An affordable green energy source—Evolving through current developments of organic,dye sensitized,and perovskite solar cells

Intensive R&D efforts made in solar photovoltaic area has enabled Si, GaAs, CdTe, and CIGS devices exhibiting nearly ideal efficiencies. However, cost incurred per unit energy does not allow them to qualify for alternate energy source besides environmental issues at production floors. Consequently, search is still continuing not only to reduce cost by improved efficiency, reduced materials cost, and simplified processing resulting in a cleaner and greener technology. Current successes in organic, dye-sensitized, and perovskite solar cells with efficiencies in 10–15% range raise concrete hope for evolving a low cost and green technology involving solution processable organic/inorganic compounds extendable to roll-to-roll production. The current status and future prospects of these three promising routes are reviewed here highlighting the possibility of an emerging alternate green energy source to supplement the conventional ones at commercial level.     

Photolysis of flumequine: identification of the major phototransformation products and toxicity measures

Direct photolysis of flumequine (FLU, 20 mg L⁻¹) in different types of water (demineralised water (DW) and synthetic seawater (SW)), was conducted in a Suntest CPS + solar simulator to evaluate its persistence and toxicity, and to identify the major phototransformation products (PTPs) generated during photolysis in DW. It was observed that FLU is susceptible to transformation when subjected to direct solar radiation. The composition of the water affects the FLU degradation kinetics, which is slower in SW. Photolytic transformation products generated during direct photolysis were identified by liquid chromatography-time of flight-mass spectrometry (LC-TOF-MS). Fourteen PTPs generated in DW were identified. The transformation of FLU begins with the opening of the heterocyclic ring by oxidation of the double bond. Loss of the fluorine atom and the hydroxylation of the aromatic ring also appear as the majority, especially in the early stages. Comparative acute toxicity evaluation by Vibrio fischeri and Daphnia magna bioassays was performed for the first and last irradiated solutions in both matrices studied. These bioassays demonstrated that in the SW matrix, the most persistent PTPs are highly toxic to D. magna but less so to V. fischeri.     

Effect of humic acids on photodegradation of chloroacetanilide herbicides under UV irradiation

The effects of two humic acids (HAs) of different origins on the photodegradation of the chloroacetanilide herbicides acetochlor, propisochlor and butachlor were investigated in this study. One of the tested HAs was a standard sample that was purchased from a commercial source, and the other was isolated from the black soil of Northeast China. The photolysis of all three herbicides followed pseudo-first-order kinetics under ultraviolet (UV) irradiation conditions, regardless of whether HAs were present or not. Both HAs improved the photolysis rates of acetochlor in a dose-reversed way, whereas they inhibited butachlor degradation under all experimental concentrations. The two HAs differed in their effects on propisochlor photolysis, changing from enhancement to inhibition, depending on the origin and concentration of HAs. Element and Fourier Transform Infrared spectroscopy analyses showed that the isolated HAs had more polysaccharides and less aliphatic groups than the commercial HAs, and it was indicated that some characteristic radicals (C═O, O─H and phenolic hydroxyls) in HAs were involved in the photolysis of the herbicides. Gas chromatography/mass spectrometry (GC/MS) analyses indicated that the presence of HAs had no effects on the photolysis pathway and photoproduct species of the three herbicides.     

可见光分解-氯碱氧化法去除废水中的铁氰化物

采用可见光分解（光解）-氯碱氧化法去除模拟废水中的Fe（CN）63-。考察了光解过程中反应时间、初始Fe（CN）63-质量浓度和初始废水pH对Fe（CN）63-去除效果及表观反应速率常数（k（Fe（CN）63-））的影响,以及光解-氯碱氧化法对Fe（CN）63-模拟废水中总氰化物（TCN）的去除效果。实验结果表明：在初始Fe（CN）63-质量浓度6.7 mg/L、初始废水pH 12、反应时间8.0 h的条件下,Fe（CN）63-的去除率为83%,光解过程符合表观一级动力学模型;在初始Fe（CN）63-质量浓度6.7 mg/L、初始TCN质量浓度4.90 mg/L、初始废水pH 12、反应时间12.0 h的条件下,采用光解-氯碱氧化法可使Fe（CN）63-模拟废水的TCN质量浓度降至0.14 mg/L,低于GB 16171—2012的要求（0.2 mg/L）,该过程的限速步骤为Fe（CN）63-的光解破络过程。     

紫外光(UV)光解油田采出水中多环芳烃

为了探讨紫外光光解人工模拟油田采出水中多环芳烃的降解效率,利用自制反应装置对油田采出水中多环芳烃(PAHs)的紫外光光解做了一个初步研究。研究结果证明,紫外光光解对油田采出水中的多环芳烃萘和芴有显著的降解能力。实验室的测试表明,与紫外UVA(365 nm)、UVB(308 nm)的光照相比,紫外UVC(254 nm)在光照60 min的条件下,2种多环芳烃各自的去除率都近似达到了99%。可见,在光解效力和暴露时间两方面,紫外UVC对采出水中萘和芴的去除具有相对稳定和比较高的效率。     

