Low-Cost Carbon-Based Materials for Selective Removal of As(III) from Waste Waters

摘要

A low-cost carbon-based material from pyrolytic carbon from recycled tyres (PCrt) has been developed for selective removal of lead or arsenite from waste waters. The PCrt material has been characterized with X-Ray Fluorescence, XRD, And FTIR spectroscopies. Arsenite and Pb uptake was studied at the ppb level by Cathodic and Anodic Stripping Voltammetry (CSV). Adsorption isotherms, kinetic and pH-edge data show that PCrt can bind arsenite at a wide pH range from 4 to 9. More specifically, PCrt after mild treatment with HNO_3 and calcination at 500 C can adsorb 8.8 mg of As (III) and 27,7 mg Pb(II) per gram of material. PCrt can selectively uptake arsenite vs. lead when the two metals are present simultaneously in the aqueous solution. Importantly, when Pb is first adsorbed by PCrt, this forms PbS sites that act as additional arsenite binding sites. This is a unique example where one toxic metal, Pb(II), acts synergistically for adsorption of another toxic, As(III) on the appropriate matrix.