多元金属氧化物对水中苯胂酸类污染物的吸附性能及机理

砷污染一直是全球关注的环境问题。以典型苯胂酸—阿散酸(p-ASA)为目标污染物,通过水热法制备了锌-铁-锆复合金属氧化物(ZnFeZrO_x)吸附剂,探究了ZnFeZrO_x对p-ASA的吸附行为和吸附机理。结果表明：在pH=4,吸附温度为60 ℃,ZnFeZrO_x投加量为2.2 g·L⁻¹,p-ASA初始质量浓度为50 mg·L⁻¹时,ZnFeZrO_x对p-ASA的去除率可达95.15%。该吸附过程符合Freundlich等温吸附模型和准二级动力学模型,最大吸附容量为595.23 mg·g⁻¹。而在吸附实际废水的实验中,ZnFeZrO_x对牲畜养殖废水中p-ASA的去除率仍保持在较高的水平(84.92%)。表征结果表明,ZnFeZrO_x在吸附过程中具有良好的化学稳定性,Fe-OH为主要吸附活性位点,Zn-O和Zr-O起到一定作用。ZnFeZrO_x具有良好的再生性能,重复使用3次后,对p-ASA的去除率仍能达到70%以上。     

Comparison of the degradation of p-hydroxybenzoic acid in aqueous solution by several oxidation processes

A comparative study is made of 12 methods of chemical oxidation applied to degrading p-hydroxybenzoic acid in aqueous solution. The oxidation processes tested were: UV, O3, UV/TiO2, O3/Fe2+, O3/H2O2, O3/UV, UV/H2O2, H2O2/Fe2+, H2O2/Fe2+/O3, UV/H2O2/O3, H2O2/Fe2+/UV and O3/UV/H2O2/Fe2+. The 12 processes were ranked by reactivity. In a kinetic study, the overall kinetic rate constant was split up into three components: direct oxidation by UV irradiation (photolysis), direct oxidation by ozone (ozonation), and oxidation by free radicals (mainly OH*).     

Ozonation of metoprolol in aqueous solution: ozonation by-products and mechanisms of degradation

This study investigated the degradation pathway of metoprolol, a widely used β-blocker, in the ozonation via the identification of generated ozonation by-products (OPs). Structure elucidation of OPs was performed using HPLC coupled with quadrupole time-of-flight high-resolution mass spectrometry. Seven OPs were identified, and four of these have not been reported elsewhere. Identified OPs of metoprolol included aromatic ring breakdown by-products; aliphatic chain degraded by-products and aromatic ring mono-, di-, and tetrahydroxylated derivatives. Based on the detected OPs, metoprolol could be degraded through aromatic ring opening reaction via reaction with ozone (O₃) and degradation of aliphatic chain and aromatic ring via reaction with hydroxyl radical (?OH).     

光催化-臭氧氧化降解H酸的研究

采用光催化-臭氧氧化技术(催化膜/UV/O3)降解H酸.研究结果表明,光催化与臭氧氧化相结合具有明显的协同作用.实验进一步讨论了臭氧投加量、废水初始pH值和H酸初始浓度对光催化-臭氧氧化降解H酸的影响.降解后的H酸,萘环结构被破坏,可生化性提高.     

光催化-臭氧氧化降解H酸的研究

采用光催化一臭氧氧化技术（催化膜／UV／O3）降解H酸。研究结果表明，光催化与臭氧氧化相结合具有明显的协同作用。实验进一步讨论了臭氧投加量、废水初始pH值和H酸初始浓度对光催化一臭氧氧化降解H酸的影响。降解后的H酸，萘环结构被破坏，可生化性提高。     

Simultaneous recovery of copper and degradation of 2,4-dichlorophenoxyacetic acid in aqueous systems by a combination of electrolytic and photolytic processes

In mixed industrial effluent the presence of metal ions can retard the destruction of organic contaminants and the efficiency of recovery of the metal is reduced by the presence of the organic species. Results are presented for copper-2,4-dichlorophenoxyacetic acid (2,4-D) system in which both effects occur. An electrochemical cell alone can be used to recover copper in the pH range 1.5-4.5 but it is not capable of achieving complete disappearance of 2,4-D by anodic oxidation. A photolytic cell alone can achieve the destruction of 2,4-D at pH 3.5 but leaves copper in solution. A combined photolytic-electrochemical system using an activated carbon concentrator cathode achieves the rapid simultaneous destruction of 2,4-D and recovery of copper. Results are presented for the recovery of more than 90% copper from, and >99.9%, destruction of the organochlorine compound 2,4-D in, a solution containing 100 mg dm(-3) copper and 50 mg dm(-3) 2.4-D. The photolytic degradation of 2,4-D depends on the intensity of the UV-probe. Only 19% degradation is achieved after 8 h with the 150 W UV-probe but the corresponding value with the 400 W UV-probe is 100%. In the case of 150 W UV-probe the degradation of 2,4-D proceeds through the formation of 2,4-dichlorophenol and phenol. The concentration of these intermediates are very low in the case of 400 W UV-probe because the speed of the degradation of 2,4-D is very fast. The addition of TiO2 (1 g dm(-3)), as a semiconductor material, and H202 (1.5 g dm(-3)) as an oxidant, increases the photolytic degradation of 2,4-D.     

