https://doi.org/10.52131/jmps.2022.0302.0028 71 Journal of Materials and Physical Sciences Volume 3, Number 2, 2022, Pages 71 - 80 Journal Homepage: https://journals.internationalrasd.org/index.php/jmps Removal of Fluoride Ions (F-1) from Contaminated Drinking Water using MnFe2O4 /Banana Peels Composite Synthesized through Chemical Co-Precipitation Method Muhammad Sajid1, Muhammad Aamir1, Muhammad Jamil1, Mukhtar Ahmad2, Shahzada Qamar Hussain3* 1 Institute of Chemical Sciences, Bahauddin Zakariya University Multan, Pakistan 2 Department of Physics, COMSATS University Islamabad (CUI) Lahore Campus, Lahore 54000 Pakistan 3 Institute of Frontier Materials, Deakin University Waurn Ponds campus Geelong, Australia ARTICLE INFO ABSTRACT Article History: Received: September 20, 2022 Revised: October 18, 2022 Accepted: December 29, 2022 Available Online: December 31, 2022 Fluoride (F) contaminated water is of immense health risk. Skeletal as well as dental fluorosis is due to the excessive Fluoride (> 1.5 mg/L) concentration in drinking water. In the present work, MnFe2O4 /banana Peels composite a unique adsorbent has been explored for the elimination of fluoride from aqueous system. These nanocomposites were characterized by XRD and FTIR. Retentivity and coercivity value of nanocomposite is determined by Hysteresis loop. The optimized conditions for the removal of 86% fluoride from field water sample was achieved at pH 8 and in 175 min. From the experimental results, it may be inferred that MnFe2O4 /banana peels composite is an adequate adsorbent for the removal of fluoride from water. Keywords: Fluoride Removal MnFe2O4/Banana Peels Composite Co-Precipitation Method M-H Loops Adsorption Study © 2022 The Authors, Published by iRASD. This is an Open Access article under the Creative Common Attribution Non-Commercial 4.0 *Corresponding Author’s Email: qamar1980@hotmail.com 1. Introduction Asian countries mainly depends upon the ground water for their water source (Kazi, Brahman, Baig, & Afridi, 2018; Raj & Shaji, 2017). The fluoride content enters into This ground water contain fluoride contents due to the natural sources like leaching of fluoride bearing rocks and minerals (Viswanathan & Meenakshi, 2010).Fluoride due to its ubiquitous property is added to the environment anthropogenically varies its contents in lithosphere from 100 to 1500 g/ton (Maheshwari, 2006). Its dual influences i.e. lower and higher absorption by human being make it of prime importance. Fluoride’s specific amount is not only beneficial for human in bone forming, prevention of tooth decay but on the other hand its higher concentration causes fluorosis, brattling of bones, curvature of bones, dwarfishness, mental derangements, cancer, etc. and in extreme cases even death (Viswanathan & Meenakshi, 2008). It is approximated about 450 million people of 30 countries using water for drinking of more than 1.0 mg/L fluoride contents which is not according to the standards of World Health Organization WHO i.e. slightly above or below 1 mg/L. In lower water intake regions, up to 1.5 mg/L fluoride level is acceptable (Chen et al., 2016). There are various methods which are difficult in operation, highly expensive and time consuming for the removal of fluorides from water such as chemical precipitation, adsorption technique through batch and column process, ion exchange, nanofiltration, electrodialysis, membrane separation, electrocolactose of plants (Dongare et al., 2017) agulation, and reverse osmosis (Aldaco, Irabien, & Luis, 2005), (Turner, Binning, & Stipp, 2005), (Cai et al., 2015), (Tor, Danaoglu, Arslan, & Cengeloglu, 2009), (Onyango, Kojima, Aoyi, Bernardo, & Matsuda, 2004), (Tahaikt et al., 2007), (Lahnid et al., 2008), (Behbahani, Moghaddam, & Arami, 2011), (Schneiter & Middlebrooks, 1983), (Dash, Sahu, Sahu, & Patel, 2015). In this work we use the Manganese Ferrite (MnFe2O4) /Banana Peels https://journals.internationalrasd.org/index.php/jmps mailto:qamar1980@hotmail.com https://en.wikipedia.org/wiki/Laccase Journal of Materials and Physical