Removal of Chlorinated Solvents in Groundwater Using Immobilized Nano Zero-Valent Iron for Advanced Oxidation Processes

Advanced oxidation processes (AOPs) are powerful methods for water treatment, particularly to eliminate organic contaminants. Developing novel catalysts with enhanced hydroxyl radical generation properties leads to improved efficiency of AOPs. In this study, nanoscale zero-valent iron (nZVI) immobilized in biochar (SBA-15) was synthesized using the two-solvent method. Several different samples were synthesized with different iron to silicon (Fe/Si) ratios and using different synthetic conditions including pH, and ultrasonication. The immobilization of ZVI nanoparticles in the biochar particles was confirmed using material characterization tools. The composition analysis results of nZVI/biochar samples verified the efficient use of materials and suggested a correlation of the synthetic conditions and the performance of the catalysts. The synthesized materials were tested for hydroxyl radical (•OH) production. The results revealed high •OH production, particularly when 500 mg/L of the catalyst sample was used. Addition of peroxymonosulfate ion to the reaction mixture resulted in a significant increase in •OH production. The best reaction conditions were tested for the degradation of trichloroethylene and tetrachloroethylene as model chlorinated solvents. Different reaction conditions were tested to simulate water quality conditions potentially found in real groundwater such as pH and ionic strength. The novel material investigated here showed interesting characteristics as Fenton-like reaction catalyst, and worth being assessed for further environmental applications, such as soil treatment, site restoration, or the removal of contaminants from wastewater effluents.