硝酸纤维素膜光降解水中对硝基苯酚的机制

为研究硝酸纤维素膜(NCM)作为新型污染物降解材料在水处理领域的应用潜力,本文以对硝基苯酚为目标污染物,NCM为活性氧物种来源,考察了溶液p H、光照条件、水体成分等因素对光解的影响及其作用机制.结果表明,NCM光致·OH量子产率为1. 30×10~(-4),是传统光催化材料TiO_2的1. 86倍.纯水中对硝基苯酚的直接光解速率仅为9. 52×10-4min-1,而在NCM存在情况下光解速率达到0. 005 5 min-1.这种促进作用主要是由NCM表面光致·OH引起的,其中UVA对光解起重要作用.水体酸性条件有利于NCM光解对硝基苯酚,在p H=2. 0时,降解率达到90%以上,相应的光解速率为0. 016 5min-1.对硝基苯酚的光解速率随光照强度、膜面积的增大而提高.水体成分对光解影响呈显著差异,NO-3可通过光致·OH的生成促进光解;而可溶性有机质主要通过滤光作用抑制对硝基苯酚的光解.气相色谱-质谱分析中间产物主要有苯酚、对苯二酚、丙二酸和草酸等,由此给出了可能的光解途径.     

布洛芬和双氯芬酸在不同构型人工湿地中的去除行为研究

在酸性药物中选取常用的布洛芬和双氯芬酸为典型对象,研究其在人工湿地中的去除行为,探讨不同工艺、有无植物、不同季节对其去除效果的影响.结果表明,工艺因素对二者的去除存在显著影响.其中,布洛芬在水平潜流和垂直潜流湿地中的平均去除率(分别为69%和60%)显著高于表面流湿地(26%),而双氯芬酸在表面流湿地中的平均去除率(58%)则显著高于水平潜流和垂直潜流湿地(分别为49%和43%).植物的存在可以显著提高布洛芬的去除率,对双氯芬酸的去除则无显著影响.配对样品t检验发现两种药物在夏季与秋季的去除效率无显著差异.双氯芬酸的去除效率与DO值、COD的去除效率呈极显著负相关,而布洛芬的去除效率与基质中好氧脱氢酶活性具有较好的正相关性,可能表明,布洛芬在湿地中主要通过好氧降解去除,双氯芬酸在湿地中的主要去除途径为光降解和厌氧降解.     

Degradation kinetics of tebufenozide in model aquatic systems under controlled laboratory conditions

Abstract

The hydrolysis of the insecticide tebufenozide was studied in the dark at 20 to 40°C in buffered (pH 4 to 10) distilled water, and at 20°C in unbuffered, sterilized and unsterilized stream water. Tebufenozide was very stable in acidic and neutral buffers at 20°C and the corresponding pseudo‐first‐order rate constants (k_obsd) and half‐lives (T_1/2) were 5.946 × 10^‐4 and 13.10 × 10^‐4 d^‐1, and 1166 and 529 d, respectively. The hydrolytic degradation was dependent on pH and temperature. At pH 10 and at 20,30 and 40°C, the k_obsd (10^‐4 d^‐1) and T_1/2 (d) values were 34.22, 66.72 and 130.0; and 203, 104 and 53.3, respectively. The energy of activation (E_a) values for the hydrolysis of tebufenozide at pH 4, 7 and 10, calculated from the Arrhenius plots, were 83.50, 66.71 and 50.87 kJ/mol, respectively. Tebufenozide was stable in sterilized stream water in the dark (T_1/2 = 734 d) but it degraded fairly rapidly in unsterilized stream water (T_1/2 = 181 d). Sunlight photodegradation of the chemical was slower (T_1/2 = 83.0 h) than the photolysis by ultraviolet radiations (T_1/2 values at 254 and 365 nm were 9.92 and 27.6 h, respectively); nevertheless, it was still appreciable during the summer months at 46°31’ N latitude. The differences in degradation rates between the unsterilized and sterilized stream water and the degradation of the chemical in the sterile, distilled water in sunlight, suggests that microbial processes and photolysis are the two main degradative routes for tebufenozide in natural aquatic systems.     

Photolysis pathway of nitroaromatic compounds in aqueous solutions in the UV/H2O2 process

IntroductionNitrobenzene (NB) was mainly used in theproduction of aniline, also used as a solvent inpetroleum refining, as well as used in the manufactureof other organic compounds such as dinitrobenzenes,dichloroanilines and acetaminophen (WHO, 2003).Nit…     

异丙草胺在水溶液中的光解动力学

常温条件下,用400W高压汞灯和太阳光分别照射处理异丙草胺水溶液,考察光照和初始浓度对异丙草胺在水溶液中光降解的影响研究表明,太阳光照射下,异丙草胺的光解反应符合一级动力学规律,降解速率相对很小,在石英试管中1h的光解率只有5.5%;汞灯照射条件下异丙草胺的光解过程可用双室降解模式来描述,1h时的光解率可达80.9%;异丙草胺的初始浓度越大,其光解率越小,降解产物的生成影响异丙草胺本身的光解进程.运用GC-MS技术鉴定出异丙草胺的主要光解产物有6种,光解过程中苯环保持完好,并推测了异丙草胺的光解反应机理.