Inhibition and dispersion of polyepoxysuccinate as a scale inhibitor

The inhibition and dispersion of polyepoxysuccinate (PESA, self-manufactured) to inorganic scale was evaluated by scale static beaker test to CaC0₃ and Ca₃(P0₄)2, stability test to zinc salt, and dispersion test to ferric oxide. The experimental results demonstrated that PESA functioned excellent scale inhibition to CaC0₃ and Ca₃(P0₄)₂, good stability to zinc salt and special dispersion to ferric oxide. Under the water with hardness 500-1200 mg/L, alkalinity 1000 mg/L, and dosage of PESA 31.2 mg/L, PESA scale inhibition ratio reached more than 85.0%. At dosage of PESA 20.8 mg/L inhibition ratio on calcium phosphate reached 38.9%, at optimum dosage of PESA 9.1 mg/L, the stability ratio was up to 96.1%; while at dosage of PESA 3.6 mg/L, transmittance ratio reached 64.4%. Therefore, PESA can be considered a soluble, high effective and versatile inhibitor.     

光催化氧化法处理染料中间体H酸水溶液

为了去除水中难氧化的有害染料中间体Ｈ酸,研究以ＴＩＯ２、ＺｎＯ、ＣｄＳ和Ｆｅ２Ｏ３为催化剂,采用低压汞灯为光源,对Ｈ酸水溶液进行光催化氧化实验．结果表明：ＴｉＯ２和ＣｄＳ的催化效果最好．采用ＴｉＯ２作催化剂,光催化氧化５ｈ后,Ｈ酸分解率可达９０％,反应速率遵从Ｌａｎｇｍｕｉｒ－Ｈｉｎｓｈｅｌｗｏｏｄ方程,Ｋ＝１２．３Ｌ／ｍｍｏｌ,ｋ＝２５．２×１０－６ｍｏｌ／ｈ．溶液中投加１０ｍｇ／Ｌ的Ｆｅ３＋或Ａｇ＋,可使反应时间缩短２—３ｈ．研究探讨了ｐＨ、ＴｉＯ２投加量和Ｈ酸浓度对催化氧化过程的影响．     

Photochemical degradation of nonylphenol in aqueous solution：The impact of pH and hydroxyl radical promoters

The degradation of nonylphenol (NP) in aqueous solution with UV, H₂O₂/UV, and Fenton/photo-Fenton processes was studied. The efficacy of direct and hydrogen peroxide photolysis proved to be dependent on the pH value. The addition of H₂O₂ to UV treatment improved NP degradation. The application of UV photolysis and the H₂O₂/UV system at pH 7 resulted in low pseudo first-order rate constants at 10^-4 sec^-1. In the experiments at elevated pH values the pseudo-first order rate constants increased to 10^-3 sec^-1. The efficacy of the Fenton process was lower in comparison with UV and hydrogen peroxide photolysis. The addition of UV irradiation to the H₂O₂/Fe²⁺ system substantially improved NP degradation efficacy. In terms of performance, the photo-Fenton process was similar to the H₂O₂/UV process. The most favourable process for complete nonylphenol degradation considering both operational cost and treatment efficacy was H₂O₂/UV at pH 11 and 250 mol/L H₂O₂.     

土壤胡敏酸的解离及其与Cu2+的络合特征

通过电位滴定法及恒定容量模式（CCM）研究了2种土壤胡敏酸的解离特性及其与Cu^2 的络合特征，结果证明在pH3－7范围内胡敏酸表现为2种一元酸组成的混合酸，实验数据适用于静电模式。胡敏酸的解离常数和Cu^2 的络合常数应用计算机程序FITEQL32表明，优化的解离常数pKHL1在3．50－4．89之间，pKHL2在6．17－8．38之间，2种形态一元胡敏酸解离常数之比小于10^5，与滴定曲线只有一个突跃区相一致。2种土壤胡敏酸与Cu^2 络合常数logK^intACu大小分别为Lou土HA1．346，黑垆土HA2．241，非静电模式的优化结果较好。     

