Abstract
This study involved novel-designed sludge biochar (SB) adsorbed for arsenic removal with lower operating 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 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. This study is the first to use Density Functional Theory (DFT) to simulate and verify the adsorption mechanism of arsenic by SB. Results showed the presence of amine/iron oxyhydroxides functional groups greatly promoted SB surface activity and its arsenic adsorption potential. The surface area, pore volume and pore size of the SB were estimated to be 525 m2 g-1, 0.35 cm3 g-1 and 8.71 nm, respectively. The DFT model result is the same as the result of arsenic adsorption performance with high adsorption energy (-246.3 kJmol-1) and shorter bond distances (1.42 Å), indicating strong chemical adsorption between arsenic and material. The reaction mechanism is divided into four pathways, including oxidation-reduction, complexation, electrostatic adsorption and pore adsorption.
Highlights
Warming of the earth is considered as the major adverse effect of climate change along with other abnormalities such as nonavailability of water resources, rise in seawater level, glaciers melting, and loss of biodiversity
The isotherms belonged to Type IV in the definition of International Union of Pure and Applied Chemistry and indicated that N2 is condensed in the pores at high relative pressures
The results clearly demonstrate the feasibility of using urban sludge as a carbon source to produce biochar
Summary
Warming of the earth is considered as the major adverse effect of climate change along with other abnormalities such as nonavailability of water resources, rise in seawater level, glaciers melting, and loss of biodiversity. Over the years, decreased agriculture production and water quality degradation have been observed due to climatic abnormalities. Crop production is highly sensitive to climate. It gets affected by long-term trends in average rainfall and temperature, annual climate variations, shocks during different stages of growth, and extreme weather events (Srivastav et al 2021). Water recycling and water conservation is under one of the sustainable development goals. Heavy metals are one of the most hazardous inorganic contaminants of both water and soil environment composition.
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