Phosphates removal from aqueous solutions by powdered marble wastes under static conditions

Powdered marble wastes (PMW) generated by marble industry with abundant amounts were used in this study as low-cost materials to investigate the phosphate anions removal from synthetic solutions. Batch assays were carried out to study the effect of some key parameters such as phosphates influent concentrations, contact time, PMW dosage, and pH on phosphate removal. The batch experiments results showed that PMW have relatively high phosphates adsorption capacity compared to several natural materials. Indeed, the adsorption capacity determined from Langmuir isotherm exceeds 35 mg g^-1. Furthermore, the adsorption process is favored for acidic pH values and also when increasing initial aqueous concentrations and marble wastes dosage. For an initial aqueous phosphates concentration of 100 mg L^-1, the removal efficiency is close to 90% for adsorbent dosage higher than 2 g L^-1. On the other hand, the adsorption modeling studies showed that phosphates adsorption is well described by second-order model and was essentially controlled by the boundary layer diffusion process. The cost effective and high adsorptive capability of PMW make them attractive and promising materials for phosphates anions removal and recovery from secondary treated wastewaters with the possibility of agronomic reuse as fertilizer.