等离子体场内CeO2催化降解甲醇的表面活性氧物种来源与作用研究

利用水热法制备了3种不同形貌(纳米棒、纳米颗粒、纳米立方体)的CeO_2催化剂,并通过比表面积测试(BET)、扫描电子显微镜(SEM)、拉曼光谱分析(Raman)、O_2程序升温脱附(O_2-TPD)手段表征其物理化学性质,结果发现,CeO_2纳米棒的表面氧空位和氧物种最多.等离子体与催化协同降解甲醇性能评价实验结果显示,CeO_2纳米棒展现出最好的催化性能.进一步设计实验(甲醇-TPD、不同气氛常温催化、催化剂内后置比较、O_3催化氧化)推测在等离子体场内CeO_2表面活性氧物种来源及其作用.结果表明:①在等离子体场内参与CeO_2表面催化反应的活性氧物种有两个来源,一是催化剂本身存在的表面氧物种,二是等离子体区域产生的短寿命物种及长寿命物种(主要是O_3),其中,O_3分解产生的活性氧物种是提高催化性能的主要因素.②不同形貌CeO_2由于表面氧空位含量不同,导致O_3在催化剂上分解产生的活性氧物种的量不同,最终影响等离子体催化性能.     

氯化铜催化二噁英生成实验及指纹特性分析

氯化铜被认为是对二■英(PCDD/F)生成促进作用最强的金属催化剂,温度和氧气含量是影响其催化二■英生成的关键因素.本文选取250～550℃间8个不同温度点及0～20%间4种不同氧气含量,系统性地研究了温度和氧气含量对含氯化铜模拟飞灰(MFA)生成二■英的影响,并通过分析指纹特性探讨二■英的生成路径和机理.结果发现,290～350℃之间二■英生成量较高,且在290℃时二■英总量达到最大值;氧气含量为10%时二■英生成量达到最高.研究二■英同分异构体分布可从分子层面为研究其生成路径和机理提供重要信息,因此,本文分析了四至八氯代PCDD/F的全部异构体的分布.结果表明,在本文所选取的温度和氧含量范围内,温度对二■英生成路径的影响高于氧气含量.最后,重点讨论了2,3,7,8位氯取代的17种有毒异构体的分布随温度和氧气的变化情况及生成路径.利用主成分分析法(PCA)证实了氯化铜催化二■英从头合成过程中存在经由氯酚路径生成的异构体,并讨论了不同工况下氯酚路径对二■英生成的影响.     

Interaction of silver nanoparticles with mediterranean agricultural soils: Lab-controlled adsorption and desorption studies

The production of silver nanoparticles (AgNPs) has increased tremendously during recent years due to their antibacterial and physicochemical properties. As a consequence, these particles are released inevitably into the environment, with soil being the main sink of disposal. Soil interactions have an effect on AgNP mobility, transport and bioavailability. To understand AgNP adsorption processes, lab-controlled kinetic studies were performed. Batch tests performed with five different Mediterranean agricultural soils showed that cation exchange capacity and electrical conductivity are the main parameters controlling the adsorption processes. The adsorption kinetics of different sized (40, 75, 100 and 200?nm) and coated (citrate, polyvinylpyrrolidone and polyethyleneglycol (PEG)) AgNPs indicated that these nanoparticle properties have also an effect on the adsorption processes. To assess the mobility and bioavailability of AgNPs and to determine if their form is maintained during adsorption/desorption processes, loaded soils were submitted to leaching tests three weeks after batch adsorption studies. The DIN 38414-S4 extraction method indicated that AgNPs were strongly retained on soils, and single-particle inductively coupled plasma mass spectrometry confirmed that silver particles maintained their nanoform, except for 100?nm PEG-AgNPs and 40?nm citrate-coated AgNPs. The DTPA (diethylenetriaminepentaacetic acid) leaching test was more effective in extracting silver, but there was no presence of AgNPs in almost all of these leachates.     

超滤膜负载UiO-66@Fe3O4@UiO-66强化PPCPs去除和膜污染控制

本研究通过聚偏氟乙烯（PVDF）膜内负载具有协同吸附和催化作用的金属有机骨架（MOFs）,吸附去除水中药品及个人护理品（PPCPs）,并且达到膜滤过程中多功能材料吸附能力再生和膜污染控制的双重目的.在膜吸附方面,共混基质膜（MMMs）内MOFs材料UiO-66@Fe₃O₄@UiO-66能够有效吸附以水杨酸（SA）和邻-苯二甲酸二甲酯（DMP）为模板化合物的两种常见PPCPs.在膜催化再生方面,UiO-66@Fe₃O₄@UiO-66中的Fe₃O₄能够催化H₂O₂生成强氧化性的羟基自由基（HO·）,实现对MOFs/PVDF膜吸附能力再生和膜内污染控制的耦合.结果表明,pH=7±0.1条件下,10% MOFs/PVDF膜对0.1 mmol·L^-1 SA和DMP吸附去除率最高,它们的去除率可分别达到64.2%和46.1%.除此之外,膜内UiO-66@Fe₃O₄@UiO-66催化5 mmol·L^-1 H₂O₂,能够使膜通量和膜吸附性能恢复率分别达到91.8%和94.2%.实验设计的这种负载多功能MOFs共混基质膜的特点是它对膜吸附能力再生和膜污染控制过程的耦合.这为生化尾水深度净化过程中PPCPs去除和膜抗污染性能改善提供了新的思路.     