Sciences 3(2), 2022 72 Composite for the removal of fluoride. Bananas are internationally known as eatable fruits with yearly cultivated up to one hundred and sixty five million tons in year 2011 (Van Thuan, Quynh, Nguyen, & Bach, 2017). More often, skin of banana includes 6-9% protein and 20-30% fibers. There are 30% and 15 % more free sugar and starch in ripe banana peels than green banana peels. The assistances of banana coverings were recognized for water cleansing to reduce ethyl alcohol, cellulose, (Deshmukh et al. 2017; Kumar et al. 2011). But the use of banana peels through batch adsorption is a time consuming and costly process because all operating variables remains constant by changing one variable at a time. The present work is aimed at facile synthesizing an efficient and economical composite of Manganese Ferrite (MnFe2O4) /Banana Peels for the removal of fluoride contents. 2. Experimental Procedure 2.1. Chemicals and Reagents Manganese(II) chloride tetra hydrate (MnCl2. 4H2O, purity ≥ 99%), Ferric chloride hexahydrate (FeCl3. 6H2O, purity =97%), Ferric sulphate heptahydrate (FeSO4.7H2O, purity ≥ 99%), Sodium hydroxide (NaOH, purity =97%), Acetic Acid (CH3COOH, purity ≥99.7%), Trisodium citrate dihydrate (Na3C6H5O7.2H2O, purity =99.9%), were purchased from Merck (Germany). Ammonia solution (NH3, purity ≥ 99.98%), Potassium hydroxide (KOH, purity ≥ 85%), Sodium fluoride (NaF, purity ≥99), Sodium Chloride (NaCl, purity ≥99%) were obtained from Sigma-Aldrich (Germany). 2.2. Preparation of Magnetic MnFe2O4 Particles The magnetic nanoparticles were prepared through the chemical co-precipitation method by dissolving 0.1M solutions 4.95g MnCl2 .4H2O, 6.758g FeCl3.6H2O, and 0.2M solution of 13.901g FeSO4.7H2O in 250 mL of deionized water under a nitrogen gas flow with constant stirring at 80℃. The precipitating reagent ammonia solution was continuously added until pH reached 10 ~ 11. The precipitates are formed when pH is maintained. These precipitates were separated by using centrifugation machine. These precipitates were centrifuged, washed two to three times with deionized water. Then these are dried into the electrical oven for 24h at 60oC. Solid material was then grinded with pestle mortar into a fine powder form of MnFe2O4. The fine powder of MnFe2O4 were annealed by heating in an electrical furnace at 650oC for 240min at the rate of 6oC per min. 2.3. Synthesis of Banana Peels Banana peels are collected from banana taking from fruit store. Banana peels are washed two or three times to remove impurities by using simple tap water. Then banana peels are dried for two days under sunlight. Furthermore, these are dried in an oven at the temperature of 100oC for 36h. Banana peels were grinded to form a fine powder with the help of simple grinder to form fine powder. 2.4. Preparation of MnFe2O4 /Banana Peels Composite MnFe2O4 /banana Peels composite was prepared by physically mixing the fine powders 1g of MnFe2O4 and 1g of fine powder of banana peels and then grinding in pestle mortar at room temperature for 30℃. 2.5. Adsorption Experiments The adsorption experiment was carried out by controlling variables such as contact time (min), concentration (ppm) and pH. Batch absorption experiments are performed in 15 ml of centrifuge tubes containing 10mg of MnFe2O4, 5ml deionized water, 2ml buffer solution and 3ml of water sample containing fluorides, 10 mg MnFe2O4, contact time was (5-240 min) and pH was adjusted (3-11) by adding 0.1M HCl and 0.1M NaOH. Then flasks were shaken at 150rpm in a shaker for 30min. than check it the concentration of fluoride absorbed from fluoride selective electrode by Manganese ferrite nanoparticles. The adsorption capacity (mg/g) of the experimental adsorbent was calculated by using by eq. Qe = (Ci - Cf)x V/m, Where C is concentration in (mg/L), qe is maximum adsorbed quantity at equilibrium, m is mass of adsorbent in (g) and V is volume of solution. https://en.wikipedia.org/wiki/Tonne https://en.wikipedia.org/wiki/Ethanol Muhammad Ahsan Shafique, Z. Zaheer, S. Sharif, H. Taskeen, S. A. Shah, Athar Naeem Akhtar, G. Murtaza 73 2.6. Instrumentation The adsorbent characterization and fluoride ion concentration from aqueous solution was determined by using scanning electron microscope (SEM), X-Ray Diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), ion selective electrode and hysteresis loop for the softness of material and fluoride sensor for adsorption tests. 