A novel technique of dual modified acid-washed layered double hydroxides-biochar for adsorption and as potential catalysts for electrochemical applications

The enhanced concentration of nitrate ions in wastewater delivered from industries has led to consequential environmental issues and severe health problems for humanity. Considering the advantages to the environment and being cost-effective, adsorption techniques based on biochar materials have appeared as a remarkable strategy to adsorb nitrate. Although the porous nature of the biochar materials aids in adsorption, the stability is a significant hindrance, thus limiting nitrate adsorption. Thus, in an effort to tackle this difficulty, layered double hydroxide (LDH) modified with cationic surfactant rice husk biochar is utilized to enhance the stability and the performance of nitrate adsorption. In the current research, pristine biochar (Pure-BC), surfactant-modified biochar (BC-S), varying concentrations of iron and magnesium-modified LDH with surfactant biochar materials (FM-SL, MF-SL) were synthesized, and batch experiments were conducted in order to explore their performance of nitrate adsorption. The acid-washed biochar exhibited novel rapid adsorption within a period of 10 min and a maximum adsorption capacity of 72 mg/g at neutral pH, whose mechanism was based on both physical and chemical adsorption. Further, the pristine and modified biochar materials were analyzed for their electrochemical behavior in order to explore their chemical reactivity and electron transfer kinetics, with an overpotential value of 67 mV. Thus, the prepared biochar materials, being inexpensive, exhibit potential adsorbents for the adsorption of nitrate from industrial sewage waters and display better electrochemical characteristics.