O3/H2O2去除水中硝基苯效果与机理

以硝基苯为目标反应物,对O₃/H₂O₂体系氧化去除水中硝基苯的效果和机理进行了研究,考察了pH值、H₂O₂剂量、自由基抑制剂或促进剂对硝基苯的去除效果的影响.研究发现,在pH≤7时,H₂O₂促进臭氧化去除硝基苯的效果较为明显,当H₂O₂投加量从1.0 mg/L增加到4.0 mg/L时,在氧化5 min内,硝基苯     

日光辐照草酸铁盐体系降解水中低浓度混合药物及产物的生物毒性评价

在太阳光辐照下以三草酸合铁酸钾为催化剂,分解H2O2产生·OH,对水中的甲硝唑、双氯芬酸钠、磺胺甲基异唑和布洛芬4种常见的痕量药物污染物间歇降解与矿化,并且对降解前后水溶液的毒性进行了评价.以体系的总有机碳为指标,探讨了H2O2的初始浓度、三草酸合铁酸钾的投加量、体系的pH值等因素对水溶液中TOC去除率的影响,确定了最佳操作条件,根据4种药物的化学结构解释了它们在水中的降解速度.以药物水溶液对小球藻的EC50值为指标,对4种药物的联合毒性,以及降解中间产物的生物毒性做出了评价.结果表明,当4种药物的初始浓度都为20mg·L-1时,降解过程适宜条件是pH值为3,H2O2的初始浓度为300mg·L-1,三草酸合铁酸钾的投加量为75mg·L-1.4种药物的降解速度为:甲硝唑布洛芬磺胺甲基异唑双氯芬酸钠.随着中间产物的生成与降解,药物水溶液的生物毒性有先增大后迅速减小的趋势.最后给出了Solar/FeOx/H2O2体系降解水中低浓度药物的表达式.     

A kinetic model of Ti（IV）-catalyzed H2O2/O3 process in aqueous solution

A kinetic model for the Ti(IV)-catalyzed H₂O₂/O₃ process was established, and the experimental results demonstrated that the model could well describe this ozone-based oxidative system mathematically and chemically.     

Pathway of the ozonation of 2,4,6-trichlorophenol in aqueous solution

The reaction mechanism and pathway of the ozonation of 2,4,6-trichlorophenol (2,4,6-TCP) in aqueous solution were investigated. The removal efficiency and the variation of H₂O₂, Cl⁻ formic acid, and oxalic acid were studied during the semi-batch ozonation experiments (continuous for ozone gas supply, fixed volume of water sample). The results showed that when there was no scavenger, the removal efficiency of 0.1 mmol/L 2,4,6-TCP could reach 99% within 6 min by adding 24 mg/L ozone. The reaction of molecular ozone with 2,4,6-TCP resulted in the formation of H₂O₂. The maximal concentration of H₂O₂ detected during the ozonation could reach 22.5% of the original concentration of 2,4,6-TCP. The reaction of ozone with H₂O₂ resulted in the generation of a lot of OH• radicals. Therefore, 2,4,6-TCP was degraded to formic acid and oxalic acid by ozone and OH• radicals together. With the inhibition of OH• radicals, ozone molecule firstly degraded 2,4,6-TCP to form chlorinated quinone, which was subsequently oxidized to formic acid and oxalic acid. Two reaction pathways of the degradation of 2,4,6-TCP by ozone and O₃/OH• were proposed in this study. Translated from Acta Scientiae Circumstantiae, 2005, 25(12): 1619–1623 [译自: 环境科学学报]     

冶炼厂SO2烟气化学催化吸收扩大试验研究

在单层塔板泡沫吸收塔中的ＳＯ２液相催化氧化进行了扩在试验研究,当ＳＯ２净化效率（单板效率）为５０％时,得到１６％（Ｗｔ）Ｈ２ＳＯ４,硫酸生成速率为１８％／ｈ,ＳＯ２吸收最佳敢化５Ｌ／Ｎｍ＾３,添加表面活性剂Ａｌ２（ＳＯ４）３及鼓氧操作对ＳＯ２液相催化氧化有明显促进作用,冶炼烟气ＳＯ２浓度波动吸收效率影响不大。     

