Optimization of Copper and Zinc ions removal from aqueous solution by modified Nano-bentonite using Response surface methodology

Presence of heavy metal ions in wastewater is an important public concern. Adsorption are commonly used technique to remove various pollutants, including the ions, from contaminated water sources. However, common methods for adsorption are not completely efficient at low ion concentrations and the adsorbent should be improved in order to reaching the acceptable levels of adsorption efficiency. We investigated removal of heavy metals (zinc and copper) ions based on modified clay. Bentonite is a type of clay that is mainly composed of montmorillonite. Modified nanobentonite adsorption efficiency was assayed using model solutions. Modified bentonite was gained by calcination at 600℃ for 2 hours. Response surface methodology (RSM) was used in combination with central composite design (CCD) to optimize the operating factors of the adsorption process. Operation time, adsorbent dosage, ion concentration and pH were the variables and percent reduction in the ions was the response. HCl and NaOH were used as chemical agents to adjust pH levels. Optimized operating conditions for Cu(II) and Zn2+ removal were: (Cu(II): initial concentration: 110.1 mg/L, pH: 7.3; time: 96.8 min and adsorbent dosage: 2.1 g/L, Zn2+: initial concentration: 105 mg/L, pH: 6.9, time: 73.1 min and adsorbent dosage: 2 g/L. Results and 3D plots exhibited significant proof to accept competence of the modified bentonite.