藻细胞和高岭土的存在对病毒MS2存活的影响

选用病毒MS2作为水中肠道病毒的指示病毒,高岭土和铜绿微囊藻分别作为无机颗粒物和有机颗粒物,研究颗粒物浓度、pH值、不同价态离子浓度、天然有机物(NOM)等水质条件下,无机(高岭土)、有机(铜绿微囊藻)颗粒物存在对病毒MS2存活的影响.结果表明,无机颗粒物高岭土对病毒MS2的存活无明显影响,但当水体钙硬度(钙离子产生的硬度)较大时,病毒MS2的表观存活量增加1个对数;铜绿微囊藻的存在会导致病毒MS2的存活量降低1个对数左右,但当溶液的pH值大于4.0或铜绿微囊藻的浓度小于1.0×106cells·L-1时,藻类对病毒的生存无明显影响;当水体钙硬度较大时,藻反而会增加病毒MS2的存活对数.因此在高浊水、高藻水中,水的钙硬度增加会使水体中病毒生存能力变强,进而增加饮用水的安全风险.     

醋酸-醋酸铵缓冲体系中柠檬酸、草酸和苹果酸对高岭石的溶解特征

采用间歇法(batch method)模拟研究醋酸-醋酸铵缓冲体系中柠檬酸、草酸和苹果酸三种低分子量有机酸对高岭石的溶解特征。结果表明:柠檬酸、草酸和苹果酸三种有机酸均能显著促进高岭石的溶解,溶解能力都是随其浓度和酸度的升高而增强;当有机酸浓度为1mmol/L,pH3.5时,草酸>柠檬酸>苹果酸;pH5.5和pH4.5时,柠檬酸>草酸>苹果酸;而当有机酸浓度≥5mmol/L时,草酸>柠檬酸>苹果酸,且对高岭石的溶解能力都大于无机酸。当柠檬酸、草酸和苹果酸浓度为1mmol/L时,反应级数(nHL)分别为0.09、0.27和0.18,速率常数(kHL)分别为4.03×10-13、2.62×10-12和4.73×10-13;当其浓度为5mmol/L时,其反应级数(nHL)分别为0.16、0.37和0.16,速率常数(kHL)分别为1.38×10-12、2.32×10-11和4.97×10-13;其浓度为10mmol/L时,反应级数(nHL)分别为0.18、0.34和0.16,速率常数(kHL)分别为2.17×10-12、2.60×10-11和6.05×10-13。对于柠檬酸和草酸而言,在促进高岭石溶解的作用上,相对于质子,配体的贡献是主要的;而对于苹果酸而言,配体的贡献是次要的。配体促进溶解速率(RL)可以用配体浓度的指数形式来表示。对柠檬酸、草酸和苹果酸而言,pH5.5时,分别为RL=10-13.01[配体]0.23、RL=10-13.28[配体]0.70和RL=10-13.72[配体]0.38;pH4.5时,分别为RL=10-13.00[配体]0.51、RL=10-13.03[配体]1.05和RL=10-14.07[配体]0.77;pH3.5时,分别为RL=10-12.99[配体]0.64、RL=10-12.72[配体]0.89和RL=10-14.61[配体]1.69。     

土壤矿物质-可溶态生物炭的交互作用及其对碳稳定性的影响

将生物质转化为生物炭并输入土壤被认为是一种很有前景的碳封存技术.生物炭颗粒在土壤中会不断释放出可溶态生物炭,这部分生物炭不稳定,易被微生物分解.探明土壤组分矿物质对可溶态生物炭稳定性的影响对评估生物炭的碳封存作用具有重要意义.因此,本文以核桃壳生物炭为研究对象,通过批次吸附实验及微生物降解实验研究了2种代表性土壤矿物质高岭土和针铁矿与核桃壳生物炭可溶有机组分的结合机理,以及这种结合作用对可溶态生物炭稳定性的影响.结果表明:低浓度(如20 mg·L-1)可溶态生物炭条件下,高岭土与可溶态生物炭之间以Ca2+架桥作用为主,约占吸附总量的65%;高浓度(如80 mg·L-1)条件下,以范德华力为主,约占吸附总量的76%.随着可溶态生物炭初始浓度的升高,针铁矿对其吸附量先升高后下降,且以范德华力为主,Ca2+会抑制针铁矿对可溶态生物炭的吸附.被矿物质吸附后的可溶态生物炭,其微生物降解性显著下降,可降解的碳下降了47.9%~85.3%,土壤矿物质能够吸附保护可溶态生物炭,提高其在土壤中的稳定性.     

Electrochemical remediation of copper contaminated kaolinite by conditioning anolyte and catholyte pH simultaneously

This report examined electrochemical remediation of copper contaminated kaojinite by controlling electrolytes‘ pH for both of anolyte and catholyte simultaneously.Results showed the electrokinetic process and remediation efficiency varied obviously when different buffer systems,including citric acid(test 1),nitric acid EDTA(test 2)and nitric acid(test 3),were used to control catholyte pH AND Na2CO3 was used at the same time to control all anolyte one.It was found that under such pH condition soil‘s pH in soil column kept at 3.0-7.0 successfully,and correspondingly no copper precipitation and decrease of soil electroconductivity appeared.which are usually observed in electrokinetic process due to OH^- introduction into soil cojumn by electrochemical reaction occurred in cathode.Electroosmosis flow rates were almost equal for these three tests,indicating that these buffers did not affect Zeta-potential of kaolinite within the examined duration.More acid and basic solution was added into electrokinetic cell when nitric acid was used as buffer than when nitric acid EDTA and then citric acid were used.Due to introduction of large amounts of ions into soil column,significant higher current was observed for test 3 than other two.Analysis of copper speciation and total quantity in kaolinite indicated that 22.5%,23.74%and 55.65% Cu were removed from kaolinite for test 1,test 2 and test 3 respectively after only 10 days‘ electrokinetic remediation.     