无机阴离子对CuO-H2O2氧化苯酚废水的影响

以苯酚为模型底物,研究了中性低温常压条件下无机阴离子对CuO-H₂O₂氧化苯酚废水的影响及机制.结果表明,CuO-H₂O₂能高效彻底氧化苯酚,10 min氧化率达94.7%,氧化遵循羟基自由基机制.无机阴离子对氧化效果有不同影响,浓度越高影响越显著.HCO^-₃加速H₂O₂的无效分解,当浓度从0增加到20 mmol·L^-1 时,H₂O₂分解速率常数由0.373 8 min^-1提高到0.534 7 min^-1,TOC去除速率常数由0.267 min^-1下降到0.019 4 min^-1.HPO^2-₄通过抑制H₂O₂分解实现对苯酚的氧化抑制,H₂O₂分解速率常数及TOC去除速率常数分别由0.373 8 min^-1、0.267 min^-1降低到0.033 8 min^-1、 0.033 8 min^-1.Cl^-能够促进H₂O₂有效分解,对苯酚氧化有利,H₂O₂分解速率常数及TOC去除速率常数分别由0.373 8 min^-1、0.267 min^-1提高到0.604 0 min^-1、0.387 9 min^-1.NO^-₃、SO^2-₄对H₂O₂的分解及苯酚的氧化影响不大.     

Study on polyepoxysuccinic acid reverse osmosis scale inhibitor

The effectiveness and applicability of polyepoxysuccinic acid (PESA) as a reverse osmosis (RO) scale inhibitor were studied using static and dynamic methods. In the static study, PESA performed very well in the treatment of water samples with various types of scale that commonly exist in RO water (i.e., CaCO₃, CaSO₄, BaSO₄, SrSO₄), showing an average scale inhibition ratio of above 90% at a dosage of 10 mg/L. SEM analysis showed a disordered CaCO₃ crystal in the presence of PESA, suggesting the scale-inhibiting mechanism. In the dynamic experiment, PESA also showed great performance in the treatment of 10 samples of synthetic tap water or sea water with different ion composition (i.e., Ca²⁺, HCO₃^?, Fe³⁺, Al³⁺). After one cycle (7 d) of RO treatment of each sample at full recycle operation mode under a constant pressure of 1×10⁶ Pa, the differences in water permeability and desalination ratio among samples are within 5%, suggesting that PESA is capable of treating waters of different quality, and has a strong resistance to ions that are harmful to scale inhibiting (i.e., Fe³⁺ and Al³⁺). All these results suggest that PESA should be an effective scale inhibitor that is applicable to RO treatment of waters with a wide range of ion compositions.     

苯水相光氧化反应形成二次有机气溶胶的实验研究

来源于机动车尾气的苯能溶于大气水滴、云雾等水相中并发生水相光氧化反应,在水分蒸发后,产物保留在颗粒相中形成二次有机气溶胶(SOA)粒子.本文采用雾化器将羟基启动苯水相光氧化反应溶液雾化产生气溶胶粒子,通过扩散干燥管除去水蒸气后产生SOA粒子,采用气溶胶激光飞行时间质谱仪进行在线检测,利用紫外可见吸收光谱仪、红外光谱仪和液相色谱串联质谱仪离线测量SOA的化学组分.实验结果表明,激光解吸附质谱中存在醛类(m/z=29(CHO~+)、57(CHOCO~+))、羧酸(m/z=44(COO~+))和苯环(m/z=39(C_3H~+_3)、65(C_5H~-_5))特征裂解碎片峰.SOA粒子的红外光谱图中存在苯环C—H和C=C双键,以及C=O双键、C—O、O—H和C—O—C键的伸缩振动吸收峰,电喷雾电离质谱中存在m/z高达915的离子峰.这表明醛类、羧酸、酚类、芳香醚类产物和酚类产物发生聚合形成的高分子量化合物是SOA粒子的主要化学组分.这为研究人为源挥发性有机化合物水相反应形成SOA的机理提供了实验依据.     

