The investigation of removal of heavy metals in water with using Dogantarla tuff as natural adsorbent

The industrialization process cause to many heavy metal ions have been discharged into the environment as waste, which causes soil pollution and water pollution. The presence of heavy metal ions in water, even at very low levels, can cause damages to ecosystem and human life, because they are not biodegradable. With this reason, adsorption process for the removal of heavy metals was investigated in this study. The most noteworthy point of this study: tuff collected from the Doğantarla region, is used as a natural adsorban for such a purpose at the first time. Methods used to remove heavy metals from wastewater include reduction and precipitation, coagulation and flotation, adsorption, ion exchange, membrane technology, and electrolysis. Adsorption has the additional advantages of applicability at very low concentrations, suitability for using batch and continuous processes, ease of operation, little sludge generation, possibility of regeneration and reuse, and low capital cost. The adsorption behaviour of Doğantarla tuff has been studied in order to determine its removal efficiency of heavy metals solutions that containing Cu2+, Pb2+, Cd2+, Ni2+ and Zn2+ respectively. Tests to determine both the rate of adsorption and the uptake at equilibrium were performed under batch conditions from single component solutions. The effect of pH, temperature, agitation time, size of adsorban and amount of adsorban on the extent of adsorption was investigated. The Redlich-Peterson isotherm and pseudo-second-order model best fitted the adsorption data of Cd2+, Cu2+, Ni2+, Pb2+ and Zn2+. The maximum adsorption capacities (Qmax) of Doğantarla tuff as obtained from Langmuir adsorption isotherm were found to be 8.12, 12.00, 13.77, 16.00 and 18.31 (mg g−1) for the adsorption of metal ions in order of Ni2+ > Pb2+ > Zn2+ > Cd2+ > Cu2+. The experimental results demonstrate that the above selective order of adsorption capacity is due to formation of stable chelating ring between the natural Doğantarla tuff and metal ions. The rate constant of pseudo-second-order model were found to be 0.0028, 0.0661, 0.0503, 0.0498 ve 0.0469 g mg-1.min-1, respectively. G and H values were found to be -0.98, -2.85, -7.36, -7.23 and -4.01 kJ mole-1, and 27.14, 27.14, 4.73, 6.89 and 35.69 kJ mole-1, respectively. According to these values, the adsorption formed on the Dogantarla tuff was determined by physical adsorption.