Evaluating the Applicability of Geopolymer Fly Ash as an Adsorbent for Phosphate Removal

Concerns of a critical nature have arisen in recent times regarding environmental challenges associated with phosphate and the depletion of resources by eutrophication. Recently, there has been research on geopolymer as environmentally friendly and cost-effective adsorbent, specifically targeting the removal of various pollutants in wastewater treatment. This investigation mainly focuses on solving challenges associated with the phosphate removal by employing Geopolymer Fly Ash (GPFA) as an adsorbent. GPFA was characterized using FESEM, EDX, FTIR and Zeta Potential. Batch experimentation was undertaken to evaluate the impact of different parameters including the initial phosphate ions concentration, pH level of the solution, contact time, temperature, and the quantity of adsorbent used. SEM imaging of GPFA revealed a granular structure with irregular pores structures. FTIR analysis identified specific functional groups on the adsorbent's surface, notably the presence of -OH groups, -CH2 vibrations, and Si-O-Si vibrations. The optimal parameters for maximal phosphate removal, resulting in 95% removal rate using adsorbent amount of 0.25 g at a temperature of 298.15K with a pH value of 5.0. For the kinetics of phosphate sorption, the pseudo-second-order model delivered a good fit, while the adsorption isothermal data was well represented by the Freundlich model suggesting the adsorption process with multilayer coverage of adsorbent. In terms of thermodynamics, the adsorption of phosphate at the solid-liquid interface was determined to be exothermic and spontaneous. This research provides affordable and efficient material for cleaning wastewater, simultaneously suggesting a useful way to manage and use industrial solid waste.