聚合氯化铝与有机高分子复合絮凝剂的形态分布研究--Al-Ferron和27Al-NMR相结合

主要研究了Al Ferron逐时络合比色法和2 7Al NMR法应用于聚合铝与有机高分子复合絮凝剂形态分布的测定 .结果表明 ,两种方法分别测定的Alb 和Al13 的结果具有一定的相关性 ;聚合铝与有机高分子复合后其形态分布发生了一定的变化 ,Alb(或Al13 )的含量有所降低 ,但仍是优势形态 ,Ala(或Al单)的含量基本保持不变 .     

微波消解逐时络合光度法快速测定聚合铝溶液中的总铝含量

聚合铝中的3种铝形态及其总铝含量的传统测定方法分别为Al-Ferron逐时络合光度法和EDTA络合滴定法．这2种方法各自存在着许多不足之处．将微波消解技术应用于逐时络合比色法以便快速测定聚合铝溶液中的总铝含量．研究表明：（1）Ferron混合显色液配制好后存放与否对测定结果的影响很大,用微波辐射处理Ferron混合显色液30s后即可使用,克服了传统光度法中必须存放5d的缺点;（2）微波消解极大地缩短了聚合铝与Ferron之间的解聚／络合反应时间,聚合铝显色溶液微波消解2min即可方便地定量测定铝盐水处理剂中的总铝含量,克服了传统络合滴定法的不足和烦琐．同时用改进的Al-Ferron逐时络合比色法验证了这种总铝测定方法的可行性．     

环境化学

X13 9502639水解聚合铝溶液中形态分布的定量模拟研究/栗兆坤…(中科院生态环境研究中心)//环境科学学报/中科院环委会一1995,一s(一),一39~47 环信X一9 通过Al一Ferron逐时络合比色法和2了AI核磁共振(NMR)法,并应用“MINEQL”化学平衡模式计算法,对采用不同反应途径制得的聚合铝(PAC)溶液中的化学形态分布规律进行了定量模拟研究和对比。模式计算结果与两种实验定量分析结果都较为吻合。结果表明,在水解聚合铝溶液中较稳定的化学形态主要有五种:一种单体形态〔Ala〕,即A13+,Al(OH)2+;AI(OH对;3种聚合形态〔AI‘〕,即Al:(OH砖+…     

高浓度聚硅氯化铝(PASC)中铝的水解-聚合特性研究

以铝酸钠为碱化剂,采用缓慢滴碱法合成了高浓度(2.0mol.L-1左右)具有不同Si/Al摩尔比的聚硅氯化铝复合混凝剂(PASC).采用Al-Ferron逐时络合比色法、碱式滴定法和红外光谱分析,研究了铝的形态分布、水解-聚合历程及铝硅间的相互作用.实验结果表明,Al-Ferron络合动力学符合At=A0+A1[1-exp(-kb1t]+A2[-exp(-kb2t)];在PASC中,硅酸钠和铝的水解产物间存在着相互作用,这种作用对铝的水解-聚合历程和形态分布有不同程度的影响.用铝酸钠制备PASC时有利于Al的形态由低聚物向中、高聚物转化,且随着PASC中Si/Al比的增加生成多核羟铝配合物的能力逐渐增强.     

羟基聚合氯化铝铁溶液的形态转化规律

采用改进的 Al-Fe-Ferron逐时络合比色法和酸滴定实验研究了典型羟基聚合铝铁(n_Al/n_Fe=9∶1,5∶5)溶液的形态转化 .结果表明 ,羟基聚合铝铁的形态转化主要由 n_Al/n_Fe值、碱化度和熟化等因素决定 ;羟基聚合铝铁的形态转化特征是优势形态之间的转变 ;当n_Al/n_Fe>5∶5,随碱化度的升高 ,[Al+Fe]_a和 [Al+Fe]_b 2类形态逐渐占优势 ;随n_Al/n_Fe值的减小 ,[Al+Fe]_a和 [Al+Fe]_c增加 ,而 [Al+Fe]_b 减少 .讨论了羟基聚合铝铁的形态转化规律 .     