3. Results and Discussion 3.1. XRD Analysis The crystallinity and purity of as synthesized Magnetic manganese ferrite composite were evaluated by powder XRD. All diffraction peaks of XRD pattern is indexed to Face Centered Cubic structure (Fig. 1). The sharpness of diffraction peaks is confirming the Crystallinity of our synthesized material without any impurities. The X-ray pattern of as prepared manganese ferrite composite depicts the peaks at (111), (220), (311), (222), (400), (422), (511), (440) which are exact corresponding peaks of magnetic manganese ferrite, as confirmed by literature. These peaks are clearly confirming the structure of our as prepared manganese ferrite formation. All lattice parameter values such as, cell unit volume ‘a’ and X- Ray density of sample was calculated by using this formula )( 3 222 2 2 2 lkh a Sin ++=   (1) Where λ is the wavelength, h,k,l are the miller indices and a is the lattice constant. i.e. a= 8.25 Å V=a3 (2) dx = 8 M/NA V (3) Here M is Molar mass, NA is Avogadro number, V is unit cell volume and 8 is number of molecules per unit cell. 10 20 30 40 50 60 70 80 220 111 In te n s it y ( a .u ) 2-theta (degree) 311 222 400 422 511 440 Figure 1: XRD patterns for single phase MnFe2O4 ferrite synthesized by co- precipitation method Journal of Materials and Physical Sciences 3(2), 2022 74 The arrangement/geometry of atoms and unit cell size is measured by angular positions and relative intensities of diffracting peaks. 3.2. FTIR Analysis FTIR spectrum of both Simple MnFe2O4 were taken which reveals the similarity of spectrum of both MnFe2O4 and Our as prepared materials, which confirms that our prepared nanocomposite is formed properly as confirmed by its representing characteristics peaks. FTIR spectrum of simple manganese ferrite is taken and its characterization peaks are observed at 3377 cm-1 , 1980 cm-1, 1378 cm-1 due to Mn-O-Fe stretching, 661cm-1 due to Fe-O and Mn-O bonds (Fig. 2). 4000 3500 3000 2500 2000 1500 1000 500 -0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 A b s o rb a n c e Wave number (cm -1 ) MnFe 2 O 4 661 1378 3377 1980 Figure 2: FTIR Spectrum of Simple Manganese ferrite FTIR spectrum of as prepared manganese ferrite composite is shown in Fig. 3. The spectrum shows four characteristic absorption bands which clearly indicate the formation of manganese ferrite. The peak at 660 and 66 cm-1 are an evidence for the presence of Fe-O and Mn-O bonds. The absorption band at 1378 cm-1 represents the Mn-O-Fe stretching whereas the peak at 1980 cm-1 is an indication of double bond character of metal-oxygen bond which may be attributed to Fe=O double bond in the manganese ferrite. The broad absorption band at 3377 cm-1 may be attributed to O-H stretching mode of certain water moieties associated with the manganese ferrite. The stretching vibrations values given below in spectrum clearly depicts the synthesis of as prepared manganese ferrite with banana peels for the removal of fluoride ions from real water samples. Table 1 Representing functional groups stretching values Sr. No. Functional group Absorption frequency 1 O-H stretching 3377 cm-1 2 Mn-O-Fe stretching 1378 cm-1 3 Fe=O bond 1980 cm-1 4 Fe-O 661 cm-1 Muhammad Ahsan Shafique, Z. Zaheer, S. Sharif, H. Taskeen, S. A. Shah, Athar Naeem Akhtar, G. Murtaza 75 Figure 3: FTIR Spectrum of MnFe2O4 Composite Spectrum of our prepared manganese ferrite composite given below, whose similarity with that of simple manganese ferrite spectrum shows that our prepared MnFe2O4 Composite accurately had synthesized. 