment with coagulants were noted carefully. The coke plant's discharged water before and after treatment with a compound of formula I (dose 1.5 gm/L) has been depicted in Figure 1. Also, Figure 6 depicts flow diagram of treatment process, using compound of formula I.
TDS AND pH MEASUREMENT
Real coke-plant discharged water was collected from Tata Steel BSL, Angul for all the studies. Total dissolved solids (TDS) and pH of wastewater samples were measured at the beginning of each experiment by using a standard method of measurement with the help of a TDS meter from Thermo Scientific and a pH meter, Thermo Scientific, respectively. TDS and pH were checked as the reaction progressed, and the pattern of change in their values was noted.
EXPERIMENTAL RESULTS FOR FLUORIDE REMOVAL
Fluoride removal experiments were carried out by varying the dosing concentration, ranging from 0.5 gm/L to 2 gm/L for all coagulants. Figure 2 describes the pattern of fluoride concentration changes with varying dosages for the cases of all coagulants. It was found that at dosing concentration of 2 gm/L, the fluoride concentration level came down to < 1ppm, which was 0.35 ppm in the case of the compound of formula I. A clear difference in fluoride concentration level was observed when a 1.5 gm/L dose was charged for each coagulant (Inset Picture, Figure2). In the presence of compound of formula I, the fluoride concentration of coke-plant discharged water reached 3 ppm, up from 105 ppm, which is within the permissible range.
During industrial application, dosing is carried out in 500 m2 dosing tank after 1.5 hrs of settling.
An experimental study was carried out for pH and TDS variation with variation in dosing of the compound of formula I. The initial pH for the tested water was 7.8. Real coke-plant discharge water was collected from Tata Steel BSL, Angul, and an Orion Star bench top pH meter, made by Thermoscientific, was used for pH measurements throughout the experiments. The TDS value for raw water collected from the same coke plant discharge stream was 3000-3030 ppm range, which was tested by using Thermoscientific Orion Star A200. When the compound's (Formula I) dosing was increased from 0.5 gm/L to 2 gm/L, a variation in pH value was observed. The pH of the treated water decreased to 5.7 when the compound of formula I was dosed at 1.gm/L, which is allowable, and there were no further changes in pH value even with increased dosing of the compound of formula I (Figure 3(a)).In the case of TDS value, it was observed that with increasing the dosing of the compound of formula I up to 1.5 gm/L, it decreases slightly, which is 2950 ppm. So, the impact of this coagulant on the TDS value of coke-plant discharge water, is very negligible [Figure 3(a)]. Figure 3(b) shows the percentage decrease in fluoride concentration in treated water as the dose of compound in formula I is increased. Furthermore, Figure 3(b) shows that at 0.5 gm/L of compound of formula I dosing, fluoride concentration decreases by 97% and reaches a steady state, while at 2 gm/L of compound of formula I dosing, fluoride concentration decreases by 99% and reaches a steady state.
Further, the effect of the amount of coagulant added has also been studied. In the case of a compound of formula I, dose concentration varied from 0.5 gm/L to 2 gm/L and kinetics was observed up to 90 min from the point of the first addition of coagulant. The first fluoride concentration in treated water, was measured after 10 min from the start of the reaction, and as the reaction progressed, at every 10 min interval, the fluoride concentration was checked up to 90 min. Fluoride concentration was checked using the same ion selective electrode. A sharp fall in concentration was noticed after 10 min from the start of the reaction, and a steady state was achieved afterwards. The fluoride concentration change value followed the same pattern for all three doses applied. Figure 4 is a graph illustrating the effect of coagulant dose on the kinetics of fluoride uptake from Coke-plant wastewater utilising the compound of formula I.
SETTLING TIME AND SETTLING VELOCITY
Settling time experiments were carried out using a compound of formula I only. In this case, it was observed that 20 min of settling was sufficient, and it has been sufficient to render the upper 3/4th portion of the total volume partially clear even without filtering. It was also found that the first 10 min of settling was fast and was the maximum. Even when operating on a laboratory scale, drawing-off the treated water can be done easily, after solid is settled or by adding a filtration connection at the bottom of the separation tube. Figure 5 shows images taken during laboratory scale performances of fluoride removal with the compound of formula I, maintaining the concentration of 1.5 gm/L. Table 2 below provides details of settling experiments. Settling time and settling velocity were checked during these experiments. The setting velocity was determined to be 1.15 cm/min.
