Purification Of Organic Pollutants Research Articles

One-Step Fabrication of Flower-Like ZnWO4/BiOBr Nanospheres with Enhanced Photocatalytic Degradation Efficiency

Flower-like zinc tungstate/bismuth bromate (ZnWO4/BiOBr) nanospheres were synthesized by a one-step hydrothermal method. The photocatalytic activity of the ZnWO4/BiOBr heterojunction was evaluated by the photocatalytic degradation of 30[Formula: see text]mg/L of rhodamine B (RhB). It was found that 10% of ZnWO4/BiOBr had the best degradation ability toward RhB. The degradation rate of RhB reached 97.7% (5 times and 358 times those of BiOBr and ZnWO4, respectively) after light-emitting diode (LED) visible light irradiation for 30[Formula: see text]min. The ZnWO4/BiOBr heterojunction had excellent photocatalytic activity because of its higher specific surface area and enhanced spectral response range. Moreover, the ZnWO4/BiOBr heterojunction improved the charge separation efficiency and promoted the generation of more holes, [Formula: see text] O[Formula: see text] and [Formula: see text] OH radicals under light irradiation; thus, improving the degradation efficiency. Finally, a possible photocatalytic degradation mechanism was proposed. This study provides a good reference for the preparation of bismuth-based composite photocatalysts for the degradation and purification of organic pollutants.

Influences of charge properties and hydrophobicity on the coagulation of inorganic and organic matters from water associated with starch-based coagulants

In this work, two series of binary graft cationic starch-based coagulants (CS-DMCs and CS-DMLs) with different hydrophobicities and charge densities (CDs) were prepared by graft copolymerization of acrylamide with 2-(methacryloyloxy)-N,N,N- trimethylethanaminium chloride and acryloyloxyethyl dimethyl benzyl ammonium chloride, respectively, on the starch (St) backbone. Kaolin particles, sodium humate (NaHA), and bovine serum albumin (BSA) were used as the simulated sources of inorganic colloidal particles and different organic pollutants in the micropolluted turbid surface water. The influences of the CD and hydrophobicity associated with the St-based coagulants on the removal of kaolin particles, NaHA, and BSA from single, binary, and ternary pollutant aqueous systems were investigated systematically. On the basis of the apparent coagulation performance, the floc characteristics, and the zeta potentials of the supernatants after coagulation, the coagulation mechanisms associated with the structural features of the St-based coagulants and the pollutants treated were explored and discussed in detail. The St-based coagulants with a higher CD and a stronger hydrophobicity showed better coagulation performance due to the synergistic effects of charge neutralization and hydrophobic association. The maximum efficiencies of the optimized St-based coagulant in removal of Kaolin, NaHA and BSA were 93.85%, 100% and 97.52% in their respective single pollutant systems. In addition to these simulated water samples, a real micropolluted turbid surface water tested and compared, further confirming the superiority of the hydrophobically modified cationic St-based coagulants, especially in the purification of organic pollutants in water.

Purification of organic pollutants in cationic thiazine and azo dye solutions using plasma-based advanced oxidation process via submerged multi-hole dielectric barrier discharge

Due to industrialization and population growth, water shortage has emerged as a critical global issue. Pollution of existing water supplies is a critical part of this issue, and organic contaminants are one of the main causes of water pollution. The non-thermal plasma-based advanced oxidation process (AOP) is one of the most widely studied and best developed processes owing to its simple structure and ease of operation. In this study, a plasma-based AOP was stably generated using submerged multi-hole dielectric barrier discharge (DBD) and added to an aqueous solution. Using a plasma system, the complexity of the process for generating hydroxyl radicals (OH) can be simplified by allowing ozone, hydrogen peroxide, ultraviolet light (UV), and OH to be generated simultaneously in one device. The electrical properties and concentrations of the active species were analyzed to establish optimal plasma operating conditions. Among the organic pollutants, methylene blue (MB) and methyl orange (MO) were selected as experimental targets because they are representative cationic thiazine and azo dyes, respectively. The results were analyzed by measuring the absorbance of UV–Vis, total organic carbon (TOC), chromaticity, and changes in solution properties. The effects of hydroxyl radical (OH) scavengers (D-mannitol) on the MB and MO degradation rates were also investigated. Based on these results, degradation mechanisms of MB and MO are proposed. After 3 min of plasma treatment, the concentration, chromaticity, and TOC of MB and MO rapidly decreased. Consequently, we believe that plasma-based AOP using submerged multi-hole DBD has advantages as an alternative technology for treating organic pollutants.