Hydroxyl radical-mediated degradation of diclofenac revisited: a computational approach to assessment of reaction mechanisms and by-products

Environmental Science and Pollution Research - Advanced oxidation processes (AOPs) are based on the in situ production of hydroxyl radicals (•OH) and reactive oxygen species (ROS) in water...     

The use of artificial neural network (ANN) for the prediction and simulation of oil degradation in wastewater by AOP

The application of advanced oxidation process (AOP) in the treatment of wastewater contaminated with oil was investigated in this study. The AOP investigated is the homogeneous photo-Fenton (UV/H₂O₂/Fe⁺²) process. The reaction is influenced by the input concentration of hydrogen peroxide H₂O₂, amount of the iron catalyst Fe⁺², pH, temperature, irradiation time, and concentration of oil in the wastewater. The removal efficiency for the used system at the optimal operational parameters (H₂O₂?=?400 mg/L, Fe⁺²?=?40 mg/L, pH?=?3, irradiation time?=?150 min, and temperature?=?30 °C) for 1,000 mg/L oil load was found to be 72 %. The study examined the implementation of artificial neural network (ANN) for the prediction and simulation of oil degradation in aqueous solution by photo-Fenton process. The multilayered feed-forward networks were trained by using a backpropagation algorithm; a three-layer network with 22 neurons in the hidden layer gave optimal results. The results show that the ANN model can predict the experimental results with high correlation coefficient (R ²?=?0.9949). The sensitivity analysis showed that all studied variables (H₂O₂, Fe⁺², pH, irradiation time, temperature, and oil concentration) have strong effect on the oil degradation. The pH was found to be the most influential parameter with relative importance of 20.6 %.     

紫外/次氯酸钠和紫外/过碳酸钠工艺降解水杨酸的影响因素及降解机理

采用紫外/次氯酸钠(UV/NaClO)和紫外/过碳酸钠(UV/SPC)工艺降解水中水杨酸(SA),且利用协同因子(R)作为评价指标,分别考察了氧化剂投加量、pH、阴离子(NO₃^-、HCO₃⁻)和腐殖酸(HA)等因素对SA去除的影响,结合TOC对比了2种工艺对SA的去除效果,通过鉴定中间降解产物探讨了SA可能的降解路径。结果表明：UV/NaClO和UV/SPC工艺中SA的去除均符合拟一级反应动力学,R与拟一级反应动力学常数(k_obs)变化趋势相似。当NaClO和SPC质量浓度分别为 3 mg·L⁻¹和12 mg·L⁻¹时,2种工艺中k_obs分别为0.173 2 min⁻¹和0.258 8 min⁻¹,而 R_UV/NaClO和R_UV/SPC分别为9.5和15.9。k_obs和R随氧化剂投加量的增加而升高,因过量的SPC消耗产生的羟基自由基(·OH)会导致k_obs降低。初始pH对SA去除有较大影响,酸性环境有利于UV/NaClO工艺去除SA,而UV/SPC工艺则在pH=7具有较好的SA去除效果。NO₃⁻与HCO₃⁻对UV/NaClO工艺去除SA有轻微的促进作用,而显著抑制UV/SPC工艺对SA的去除。HA对2种工艺中SA的去除均有抑制作用。相比UV/NaClO,UV/SPC工艺对TOC去除更为显著。通过分析SA的密度泛函理论(DFT)并结合主要的降解产物推测SA的降解机理主要为自由基的取代和氧化。     

光催化电化学联合降解水中苯酚的研究

采用电化学、光催化联合工艺降解水中苯酚,在对其降解机理、反应动力学进行分析的基础上,考察了电解质浓度、电流密度及溶液pH等控制因素对降解速率的影响。实验结果表明：电化学和光催化同时作用时,产生了协同作用;以氯化钠为电解质可增强协同作用;光电联合工艺降解苯酚符合准一级反应动力学;弱酸性环境有利于降解反应的进行。在电流密度...     

