Rapid adsorption of Pb (II) and Cr (VI) from aqueous solution by Aluminum hydroxide nanoparticles: Equilibrium and kinetic evaluation

Abstract

Pollution of water due to excessive lead and chromium levels in groundwater and wastewater has contributed to severe health issues, which has increased concern over the provision of clean water. There is a dire need for successfully eliminating these pollutants through the use of low-cost and ecosystem-friendly materials. This paper reports the synthesis of aluminum hydroxide nanoparticles of 9.9 nm as calculated through X-Ray Diffraction (XRD) analysis. Fourier-transform infrared spectroscopy (FTIR) and pH of Point Zero Charge (pHPZC) were used to establish nanomaterial and surface charge formation on the material. The effects of the various parameters, i.e., the number of nano adsorbents, contact time, initial heavy metal concentration, and pH, were examined in detail on the lead and chromium removal rate. Kinetic studies were reported to fit better with the second-order kinetics model, and experimental adsorption equilibrium data fitted well with the Freundlich isotherm model under optimized conditions. The maximum removal of 95% for Pb(II) obtained for nano adsorbent dose was: 0.5 g/L, pH: 5.5, initial lead concentration: 10 mg/L at 30 min of contact time, and maximum removal of 97% for Cr(VI) for nano adsorbent dose: 1 g/L, pH: 5, initial: 15 mg/L and 60 min of contact time.