不同改性黏土矿物吸附净化磷污染水体的性能比较

比较了酸、热及其复合改性对凹凸棒石黏土、膨润土和高岭土等3种黏土矿物吸附净化不同程度磷污染水体能力的影响。结果发现,2%浓度酸处理、300℃热活化及酸热复合改性均可以显著提高凹凸棒石黏土的磷吸附净化能力,且以复合改性效果最好,Ⅴ类和劣Ⅴ类水的磷去除率均比原土提高30%以上;酸、热改性均能显著提高膨润土的磷吸附净化能力,但综合不同程度磷污染水体来看,热活化略优于酸改性,但酸热复合改性没有呈现更佳的效果;热改性显著提高高岭土的磷吸附净化能力,而酸改性却不同程度地降低了高岭土的磷吸附净化能力,酸热复合改性的效果亦不如热单独改性。结果表明,在针对不同程度磷污染水体时需根据黏土矿物特性选用酸处理、热活化或酸热复合改性方法来提高污水的吸附净化效率。     

天然膨润土的矿物特性及其磷吸附性能研究

比较了不同天然膨润土共7个样品对不同程度磷污染水体的吸附净化性能,通过等温吸附实验,探讨了膨润土对磷的吸附机制.结果发现,供试膨润土对水体磷均有一定的吸附净化潜力,但针对不同程度磷污染水体存在一定差异,且同一属型膨润土的吸附净化能力因矿物组成差异而不同.针对模拟V类水(P 0.4 mg/L)和劣V类水(P 1.0 mg/L),BN-2的吸附净化能力最强,BN-6的吸附净化能力较差,而其余膨润土对磷的吸附净化能力稍显差异.天然膨润土对磷的吸附等温曲线符合Freundlich方程,说明膨润土对磷的吸附可能属于不均匀介质的多分子层吸附.结果表明,在针对不同程度磷污染水体时,需根据膨润土的矿物特性,使各具特殊性质的不同天然膨润土矿样得到有效的应用.     

改性高岭土对废水中磷的吸附性能及机理研究

采用盐酸和煅烧2种方法对苏州高岭土进行了改性,分析其对模拟含磷废水中磷的吸附效果,并初步探讨了其作用机制,继而进行了等温吸附和吸附动力学试验研究。结果显示,酸、热改性均不同程度地提高了高岭土对模拟废水中磷的吸附净化能力,尤以9%酸改性和500℃煅烧效果最为明显。在处理25 ml浓度为20 mg/L的模拟含磷废水中,高岭土投加量为2%(重量比)时,经9%酸改性高岭土对磷去除率达81.8%,较天然高岭土提高了44.6%。在处理50 ml浓度为20 mg/L的模拟含磷废水时,经500℃煅烧改性高岭土对磷的去除率高达99.5%,残留溶液中磷浓度仅为0.10 mg/L,达到我国相应排放标准。酸改性可通过改变高岭土的吸附活性点位来提高其对磷的吸附净化性能,而煅烧通过活化高岭石中的铝而提高其对磷的吸附净化性能。天然、9%酸改性及500℃煅烧高岭土磷吸附等温线均符合Freundilch和Langmuir方程,皆达极显著水平(P<0.01)。天然、9%酸改性及500℃煅烧高岭土对磷的动力学吸附特征一致,皆与准二级方程拟合最佳,达极显著水平(P<0.01)。500℃煅烧高岭土对磷的饱和吸附量最大,在净化含磷废水中具有良好的应用前景。     

BS-12改性不同磁性黏土矿物对苯酚的吸附

采用共沉淀法制备磁性海泡石(MST)、磁性沸石(MZT)和磁性凹凸棒石(MAT),并以两性表面活性剂十二烷基二甲基甜菜碱(BS-12)对其进行改性,以X射线衍射(XRD)对不同吸附剂材料进行表征分析,通过批处理法比较不同磁性黏土矿物经BS-12改性后对苯酚的吸附特征,同时考察温度、pH和离子强度对BS-12改性磁性黏土矿物吸附苯酚的影响。结果表明,三种黏土矿物原样和磁化样对苯酚的吸附能力分别呈NATNSTNZT、MATMSTMZT的大小顺序,磁化对凹凸棒石的苯酚吸附能力影响最大,这与Fe3O4在凹凸棒石上的覆盖度较高有关。经BS-12改性后,三种改性磁性黏土矿物对苯酚的吸附量均随改性比例的增大而增加,具有一致性;三种磁性黏土矿物中,BS-12改性对磁性海泡石的苯酚吸附能力提升最多,这与BS-12在磁性海泡石的改性率较高有关。温度和溶液初始pH的升高不利于BS-12改性磁化样对苯酚的吸附,但离子强度的增加对BS-12改性磁化样吸附苯酚具有促进作用。BS-12改性磁性黏土矿物对苯酚的吸附以疏水分配作用为主,吸附能力取决于有机碳含量。三种改性磁性黏土矿物中,BS-12改性磁性凹凸棒石上的有机碳含量最高,对苯酚的吸附能力最强,且吸附受温度、pH和离子强度的影响最小。     