碘化阶层孔氧化硅纳米球对水中典型有机氯污染物的吸附性能研究

采用共缩聚法,成功地原位合成了碘改性的阶层多孔氧化硅纳米球（SiO₂-I）,研究了其基于卤键作用对典型有机氯污染物六六六的吸附性能,并考察了改性剂I-硅烷含量和pH值对吸附效果的影响.实验结果表明,该纳米材料对六六六表现出优异的吸附富集性能,吸附速率快,60 min内对六六六的去除率为71.6%,240 min内达到吸附平衡,去除率可达98.3%,最大吸附量为178.6 mg·g^-1;吸附动力学符合拟二级动力学模型;碘物种的加入提高了阶层多孔氧化硅的吸附速率和吸附效率.另外,为了便于纳米吸附材料的分离,本研究对SiO₂-I纳米球进行了磁性化.研究发现,磁性化修饰后,SiO₂-I纳米材料仍然保留对六六六优异的吸附富集性能,240 min时的吸附去除率达90.3%.     

响应面法优化Fenton预处理精细化工废水

甘肃省某精细化工企业实际生产废水成分复杂、有机物含量高、可生化性差,为满足后续生化工艺需求,急需开展适宜的预处理技术研究.采用Fenton氧化工艺对该企业废水进行预处理,在单因素试验基础上,以初始pH、H₂O₂投加量、n（H₂O₂）:n（Fe2+）、反应时间为考察因素,COD_Cr去除效果为响应值,构建响应曲面模型,分析4个独立因素及各因素之间的交互作用对COD_Cr去除效果的影响;同时,对反应过程进行表观反应动力学分析,采用紫外光谱及傅立叶变换红外光谱分析废水有机物结构变化,探究该反应过程机理.结果表明:①废水预处理的最佳工艺条件为初始pH 4、H₂O₂投加量8 mL/L、n（H₂O₂）:n（Fe2+）12、反应时间88 min,废水COD_Cr去除率达30.15%;模型的实际运行结果与预测值接近,模型可靠.②Fenton氧化降解该精细化工废水中有机物途径复杂,难以通过单一的底物模型进行拟合.③Fenton氧化能有效降解废水中不饱和有机物,但出水中仍含有酰胺类、不饱和醛类和芳香类化合物.研究显示,Fenton预处理能有效降解废水中难降解有机物,但出水仍未达到后续生化处理要求,还需进一步优化或与其他预处理工艺组合.      

Density functional theory (DFT) studies of vanadium-titanium based selective catalytic reduction (SCR) catalysts

Based on density functional theory (DFT) and basic structure models, the chemical reactions on the surface of vanadium-titanium based selective catalytic reduction (SCR) denitrification catalysts were summarized. Reasonable structural models (non-periodic and periodic structural models) are the basis of density functional calculations. A periodic structure model was more appropriate to represent the catalyst surface, and its theoretical calculation results were more comparable with the experimental results than a non-periodic model. It is generally believed that the SCR mechanism where NH₃ and NO react to produce N₂ and H₂O follows an Eley-Rideal type mechanism. NH₂NO was found to be an important intermediate in the SCR reaction, with multiple production routes. Simultaneously, the effects of H₂O, SO₂ and metal on SCR catalysts were also summarized.     

准分子灯光照降解水相中烷基酚的动力学

准分子灯辐射的206 nm紫外光可以直接光解4-壬基酚(4-NP)和4-辛基酚(4-OP),但不能使之完全氧化为CO2.相同光照条件下,4-OP的去除率高于4-NP.采用拟一级动力学模型和修正的动力学模型对光解过程进行拟合,得到两种烷基酚206 nm直接光解的速率常数.结果表明,烷基酚初始浓度越低,光解速率常数越高.两种动力学模型对低浓度烷基酚直接光解都具有一定的适用性,但修正的模型不适合高浓度4-OP直接光解.UV/H2O2体系中,烷基酚的降解速率明显提高,但只有当H2O2加入量很高时,TOC去除才比较明显.最后,推导出4-OP直接光解的速率常数kd为0.0328 min-1,4-OP与H2O2反应的速率常数kpH为17.4520 L·(mol·min)-1.     

