Adsorption removal of phosphate from aqueous solution by active red mud

Red mud is the waste of alumina industry and has high TiO_2 and Fe_2O_3 content which are active components for the adsorption of anion pollutants.In this study,the uptake of phosphate by red mud activated by heat treatment and acid-heat treatment was investigated. The factors influencing the adsorption were also investigated.The result showed that the red mud sample treated using acid-heat method at 80℃with 0.25 mol/L HC1 for 2 h achieved the highest phosphate removal.For the heat-activated red mud,the sample heated at 700℃for 2 h preformed better than the other heat treatment.Phosphate removal by the activated red mud was significantly pH dependent,and pH 7 was the optimal pH for phosphate removal.The adsorption fits Langmuir isotherm model well and the maximum adsorption capacities of the acid-heat activated red mud and the heat activated samples were 202.9 mgP/g and 155.2 mgP/g,respectively.     

Active Moss Biomonitoring Applied to an Industrial Site in Romania: Relative Accumulation of 36 Elements in Moss-Bags

Active moss biomonitoring using the species Sphagnum girgensohnii was tested at a strongly polluted site in Romania (Baia Mare) according to a novel sampling design. Nine moss transplants from each of the two background areas (Dubna, Russia and Vitosha Mountain, Bulgaria) were deployed in parallel on balconies about 24 m above street level for 4 months. The samples were analyzed for 36 elements using instrumental neutron activation analysis (INAA). Based on the results obtained the sampling variability is discussed in relation to the analytical variability, and the relative uptake of the different elements is assessed. The moss-bags using Sphagnum girgensohnii demonstrate a high or a very high relative uptake for a majority of the 36 investigated elements, but the values depend on the initial element concentration in the moss. Moss leaves analyzed separately showed somewhat higher levels than stems for many elements. Practical considerations however still speak in favor of using the whole moss for transplants.     

电活化过硫酸盐降解全氟辛酸及其中间产物的探究分析

全氟化合物（PFCs）是一种新兴的持久性有机污染物,具有环境持久性、高毒性和难降解性,因此急需研发高效的降解方法.本文采用电化学恒电位电解法活化过硫酸盐,利用得到的具有强氧化性的SO₄^·-有效降解全氟辛酸（PFOA）,考察了恒定电位值、过硫酸钠的初始浓度、溶液初始pH值和共存离子对电活化过硫酸盐降解PFOA的影响.同时,结合超高效液相色谱-三重串联四级杆质谱联用仪（UPLC-MS/MS）和气相色谱与质谱联用仪（GC-MS）,对其降解的液相和气相中间产物进行探究.结果表明,在控制阴极电位为-1.8 V,初始过硫酸钠溶液浓度为200 mmol·L^-1,初始溶液pH=3.29,恒电位电解4 h后,PFOA去除率约达到60%.当体系中有NO₃^-、异丙醇和过硫酸钠共存时,PFOA降解效率明显提高（91%,4 h）,当有ClO₄^-存在时PFOA去除率约达到76.8%,但HCO₃^-和Cl^-的存在会出现抑制效果.通过对降解中间产物（短链PFCAs和加氢产物）和TOC去除率（62.5%,24 h）的监测分析,进而推断其可能的降解机理为SO₄^·-介导的Kolbe脱羧过程和羧酸逐步被加氢还原的过程.     

改性生物炭活化过硫酸盐对水中苯和氯苯的去除机制

采用传统的液相沉淀法合成铁盐改性花生壳生物炭（Fe-BC）,将其作为活化过硫酸盐（PS）的活化剂用于去除水体中的苯和氯苯.通过扫描电子显微镜、X射线衍射、傅里叶变换红外光谱、Boehm滴定法和BET测量对合成材料的结构和形态进行了表征,研究了pH值和水中阴离子对反应体系的影响以及材料的再利用性能.结果表明,在Fe-BC/PS体系中,反应3h后苯和氯苯的去除率均高达100%.Fe-BC/PS去除苯和氯苯协同机制包括BC的吸附、自由基的氧化等.在中性及酸性溶液中,苯和氯苯的去除率均能够达到100%.水中常见阴离子对反应体系具有不同程度的抑制作用,抑制强度依次为HCO₃^->HPO₄^->Cl^->NO₃^-.Fe-BC材料具有良好的再利用性能,是一种高效、廉价的PS活化剂.     

Mesoporous cobalt monoxide-supported platinum nanoparticles: Superior catalysts for the oxidative removal of benzene

Mesoporous Co_3 O_4(meso-Co_3 O_4)-supported Pt(0.53 wt.% Pt/meso-Co304) was synthesized via the KIT-6-templating and polyvinyl alcohol(PVA)-assisted reduction routes.Mesoporous CoO(meso-CoO) was fabricated through in situ reduction of meso-Co304 with glycerol,and the 0.18-0.69 wt.% Pt/meso-CoO samples were generated by the PVA-assisted reduction method.Meso-Co_3 O_4 and meso-CoO were of cubic crystal structure and the Pt nanoparticles(NPs) with a uniform size of ca.2 nm were well distributed on the mesoCo_3 O_4 or meso-CoO surface.The 0.56 wt% Pt/meso-CoO(0.56 Pt/meso-CoO) sample performed the best in benzene combustion(T_(50%)=156℃and T_(90%)=186℃at a space velocity of 80,000 mL/(g h)).Introducing water vapor or C02 with a certain concentration led to partial deactivation of 0.56 Pt/meso-CoO and such a deactivation was reversible.We think that the superior catalytic activity of 0.56 Pt/meso-CoO was intimately related to its good oxygen activation and benzene adsorption ability.     

