Calcium peroxide (CP) combined persulfate (PS) oxidation is an emerging in situ chemical oxidation (ISCO) technology for ground water remediation. Many field cases also confirm its effectiveness in ground water remediation while few research articles document it. This study investigated the performance of α-methylnaphthalene (MN) degradation by PS/CP to further understand this dual oxidant application in ISCO. Results showed that MN could be completely oxidized in 72 h with 1 g L −1 PS and 1 g L −1 CP. The degradation rates of MN increased with the increase of PS and CP concentration. MN degradation was significantly enhanced with the solution pH decrease, because CP was easier to dissolve and generated more radicals in acidic condition. Solutes in ground water including chloride ions, alkalinity and natural organic matters presented inhibitory effect on MN degradation in this dual oxidant system. Plausible mechanisms of the sulfate and hydroxyl radicals in the system were proposed based on the results of radical scavenging experiments and electron spin resonance (ESR) tests. It appeared that surface OH of CP was also responsible for the MN removal. The major oxidation products in this study were 1-naphthaldehdye, naphthalene-1-ylmethanol and 4-hydroxy-4-methylnaphthalen-1(4H)-one. To better understand PS/CP in ISCO, the degradation of MN was tested in ground water matrix, which showed satisfactory efficiency. The results of this study provided some detail information of PS/CP dual oxidant in degradation organic contaminants, which might provide some references for the application of this technology in ISCO.
Fangyuan Zhang,Mei Hong,Jing Bai,Zhi Liu,Aiyuan Jia,Zhisheng Liu,Can Shi,Yangxue Li
Levofloxacin (LEV) infiltrated in groundwater has threatened the safety of drinking water . For in-situ remediation of LEV-contaminated groundwater, there exists a main challenge of exploiting proper high efficient backfill medium in utilizing charming permeable reactive barriers (PRBs). Herein, three porous shapeable three-component hydrogen-bonded covalent organic aerogels (H C OA-1, H C OA-2 and H C OA-3) were fabricated based on a multiple-linking-site strategy to evaluate for adsorptive removal of LEV. The three H C OAs exhibited satisfactory performance in LEV adsorption that could integrate high adsorption capacity, good antiion interference, excellent recyclability and wide pH tolerance. The different regularity of kinetics and isotherms of three H C OAs signified that electrostatic effect, pore preservation, hydrogen bonding probably govern the adsorption process in combination, coupling with π-π electron-donor-acceptor (EDA), dipole-dipole and hydrophobic-hydrophobic interaction besides. In addition, the response surface methodology (RSM) was employed for studying the single and synergetic effects of selected variables and optimizing operation conditions. Furthermore, a laboratory PRB column packed with processable H C OA-2 was set up to investigate the LEV removal, and the breakthrough data was explained by Adams-Bohart, Thomas, BDST and Yoon-Nelson models. We believe could hopefully bring H C OAs into the real in-situ remediation of such challenging and persistent LEV-polluted groundwater with further massive-scale efficiently.
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