Hematite-titaniferous sand as a new low-cost adsorbent for orthophosphates removal: Adsorption, mechanism and Process Capability study

In this work, a new natural performing material Hematite-titaniferous sand (HTS) is used to study the adsorption of Orthophosphates, and to obtain the optimum conditions for maximum removal. The adsorbent used was characterized and inspected employing (XRD) X-ray diffraction, (XRF) X-ray fluorescence, (SEM) scanning electron microscopy coupled with (EDS) energy dispersive X-ray spectroscopy and (FTIR) Fourier-transform infrared spectroscopy. The adsorption of Orthophosphates on Hematite-titaniferous sand has found to be dependent on different variables such as contact time, solution pH, solution temperature and initial concentration. These variables were investigated using Batch Method. According to the results of the experiments in this research, adsorption kinetic was found to adopt the pseudo-second order kinetic model, which was the best appropriate model to describe the adsorption process. It was found that the Langmuir isotherm model fitted the adsorption data with the highest correlation (R-2 > 0,99) at various temperatures. The adsorbed amount was found to be 0,612 mg/g. The thermodynamic parameters explain that the adsorption is spontaneous and favorable. Moreover, the optimum conditions were found to be pH = 5, 1500 mg of adsorbent and a contact time of 120 min at adsorption temperature T = 45 degrees C +/- 1. The process capability study demonstrated that the adsorption process was capable, and was stable for large-scale application. (C) 2018 Elsevier B.V. All rights reserved.