study of nickel removal on raw and acid activated nanostructure montmorillonite

چکیده مقاله

Heavy metals like nickel for human health are harmful due to their toxicity and stability and are contaminating to the environment through some industrial processes such as nickel alloys, oil and coal-burning power plants, trash incinerators, mineral processing, paint formulation, electroplating, and porcelain enameling. The toxicity of nickel causes some fatal diseases such as chronic bronchitis, emphysema, impaired lung function and lung cancer. In this study, raw bentonite from Ghaen (I. R. Iran) and its acid activated has been used as the adsorbent for the removal of Ni+2 ions from wastewater. Raw bentonite was activated using 2 and 6 M concentration of sulfuric acid for 4.5 to 6 h at 95°C. The samples were characterized using X-ray diffraction (XRD), X–ray fluorescence (XRF), fourier transform infrared spectroscopy (FTIR), Brunauer Emmett and Teller (BET) and Indutively Coupled Plasma (ICP). The effect of pH, temperature of reaction, presence of other ions, rate of shaking, initial metal concentration, and equilibrium contact time were studied. The equilibrium time of contact for bentonite was obtained about 180 min. The sorption kinetics of Ni+2 was analyzed by kinetic models. The experimental results showed that the best fit is obtained with the pseudo-second order kinetic model. Also, the experimental results have been explored by different adsorption isotherm models. The results indicated that the Langmuir and Florry–Huggins models provided good fit with experimental data for the raw and acid activated bentonites, respectively.