胡敏酸与Fe3+络合反应稳定性及热力学特征研究

采用离子交换平衡法研究了在不同酸度、离子强度、温度条件下胡敏酸(HA)与Fe3 络合反应的稳定性和热力学特征.结果表明,在相同离子强度、反应温度条件下,随着pH的升高,HA与Fe3 络合表观稳定常数和配位数均增加,有利于络合反应的进行;相同pH和温度下,离子强度从0到0.10 mol·L-1,HA与Fe3 络合反应表观稳定常数和配位数增加,但离子强度从0.10 mol·L-1继续上升到0.15 mol·L-1,则上述2个特征常数呈现下降的趋势;胡敏酸络合Fe3 标准自由能变△Gθm、焓变△Hθm、熵变△S:在298.2、308.2 K温度下均为负值,反应是自发进行的放热反应,较低的温度有利于反应的进行.     

Arsenic release from microbial reduction of scorodite in the presence of electron shuttle in flooded soil

Scorodite (FeAsO₄·H₂O) is a common arsenic-bearing (As-bearing) iron mineral in nearsurface environments that could immobilize or store As in a bound state.In flooded soils,microbe induced Fe(Ⅲ) or As(Ⅴ) reduction can increase the mobility and bioavailability of As.Additionally,humic substances can act as electron shuttles to promote this process.The dynamics of As release and diversity of putative As(Ⅴ)-reducing bacteria during scorodite reduction have yet to be investigat...     

Remediation performance and mechanisms of Cu and Cd contaminated water and soil using Mn/Al-layered double oxide-loaded biochar

The combined pollution of heavy metals is ubiquitous worldwide. Mn/Al-layered double oxide-loaded crab shells biochar (LDO/BC) was prepared, so as to remediate the combined pollution of Cd and Cu in soil and water. The pristine and used LDO/BC were characterized and the results revealed that the layered double oxide was successfully loaded on crab shells biochar (BC) and metal element Ca in crab shells was beneficial to the formation of more regular layered and flake structure. The maximal adsorption capacity (Q_m) of LDO/BC for aqueous Cu²⁺ and Cd²⁺ was 66.23 and 73.47 mg/g, respectively. LDO/BC and BC were used to remediate e-waste-contaminated soil for the first time and exhibited highly efficient performance. The extraction amount of Cu and Cd in the contaminated soil by diethylene triamine penta-acetic acid (DTPA) after treating with 5% LDO/BC was significantly reduced from 819.84 to 205.95 mg/kg (with passivation rate 74.8%) and 8.46 to 4.16 mg/kg (with passivation rate 50.8%), respectively, inferring that the bioavailability of heavy metals declined remarkably. The experimental result also suggested that after remediation by LDO/BC the exchangeable and weak acid soluble Cu and Cd in soil translated to reducible, residual and oxidizable fraction which are more stable state. Precipitation, complexation and ion exchange were proposed as the possible mechanisms for Cd and Cu removal. In general, these experiment results indicate that LDO/BC can be a potentially effective reagent for remediation of heavy metal contaminated water and soil.     

铁-草酸配合物光分解降解活性染料的研究

研究了铁（Ⅲ)-草酸配合物在可见光及太阳光照射下，对活性染料的光解降解作用。结果表明，在pH=4．0、Fe(Ⅲ)／H2E2O4=0．060mmol／L／2．88mmol／L(草酸分2次加入)、光照3h的条件下，20mg／L的活性红的降解率为97．5％。溶液pH值、铁与草酸浓度比和活性染料浓度均对降解效果产生影响。     

从废旧锌锰电池中回收锌和锰的工艺研究

废旧锌锰干电池经过剖开、焙烧处理，去除汞和碳粉，再用硫酸浸取，滤液采用沉淀法分离锌和锰。锌和锰的回收率分别为94．5％和93．6％。     

胡敏酸和富里酸与Fe3+氧化还原动力学研究

采用邻二氮菲比色法研究了Fe3 与不同浓度的胡敏酸(HA)和富里酸(FA)的氧化还原反应动力学特征.结果表明,采用常用动力学方程对反应过程进行拟合,二级反应方程比较满意.在相同腐殖酸浓度下,随着Fe3 初始浓度的增加,腐殖酸还原Fe3 的速度常数k2降低,而还原反应半衰期t1/2增大;HA还原Fe3 的速率常数k2大于FA,半衰期小于FA. HA对Fe3 的还原能力较FA高,氧化还原容量亦比后者大.     

