Activated carbons which prepared from residual or waste biomaterials are widely examined as low-cost adsorbents for wastewater treatment, as well as heavy metal ions in wastewater have become a serious environmental problem. In addition, the removal efficiency of new cheap modified adsorbent from agricultural waste is important and would probably increase the quality of the environment. Therefore, it is necessary to investigate the understanding of adsorptive removal mechanism and removal efficiency of the adsorbent.
This study is aimed to evaluate the removal efficiency of Pb(II), Ni(II), Zn(II), and Cd(II) in aqueous solution by using a modified sunflower seed husk (MSSH) for industrial wastewater treatment. The husk as an adsorbent was treated by 0.8 M K2CO3, afterward; it was heated at 400 °C, sieved to a size of 500 to 710 µm (400-K2CO3MSSH). As a result, it was found that the Methylene blue number of 400-K2CO3MSSH was 50.80 mg/g and the Iodine number was 808.54 mg/g. The adsorption experiments were conducted with an initial metal ion concentration of 100 mg/L and pH of 5. In a batch experiment of single metal ion synthetic wastewater, it was observed that the adsorption percentage of Ni(II), Zn(II), Pb(II), and Cd(II) were 96.50, 97.03, 96.98, and 97.54, respectively. For mixed synthetic wastewater, the adsorption percentage of Ni(II), Zn(II), Pb(II), and Cd(II) were 87.16, 94.30, 98.02, and 97.01, respectively. Competitive adsorption decreased the removal of metal ions, and the equilibration time was showed longer result than that in the single system. Wastewater from the automotive industry was consisted of Ni(II), and Zn(II) which had the percentages of removal at 75.25 and 87.50, respectively. Whereas the lathe work demonstrated the percentage of Zn(II) and Pb(II) at 78.18 and 88.34 of removal. Experimental results were found that the Langmuir isotherm model was matched with a monolayer adsorption capacity per g adsorbent of 79.37 mg Ni(II), 76.34 mg Zn(II), 74.07 mg Pb(II), and 81.97 mg Cd(II). From our results, it can be concluded that 400-K2CO3MSSH could be potentially used as an attractive low-cost adsorbent for Ni(II), Zn(II), Pb(II) and Cd(II) containing industrial wastewaters.