Studies on batch adsorptive removal of cadmium and nickel from synthetic waste water using silty clay originated from Balochistan-Pakistan

The potentials of silty clay (SC), acquired from Chaman, Balochistan, were investigated as adsorbent for Ni (II) and Cd (II) removal from contaminated media. The influence of different operating factors like dose, pH, temperature, and time of contact was explored, and optimum values were noted under batch adsorption method. Isothermal study was conducted with varying concentrations of solutions on optimized conditions and different adsorption models i.e., Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherm, which were employed to interpret the process. The isothermal data of both Ni (II) and Cd (II) were well fitted to Langmuir isotherm suggesting the formation of monolayer of metal ions on silty clay. The values of adsorption capacity noted for Ni (II) and Cd (II) were 3.603 mg .g(-1) and 5.480 mg.g(-1), respectively. Kinetic studies affirmed that pseudo second order (PSO) kinetics was being obeyed by the removal of Ni (II) and Cd (II). Thermodynamic variables like free energy change (Delta G degrees), enthalpy change (Delta H degrees) and entropy change (Delta S) were calculated. The negative value of Delta G degrees and the positive values of Delta H degrees and Delta S degrees unfolded that the removal process of both metal ions of by SC was spontaneous, endothermic and feasible. (C) 2019 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.