Remediation of phenol contaminated soil using persulfate activated by ball-milled colloidal activated carbon.

The degradation of phenolic compounds through persulfate (PS) activation is a valuable approach for soil/groundwater remediation. Several reports have been made related to PS activation and contaminant degradation using carbo-catalysts; however, there is no detailed study on soil remediation by colloidal activated carbon. This study demonstrates the phenol (PhOH) degradation efficiency in spiked and field-contaminated soils by a novel and low-cost ball-milled colloidal activated carbon (CAC) catalyst. The CAC/PS system exhibited outstanding degradation performance for PhOH in both spiked and field-contaminated soils. Optimum condition for degradation of 5.63 mmol PhOH kg soil was achieved at 2.5 mg CAC g soil, 5 mM PS, and a solid-liquid ratio of 1:5 at 25 °C in the wide pH range of 3-11. Radical scavenger experiments and electron spin resonance (ESR) spectroscopy revealed that both radical (OH and SO) and non-radical (O) species were involved in the CAC/PS system. PhOH degradation in soil phase followed several degradation pathways, resulting in various intermediate byproducts such as acetic acid, maleic acid, p-benzoquinone, fumaric acid, and ferulic acid as analyzed by ultra-high-performance liquid chromatography with mass spectroscopy (UPLC-MS). The CAC/PS system showed a promising potential in the remediation of organic-contaminated soil.