Photocatalytic activity of Fe-doped CaTiO3 under UV-visible light

The photocatalytic degradation of methylene blue（MB） over Fe-doped CaTiO3 under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction（XRD）, scanning electron microscope（SEM） equipped with an energy dispersive spectrometer（EDS） system, Fourier transform infrared spectra（FT-IR）, and UV-visible diffuse reflectance spectroscopy（DRS）. The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO3 in the visible light region. The Fe-doped CaTiO3 exhibited higher photocatalytic activity than CaTiO3 for the degradation of MB.However, the photocatalytic activity of the Fe-doped CaTiO3 was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO3 prepared at500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB（10 ppm）under UV-visible light for 180 min.     

Arsenic removal from groundwater by acclimated sludge under autohydrogenotrophic conditions

Arsenic in the environment is attracting increasing attention due to its chronic health effects. Although arsenite(As(III)) is generally more mobile and more toxic than arsenate(As(V)), reducing As(V) to As(III) may still be a means for decontamination, because As(III) can be removed from solution by precipitation with sulfide or by adsorption or complexation with other metal sulfides. The performance of As(V) bio-reduction under autohydrogenotrophic conditions was investigated with batch experiments. The results showed that As(V) reduction was a biochemical process while both acclimated sludge and hydrogen were essential. Most of the reduced arsenic remained in a soluble form, although 20% was removed with no addition of sulfate, while 82% was removed when sulfate was reduced to sulfide. The results demonstrated that the reduced arsenic was re-sequestered in the precipitates, probably as arsenic sulfides. Kinetic analysis showed that pseudo first-order kinetics described the bio-reduction process better than pseudo second-order. In particular, the influences of pH and temperature on As(V) reduction by acclimated sludge under autohydrogenotrophic conditions and total soluble As removal were examined. The reduction process was highly sensitive to both pH and temperature, with the optimum ranges of pH 6.5–7.0 and 30–40°C respectively. Furthermore, Arrhenius modeling results for the temperature effect indicated that the As(V) reduction trend was systematic. Total soluble As removal was consistent with the trend of As(V) reduction.     

铁碳微电解法预处理聚氯乙烯(PVC)离心母液废水

采用铁碳微电解法对聚氯乙烯(PVC)离心母液废水进行预处理。分别考察反应时间、铁粉投加量、Fe/C(质量比)、pH值及曝气速率对母液废水中的COD和聚乙烯醇(PVA)去除率的影响,并在此基础上通过正交实验确定了废水COD的最佳处理条件。结果表明,最佳处理条件为:反应时间为4 h、铁粉投加量为30 g/L、Fe/C为1:2、pH值为2、曝气速率为0.8 L/min。在该条件下,废水中COD、PVA和TOC的平均去除率分别为(67%±2)%、(98%±1)%和(55%±3)%,废水的BOD/COD值从0.3提高到0.5,可生化性得到了显著提高。同时,废水中的NH3-N、浊度也在很大程度上得到了去除,出水中总铁含量也很低。     

高效去除难降解毒害污染物的零价铁技术装备

文章综述了可高效去除硝基芳烃、氯代有机物、毒害重金属等典型难降解毒害污染物的零价铁技术的降解机理及应用效能,重点总结了其技术装备的改良优化与集成强化方式,系统比较了多种技术装备及应用流程的性能优势及应用缺陷。进一步展望了该技术国内外的最新方向及应用前景。     

强化混凝处理低温低浊松花江水研究

针对低温低浊水出水浊度不达标的问题进行了絮凝试验研究。结果表明,投加混凝剂聚合氯化铝(PAC)或聚合氯化铝铁(PAFC),剩余浊度、剩余CODMn均有所降低,继续加大投药量,浊度反而升高。进一步试验表明:在PAFC用量为12 mg/L,改性活化硅酸用量为0.12 mg/L条件下,剩余浊度、剩余CODMn分别达到0.21 mg/L和0.64 mg/L。改性活化硅酸的投加时间对混凝效果有一定的影响,混凝开始后330s投加改性活化硅酸可以提高混凝效果。     

