Biochar Enhanced The Degradation Of Organic Pollutants Through A Fenton Process Using Trace Aqueous Iron

The Fenton process is among the most popular technique for oxidation of organic pollutants, but faces the challenges of slow Fe(III)/Fe(II) cycling, limited (OH)-O-center dot production, and the by-production of hazardous ironcontaining sludge. In this work, two biochars (LB700 and LB500) were added in a Fenton process using trace aqueous iron (0.2-1.8 mg/L), so as to enhance the degradation of organic pollutants while minimizing the production of iron-containing sludge. The results indicate that the addition of biochar in the Fenton process accelerated the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP). The pseudo-first order rate constants (Irobs) for 2,4-D degradation in the combined biochar and Fe(II)/H2O2 systems are enhanced to 3.09-4.97 times that in the homogenous Fe(II)/H2O2 system and 4.61-5.80 times that in the biochar/H2O2 systems. The mechanism investigations using electron spin resonance (ESR) and a chemical probe method indicate that addition of biochar increased the cumulative production of (OH)-O-center dot in Fenton system, and the high temperature biochar LB700 led to more (OH)-O-center dot production and consequently quicker 2,4-D degradation. The biochar can also facilitate the Fe(III)/Fe(II) cycling and initiate the Fenton-like oxidation of 2,4-D using trace aqueous Fe(III). This research work suggests a facile and environmentally friendly way to enhance the efficiency of advanced oxidation of refractory pollutants.