滇池水体BOD5和CODMn空间变化研究

通过对滇池进行全湖集中采样和分析,揭示了滇池水体五日生化需氧量(BOD5)和高锰酸盐指数(CODMn)的空间变化规律.BOD5和CODMn变化范围分别是2.3～7.9mg/L,5.1～15.4mg/L,BOD5平均值草海(5.9mg/L)高于外海(5.1mg/L)CODMn平均值外海(10.17mg/L)高于草海(8.67mg/L),2个指标在入河口水域都相对较高.水平方向上,BOD5变化特点是南北高,中间低,西部高,东部低.垂直方向向上BOD5随水深增加递减.而CODMn的高值区域主要出现在草海和外海海埂、盘龙江、大青河入湖口水域、西部观音水域以及东北部宝象河、东部梁王河和捞鱼河入湖口水域、东南柴河入湖口水域.垂直方向上,从表层到水-沉积物界面水体,其CODMn都呈增加趋势.随着工业点源污染的控制,城市生活污水的排入和面源有机污染物的输入以及内源释放是决定滇池BOD5和CODMn空间变化的主要原因.     

纳米级Fe3O4-Pd/Fe复合材料催化脱氯2,4-D研究

采用共沉淀法制备纳米级Fe_3O_4,将其包覆在纳米Pd/Fe颗粒表面制成纳米级Fe_3O_4-Pd/Fe复合材料,并用于2,4-二氯苯氧乙酸(2,4-D)的催化脱氯.同时,采用透射电镜(TEM)、扫描电镜(SEM)等方法对复合材料的结构进行分析,并考察了初始pH、钯化率、反应温度、纳米Fe_3O_4投加量等实验参数对n Fe_3O_4-Pd/Fe复合材料催化脱氯2,4-D的影响.结果发现,纳米Fe_3O_4粒径小于Pd/Fe纳米颗粒,具有一定的磁性,包覆于纳米Pd/Fe表面,提高了纳米材料的稳定性及分散性,并有利于复合材料的回收和循环利用.此外,纳米Fe_3O_4具有一定的导电性,可作为良好的电子通道为纳米Pd/Fe颗粒传递电子,促进反应的进行,增强2,4-D的去除效果.实验结果表明,较高的钯化率、反应温度、Fe_3O_4∶Fe质量比及中性pH条件均有利于反应的进行.当纳米Fe投加量为1.0 g·L-1,m(Fe_3O_4)∶m(Fe)为1∶1,初始pH为7.0,钯化率为0.15%,反应温度为25.0℃时,反应90 min后,40.0 mg·L-1的2,4-D的去除率达到100%,苯氧乙酸(PA)的生成率达99.8%.     

间接光度法测定饮水中二氧化氯的浓度

在酸性介质中 ,将二氧化氯与过量的亚铁离子反应 ,未反应的亚铁离子再与邻菲罗啉显色 ,通过测定显色溶液吸光度值的改变来实现对水中二氧化氯的定量。本文通过大量实验确定了该方法的实验条件以及干扰因素。本法操作简便无毒 ,专一性强 ,分析速度快 ,准确度与灵敏度较高。检出限为 :( 5 3 6× 10 -3 1 3 3 )mg/L。相关系数为 :0 9997。变异系数为 :2 5 5 %。     

粉煤灰基质滤料处理含锰废水的研究

通过静态吸附试验研究了粉煤灰基质滤料对废水中Mn2+的吸附性能,主要探讨了滤料投加量、吸附时间、原水浓度、振荡频率等因素对吸附效果的影响。结果表明:随着投加量增加,Mn2+去除率提高,单位吸附量线性下降;随着吸附时间延长,Mn2+去除率提高,超过80 min后提高幅度变缓,吸附过程符合二级动力学模型;振荡频率的增大对吸附有一定的促进作用,但超过200 r/min后提高不明显。