Heavy Metal Removal from Synthetics Wastes by Natural and Acid-Activated Bentonites

This paper examines heavy metals removal from synthetics wastes by the use of natural and sulfuric acid-activated bentonite so that a cheap adsorbent can be attained for removing these metals from the wastes. Bentonite is a 2:1 layer aluminnisilicate whose dominant mineral is montmorillonite which is a nano-structure and nanoporous material. Montmorillonite affects all the properties of bentonite. In the next step, the effect of acid activation on the adsorption of both of lead (Pb) and thallium (Tl) is studied. In this research, after the mineralogical and chemical composition analyses by X-ray diffraction and fluorescence (XRD and XRF) methods, granulometric analysis is carried out on five samples namely, S2-RAW, S3-RAW, ES3-RAW, G1-RAW and GH1-RAW to remove the heavy metals such as Cr, Co, Cu, Fe, Pb, Tl, Ni, and Zn accompanying atomic absorption spectroscopy (AAS). Then, the effect of four factors including concentration, liquid to solid ratio (L/S), time, and activation temperature in acid activation process were studied. This process is done by a mineral acid, sulfuric acid, to promote the adsorbability of lead and thallium in both natural and activated types of ES3-RAW and GH1-RAW. In all case, due to the presence of dominant mineral of nano-montmorillonite and its unique structure, montmorillonite has a higher adsorbability in comparison with that of the other clay minerals.