The synergistic effect of Ag/AgCl@ZIF-8 modified g-C3N4 composite and peroxymonosulfate for the enhanced visible-light photocatalytic degradation of levofloxacin

In this work, a series of Ag/AgCl@ZIF-8 modified g-C3N4 composites were synthesized and used to degrade levofloxacin (LVFX) in water under visible light irradiation with the assistant of peroxymonosulfate (PMS). The morphologies and physicochemical properties of the materials were characterized by SEM, TEM, XRD, XPS, FTIR, and DRS technologies. The results of photocatalytic experiments showed that in the presence of PMS, the degradation rate of LVFX reached 87.3% in 60min. Furthermore, factors affecting photocatalytic efficiency such as the concentration of PMS, photocatalyst dosage and different pH values were investigated. The degradation products of LVFX were analyzed by LC-MS and the degradation pathway was inferred. Active species trapping experiments indicated that O2–, h+ and SO4− played important roles in the degradation process in the presence of PMS and the possible degradation mechanism was put forward. This work provides a photocatalyst system that is beneficial to the separation of photogenerated carriers and demonstrates the great potential of PMS-assisted photocatalysis in the purification of organic pollutants.

Au-BiOCl1−xBrx composites with highly enhanced photocatalytic activity for phenol decomposition

Au nanoparticles (Au NPs) were deposited onto BiOCl1−xBrx nanosheets by using a facile ultrasonic treatment. The obtained Au-BiOCl1−xBrx composites exhibit excellent photocatalytic property in the reaction of decomposing phenol aqueous solution under simulated solar light irradiation. There is a positive relationship exists in the surface plasmon resonance (SPR) of Au NPs and enhanced activities, which is contributed to the separation of photo-induced electrons and holes as well as facilitate the absorption of visible light. In addition, the tunable energy band structure might be beneficial to enhance the photocatalytic activities of Au-BiOCl1−xBrx composites for optimizing the bandgap. And the OH and h+ species were the main active species in photocatalytic reactions. In this paper, the Au-BiOCl1−xBrx photocatalysts were demonstrated to be a promising material for practical applications in the purification of organic pollutants.

Preparation and Study on Photocatalytic Activity of N-doped TiO2 Decorated N-doped graphene

Titanium dioxide (TiO2) is generally considered to be one of the most promising photocatalysts in the purification of organic pollutants in air or water. To improve its performance, N-doped TiO2 samples decorated with N-doped graphene are prepareted via sol-gel method. The samples are characterized by XRD, XPS and SEM. The photocatalytic activity of the composite materials is evaluated by photocatalytic degradation of methylene blue aqueous solution, a typical organic pollutant. The experimental results are as follows: 1) the samples or the N-graphene/N-TiO2 composite materials have better degradation efficiency than TiO2 doped with N element; 2) Either too much or too little loading of graphene is not conducive to the photocatalytic efficiency of composite materials; 3) Temperature actually affects the optimal loading of graphene; 4) N-RGO (0.5wt%)/N-TiO2-400℃ has the highest photocatalytic efficiency and good stability.

スポンジ担体を用いた傾斜土槽法による有機性汚濁物質と栄養塩類の同時浄化

スポンジ担体を用いた傾斜土槽法による有機性汚濁物質と栄養塩類の同時浄化

Synthesis of BiOI nanobelt and its visible‐light photocatalytic activity

BiOI nanobelts were synthesised by a one-pot solvothermal process in the presence of [Bmim]I. As-synthesised BiOI nanobelts showed higher photocatalytic activity in the aqueous RhB photodegradation system than BiOI nanosheets under visible-light irradiation. It could be widely used for the environmental purification of organic pollutants in an aqueous solution.

Land spreading of manure from animal production units

In order to quantify the manure output from pig fattening houses, a computer simulation model of a group of pigs has been devised, using empirical ratios of output to dietary input. Values from the model, and from different sources for other animals, are used in a second simulation model of land spreading of manure. This is designed to indicate, in any particular farming situation, the maximum hydraulic and chemical loading rates, that may be applied without producing subsequent water pollution, or soil and crop damage. Purification of organic pollutants is confined to the topsoil by precluding land spreading when the soil is saturated or the temperature is too low for rapid degradation of organic matter. Maximum hydraulic loading is assessed as a balance between rainfall and evapotranspiration. Maximum chemical loading is dependent upon the expected removal of fertilizer nutrients in the crop to which manure is applied.