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While the β-lactam antibiotics are known to be susceptible to oxidative degradation by sulfate radical (SO), here we report that peroxymonosulfate (PMS) exhibits specific high reactivity toward β-lactam antibiotics without SO generation for the first time. Apparent second-order reaction constants (k) were determined for the reaction of PMS with three penicillins, five cephalosporins, two carbapenems, and several structurally related chemicals. The pH-dependency of k could be well modeled based on species-specific reactions. On the basis of reaction kinetics, stoichiometry, and structure-activity assessment, the thioether sulfur, on the six- or five-membered rings (penicillins and cephalosporins) and the side chain (carbapenems), was the main reaction site for PMS oxidation. Cephalosporins were more reactive toward PMS than penicillins and carbapenems, and the presence of a phenylglycine side chain significantly enhanced cephalosporins' reactivity toward PMS. Product analysis indicated oxidation of β-lactam antibiotics to two stereoisomeric sulfoxides. A radical scavenging study and electron paramagnetic resonance (EPR) technique confirmed lack of involvement of radical species (e.g., SO). Thus, the PMS-induced oxidation of β-lactam antibiotics was proposed to proceed through a nonradical mechanism involving direct two-electron transfer along with the heterolytic cleavage of the PMS peroxide bond. The new findings of this study are important for elimination of β-lactam antibiotic contamination, because PMS exhibits specific high reactivity and suffers less interference from the water matrix than the radical process.

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To improve the adsorption capacity, reduce the disposal cost, and enhance the separation efficiency of common activated carbon as an adsorbent in wastewater treatment, a novel thiol-modified magnetic activated carbon adsorbent of NiFe 2 O 4 -PAC-SH was successfully synthesized with a facile and safe hydrothermal method without any toxic and harmful reaction media. The as-prepared NiFe 2 O 4 -PAC-SH can effectively remove mercury(II) ions from aqueous solution. The maximal adsorption capacities from the experiment and Langmuir fitting achieve 298.8 and 366.3 mg/g at pH 7, respectively, exceeding most of adsorptive materials. The as-prepared NiFe 2 O 4 -PAC-SH has an outstanding regeneration performance, remarkable hydrothermal stability, and efficient separation efficiency. The data of kinetics, isotherms, and thermodynamics show that the adsorption of mercury(II) ions is spontaneous and exothermic. Ion exchange and electrostatic attraction are the main adsorption factors. The experimental results exhibit that the NiFe 2 O 4 -PAC-SH can be a prominent substitute for conventional activated carbon as an adsorbent.