Removing Pb(II) by means of natural and acid-activated nanoporous clays

Heavy metals such as Pb(II) are harmful to both the environment and human health as they are both toxic and stable. Bentonite clays contain Montmorillonite, which is a nano-porous and nano-structured mineral that can act to remove metals. In these experiments, natural bentonite S1 was activated using sulfuric acid solutions under various conditions with a range of Liquid to Solid ratios (L/S), Temperatures (T), Times (t) and Concentrations (C). The activated samples S2 (L/S= 16 mL/g, T=95 degrees C, t=4 h, C=5 M) and S3 (L/S= 16 mL/g, T=95 degrees C, t= 6 h, C=0.5 M) showed the highest and the lowest amounts of Pb(II) removal, respectively. The characterisation of natural and acid-activated bentonites in terms of Pb(II) separation applications were examined using Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), X-Ray fluorescence (XRF), Brunauer-Emmett-Teller (BET) surface area measurements, and Fourier Transform Infrared Spectroscopy (FTIR). Metal removal experiments were conducted using a suspension of 0.3 g suspended in 25 mL Pb(NO3)(2) solution under fixed solution concentrations of 2,000 mg/L. The suspensions were thoroughly mixed for 24 hours at 250 rpm. The results showed the removal capacities of samples followed the order of S2 > S3 > S1, and suggested that the prevailing Pb(II) removal processes were adsorption and ion exchange.