Performance of novel pillared eggshell-bentonite clay bio-composite for enhanced phosphate adsorption from aqueous media
Sandhya Sudhakaran, Harsha Mahadevan, Linsha Fathima S, K. Anoop Krishnan
Abstract
Modified clay mineral is a potential technique for phosphorus adsorption and has received much attention in the high phosphate pollution witnessing regions. In the present work, an iron-pillared eggshell-modified bentonite clay bio composite (IP-ESMB) is used to test the adsorption of phosphate from the aqueous medium. The characteristics of the prepared IP-ESMB bio composite were analyzed using XRF , SEM, EDX , FTIR, XRD , BET, TG and DTG analysis to study its physicochemical characteristics. The diffusion process, electrostatic interaction , and ion exchange mechanisms work in concert to remove the phosphate ions effectively at a pH of 3.0. The adsorption capacity is influenced by the initial phosphate concentrations, adsorbent dose (2 g/L), contact time (50 min), temperature (303 K) and pH (3.0) of the solution. Kinetic studies revealed that the pseudo-second-order model best described the experimental data. The Langmuir isotherm model provided the best fit for the equilibrium isotherm data of the IP-ESMB, and the determined Q 0 value was found to be 60.51 mg/g at pH 3.0 and 30 0 C. The reaction was endothermic and spontaneous, according to thermodynamic analysis , with overall changes in enthalpy ( ΔH 0 ) and entropy ( ΔG 0 ) of 10.08 KJmol -1 and 0.09 KJmol −1 K −1 , respectively. It is also found that the IP-ESMB bio composite has excellent reusability over several adsorption cycles. Designing an adsorption reactor provides another means of calibrating the performance of the created bio-composite during factorial operations. This study confirms that to curb eutrophication in a natural water system, the present modified clay mineral can efficiently act as a green adsorbent.