Improved dark ambient degradation of organic pollutants by cerium strontium cobalt perovskite

This work investigates the effect of cerium substation into strontium cobalt perovskites(CeSrCoO) for the oxidative degradation of Orange Ⅱ(OII) in dark ambient conditions without the aid of any external stimulants such as light,heating or chemical additives.The OII degradation rate by CeSrCoO reached 65% in the first hour,whilst for the blank sample without cerium(SrCoO) took over 2 hr to reach the same level of OII degradation.Hence,the cerium substitution improved the catalytic activity of the perovskite material,mainly associated with the Ce_(0.1)Sr_(0.9)CoO_3 perovskite phase.Upon contacting CeSrCoO,the-N=Nazo bonds of the OII molecules broke down resulting in electron donation and the formation of by-products.The electrons are injected into the CeSrCoO and resulted in a redox pair of Co~(3+)/Co~(2+),establishing a bridge for the electron transfer between OII and the catalysts.Concomitantly,the electrons also formed reactive species(·OH) responsible for OII degradation as evidenced by radical trapping experiment.Reactive species were formed via the reaction between 02 and donated electrons from OII with the aid of cobalt redox pair.As the prepared materials dispensed with the need for light irradiation and additional oxidants,it opens a window of environmental applications for treating contaminated wastewaters.     

Direct electrochemical detection of glyphosate at carbon paste electrode and its determination in samples of milk,orange juice,and agricultural formulation

Abstract

This paper describes a simple, inexpensive, highly sensitive, selective, and efficient electrochemical method to determine glyphosate (GLY) in samples of milk, orange juice, and agricultural formulation. The oxidation reaction on the electrode surface was electrochemically characterised by cyclic voltammetry (CV) and square wave voltammetry (SWV). The investigation of GLY at carbon paste electrode revealed a non-reversible oxidation peak at +0.95 V versus Ag/AgCl, which was used for electrochemical detection of GLY. The operating parameters (pH, frequency, step potential, and amplitude) were optimised in relation to the peak current intensity, and a calibration curve was set up in a concentration range of 4.40?×?10^?8–2.80?×?10^?6 mol L^?1, with a detection limit of 2?×?10^?9 mol L^?1. After calibration curve was plotted, the developed procedure was applied to determine GLY in previously contaminated samples: milk and orange juice, and in a commercial formulation, obtaining recovery values between 98.31% and 103.75%. These results show that the proposed method can be used for GLY quantification in different samples with high sensitivity, specificity, stability, and reproducibility.     

一个适宜发展脐橙的区域

这是一篇关于三峡低山河谷脐橙引种栽培情况的调查报告。本文简略地介绍了三峡地区的地理和气候概况,报道该区域引种栽培试验的脐橙产量和品质的情况,也论证了脐橙对该区气候的适应性。通过论证说明了三峡低山河谷是一个很适宜商品性脐橙生产的区域。     

PSF多相UV-Fenton体系原儿茶酸与龙胆酸的增效对比

对比研究了原儿茶酸和龙胆酸对聚合硅酸铁（PSF）多相UV-Fenton体系降解橙Ⅱ的增效能力,分析了两种增效体系中铁离子转化、H₂O₂分解以及·OH生成之间的关系,探讨了两种增效试剂对PSF多相UV-Fenton体系的增效机制.结果表明：原儿茶酸和龙胆酸均能够有效促进催化剂Fe²⁺生成与释放,进而提高体系·OH的浓度、促进橙Ⅱ的降解.相对原儿茶酸,龙胆酸对PSF的还原能力更强,其相应增效体系中·OH的浓度更高、橙Ⅱ的降解速度更快.0.2mmol/L的增效浓度下,橙Ⅱ在原儿茶酸和龙胆酸增效体系中第一段脱色速率常数能分别从基础体系的0.11min^-1提高至1.68和2.48min^-1,分别增加14.27倍和21.55倍.原儿茶酸和龙胆酸能够循环增效PSF多相UV-Fenton体系降解橙Ⅱ,反应结束后PSF对Fe³⁺的再吸附使得溶液总铁离子浓度低于5mg/L,从而避免催化剂铁元素的损失以及铁离子的二次污染,表明原儿茶酸和龙胆酸均是PSF多相UV-Fenton体系的高效增效试剂.     