试验环境下耐高温噪声测量技术概述

本文针对试验环境下的耐高温噪声测量,介绍了加装冷却水套、光纤传声器、等离子体传声器以及声波导管等四种噪声测量技术,简述了每种技术的基本原理,并用实例介绍了每种技术的应用情况。其适用的环境条件不同,性能也有差别,工程应用时应根据具体试验工况进行相应的选择。     

晶面协同TiO2的制备及其可见光催化特性

以不同氟化物为晶面控制剂,采用超声辅助-溶胶凝胶法制备｛001｝和｛101｝晶面协同的F-TiO₂,借助XRD、TEM和EDS表征其物相结构、微观形貌和元素组成,通过改变氟化物种类和添加量确定F-TiO₂的最佳制备条件,并探讨其可见光催化过程中的主要活性物种及作用机理,研究关键反应参数对F-TiO₂光催化活性的影响.结果表明,引入NH₄F、NaF和HF可调控TiO₂沿｛001｝、｛101｝晶面生长,同时F^-掺杂能够增大材料的比表面积,制备所得材料的光催化性能均高于纯TiO₂.但在NaBF₄调控下合成的TiO₂为锐钛矿/金红石/Na₃TiF₆三相共存的半导体耦合结构,可见光催化活性显著下降.当NH₄F添加量为0.1 g时,材料显示出最强的光催化性能,可见光照射60 min后RhB的降解率为97.24%,矿化率达78.39%.降解反应符合一级反应动力学规律,速率常数为0.1321 min^-1.通过自由基捕获实验和ESR测试发现,h⁺、·OH均以关键活性因子参与F-TiO₂的可见光催化过程.F-TiO₂光催化活性增强主要归因于｛001｝和｛101｝晶面的协同作用和表面异质结的形成,其能有效提高光催化反应过程中光生电子空穴对的分离和迁移效率.在可见光照射下,适当增加催化剂投加量,降低RhB初始浓度,控制溶液为中性环境,可显著提高材料的降解速率.     

载银施氏矿物的制备及其对甲基橙的催化还原降解

采用硼氢化钠还原方法制备了不同载银量的银纳米粒子/施氏矿物复合催化剂（AgNPs/Sch）,利用扫描电镜（SEM）、X射线能谱（EDS）和X射线衍射（XRD）等测试方法对所制备催化剂的表面形貌、元素组成和物相组成进行了表征,证明了Ag成功负载于施氏矿物上.以甲基橙为目标污染物,硼氢化钠为还原剂,考察了不同载银量施氏矿物对甲基橙的催化降解性能,并探究了载银施氏矿物的投加量、硼氢化钠浓度、 甲基橙初始浓度、溶液初始pH等因素对甲基橙的催化还原降解效果的影响.结果表明,在甲基橙浓度为20 mg?L^-1、NaBH₄浓度为10 mmol?L^-1、初始pH=6条件下,反应90 min后,未载银的施氏矿物对甲基橙的降解率仅为7.5%,然而硝酸银添加量为0.10 g制备的AgNPs/Sch对甲基橙的降解率可达97.0%,该催化剂作为电子介质,能够将电子从还原剂（NaBH₄）转移到甲基橙中,进而加速甲基橙的降解.AgNPs/Sch在最佳的实验条件下5次循环性反应后,仍具有较高的催化稳定性.由此可见,载银施氏矿物作为一种新型的催化剂,在有机染料废水净化方面具有良好的应用前景.     

Low-temperature plasma induced phosphate groups onto coffee residue-derived porous carbon for efficient U(VI) extraction

For the continuous utilization of nuclear energy and efficient control of radioactive pollution, low-cost materials with high efficient U(VI) removal are of great importance. In this study, low temperature plasma method was applied for the successful modification of O-phosphorylethanolamine (O-PEA) on the porous carbon materials. The produced materials (Cafe/O-PEA) could adsorb U(VI) efficiently with the maximum sorption capacity of 648.54 mg/g at 1 hr, T=298 K, and pH=6.0, much higher than those of most carbon-based composites. U(VI) sorption was mainly controlled by strong surface complexation. From FTIR, SEM-EDS and XPS analyses, the sorption of U(VI) was related to the complexation with -NH₂, phosphate and -OH groups on Cafe/O-PEA. The low temperature plasma method was an efficient, environmentally friendly and low-cost method for surface modification of materials for the effective enrichment of U(VI) from aqueous solutions.