3.3. Magnetic Measurements Magnetic measurements were carried out of our as prepared material with vibrating sample magnetometer and its hysteresis loop was obtained. These measurements were carried out for investigating the magnetic properties of that as prepared material. The hysteresis loop is exhibiting the soft magnetic nature of our material, as very small area occupied by closed curve is basically related to soft magnetic materials properties (Fig. 4). These properties are dependent upon sintering temperature, metal ions in ferrite structure and preparation methods. -8000 -6000 -4000 -2000 0 2000 4000 6000 8000 -30 -20 -10 0 10 20 30 M a g n e ti z a ti o n ( e m u /g ) Magnetic Field (Oe) Ms = 30.28 emu/g Mr = 6.70 emu/g Hc = 286 Oe Figure 4: Hysteresis loop of Single phase MnFe2O4 ferrite synthesized by Co- precipitation method Journal of Materials and Physical Sciences 3(2), 2022 76 Magnetic moment value of the sample was calculated by magnetization saturation data by given formula (Raghuvanshi, Satalkar, Tapkir, Ghodke, & Kane, 2014). The calculated data is in full agreement to the saturation magnetization as both the parameters are directly related to each other. nB (µB) = M ×Ms / 5585 (4) where nB is magnetization moment, M is the molecular weight of sample, Ms is saturation magnetization and Hc is coercivity of manganese ferrite. 3.4. Adsorption Study For exploring the adsorption performance and for ensuring the reliability, accuracy and reproducibility of our material, adsorption experiments were carried out. Adsorption removal studies for removing fluoride by both simple manganese ferrite and our magnetic manganese ferrite composite were investigated and compared the capabilities of our materials. 3.4.1.Factors Affecting Adsorption The following two parameters i.e., time and pH were carried out for adsorption studies. 3.4.1.1. Effect of Contact Time The data obtained from different contact time experiments by both materials i.e., Mn2FeO4 and Mn2FeO4/banana peels were plotted in Fig. 5. From fig, it can be clearly observed that adsorption removal efficiency increased with contact time till 175 min, then equilibrium constant value was achieved. This was probably due to the abundant adsorption sites of our Composite material at initial states (Wang et al., 2022), as the interaction sites becomes occupied with passage of time, adsorption of fluoride becomes lower by adsorbent (Wang et al., 2022). When the equilibrium is achieved, all sites become fully saturated. The optimum time for equilibrium is 175 min. as it is much more efficient in adsorption removal of fluoride ion as compared to simple manganese ferrite. The fluoride specific amount of uptake (qt), was determined by given formula i.e. Qt = V (Co – Ct) / W (5) And the percentage removal efficiency of fluoride was calculated by % adsorption = 100 × (Co – Ct) / Co (6) Where Co (mg/ L) is initial concentration, Ct (mg/L) is concentration at time t. V is volume (L) of solution and W (g) is mass of adsorbent. After treatment with manganese ferrite for 175 min, total amount of adsorbate after time t (qt), onto adsorbent is maximum in case of our composite i.e., 8.9 value is being calculated. As qt is total amount of fluoride ions uptake after time t. The results obtained by this study in Table 2 as given below. Table 2 Effect of Contact Time on removal of fluoride MnFe2O4 Time (min) 5 10 15 30 60 175 180 240 qe (mg/g) 2.9 3.9 4.1 8.3 8.6 8.7 5.7 4.9 MnFe2O4/Banana peels qe (mg/g) 3.4 4.2 5.9 8.6 8.7 8.9 6.1 5.2 Muhammad Ahsan Shafique, Z. Zaheer, S. Sharif, H. Taskeen, S. A. Shah, Athar Naeem Akhtar, G. Murtaza 77 0 50 100 150 200 250 0 2 4 6 8 10 q t (m g /g ) Time (min) MnFe 2 O 4 MnFe 2 O 4 /Banana peels Figure 5: Effect of Contact time on fluoride removal 3.4.1.2. Effect of pH on Adsorption Capacity (qe) Effect of pH on adsorption of fluoride ions on both MnFe2O4 and MnFe2O4 Composite was investigated by keeping different pH of same solutions. It reveals the dependence of pH on adsorption capacity of our as prepared material. The adsorption is high at low pH values and low at high pH. This high uptake at low pH was ascribed to high hydrogen