Fabrication of a novel electrochemical sensor based on MnFe_(2)O_(4)/graphene modified glassy carbon electrode for the sensitive detection of bisphenol A

Manganese ferrite(MnFe_(2)O_(4))has the advantages of simple preparation,high resistivity,and high crystal symmetry.Herein,we have developed an electrochemical sensor utilizing graphene and MnFe_(2)O_(4) nanocomposites modified glassy carbon electrode(GCE),which is very efficient and sensitive to detect bisphenol A(BPA).MnFe_(2)O_(4)/graphene(GR)was synthesized by immobilizing the MnFe_(2)O_(4) microspheres on the graphene nanosheets via a simple one-pot solvothermal method.The morphology and structure of the MnFe_(2)O_(4)/GR nanocomposite have been characterized through scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).In addition,electrochemical properties of the modified materials are comparably explored by means of cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS)and differential pulse voltammetry(DPV).Under the optimal conditions,the proposed electrochemical sensor for the detection of BPA has a linear range of 0.8-400μmol/L and a detection limit of 0.0235μmol/L(S/N=3)with high sensitivity,good selectivity and high stability.In addition,the proposed sensor was used to measure the content of BPA in real water samples with a recovery rate of 97.94%-104.56%.At present,the synthesis of MnFe_(2)O_(4)/GR provides more opportunities for the electrochemical detection of BPA in practical applications.

A Simple and Rapid Method for the Detection of Non-Ionic Surfactants

A spectrophotometric approach for the detection of non-ionic surfactant (Triton X-100) has been proposed in this paper. This method does not involve extraction of the ion-associate with harmful solvents, but employs adhesion of the ion-association of potassium/non-ionic surfactants complex and tetraphenylporphyrin tetrasulfonic acid obtained by vigorous shaking. The adhered ion-associate was dissolved with water and its absorbance was measured. The sensitivity for Triton X-100 was determined to be 0.146 (expressed as absorbance of 1 mg/L solution). The adhesion tendency of ion-associate was found to be dependent on the water contact angle, which in turn was influenced by a high adhesion of the ion-associate and by low blank values. In this respect, a tetrafluo-roethylene vessel was found to be the most suitable for the detection of non-ionic surfactants. This spectrophotometrical method is simply and rapidly performed by a procedure based on mechanical shaking and can be employed to detect non-ionic surfactants containing more than 7 polyethylene oxide units.

黄河流域煤炭-煤电-煤化工场地特征精准智能识别方法及应用

黄河流域是“能源流域”,兼具生态环境治理和经济社会发展的重任,涉煤产业场地类型、数量及特征的精准智能识别是流域能源资源-低碳发展-生态保护的关键基础问题。研究融合多源数据与深度学习算法,从流域-基地-场地尺度对黄河流域13个大型煤电基地的煤基场地特征精准解析,获得煤电基地高精度、高质量的本底信息,提出一种实时实景智能识别涉煤产业空间特征的新方法。(1)筛选Google image、GF-6影像、Sentinel-2影像等多源数据,采集13个大型煤电基地煤基场地样本,构建煤炭场地(露天)、煤炭场地(井工)、煤电场地、煤化工场地4类数据集,涵盖21种样本类型。按照每种样本六面体设定6×10个样本,共计1 260个场地样本,分析得出最适样本数量-最高识别效率-最优识别模型的置信区间为80%~86%。(2)建立了煤基场地类型量化模型(Coal-based Site Classification Quantitative Model, CSCQM)和煤基场地范围特征模型(Coalbased Site Range Characteristic Model, CSRCM),模型平均精准度为0.837。明析了黄河流域涉煤产业场地本底信息,提出Google image底图叠加场地智能识别模型解算结果的高精度场地智能识别方法。(3)解析了流域神东煤炭-煤电产业集聚区精准本底数据,依据遥感生态指数(Remote Sensing Based Ecological Index,IRSE)分析,煤基场地分布2 km核心区地表生态质量受煤炭、煤电产业影响明显,5 km缓冲区则影响不明显,而8 km控制区基本不受煤炭、煤电产业影响,从而给出了“动态修复”与分区域、分阶段重点治理等低碳路径。(4)解析了流域宁东煤炭-煤电-煤化工产业集聚区精准本底数据,2022年煤炭场地17.81 km^(2)、占比34.1%,煤化工场地22.3 km^(2)、占比42.6%,煤电场地12.2 km^(2)、占比23.3%,煤化工场地>煤炭场地>煤电场地。进而采用PSR(Pressure-State-Response)模型得到风险管控综合得分53.93分,较2003年提高了27.2%。划分生态维护区、生产监测预警区、损毁修复重建区、其他调控区的分区管控模式。研究为涉煤产业煤基场地潜在污染控制、场地治理及区域生态修复提供技术方法与实践支撑。