高岭石吸附水溶液中铅离子的动力学研究

研究了高岭石吸附水相中铅离子的动力学行为.结果表明:高岭石对水溶液中铅离子的吸附是一个复杂的非均相固液反应,从动力学角度来看,大致可以分为2个阶段:初期阶段反应速度快,动力学过程复杂,有待于深入研究;后期阶段反应速度较慢,并符合一级反应动力学方程.吸附速率常数k与温度T之间的关系符合阿累尼乌斯公式,吸附的活化能为Ea=26.44 J/mol,吸附的频率因子A=603s-1.ln(k/T)与1/T之间的关系符合Eyring公式,其活化焓△H=23.94J/mol,活化熵△S=-200J/K·mol.同时,k与铅离子初始浓度呈负相关性,与高岭石用量、介质pH值呈正相关性.     

甲萘威在蒙脱石和高岭石表面的吸附行为研究

研究了甲萘威在蒙脱石和高岭石两种粘土矿物表面的吸附行为,考察了时间、pH值和农药浓度对吸附的影响,并用FTIR探讨了其吸附机理。结果表明,蒙脱石和高岭石对甲萘威的吸附是一个先快后慢的过程,10h吸附可基本达到平衡。用动力学方程对甲萘威的吸附过程进行拟合,发现Elovich方程为最佳模型(R20.93,p0.05,n=12),其次是一级动力学方程和双常数方程;甲萘威在蒙脱石和高岭石表面的等温吸附均很好地符合Langmuir方程(R20.99,p0.05,n=6),其最大吸附量分别为3.651mg/g和1.688mg/g;蒙脱石对甲萘威的吸附强度大于高岭石;在实验pH范围内,甲萘威在两种矿物表面的吸附量均随体系初始pH的升高而减小;红外光谱分析结果表明,甲萘威分子可能通过氢键与蒙脱石和高岭石发生结合。     

光照下高岭土悬浮液中产生羟基自由基的测定

对高岭土悬浮水溶液在光照过程中产生的羟基自由基(·OH)进行了测定.在pH2.0,苯浓度为7.0mmol·l-1的条件下,经过250W金属卤素灯(λ≥365nm)光照5h,高岭土浓度为20.0g·l-1的悬浮液中,·OH的产生量为21.6μmol·l-1.在pH 2.0-10.0范围内,·OH产生量随pH值的降低而增加.高岭土浓度在0-20.0g·l-1的范围内,·OH产生量随高岭土浓度的升高而增加,高岭土浓度增加到25.0g·l-1时,·OH产生量反而减少.高岭土中的铁是·OH产生的重要因素.     

Adsorption characterizations of fulvic acid fractions onto kaolinite

Fulvic acids extracted from a typical rice-production region near Taihu Lake of China were fractionated into three fractions including F4. 8, F7. 0 and F11. 0(eluted by pH4. 8 buffer, pH 7. 0bufferandpH 11. 0buffer, respectively). Sorption of fulvic acid(FA)fractions onto kaolinite was studied by batch adsorption experiments, and characterizations of kaolinite before and after adsorption were investigated using scanning electron microscopy(SEM). Adsorption isotherms of kaolinite for three FA fractions fit well with the Langmuir adsorption model. The adsorption density of the three fractions was positively correlated with the ratio of the amount of the alkyl carbon to that of carboxyl and carbonyl carbon in FA fractions and followed an order of F11. 0>F7. 0>F4.8.Hydrophobic interaction Was one of the control mechanisms for the sorption of FA fraction onto kaolinite. SEM images confirmed that compared to blank kaolinite samples, kaolinite samples coated by a FA fraction displayed an opener and more dispersed conformation resulting from the disruption of the floe structure in complex. Dispersion of kaolinite after adsorption was due to the repulsion between negatively charged FA. coated particles, which is closely related to the amount of FA fractions absorbed on kaolinite.     

苄嘧磺隆对Cu2+在粘土矿物上吸附-脱附的影响

选择两种粘土矿物Ca－蒙脱石和高岭石作为吸附体，研究Cu^2 的吸附－脱附行为，以及苄嘧磺隆对Cu^2 吸附－脱附的影响，结果表明，Cu62 在比表面积、CEC大的Ca－蒙脱石上吸附量较高；而在比表面积、CEC小的高岭石上吸附量较低，蒙脱石对Cu^2 的吸附主要是静电吸附，吸附的Cu^2 较易脱附；高岭石主要通过专性吸附机制而吸附Cu^2 ，吸附的Cu^2 较难脱附，苄嘧磺隆对Cu^2 在粘土矿物上吸附－脱附的影响显著，苄嘧磺隆增加了Cu^2 在Ca-蒙脱石上的吸附，苄嘧磺隆作为桥而连接Ca-蒙脱石和Cu^2 ，苄嘧磺隆的浓度越高，Cu^2 的吸附量越大，解吸量赵低，苄嘧磺隆对Cu^2 在高岭石上吸附的影响，则是低pH值增加Cu^2 吸附，高pH值时降低Cu^2 吸附，解吸率的变化相反。