MoS2 boosts the Fe2+/PMS process for carbamazepine degradation.

Activation of peroxymonosulfate (PMS) by Fe2+ is a green oxidation process for degradation of organic contaminants. However, the formation of iron mud and low PMS utilization lead to the decreased oxidation efficiency. In this work, commercial MoS2 particles were used as the catalyst for boosting the Fe2+/PMS process for carbamazepine (CBZ) removal. The CBZ removal efficiency by the MoS2/Fe2+/PMS process was significantly enhanced, increasing to 6.5 times that of the Fe2+/PMS process. The Fe3+ was reduced to Fe2+ by the exposed Mo4+ on the surface of MoS2, leading to the enhanced PMS utilization rate and increased Fe2+ concentration. The relative intensity of DMPO-HO• and DMPO- SO4-• followed the order of MoS2/PMS < Fe2+/PMS < MoS2/Fe2+/PMS, also suggesting the enhanced oxidation activity with the addition of MoS2 in the process of Fe2+/PMS. The commercial MoS2 had good stability shown by the CBZ removal efficiency remaining almost unchanged during 8-time cycling use. Finally, a possible CBZ degradation pathway was proposed for helping understand the oxidation mechanism of the MoS2/Fe2+/PMS process.

Inhibition of typical phenolic compounds entering into condensed freshwater by surfactants during solar-driven seawater distillation.

Recently, solar-driven seawater desalination based on air-water interfacial heating has triggered significant research interest due to its high water evaporation rate, high photothermal conversion efficiency, low energy consumption, simple operation and low cost. However, as the air-water interface temperature reaches as high as 40-70 °C, volatile organic compounds (VOCs) will volatilize into the condensed desalinated water and results in the polluted freshwater. In this work, anionic, cationic, and nonionic surfactants were applied for the first time to inhibit the phenolic compounds such as phenol, p-methylphenol and p-chlorophenol entering into the condensed freshwater. Results showed that the concentration of phenol could be reduced by the addition of cetyl trimethyl ammonium bromide (CTAB). The phenol's distillation concentration ratio (RD) reduced from 76% to 35% due to the electrostatic interaction and the micellar encapsulation between the CTAB and phenol. Moreover, parameters including CTAB dose, initial phenol concentration, solar intensity, pH, and salinity that affecting the RD were also investigated. Finally, a real seawater solar-driven distillation experiment also revealed that the water quality of freshwater was improved by the addition of CTAB. This work revealed that the surfactants such as CTAB can be potentially used to inhibit VOCs entering into the condensed freshwater during solar-driven seawater distillation.

Microstructure and Soil Wear Resistance of D517 Coating Deposited by Electric Spark Deposition.

The abrasion failure is the key factor for prolonging the service life and energy saving of furrow openers. The hardness enhancement was reported to be an effective strategy to increase the wear resistance against the soil abrasion. D517 coatings were deposited on Q235 steel by electric spark to improve the wear-resistant property with an affordable cost for farmers. The wear behavior of the coatings was characterized in a pin on disk friction equipment and a homemade soil abrasion simulation system. The soil adhesion, which is highly related to energy consumption, was also evaluated. Results showed that D517 coatings revealed dendrite structure with some randomly distributed carbides. The electric current exerted a great influence on the microstructure, hardness, friction coefficient, and soil wear rate. The wear rate of samples deposited with 80 A and 90 A reduced to 79% and 84%, respectively, as compared with the normalized heat-treated 65 Mn steel after 6 h in soil. This work provides a promising solution to increase the wear resistance of furrow openers. It needs to be noted that the coating would increase the soil adhesion of the opener, which needs to be further explored to decrease the energy consumption.

g-C3N4/MoS2 based floating solar still for clean water production by thermal/light activation of persulfate.

Currently, seawater desalination based on air-water interface solar heating has triggered significant research interests because it effectively makes use of the solar energy and avoids fossil fuel consumption. However, to prevent the volatile organic compounds (VOCs) from volatilizing with water vapor which later will liquefy and enter the condensed freshwater is still a challenge. In this work, a g-C3N4/MoS2 based floating solar still (CM-FSS) combined with thermal/light activation of persulfate (PS) at air-water interface was applied for clean freshwater production for the first time. The CM-FSS was composed of a g-C3N4/MoS2 top layer for solar absorption, simultaneous thermal/light activation of PS and then VOCs degradation at air-water interface, a floating layer of expandable polyethylene (EPE) foam for heat isolation, and a transport channel of air-laid paper (ALP) for seawater and PS solution delivery. The water evaporation rate of the CM-FSS was measured at 1.23 kg m-2 h-1 under 1 kW m-2, which is 4.09 times higher than that of pure water without an evaporator. With the assistance of g-C3N4/MoS2 photocatalytic degradation and thermal/light activation of PS at the air-water interface, a high removal efficiency of a selected model VOCs pollutant of nitrobenzene (NB) could reach to 98.2% in condensed freshwater. Finally, when real seawater samples were employed as source water for solar distillation, the typical water-quality indices such as salinity, turbidity, anions, cations and organics of the condensed freshwater were below the limit values of the Standards for Drinking Water Quality in WHO, US EPA and China.