用Nano-TiO2/O3和Nano-TiO2/UV/O3去除腐殖酸并控制臭氧副产物的生成

采用Nano-TiO2/O3和Nano-TiO2/UV/O3进行小试实验。通过对DOC、UV254、BrO3-和甲醛进行检测分析,研究了不同体系去除腐殖酸（HA）并控制臭氧副产物生成的效果。结果表明,当HA浓度为10 mg·L-1时,Nano-TiO2/O3体系对DOC的去除主要在反应进行20 min内完成,去除率仅达12.0%左右,对UV254的去除主要发生在2 min内,去除率仅达14.5%左右;而Nano-TiO2/UV/O3体系DOC和UV254的去除率分别达32.8%和53.3%。HA的存在显著减少了Nano-TiO2/O3体系BrO3-的生成量,出水BrO3-浓度为29.00 μg·L-1,而Nano-TiO2/UV/O3体系出水BrO3-浓度为5.00 μg·L-1。研究表明,相比Nano-TiO2/O3体系,Nano-TiO2/UV/O3体系能更好地控制BrO3-生成,同时能提高对HA的去除效果,且无甲醛生成的风险。     

挥发性溴代消毒副产物在不同水处理工艺过程中的变化

对中国沿海某市2个自来水厂的常规和深度水处理工艺过程中挥发性溴代消毒副产物的变化规律进行了研究。在选取的7种挥发性溴代消毒副产物中,只有一溴二氯甲烷、二溴一氯甲烷、二溴甲烷和三溴甲烷这4种被检出,除二溴甲烷只在深度水处理工艺过程中被检出外,其余3种化合物在2种不同水处理工艺过程中均有检出。一溴二氯甲烷和二溴一氯甲烷在常规和深度水处理工艺过程中的部分工艺段出水中的检出浓度超过了GB 5749-2006中规定的限值（饮用水中一溴二氯甲烷和二溴一氯甲烷的的浓度限值分别为60 μg·L-1和100 μg·L-1）,应被给予足够的重视。挥发性溴代消毒副产物在常规水处理工艺过程中的检出浓度随水处理工艺流程而逐渐升高,而在深度水处理工艺过程中检出的挥发性溴代消毒副产物（除二溴甲烷外）浓度变化则表现为随水处理工艺流程先轻微降低后大幅升高的趋势。与常规水处理工艺相比,挥发性溴代消毒副产物在深度水处理工艺过程中的检出浓度明显低于其在常规水处理工艺过程中对应工艺段出水中的检出浓度,但对于在常规和深度水处理工艺过程中均被检出的3种挥发性溴代消毒副产物来说,它们的最大值均出现在加氯后出厂水中。     

Kinetic degradation of the pollutant guaiacol by dark Fenton and solar photo-Fenton processes

This work is first intended to optimize the experimental conditions for the maximum degradation of guaiacol (2-methoxyphenol) by Fenton’s reagent, and second, to improve the process efficiency through the use of solar radiation. Guaiacol is considered as a model compound of pulp and paper mill effluent. The experiments were carried out in a laboratory-scale reactor subjected or not to solar radiation. Hydrogen peroxide solution was continuously introduced into the reactor at a constant flow rate. The kinetics of organic matter decay was evaluated by means of the chemical oxygen demand (COD) and the absorbance measurements. The experimental results showed that the Fenton and solar photo-Fenton systems lead successfully to 90% elimination of COD and absorbance at 604 nm from a guaiacol solution under particular experimental conditions. The COD removal always obeyed a pseudo-first-order kinetics. The effect of pH, temperature, H₂O₂ dosing rate, initial concentration of Fe²⁺, and initial COD was investigated using the Fenton process. The solar photo-Fenton system needed less time and consequently less quantity of H₂O₂. Under the optimum experimental conditions, the solar photo-Fenton process needs a dose of H₂O₂ 40% lower than that used in the Fenton process to remove 90% of COD.     

Biotic and abiotic degradation of illicit drugs, their precursor, and by-products in soil

This study presents the first systematic information on the degradation patterns of clandestine drug laboratory chemicals in soil. The persistence of five compounds - parent drugs (methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA)), precursor (pseudoephedrine), and synthetic by-products N-formylmethylamphetamine and 1-benzyl-3-methylnaphthalene) - were investigated in laboratory scale for 1 year in three different South Australian soils both under non-sterile and sterile conditions. The results of the degradation study indicated that 1-benzyl-3-methylnaphthalene and methamphetamine persist for a long time in soil compared to MDMA and pseudoephedrine; N-formylmethylamphetamine exhibits intermediate persistence. The role of biotic versus abiotic soil processes on the degradation of target compounds was also varied significantly for different soils as well as with the progress in incubation period. The degradation of methamphetamine and 1-benzyl-3-methylnaphthalene can be considered as predominantly biotic as no measureable changes in concentrations were recorded in the sterile soils within a 1 year period. The results of the present work will help forensic and environmental scientists to precisely determine the environmental impact of chemicals associated with clandestine drug manufacturing laboratories.     

