Performance evaluation of biopolymeric hybrid membrane and their mechanistic approach for the remediation of phosphate and nitrate ions from water

A biopolymeric hybrid membrane, viz. lanthanum interconnected carboxymethylcellulose-bentonite (La@CMC-Bt) was prepared successfully and utilized for the remediation of phosphate and nitrate ions from water. The various adsorption influencing parameters such as agitation time, adsorbent dosage, solution pH, co-anions and temperature were optimized. The physiochemical properties of the La@CMC-Bt membrane was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermal analysis (TGA-DSC), scanning electron microscopy, energy dispersive X-ray analysis with mapping analysis, and atomic force microscopy to clarify the phosphate and nitrate adsorption mechanism. The La@CMC-Bt membrane showed superior adsorption capacity at 80.2 and 67.7 mg/g for phosphate and nitrate ions, respectively. Furthermore, the adsorption kinetic studies were calculated using reaction and diffusion-based kinetic models. The thermodynamic parameters like Delta G degrees, Delta S degrees and Delta H degrees have revealed that the nature of the adsorption process was favourable, spontaneous and endothermic in nature. The experimental results indicate that the possible mechanism of phosphate and nitrate adsorption onto La@CMC-Bt membrane was governed by the adsorption mechanisms like complexation, electrostatic interaction followed by ion exchange. The suitability at the field condition was carried out with the eutrophicated water sample taken from the nearby eutrophic endemic area. Therefore, based on the high efficiency and low-cost of La@CMC-Bt membrane, to be an ideal candidate to remove phosphate and nitrate ions from water/wastewater.