Sulfidated zero-valent iron (S-ZVI) enhances the degradation of chlorinated hydrocarbon (CHC) in contaminated groundwater. Despite numerous studies of S-ZVI, a versatile strategy to improve its dechlorination kinetics, electron efficiency (ε e ), and dechlorination capacity is still needed. Here, we used heteroatom incorporation of N(C) and S by ball-milling of microscale ZVI with melamine and sulfur via nitridation and sulfidation to synthesize S-N(C)-mZVI bm particles that contain reactive Fe-N X (C) and FeS species. Sulfidation and nitridation synergistically increased the trichloroethene (TCE) dechlorination rate, with reaction constants k SA of 2.98 × 10 −2 L•h −1 •m −2 by S-N(C)-mZVI bm , compared to 1.77 × 10 −3 and 8.15 × 10 −5 L•h −1 •m −2 by S-mZVI bm and N(C)-mZVI bm , respectively. Data show that sulfidation suppressed the reductive dissociation of N(C) from S-N(C)-mZVI bm , which stabilized the reactive Fe-N X (C) and reserved electrons for TCE dechlorination. In addition to lowering H 2 production, S-N(C)-mZVI bm dechlorinated TCE to less reduced products (e.g., acetylene), contributing to the material's higher ε e and dechlorination capacity. This synergistic effect on TCE degradation can be extended to other recalcitrant CHCs (e.g., chloroform) in both deionized and groundwater. This multiheteroatom incorporation approach to optimize ZVI for groundwater remediation provides a basis for further advances in reactive material synthesis.

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Glutaraldehyde cross-linked chitosan-coated Fe 3 O 4 nanocomposites (MCNPs) were successfully synthesized for the removal of methyl orange (MO) from wastewater. Experimental conditions such as the pH, cation surfactant dosage, nanoadsorbent dosage, and ionic strength were also investigated. Kinetics date was better fit by a pseudosecond-order model, indicating that adsorption was the ratelimiting step. The Freundlich models (R 2 = 0.9794) fit the experimental data better than the Langmuir models, and the theoretical maximum adsorption capacity was 758 mg g −1 . The values of the Gibbs free energy (ΔG°= −7.27 kJ mol −1 ), enthalpy (ΔH°= 0.001 kJ mol −1 ), and entropy (ΔS°= 23.58 J mol −1 ) indicated the spontaneous and endothermic process of MO adsorption. The prepared MCNPs showed 96−98% adsorption of MO by adding 0.2 mg of cationic surfactant cetyltrimethylammonium bromide (CTAB) to form mixed hemimicelles and can be easily regenerated with a 0.1 mol L −1 HCl solution.