聚合氯化铝铁在矿井水处理中的应用前景展望

针对我国当前矿井水净化处理现状,指出了矿井水混凝处理过程中存在的主要问题,阐述了传统絮凝剂聚合氯化铝的不足之处。根据对聚合氯化铝铁性能、特点以及经济性等方面的详细论述,分析了聚合氯化铝铁在矿井水混凝处理中的优势及应用前景,并对聚合氯化铝铁今后在矿井水处理应用中的发展方向提出了建议。     

汽车的未来新能源——氢

正丰田汽车最近宣布将推出首款商用氢燃料电池汽车,新车将于明年上市销售。不仅仅是丰田,现在主流的汽车厂商几乎都有一个氢燃料汽车计划:2015年开始,现代计划在美国出租1 000辆氢燃料汽车;雷诺和日产宣布,与戴姆勒、福特共同分担研发成本的氢燃料汽车最快将在2017年推出;通用与本田2013年宣布将组建一家合资公司,在2020年量产氢燃料汽车。     

地下水中常见离子对纳米零价铁除Se（Ⅳ）动力学的影响

采用间歇实验对纳米零价铁(nZVI)除四价硒(Se(Ⅳ))进行实验性研究,考察了地下水中共存离子对nZVI除Se(Ⅳ)动力学的影响.结果表明,在厌氧条件下,当nZVI投加量为0.1 g·L-1,Se(Ⅳ)浓度为100μmol·L-1,NaCl浓度为0.01 mol·L-1,pH=7.0,T=25℃±1℃时,投加CO2-3或SO2-4浓度为1 mmol·L-1、腐殖酸(humic acid,HA)为5 mg·L-1时,明显抑制了Se(Ⅳ)的去除.投加0.5 mmol·L-1Ca2+或Mg2+时,对除Se(Ⅳ)影响不大;而Ca2+(3 mmol·L-1)、Mg2+(3 mmol·L-1)时,Se(Ⅳ)的去除效率明显下降.未加共存离子时,Se(Ⅳ)在20 min时基本去除完,共存离子存在的情况下,nZVI对Se(Ⅳ)的去除率在30 min时达到100%.反应过程中二价铁(Fe2+)随着Se(Ⅳ)的去除趋于平稳.ORP在反应过程中快速从正值下降至负值,由此说明nZVI除Se(Ⅳ)的过程发生了还原反应.     

自然光照对淹水条件下三峡库区消落带典型土壤磷释放影响

为研究淹水条件下光照对土-水界面磷释放的影响,以三峡库区消落带典型土壤为对象,通过室内自然光照试验,讨论了铁还原及有机质降解对磷释放的影响,分析光照对淹水土壤磷释放的影响机制.结果表明,光照对淹水土壤磷释放存在一定程度的抑制作用,光照作用下淹水紫色潮土上覆水体中TP浓度范围为0.018~0.033 mg·L-1,避光处理为0.02~0.057mg·L-1,灰棕紫泥光照下TP浓度范围为0.028~0.045 mg·L-1,避光处理为0.04~0.084 mg·L-1.光照引起淹水土壤中铁氧化物的变化可能是光照抑制磷释放的重要原因.光照导致土壤中铁氧化物饱和程度降低,铁还原和无定形铁生成受阻进一步加深了光照对磷释放的抑制影响.CO2和CH4反映淹水土壤有机质分解情况,光照降低有机碳的转化效率,加速土壤中无机电子受体的消耗,解释了光照作用下铁氧化物的变化.由此可见,光照对淹水土壤磷释放的抑制与淹水土壤中铁还原和有机质分解密切相关.     

填埋场中铁的生物化学循环对反硝化的影响

在模拟填埋体系中,以填埋场稳定的垃圾为接种物,通过控制有机物和硝氮负荷,研究了铁的生物化学循环对反硝化的影响.结果表明,垃圾填埋场内蕴藏着能实现铁的厌氧氧化还原并同步还原硝氮的复合功能菌群.通过改变有机物和硝氮的负荷,可使得填埋场内持续进行着铁的氧化还原循环和同步氮素转化.从氮素转化产物来看,铁的循环体系中氨氮浓度比传统的反硝化体系低4 mmol·L-1.填埋场内铁的生物化学循环过程对于原位脱氮具有极大贡献.