Development of adsorbents from used tire rubber: Their use in the adsorption of organic and inorganic solutes in aqueous solution

Using used tire rubber (UTR), carbonaceous adsorbents (CAs) were prepared by chemical treatment of the material with HCl, HNO3 and NaOH aqueous solutions and by heat treatment at 900 °C for 2 h in N2 atmosphere (H900). UTR and the UTR-derived products were first characterized in terms of texture by N2 adsorption at − 196 °C and of oxygen surface groups by FT-IR spectroscopy and pH of the point of zero charge (pHpzc). Then, the products were tested as adsorbents of phenol, p-aminophenol, p-nitrophenol, and p-chlorophenol and of chromium, cadmium, mercury and lead in aqueous solution. The development of porosity is very poor in UTR and in the chemically treated products. H900 is the only CA with a better developed porosity, mainly in the regions of meso and macropores. pHpzc is close to 7.0 for most of the CAs. As an exception to the rule, pHpzc is 8.4 for H900. For this CA, the adsorption of all the adsorptives is greater. Usually, adsorption kinetics are fast. This is so in particular for p-nitrophenol and p-chlorophenol, on the one side, and for mercury and lead, on the other side. Adsorption is much higher for mercury and lead than for the remaining adsorptives.