Performance of novel pillared eggshell-bentonite clay bio-composite for enhanced phosphate adsorption from aqueous media

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 Q0 value was found to be 60.51 mg/g at pH 3.0 and 30 0C. The reaction was endothermic and spontaneous, according to thermodynamic analysis, with overall changes in enthalpy (ΔH0) and entropy (ΔG0) of 10.08 KJmol-1 and 0.09 KJmol−1K−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.