ions concentration at lower pH which causes the increase in positive charges at the sorbent surfaces leading to increase amount of fluoride removal. Similar results were observed by Sahira et al in 2012, while they were removing the same fluoride ions from water by using Zirconyl - impregnated activated carbon which were prepared by lapsi seed stone. They also noted the same thing that pH had great influence on surface charge of adsorbents as it increased the interaction of fluoride ions with adsorbent (Joshi, Adhikari, & Pradhananga, 2012). At higher pH (> 8), due to presence of higher concentration of hydroxide ions, they hindered the diffusion of fluoride ions which leads to low uptake of the fluoride ions. That hindrance is caused due to repulsive forces occurring between the negative charges of fluoride ions and hydroxide ions. 𝑞𝑒 = 𝐶𝑖− 𝐶𝑓 𝑚 ∗ 𝑉 (7) Where C is concentration, qe is maximum adsorbed quantity at equilibrium, m is mass of adsorbent and V is volume of solution. Batch experiments results confirmed our biomaterial is given better results at pH 8, i.e.8.9 than that of Simple ferrites at the same pH as can be seen by Fig. 6. At room temperature (initial concentration Ci = 10 mg/L, shaking time = 2h, T = 25 oC, pH = 7 ± 0.1, m = 10 mg and V = 10 mL). Journal of Materials and Physical Sciences 3(2), 2022 78 Table 4 Effect of pH on adsorption removal MnFe2O4 pH 3 4 5 6 7 8 9 10 11 Qe (mg/g) 2.9 3.9 4.1 8.3 8.6 8.7 5.7 4.9 3.8 MnFe2O4/Banana peels Qe (mg/g) 3.4 4.2 5.9 8.6 8.7 8.9 6.1 5.2 3.9 2 3 4 5 6 7 8 9 10 11 12 2 3 4 5 6 7 8 9 MnFe 2 O 4 q e ( m g /g ) pH MnFe 2 O 4 /Banana peels Figure 6: Effect of pH on adsorption removal 3.4.2.Real Time Application It is important to determine the adsorption mechanism which is essential for determining its residence time. The mechanism of adsorption removal from aqueous system by porous adsorbents require four basic steps i.e. 1. Migration of ions from aqueous system to boundary layer or film surrounding adsorbents. 2. Diffusion of ions to exterior layer of adsorbents known as external diffusion. 3. Transport of ions from exterior to interior surface through pore diffusion mechanism. 4. Uptake of ions by available sites. The slowest step defines the uptake rate and rate determining step. Here in given Fig. 7, value of C determines the boundary layer thickness of adsorbent. It provides the understanding of ions either those had been got adsorbed or remained in solution. Higher value of c exhibits higher adsorption. Table 5 Real water sample analysis at room temperature (initial concentration Ci = 10 mg/L, T = 25 oC, pH = 7 ± 0.1, m = 10 mg and V = 10 mL) Time (min) 5 10 15 30 60 120 180 240 Ct (mg/L) 10 9.4 8.1 6.3 4.2 2.1 1.2 0.9 Muhammad Ahsan Shafique, Z. Zaheer, S. Sharif, H. Taskeen, S. A. Shah, Athar Naeem Akhtar, G. Murtaza 79 0 40 80 120 160 200 240 0 2 4 6 8 10 C t (m g /L ) Time (min) WHO limit (1.5 mg/L) MnFe 2 O 4 + Banana peels Figure 7: Effect of time on adsorption tendency of adsorbent Conclusion The magnetic material was successfully synthesized and that was confirmed by FTIR studies which indicated the existence of the anchored functional groups.it was found to be effective removal up to 86 %. The optimum contact time and pH were found to be 175 min and 8 respectively. Fluoride ions cause oxidant effect which is responsible for several diseases like thyroid problems, neurological problems cardiovascular problems reproductive issues and bone cancer. Manganese ferrite/Banana peel composite is very good fluoride ion adsorber. From our research it is identified that maximum amount of fluoride ions is adsorbed easily by our material. This material had potential application for fluoride removal and is biodegradable, economic and environmentally friendly. It can be beneficial at industrial scale if prepared at bulk scale. References Aldaco, R., Irabien, A., & Luis, P. (2005). Fluidized bed reactor for fluoride removal. Chemical Engineering Journal, 107(1-3), 113-117. Behbahani, M., Moghaddam, M. A., & Arami, M. (2011). Techno-economical evaluation of fluoride removal by electrocoagulation process: optimization through response surface methodology. Desalination, 271(1-3), 209-218. Cai, H., Chen, G., Peng, C., Xu, L., Zhu, X., Zhang, Z., . . . Gao, H. (2015). Enhanced removal of fluoride by tea waste supported hydrous aluminium oxide nanoparticles: anionic polyacrylamide mediated aluminium assembly and adsorption mechanism. RSC advances, 5(37), 29266-29275. Chen, L., Zhang, K., He, J., Cai, X.