非均相催化过硫酸盐氧化技术研究进展

活化过硫酸盐氧化技术因其自由基持续时间长、pH适用范围广、前体氧化剂稳定等优势,在高级氧化技术的开发和应用中备受关注。本文综述了有效活化过硫酸盐的非均相催化材料(金属氧化物、金属基复合材料、碳材料、天然矿物等),探讨了非均相催化剂的不同催化机制及其催化活性、稳定性、可重复利用性等,并在此基础上提出了非均相催化与其他技术(紫外光辐射、超声、热、微波等)联用以提高其处理效率及范围的发展方向。     

高温老化气氛对单钯三元催化剂活性的影响

本文制备了一种含Y、Ce和Zr的单钯三元催化剂(Pd-YCZ).在1050℃下,分别于空气和配气中对这一催化剂进行了高温老化,并对其催化活性进行了测试.实验结果表明,Pd-YCZ在空气中老化后的活性优于其在配气中老化后的活性.     

非均相活化剂磁性纳米CoFe2O4的制备及其活性评价

采用溶胶-凝胶法制备了磁性纳米铁酸钴（CoFe₂O₄）固体颗粒，并采用扫描电镜（SEM），X射线衍射仪（XRD），傅里叶变换红外光谱仪（FT-IR）和振动样品磁强计对样品进行表征分析.以磁性纳米CoFe₂O₄颗粒活化过硫酸盐氧化去除水中四环素为探针反应，评价CoFe₂O₄颗粒的活化性能.结果表明，600℃焙烧温度下制备出的固体颗粒，其活性较高，颗粒表面金属离子浸出率较低；优化温度下制备的CoFe₂O₄颗粒在较宽的pH值范围（4.4~9.0）内均具有较高活性；控制实验条件PDS₀ 1g/L，CoFe₂O₄ 1g/L，TCH₀ 50mg/L，20℃，pH₀ 4.4，反应4h后TCH去除率达到82.0%.CoFe₂O₄颗粒循环重复利用10次后仍保持较高的活性和结构稳定性，而且因其特殊的磁性能便于回收利用.     

典型硼化合物与磷酸二氢铵协效阻燃松木的燃烧性能及热解动力学研究

利用木垛法和热重分析法比较研究了硼酸、硼砂与磷酸二氢铵复配阻燃松木的燃烧性能、热解特性及热解反应动力学。结果表明,单种阻燃剂使用时,磷酸二氢铵的阻燃效果优于硼酸和硼砂;两两复配使用具有明显的协效作用,其中阻燃效果:磷酸二氢铵/硼酸＞磷酸二氢铵/硼砂＞硼酸/硼砂,而硼酸与磷酸二氢铵在质量比为2:3时,协效阻燃效果最好。与未处理松木相比,阻燃剂的加入降低了松木在热解阶段的初始分解温度和峰值分解温度,缩短了热解区间,并降低了松木在主要热解阶段的表观活化能,其中热解阶段活化能越低的阻燃松木在燃烧过程中成炭效果和阻燃性能越好。     

Fe2+与Fe0活化过二硫酸盐降解活性艳蓝KN-R

为了解Fe2+与Fe0在活化PDS(过二硫酸盐)降解活性艳蓝KN-R时的差异,通过序批试验,考察了Fe2+/PDS和Fe0/PDS体系中c(Fe2+)、ρ(Fe0)、c(PDS)和初始pH对KN-R降解的影响. 结果表明:在Fe2+/PDS体系中,最佳反应条件〔初始pH为3.0,c(Fe2+)为1.0 mmol/L,c(PDS)为2.0 mmol/L〕下,180 min后KN-R的去除率达到96.55%;过高的pH和c(Fe2+)对KN-R的降解均有明显的抑制作用. 在Fe0/PDS体系中,当pH和ρ(Fe0)过高时,KN-R的去除率仍维持在较高水平,当pH为9.0时,180 min后KN-R的去除率为90.53%;当ρ(Fe0)为448 mg/L时,50 min后KN-R的去除率就能达到94.35%. 在2个体系中,c(PDS)的升高均能显著提高KN-R的去除率,当c(PDS)由0.5 mmol/L增至8.0 mmol/L时,KN-R的去除率由47.25%(Fe2+/PDS体系)和57.00%(Fe0/PDS体系)增至100%. 动力学分析显示,KN-R的降解均遵循一级反应动力学;最佳反应条件下2个体系中的活性自由基均以硫酸根自由基(SO₄-·)为主. 因此,在降解KN-R过程中,Fe0/PDS体系的性能明显优于Fe2+/PDS体系.