Time (min) Height reduced (cm) Settling velocity
0 0
1.15 cm/min
02 9
10 19
20 23
Table 2. Experimental data for settling velocity measurement
REACTION PATHWAY FOR FLUORIDE REMOVAL BY ALUMINA BASED ADSORBENT
As the affinity towards cations increases with cationic charges, the order of affinity for F-ions towards various cations follows this order: Al3+ > Fe2+ > Ca2+. The different ways F- reacts with Al3+ are mentioned below:
In water, the solubility of AlF3 is very poor. However, it becomes completely soluble after its conversion to AlF4-. Formation of various fluoride complexes with Al3+ is an important reason for the adsorption of fluoride from water samples. Ionic forms of aluminium fluoride complexes are soluble in water. Thus, to precipitate the AlF4-, a cation is essential. Ca2+ plays an important role following the reaction Ca2+ + AlF4-? Ca(AlF4)2, where Ca(AlF4)2 is the precipitate. Additionally, Ca2+ also has a high affinity towards F-. Therefore, the presence of both Ca2+ and Al3+ in the system, can enhance the F- removal from wastewater.
An aqueous solution of fluoride ions containing activated alumina may not be clearly soluble and form various aluminium species, including several fluoride and hydroxyl-aluminium complexes. The spontaneous interaction of Al3+ ions with hydroxide ions (OH-) in water results in the formation of insoluble Al(OH)3 flocs. Adsorption of the fluoride ion by Al(OH)3 results in the formation of aluminium fluoride hydroxide complexes [AlnFm(OH)3n-m].In addition, fluoride ions can also be removed from water by co-precipitation of Al3+, F- and OH- ions. Both the approaches, like adsorption and co-precipitation reaction mechanisms, have been mentioned in Scheme 1. In the present disclosure, aluminium based inorganic polymeric compounds were used along with aluminium sulphate in 70:30 percentage ratio. During investigation, it was found that IPC has greater efficiency than other aluminium sulphate salts used. To optimise the cost of the total process for industrial use, an optimum composition of IPC and AS1 has been established, which works very effectively in F- removal from coke-plant discharge water.
Scheme 3: Probable reaction scheme for F- adsorption and co-precipitation
Reversibility of reaction
In the case of compound of formula I, reversibility of 5–10% was observed during the compound's formation reaction. Reversibility can be avoided by adding more IPC.
Equivalents
With respect to the use of substantially plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. Various singular/plural permutations may be expressly set forth herein for the sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.).
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
Documents
Application Documents
| # | Name | Date |
|---|---|---|
| 1 | 202231018755-STATEMENT OF UNDERTAKING (FORM 3) [30-03-2022(online)].pdf | 2022-03-30 |
| 2 | 202231018755-REQUEST FOR EXAMINATION (FORM-18) [30-03-2022(online)].pdf | 2022-03-30 |
| 3 | 202231018755-POWER OF AUTHORITY [30-03-2022(online)].pdf | 2022-03-30 |
| 4 | 202231018755-FORM-8 [30-03-2022(online)].pdf | 2022-03-30 |
| 5 | 202231018755-FORM 18 [30-03-2022(online)].pdf | 2022-03-30 |
| 6 | 202231018755-FORM 1 [30-03-2022(online)].pdf | 2022-03-30 |
| 7 | 202231018755-DRAWINGS [30-03-2022(online)].pdf | 2022-03-30 |
| 8 | 202231018755-DECLARATION OF INVENTORSHIP (FORM 5) [30-03-2022(online)].pdf | 2022-03-30 |
| 9 | 202231018755-COMPLETE SPECIFICATION [30-03-2022(online)].pdf | 2022-03-30 |
| 10 | 202231018755-Proof of Right [31-05-2022(online)].pdf | 2022-05-31 |
| 11 | 202231018755-Power of Attorney [09-04-2023(online)].pdf | 2023-04-09 |
| 12 | 202231018755-Form 1 (Submitted on date of filing) [09-04-2023(online)].pdf | 2023-04-09 |
| 13 | 202231018755-Covering Letter [09-04-2023(online)].pdf | 2023-04-09 |
| 14 | 202231018755-FORM 3 [10-04-2023(online)].pdf | 2023-04-10 |
| 15 | 202231018755-FER.pdf | 2024-10-22 |
| 16 | 202231018755-FORM 3 [11-12-2024(online)].pdf | 2024-12-11 |
| 17 | 202231018755-FER_SER_REPLY [22-04-2025(online)].pdf | 2025-04-22 |
| 18 | 202231018755-FORM-26 [16-05-2025(online)].pdf | 2025-05-16 |
| 19 | 202231018755-PatentCertificate09-06-2025.pdf | 2025-06-09 |
| 20 | 202231018755-IntimationOfGrant09-06-2025.pdf | 2025-06-09 |
Search Strategy
| 1 | 202231018755E_21-10-2024.pdf |