-G., Xu, W., & Liu, J.-H. (2016). Performance and mechanism of hierarchically porous Ce–Zr oxide nanospheres encapsulated calcium alginate beads for fluoride removal from water. RSC advances, 6(43), 36296-36306. Journal of Materials and Physical Sciences 3(2), 2022 80 Dash, S. S., Sahu, M. K., Sahu, E., & Patel, R. K. (2015). Fluoride removal from aqueous solutions using cerium loaded mesoporous zirconium phosphate. New Journal of Chemistry, 39(9), 7300-7308. Dongare, P. D., Alabastri, A., Pedersen, S., Zodrow, K. R., Hogan, N. J., Neumann, O., . . . Elimelech, M. (2017). Nanophotonics-enabled solar membrane distillation for off-grid water purification. Proceedings of the National Academy of Sciences, 114(27), 6936- 6941. Joshi, S., Adhikari, M., & Pradhananga, R. R. (2012). Adsorption of fluoride ion onto zirconyl-impregnated activated carbon prepared from lapsi seed stone. Journal of Nepal Chemical Society, 30, 13-23. Kazi, T. G., Brahman, K. D., Baig, J. A., & Afridi, H. I. (2018). A new efficient indigenous material for simultaneous removal of fluoride and inorganic arsenic species from groundwater. Journal of Hazardous materials, 357, 159-167. Lahnid, S., Tahaikt, M., Elaroui, K., Idrissi, I., Hafsi, M., Laaziz, I., . . . Elmidaoui, A. (2008). Economic evaluation of fluoride removal by electrodialysis. Desalination, 230(1-3), 213-219. Maheshwari, R. (2006). Fluoride in drinking water and its removal. Journal of Hazardous materials, 137(1), 456-463. Onyango, M. S., Kojima, Y., Aoyi, O., Bernardo, E. C., & Matsuda, H. (2004). Adsorption equilibrium modeling and solution chemistry dependence of fluoride removal from water by trivalent-cation-exchanged zeolite F-9. Journal of Colloid and Interface Science, 279(2), 341-350. Raghuvanshi, S., Satalkar, M., Tapkir, P., Ghodke, N., & Kane, S. (2014). On the structural and magnetic study of Mg1− xZnxFe2O4. Paper presented at the Journal of Physics: Conference Series. Raj, D., & Shaji, E. (2017). Fluoride contamination in groundwater resources of Alleppey, southern India. Geoscience Frontiers, 8(1), 117-124. Schneiter, R. W., & Middlebrooks, E. J. (1983). Arsenic and fluoride removal from groundwater by reverse osmosis. Environment International, 9(4), 289-291. Tahaikt, M., El Habbani, R., Haddou, A. A., Achary, I., Amor, Z., Taky, M., . . . Elmidaoui, A. (2007). Fluoride removal from groundwater by nanofiltration. Desalination, 212(1- 3), 46-53. Tor, A., Danaoglu, N., Arslan, G., & Cengeloglu, Y. (2009). Removal of fluoride from water by using granular red mud: batch and column studies. Journal of Hazardous materials, 164(1), 271-278. Turner, B. D., Binning, P., & Stipp, S. (2005). Fluoride removal by calcite: evidence for fluorite precipitation and surface adsorption. Environmental science & technology, 39(24), 9561-9568. Van Thuan, T., Quynh, B. T. P., Nguyen, T. D., & Bach, L. G. (2017). Response surface methodology approach for optimization of Cu2+, Ni2+ and Pb2+ adsorption using KOH-activated carbon from banana peel. Surfaces and Interfaces, 6, 209-217. Viswanathan, N., & Meenakshi, S. (2008). Enhanced fluoride sorption using La (III) incorporated carboxylated chitosan beads. Journal of Colloid and Interface Science, 322(2), 375-383. Viswanathan, N., & Meenakshi, S. (2010). Enriched fluoride sorption using alumina/chitosan composite. Journal of Hazardous materials, 178(1-3), 226-232. Wang, Z., Zhang, L., Zhang, K., Lu, Y., Chen, J., Wang, S., . . . Wang, X. (2022). Application of carbon dots and their composite materials for the detection and removal of radioactive ions: A review. Chemosphere, 287, 132313.