Characterization of carbon fibers recovered through mechanochemical-enhanced recycling of waste carbon fiber reinforced plastics

In this study,we present the characterization of the carbon fibers recovered from the mechanochemical-enhanced recycling of carbon fiber reinforced fibers.The objectives of the study were to investigate the effect of our modified recycling method on the interfacial properties of recovered fibers.The reinforced plastics were recycled;the recycling efficiency was determined and the recovered fibers were sized using 1 wt%and 3 wt%concentration of(3-aminopropyl)triethoxysilane.We characterized the morphologies utilizing the electron spectroscopy for chemical analysis(ESCA),atomic force microscopy(AFM),FTIR-attenuated total reflection(ATR)spectroscopy and scanning electron microscopy(SEM).Although the surface of the fibers had no cracks,there was evidence of contaminations which affected the interfacial properties and the quality of the fibers.Results showed that the trends in the recovered and virgin fibers were similar with an increase in sizing concentration.The results highlighted the perspectives of increasing the quality of recovered fibers after the recycling process.

Overview of Simple Test for Determination of Surfactants by Adhesion Method

A simple, sensitive, and rapid analytical method is reported for the determination of surfactants. This is based on the use of an oppositely charged dye as the ion pair to form an ionic associate with the surfactant in a vessel, thus affording ion-associated adhesion on the inner wall of the vessel. After the adhesion, the remaining solution in the vessel is removed, and the ionic associate is dissolved in a suitable solvent. The absorbance of the resulting solution is measured spectrophotometrically to determine the concentration of the surfactant. Further, the mechanism of adhesion is elucidated.

A Simple Bioassay Using Fluorescent Microbeads and Daphnia magna

The amount of microbeads ingested by Daphnia magna decreases on exposure to toxic materials; tins oenawor was used to develop a toxicity test. To determine the toxicity of seven metals, D. magna were collected and homogenized, and the fluorescence intensity of the microbeads ingested by D. magna was measured. The amount of ingestion was determined from fluorescence intensity. The fluorescence intensity was half of that of the controls which was measured as the 30 min-FI50, and these data correlated well with those from an acute immobilization method （24 h-EC50）. An advantage of the method using fluorescent beads is that an estimate of the 24 h-EC50 can be obtained.

Nitrogen Derivatives of Irrigation in Chihuahua＇s Parks with Wastewater Treatment Residuals

Since 2000 Chihuahua City has distribution system Waste Water Treatment （WTR）, watering city＇s green areas. The need to cover the growing demand for drinking water has encouraged the use of non-potable water where water quality is not an issue despite being used by 10 years ago, it is not known whether nitrogen compounds derived from WTR pose risks to the environment and public health. Therefore, in order to minimize health and environmental risks, this is needed to assess the impact and policy support for water use. The aim of this study is to determine the constitution and the concentration of nitrogen compounds through selection and characterization of park＇s representative. It＇s divided into physical properties and main parameters that affect nitrogen transformations. It was determined that sand was material that allowed more favorable oxidation and reduction of nitrate in soil and atmosphere, opposite of the clay, When used WTR, nitrates, nitrites and ammonia nitrogen were identified in the subsurface and NOx and N20 were identified in the atmosphere. When drinking water was used, none of these compounds was found. However, it was determined that despite having high concentrations of nitrates, the WTR was within the limits allowed by the Mexican standard for the use of WTR in public places.