A clean production process of sodium chlorite from sodium chlorate

This paper presents a novel cleaner production process for producing sodium chlorite by reducing sodium chlorate with hydrogen peroxide. In the new process, chlorine dioxide is generated by reducing chlorate ions with hydrogen peroxide in the presence of sulfuric acid: it then reacts with aqueous sodium hydroxide solution and hydrogen peroxide to produce sodium chlorite. The reaction conditions that were experimentally investigated included: reaction temperatures, concentrations of sodium chlorate solution, molar ratio of NaClO₃:H₂SO₄:H₂O₂, and acidity. Waste acid in the chlorine dioxide generator is dramatically reduced with recycling in the new process. The by-produced sodium sulfate in sulfuric acid is minimized and reclaimed.     

膜萃取处理水溶液中镉、锌离子的工艺

以P204+正庚烷为萃取剂,将中空纤维膜萃取技术用于处理水溶液中镉离子、锌离子.研究了两相流速、初始浓度及溶液pH等因素对传质系数和萃取率的影响,计算了膜萃取器的传质单元高度(HTU)_w,同时还研究了萃取剂的再生问题.实验结果表明,在低浓度下(＜500 mg/L),平衡分配系数较大,传质阻力主要是在水相;在初始浓度较高时(＜2000mg/L),由于分配系数较小,三项传质阻力均不可忽略;在初始浓度很高时(＞2000mg/L),传质由有机相和膜相阻力控制.实验还表明通过膜器串联可以实现萃取剂的再生.对于稀溶液(＜200mg/L),中空纤维膜萃取可以使水溶液中金属离子浓度减小2个数量级,通过计算,中空纤维膜萃取器(HTU)_w在15～30cm之间,大大低于传统的萃取塔.     

Ce-Mn/Al2O3-H2O2催化氧化皮革废水的研究

以浸渍法制备了Ce-Mn/Al_2O_3催化剂,研究该催化剂在H_2O_2非均相类Fenton体系中对皮革废水污染物的催化降解性能.在单因素试验的基础上,以COD去除率为响应值,采用Box-Behnken响应曲面法考察了催化剂投加量、H_2O_2投加量、初始pH、反应时间等4个因素之间的单独作用及交互作用,实验数据用Design-Expert 8.0.6软件进行处理,得到二次响应曲面模型.结果表明,4个独立变量对响应值的影响顺序如下:初始pHH_2O_2投加量催化剂投加量反应时间,数学模型拟合度高(R_(adj)~2=0.9349),利用该模型预测的最大COD去除率为78.86%,最佳反应条件为:催化剂投加量56.63 g·L~(-1),H_2O_2投加量315.15 mg·L~(-1),初始pH3.51,反应时间2 h,经实验验证COD去除率为80.94%,与模型预测值偏差2.08%.     

Environmental factors affecting degradation of perfluorooctanoic acid (PFOA) by In2O3 nanoparticles

Nanophotocatalysts have shown great potential for degrading poly- and perfluorinated substances (PFAS). In light of the fact that most of these catalysts were studied in pure water, this study was designed to elucidate effects from common environmental factors on decomposing and defluorinating perfluorooctanoic acid (PFOA) by In₂O₃ nanoparticles. Results from this work demonstrated that among the seven parameters, pH, sulfate, chloride, H₂O₂, In₂O₃ dose, NOM and O₂, the first four had statistically significant negative effects on PFOA degradation. Since PFOA is a strong acid, the best condition leading to the highest PFOA removal was identified for two pH ranges. When pH was between 4 and 8, the optimal condition was: pH = 4.2; sulfate = 5.00 mg/L; chloride = 20.43 mg/L; H₂O₂ = 0 mmol/L. Under this condition, PFOA decomposition and defluorination were 55.22 and 23.56%, respectively. When pH was between 2 and 6, the optimal condition was: pH = 2; sulfate = 5.00 mg/L; chloride = 27.31 mg/L; H₂O₂ = 0 mmol/L. With this condition, the modeled PFOA decomposition was 97.59% with a defluorination of approximately 100%. These predicted results were all confirmed by experimental data. Thus, In₂O₃ nanoparticles can be used for degrading PFOA in aqueous solutions. This approach works best when the target contaminated water contains low concentrations of NOM, sulfate and chloride and at a low pH.