Novel Design of Amine and Metal Hydroxide Functional Group Modified Onto Sludge Biochar for Arsenic Removal

Abstract

Among the arsenic removal technologies, the adsorption method is found to be an efficient, inexpensive and simple method with obvious advantages and application value for arsenic removal in water. While, each method has its limitations, the traditional adsorption method used for arsenic removal due to its high operating cost and low adsorption efficiency. Consequently, this study explicitly designed sludge biochar (SB) adsorbed for arsenic removal with lower operation costs and higher adsorption efficiency properties. Generally, biochar only relies on micropores for pollutant adsorption, but physical adsorption is not highly efficient for arsenic removal. Therefore, in order to improve the removal efficiency of arsenic by SB, diethylenetriamine (DETA) and FeCl3 were used in this study to modify the surface of SB by an immersion method. The modified SB has not only pore adsorption characteristics but also electrostatic adsorption, oxidation-reduction and complexation characteristics. The objectives of this research are to obtain optimum operation conditions by assessing the effect of different Fe content, pH and initial concentration on adsorbing arsenic. The arsenic adsorption mechanism on SB was studied using Density Functional Theory (DFT) to understand the functional effect on arsenic adsorption. Results showed the presence of amine and iron oxyhydroxides functional greatly promoted SB surface activity and its arsenic adsorption potential. DFT model result is the same as the result of arsenic adsorption performance with the high adsorption energy. The reaction mechanism is divided into four pathways, including oxidation-reduction, complexation, electrostatic adsorption and pore adsorption.