环境化学

X 13 9700041AI Ferr(in逐时络合比色法研究PACS中铝的水解聚合形态/高宝玉…(山东大学环境工程系)沼环境化学/中科院生态环境研究中心一1996,15(3)一234一238环信X一87 制备了碱化度(B)及不同A13+/S()牙一摩尔比的系列P八CS,用八1一Ferron逐时络合比色法研究了铝的形态分布,考察了碱化度(B)、A13十/S()芍卒尔比、稀释作用及pH值对铝的形态分布的衫响。实验结果表明,A13十/S(滩一摩尔比及溶液的Pll位对铝的形态分布有较大的影响,稀释作J手J对铝的形态分布影响较小。A13+/S()军一摩尔比愈小,pH位愈高,铝的水解聚合大分子及胶体粒…     

聚合铝形态分布特征及转化规律

采用多种实验方法,对Al(Ⅲ)的水解—聚合—沉淀反应特征及其转化规律、形态分布及规范分子量大小进行了研究,同时应用X-射线衍射光谱仪和红外光谱仪对聚合铝形态进行了表征。由研究结果似可推断,Al(Ⅲ)水解—聚合过程的形态转化过程为线型→环型→体型。其聚合形态分布取决于翔/铝比值或pH值以及其它因素。在一定羟/铝比值时,聚合铝溶液中可划分为三种类型的形态分布。提出了相应的形态转化模式来表达聚合铝的形态及转化规律。     

聚合铝水解聚合形态分布的影响因素研究

聚合铝的水解聚合形态有Ala、Alb、Alc，其中最佳絮凝形态Alb的含量是衡量聚合铝絮凝活性的主要指标。采用一次加碱法制备聚合铝时，水解聚合形态分布的主要影响因素依次为：碱化度，加热温度，氯化铝浓度，碱浓度。实验确定的优化工艺条件为：碱化度2．2，加热温度72℃，氯化铝浓度0．5mol／L，碱浓度0．7～1．0mol／L。检测结果表明：在优化工艺条件下，制备的聚合铝中Alb含量为80．26％。应用实验表明：在同等加药量的条件下，高Alb含量聚合铝对生活污水絮凝效果明显优于工业聚合铝和氯化铝。     

不同铝聚合形态对聚合铝混凝效果的影响

通过氯化铝(铝单体或初聚物形态Ala)、高Alb含量聚合铝(中等聚合形态Alb)、高Alc含量聚合铝(铝溶胶等高聚合形态Alc)和工业PACl(不同聚合度铝的混合形态Alabc)对某水厂沉后水实际水样进行烧杯混凝实验,依据絮体生长状况、浊度、UV254、颗粒数和过滤指数等参数综合评价不同铝形态的混凝作用效果,从而得出铝的最佳混凝形态.结果表明,高Alb含量聚合铝对浊度去除较好;而高Alc含量聚合铝对于颗粒物和UV254的去除效果较佳.     

聚合氯化铝与有机高分子复合絮凝剂形态分布研究

以聚合氯化铝PAC和自制有机高分子絮凝剂为原料制备了复合絮凝剂 (PACO)。采用Al Ferron逐时络合比色法研究了聚合氯化铝与有机高分子复合絮凝剂溶液中铝盐的形态分布及转化。考察了O A、碱化度B和熟化等因素对铝盐形态分布的影响。结果表明 ,当碱化度B为 2 .0 ,有机高分子与铝盐质量比 0 A从 0增加至 4时 ,Ala 含量从 2 0 .45 %缓慢降至 1 8.52 % ,Alb 含量从 49.54%升至55 .0 1 % ;当O A =1 ,B从 0 .5升至 2 .0时 ,Ala 含量从 65 .2 6 %降至 1 8.95 % ,Alb 含量从 2 6.76 %升至 53 .1 3 % ;此外 ,当熟化时间由 2 4h增加至 72h时 ,PAC中Ala 含量下降了 5 .93 % ,而相应PACO中Ala 含量仅下降 2 .62 % ,表明PACO溶液相对于PAC溶液具有较强的稳定性。     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.     

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment

Zeolite synthesized from fly ash （ZFA） without modification is not efficient for the purification of NH4＋ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 （≥0.9 mol/L） resulted in a limited maximum phosphate immobilization capacity （PIC）. It was concluded that through a previous mild acid treatment （e.g. 0.01 mol/L of H2SO4）, ZFA can be used in the simultaneous removal of NH4＋ and P at low concentrations simulating real effluent.