柑橘皮中果胶提取条件的研究

利用酸性水解乙醇沉淀法提取果胶,分别测定了不同的浸泡时间、酸碱度及水解温度对果胶产率的影响.结果表明:浸泡时间与水解时间过长或过短,酸碱度及水解温度过高或过低,果胶的产率均不高,只有浸泡时间在2h左右、水解时间在2～2.5h、pH在2～3之间、水解温度在80～95℃时果胶的得率最大.     

TiO_2-SO_4~(2-)/Glass光催化降解甲基橙溶液的方法

研究以平玻璃和毛玻璃为载体,用Sol gel法制备附载型TiO2/Glass光催化剂,并用H2SO4溶液浸泡制得TiO2 SO2-4/Glass光催化剂。考察了光催化剂对甲基橙溶液的光催化性能。结果表明:平玻璃附载TiO2的光催化活性低于毛玻璃附载TiO2的光催化活性。且毛玻璃附载TiO2经连续6次使用后光催化活性基本不变。毛玻璃附载TiO2经H2SO4溶液处理后光催化活性明显升高。     

新生MnO2对甲基橙的脱色作用研究

以化学法合成的新生MnO2作吸附剂，对水中甲基橙染料进行吸附脱色研究，探讨了影响吸附的因素和吸附机理。结果表明：新生MnO2对甲基橙的吸附符合Langmuir吸附等温式，吸附速率大吸附前溶液pH值是影响染料脱色效果的最主要因素，吸附后溶液pH值和温度影响程度较小。在实验条件下可使甲基橙脱色率达99％。     

吖啶橙非均相光敏氧化处理垃圾渗滤液的研究

用碳纤维负栽吖啶橙进行非均相处理垃圾渗滤液。结果发现，不但光敏氧化体系对废水COD去除率高，达到63．5％，而且吖啶橙光敏剂可以多次重复利用。当吖啶橙浓度为12mg／L时，获得了碳纤维吸附吖啶橙最佳量为1．5L／m^2：当光源采用200W白炽灯、光照距离约10cm时，获得了碳纤维处理垃圾渗滤液的最佳量5．6～7．5L／m^2，最佳面积负荷554．9gCOD／m^2。     

Sonocatalytic degradation of methyl orange in the presence of (nanometer and ordinary) anatase TiO2 powders

The nanometer and ordinary anatase titanium dioxide(TiO2 ) powders were adopted as the sonocatalysts for the degradation of methyl orange used as a model compound for the first time. It was found that the sonocatalytic degradation effect of methyl orange in the presence of TiO2 powder were much better than that without TiO2, but the sonocatalytic activity of the nanometer anatase TiO2 particle was obviously higher than that of ordinary anatase TiO2 particle. Although there are many factors influencing sonocatalytic degradation of methyl orange, the experimental results showed that the best degradation ratio of methyl orange could be obtained when the experimental conditions were: initial concentration 15 mg/L, nanometer anatase TiO2 adding amount 750 mg/L, ultrasonic frequency 40 kHz, output power 50 W, pH = 3.0 and temperature 40℃ within 150 min. In addition, the catalytic activity of reused nanometer anatase TiO2 catalyst was also studied and found to decline gradually comparing with initial nanometer anatase TiO2 catalyst. All experiments indicated that the method of the sonocatalytic degradation of organic pollutants in the presence of TiO2 powder was an advisable choice for non-or lowtransparent organic wastewaters.     

粉煤灰脱色的试验研究

对粉煤灰去除水中色度的可行性进行了试验，得出了最佳反应条件：甲基橙废水浓度：3．15mg／L、碱性改性粉煤灰投加量=36g／L、反应时间=20min、pH=6-8、反应温度=室温时，脱色率最高，可达98．6％左右。