Synthesis of nanosheet layered double hydroxides at lower pH: Optimization of hardness and sulfate removal from drinking water samples

Abstract

A comprehensive study involving the use of Mg/Al layered double-hydroxide nanosheets (nLDHs) was conducted for the first time in simultaneous adsorption of sulfate and hardness agents from real drinking water. The prepared adsorbent was in nano size and synthesized by only hydrolysis of urea without any addition of alkali and in the presence of hydrogen peroxide. High concentrations of hardness and sulfate agents were used for the first time to evaluate the efficiency of the prepared adsorbent for both synthetic solution and real water sample. According to scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy, the synthesized adsorbent exhibited hexagonal plates with widths of 500 to 1500 nm and thicknesses of 30 to 100 nm. A multi-response optimization-based modeling and factor analysis were also performed for assessing the optimal conditions for several responses obtained within the framework of the present adsorption process. The optimum values of the three test variables were computed as pH(0) = 5.57, T-C = 119.9 min and C-0 = 10 g/L by using a multi-objective optimization algorithm, and the corresponding removal efficiency values were found to be 65.1% and 69.2% for hardness and sulfate, respectively. (C) 2014 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.