A comparative study on the alternating mesophilic and thermophilic two-stage anaerobic digestion of food waste

An alternating mesophilic and thermophilic two stage anaerobic digestion （AD） process was conducted. The temperature of the acidogenic （A） and methanogenic （M） reactors was controlled as follows： System 1 （S1） mesophilic A-mesophilic M; （S2） mesophilic A-thermophilic M; and （S3） thermophilic A-mesophilic M. Initially, the AD reactor was acclimatized and inoculated with digester sludge. Food waste was added with the soluble chemical oxygen demand （SCOD） concentrations of 41.4-47.0 g/L and volatile fatty acids of 2.0-3.2 g/L. Based on the results, the highest total chemical oxygen demand removal （86.6%） was recorded in S2 while S3 exhibited the highest SCOD removal （96.6%）. Comparing S1 with S2, total solids removal increased by 0.5%;S3 on the other hand decreased by 0.1% as compared to S1. However, volatile solids （VS） removal in S1, S2, and S3 was 78.5%, 81.7%, and 79.2%, respectively. S2 also exhibited the highest CH4 content, yield, and production rate of 70.7%, 0.44 L CH4/g VSadded, and 1.23 L CH4/（L.day）, respectively. Bacterial community structure revealed that the richness, diversity, evenness, and dominance of S2 were high except for the archaeal community. The terminal restriction fragments dendrogram also revealed that the microbial community of the acidogenic and methanogenic reactors in S2 was distinct. Therefore, S2 was the best among the systems for the operation of two-stage AD of food waste in terms of CH4 production, nutrient removal, and microbial community structure.

圆柱阵列换热器底部壁面对流换热的初步研究

圆柱阵列换热器是最具潜力的太阳能热电站换热器。该文分析了圆柱阵列换热器底部壁面对流换热特性 ,编制了基于最小二乘法的计算程序 ,并据此利用现有实验数据拟合出具有普遍意义的圆柱阵列换热器底部壁面对流换热的无量纲换热参数的表达式。对比分析表明 ,该表达式真实地反映了圆柱阵列的存在及其尺度的变化对底部壁面换热的影响。

Bio-assembled MgO-coated tea waste biochar efficiently decontaminates phosphate from water and kitchen waste fermentation liquid

Crystal morphology of metal oxides in engineered metal-biochar composites governs the removal of phosphorus(P)from aqueous solutions.Up to our best knowledge,preparation of bio-assembled MgO-coated biochar and its application for the removal of P from solutions and kitchen waste fermentation liquids have not yet been studied.Therefore,in this study,a needle-like MgO particle coated tea waste biochar composite(MTC)was prepared through a novel biological assembly and template elimination process.The produced MTC was used as an adsorbent for removing P from a synthetic solution and real kitchen waste fermentation liquid.The maximum P sorption capacities of the MTC,deduced from the Langmuir model,were 58.80 mg g^(−1) from the solution at pH 7 and 192.8 mg g^(−1) from the fermentation liquid at pH 9.The increase of ionic strength(0-0.1 mol L^(−1) NaNO_(3))reduced P removal efficiency from 98.53%to 93.01%in the synthetic solution but had no significant impact on P removal from the fermentation liquid.Precipitation of MgHPO4 and Mg(H2PO4)2(76.5%),ligand exchange(18.0%),and electrostatic attraction(5.5%)were the potential mechanisms for P sorption from the synthetic solution,while struvite formation(57.6%)and ligand exchange(42.2%)governed the sorption of P from the kitchen waste fermentation liquid.Compared to previously reported MgO-biochar composites,MTC had a lower P sorption capacity in phosphate solution but a higher P sorption capacity in fermentation liquid.Therefore,the studied MTC could be used as an effective candidate for the removal of P from aqueous environments,and especially from the fermentation liquids.In the future,it will be necessary to systematically compare the performance of metal-biochar composites with different metal oxide crystal morphology for P removal from different types of wastewater.