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Removal of nitrate and phosphate ions using Zr4+ ions embedded chitosan-soya bean husk activated bio-char composite beads (Zr-CS-SAC) was carried out by batch mode to overcome the environmental problems due to eutrophication. The adsorbent was well characterized by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) analysis with energy dispersive X-ray analyzer (EDX), X-ray diffraction analysis (XRD), Brunauer–Emmett–Teller surface analyzer (BET), thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA) etc. The adsorption equilibrium models of Langmuir, Freundlich and D-R isotherms were evaluated and the results described that the Freundlich model was the best for both the adsorbates of nitrate and phosphates ions with respective capacities of 90.09 and 131.29 mg g−1 at 30 °C. Studies on thermodynamic parameters revealed the endothermic and spontaneous nature of the adsorption. Different kinetic models were studied and found that pseudo-second-order kinetic data were well fitted for adsorption process. These results suggested that Zr-CS-SAC composite beads as a promising adsorbent for the removal of nitrate and phosphate ions from water with good removal efficiency, adsorbability, recyclability and non- toxicity.

The present study deals with the removal of phosphate ions from aqueous solution using Lanthanum loaded chitosan-alginate composite (La-CS-AG) as adsorbent. To investigate the effect of phosphate adsorption, various parameters such as contact time, initial phosphate concentration, dosage, pH, co-ions and temperature. The experimental data obtained were interpreted by the different isotherms and thermodynamic studies. Phosphate was found to be removed by outer sphere mechanism. The negative ΔH° and ΔG° values revealed that the adsorption of phosphate were exothermic and spontaneous process. The adsorption data were best fitted with Freundlich adsorption isotherm. The composite was characterized using FTIR, SEM and EDX .

In this work, quaternization of melamine formaldehyde resin (MFQ) as a novel sorbent was synthesized for the removal of nitrate ions from water through adsorption process. MFQ resin was characterized by FTIR, XRD and SEM with EDAX analysis. Sorption experiments were carried out in batch mode to optimize various parameters viz., contact time, initial nitrate ion concentration, pH, co-ions and temperature. Adsorption equilibrium and kinetic studies were investigated. Equilibrium and kinetic data agreed well with the Freundlich isotherm and pseudo-second-order kinetic models. Thermodynamic studies revealed that the nature of sorption is spontaneous and exothermic. The MFQ resin removed nitrate ions by means of electrostatic and ion exchange mechanism and the resin was effectively regenerated using 0.025 M NaCl. Sorption capacity of MFQ resin was compared with other sorbents suggested that this sorbent was quite useful for removing nitrate ions from aqueous solution.

Removal of nitrate and phosphate ions using Zr

In the present work, lanthanum (III) encapsulated chitosan-montmorillonite composite (La-CS-MMT) was prepared as an adsorbent for the effective removal of phosphate ions from aqueous solution. Characterization of the adsorbent using FT-IR, XRD, SEM with EDX, TGA and DTA techniques were carried out. Batch adsorption experiments were carried out to optimize the effects of various operating parameters viz., shaking time, initial concentration of phosphate ions, dosage, competitor co-existing ions, pH and temperature. Phosphate ions adsorbed effectively on La-CS-MMT composite through hydrogen bonding and by outer-sphere complex formation mechanism. Freundlich isotherm model fit well with the equilibrium isotherm data. The experimental values of ∆G°, ∆S° and ∆H° revealed that the nature of adsorption was feasible, spontaneous and exothermic. The kinetic study was well fitted with pseudo-second-order model. Regeneration study of the spent La-CS-MMT-P composite was carried out upto five cycles and found that about 70% of adsorption efficiency was retained.