Removal of hexavalent chromium had attracted much attention as it is a hazardous contaminant. An electrocoagulation-like technology electro-reduction was applied. The chromium (VI) in the wastewater was reduced to chromium (III) by the electron supplied by electricity power and Fe2+, formed from corrosion of steel electrodes in acidic conditions. The mechanism and parameters affecting the reaction were investigated. The results optimized by response surface methodology indicated that the influence of single factor on the reduction efficiency followed the order: A: dosage of H2SO4 > C: reaction time > D: reaction temperature > B: current intensity. The reduction efficiency was hardly affected by current intensity, while it was increased with the increasing of reaction time and acid concentration. The reducing agent, Fe2+ an and extra free electron, acted as a reducing agent and could easily reduce hexavalent chromium to trivalent chromium at high temperatures in an acidic medium.

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Oxidative C−C/P−H cross-coupling is achieved via Pd-catalyzed decarbonylative cross-coupling of aroylhydrazides with P(O)H compounds. The unique cooperative reaction system, especially the Brønsted acid and bidentate phosphine ligand, allows the selective activation of the inert C−C bond and the suppression of the undesired oxidation and coordination of >P(O)−H compounds, leading to a general oxidative synthesis of aryl phosphorus compounds from easily available substrates.

A simple, efficient, and environmentally friendly electro-Fenton (EF) process is highly demanded for EF practical application. Herein, a highly practical double-cathode EF system has been developed: (1) KOH-activated graphite felt (AGF) for H2O2 production and (2) FeOCl-modified carbon cloth (FeOCl/CC) for H2O2 activation. The H2O2 production at the AGF cathode reaches 3.4 mmol/L in 60 min (pH 3, −0.6 V vs Ag/AgCl), and the FeOCl/CC cathode shows an excellent H2O2 activation performance where the removal percentage of tetracycline (TC, a rising refractory organic pollutant) reaches 98.2% in 5 min ([H2O2] = 1.0 mmol/L, C 0 = 10.0 mg/L, pH 3, and −0.8 V vs Ag/AgCl). The double-cathode EF system is proved by TC degradation. The removal percentage of TC achieves 96% in 20 min and total organic carbon (TOC) removal percentage reaches 92% in 2 h (C 0 = 10.0 mg/L, pH 5, and −0.6 V vs Ag/AgCl) in a static system. Furthermore, the system is highly effective in a wide pH range from 3 to 7. Significantly, in the continuous-flow system, the TC degradation percentage reaches 95% within 1.5 h, the mineralization reaches 88% within 4 h (C 0 = 10.0 mg/L, v = 4 mL/min, pH 5, and −0.6 V vs Ag/AgCl), and the performance remains highly stable even after prolonging for 15 h. The system has a high oxidative flux (1510 mg/(min m2)) and low energy consumption (45 kWh/(kg TOC)). Encouragingly, such a small-scale reactor (V = 100 mL, 4 mL/min) can treat 5.76 L of TC wastewater in one day. The toxicity of TC solution is remarkably reduced after EF treatment. This study would advance the practical application of an EF treatment process.