Flue gas desulfurization by-products additions to acid soil: alfalfa productivity and environmental quality

Flue gas desulfurization (FGD) by-products are created when coal is burned and SO2 is removed from the flue gases. These FGD by-products are often alkaline and contain many plant nutrients. Land application of FGD by-products is encouraged but little information is available related to plant responses and environmental impacts concerning such use. Agricultural lime (ag-lime) and several new types of FGD by-products which contain either vermiculite or perlite were applied at 0, 0.5, 1.0, and 2.0 times the soil's lime requirement (LR) rate to an acidic soil (Wooster silt loam). The highest FGD by-products application rate was equivalent to 75.2 Mg ha(-1). Growth of alfalfa (Medicago sativa L.) was significantly increased compared to the untreated control in the second year after treatment with yields for the 1 x LR rate of FGD approximately 7-8 times greater compared to the untreated control and 30% greater than for the commercial ag-lime. Concentrations of Mo in alfalfa were significantly increased by FGD by-products application, compared to the untreated control, while compared to the ag-lime treatment, concentrations of B increased and Ba decreased. No soil contamination problems were observed, even at the 2xLR rate, indicating these materials can be safely applied to agricultural soils.     

Evaluation and comparison of advanced oxidation processes for the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D): a review

Environmental Science and Pollution Research - Organochlorine pesticides have generated public concern worldwide because of their toxicity to human health and the environment, even at low...     

Studies on degradation of glyphosate by several oxidative chemical processes: Ozonation,photolysis and heterogeneous photocatalysis

Several different Advanced Oxidation Processes (AOPs) including ozonation at pH 6.5 and 10, photolysis and heterogeneous photocatalysis using TiO₂ as semiconductor and dissolved oxygen as electron acceptor were applied to study the degradation of glyphosate (N-phosphonomethyl glycine) in water. The degree of glyphosate degradation, the reactions kinetic and the formation of the major metabolite, aminomethyl phosphonic acid (AMPA), were evaluated. Ozonation at pH 10 resulted in the maximum mineralization of glyphosate. It was observed that under the experimental conditions used in this study the degradation of glyphosate followed the first-order kinetics. The half-life obtained for glyphosate degradation in the O₃/pH 10 process was 1.8 minutes.     

Decomposition of 2-nitrophenol in aqueous solution by ozone and UV/ozone processes.

The decomposition of 2-nitrophenol in aqueous solutions by ozone and UV/ozone processes was found to be technically feasible under adequate experimental conditions. Formation of nitrate ions was observed following the decomposition of 2-nitrophenol by ozone and UV/ ozone processes. Increasing ozone dosage and UV light intensity accelerated the decomposition rate of 2-nitrophenol in an aqueous solution. The species distribution of 2-nitrophenol under various solution conditions plays a significant role in determining decomposition behavior. In most experiments conducted in this study, the decomposition of 2-nitrophenol by ozone and UV/ozone processes was favored to occur in alkaline conditions. The addition of 2-butanol accelerated the rate of gaseous ozone transfer to an aqueous phase by reducing the surface tension of aqueous solution and therefore enhancing the decomposition rate of 2-nitrophenol by ozone and UV/ozone processes.     

Fate of products of degradation processes: consequences for climatic change

The end products of atmospheric degradation are not only CO2 and H2O but also sulfate and nitrate depending on the chemical composition of the substances which are subject to degradation processes. Atmospheric degradation has thus a direct influence on the radiative balance of the earth not only due to formation of greenhouse gases but also of aerosols. Aerosols of a diameter of 0.1 to 2 micrometer, reflect short wave sunlight very efficiently leading to a radiative forcing which is estimated to be about -0.8 watt per m2 by IPCC. Aerosols also influence the radiative balance by way of cloud formation. If more aerosols are present, clouds are formed with more and smaller droplets and these clouds have a higher albedo and are more stable compared to clouds with larger droplets. Not only sulfate, but also nitrate and polar organic compounds, formed as intermediates in degradation processes, contribute to this direct and indirect aerosol effect. Estimates for the Netherlands indicate a direct effect of -4 watt m-2 and an indirect effect of as large as -5 watt m-2. About one third is caused by sulfates, one third by nitrates and last third by polar organic compounds. This large radiative forcing is obviously non-uniform and depends on local conditions.