BS-12改性不同磁性黏土矿物对苯酚吸附及机制的比较

采用共沉淀法制备磁性海泡石（MST）、磁性沸石（MZT）和磁性凹凸棒石（MAT）,并以两性表面活性剂十二烷基二甲基甜菜碱（BS-12）对其进行改性,以X射线衍射（XRD）对不同吸附剂材料进行表征分析,通过批处理法比较了BS-12改性不同磁性黏土矿物对苯酚的吸附特征,同时考察了温度、pH和离子强度对不同磁性黏土矿物间及不同改性比例下吸附苯酚的影响。结果表明,三种黏土矿物原样和磁化样对苯酚的吸附能力分别呈NAT＞NST＞NZT、MAT＞MST＞MZT的大小顺序,磁化对凹凸棒石的苯酚吸附能力影响最大,这与Fe3O4在凹凸棒石上的覆盖度较高有关。经BS-12改性后,三种改性磁性黏土矿物对苯酚的吸附量均随改性比例的增大而增加,具有一致性;三种磁性黏土矿物中,BS-12改性对磁性海泡石的苯酚吸附能力提升最多,这与BS-12在磁性海泡石的改性率较高有关。温度和溶液初始pH值的升高不利于BS-12改性磁化样对苯酚的吸附,但离子强度的增加对BS-12改性磁化样吸附苯酚具有促进作用。BS-12改性磁性黏土矿物对苯酚的吸附以疏水分配作用为主,吸附能力取决于有机碳含量。三种改性磁性黏土矿物中,BS-12改性磁性凹凸棒石上的有机碳含量最高,对苯酚的吸附能力最强,且吸附受温度、pH和离子强度的影响最小。     

四种典型重金属污染对土壤吸附磷的影响

以空白土壤和人工制备的不同浓度铜、砷、镉和铅污染土壤为对象,研究了在不同pH值、温度和柠檬酸浓度条件下重金属污染对土壤吸附磷的影响,并对其进行了相关过程的等温和吸附动力学的机理分析。研究结果表明,空白土壤和As污染土壤吸附磷的等温吸附过程符合Temkin方程,Cu、Pb、Cd污染土壤吸附磷的等温吸附过程符合Freundlich方程,空白土壤和重金属污染土壤吸附磷的动力学过程均符合Elovich方程;重金属污染对土壤吸附磷有一定的抑制作用,抑制程度与污染物浓度呈现显著的正相关,且随外在环境因子的改变而不同。当重金属元素铜、铅、砷、镉的含量分别为200、80、25、0.8 mg kg^-1时:pH值为5时,重金属对土壤吸附磷抑制作用最小,土壤吸附磷量分别降低了30.18%、13.54%、30.74%、37.23%,其抑制作用程度为:Cd> As> Cu> Pb;土壤吸附磷量与温度呈现显著的正相关,温度变化为25~45℃时,土壤对磷的吸附量分别增大了17.14%~28.83%、6.72%~16.05%、8.68%~9.13%、10.30%~23.45%,同一条件下重金属对土壤吸附磷抑制作用程度为Cu> Cd> As> Pb;重金属污染土壤吸附磷量与柠檬酸浓度成负相关,柠檬酸浓度为50 mg L^-1时,土壤吸附磷量分别降低了19.87%、21.94%、23.18%、24.84%,相同柠檬酸浓度下其抑制作用程度为Cd> As> Pb> Cu。     

大气氮湿沉降及其对惠州西湖水体富营养化的影响

根据2000～2004年广东省惠州市降水中氮浓度,采用单因子评估模式评价了大气氮湿沉降及其对惠州西湖水体富营养化的影响.结果表明,近5年惠州市湿沉降平均NO-3 -N含量为0.469 mg · L-1,NH 4 -N含量为0.391 mg · L-1,总无机氮(TIN)含量为0.861 mg · L-1,远大于富营养水体中氮浓度阀值(0.2 mg · L-1).湿沉降中氮含量呈逐年增加趋势,2004年湿沉降氮含量较2000年增加了近1倍.依据降水中氮浓度,2000～2004年湿沉降中总氮含量为Ⅲ～Ⅳ类水;而降水氮含量季节变化中,总氮为Ⅱ类～劣Ⅴ类水,Ⅴ和劣Ⅴ类水质开始频繁出现.湿沉降每年输入惠州市的TIN为16.26 kg · hm-2,湿沉降中氮浓度已超过水体富营养化阈值.因此,湿沉降输入氮对惠州西湖水生态环境,特别是水体富营养化的影响值得关注.     

改进灰色模式识别模型评价洱海雨季灌排沟渠水质

为揭示洱海流域农田生产与农村生活单元交替分布对灌排沟渠水质的综合影响及污染物贡献率,选取流域典型灌排沟渠不同断面进行连续取样观测,在分析化学需氧量(chemical oxygen demand,COD)、总氮(total nitrogen,TN)、总磷(total phosphorus,TP)及铵态氮(ammonium nitrogen,NH_4~+-N)浓度变化特征基础上,采用"中心化"灰色模式识别模型和综合平均污染指数对沟渠农田入口-农田出口-村落出口-农田出口-村落出口-农田出口断面水质进行综合评价。结果表明:沟渠断面TP和总可溶磷(totaldissolved phosphate,TDP)浓度沿水流方向持续增加,TN和硝态氮(nitrate nitrogen,NO_3~--N)浓度先增加随后稳定,沟渠农田出口段NH_4~+-N和COD浓度分别削减13.43%～57.88%和2.88%～19.33%,而流经村落段浓度相应增加。灰色模式识别模型分析发现沿水流方向沟渠断面水质类别分别为Ⅲ类、Ⅱ类、Ⅳ类、Ⅳ类、Ⅴ类和Ⅴ类,综合平均污染指数法表明沟渠中TN和COD是水体主要污染因子,而NO3--N是水体TN的最主要形态。该研究可揭示洱海流域氮磷污染来源与贡献,为明确面源污染防治的主要污染因子提供科技支撑。     

内蒙古乌梁素海入湖水质超标风险率分析

以内蒙古乌梁素海入流水体为研究对象,考虑湖泊水质的随机性和灰色不确定性,以灰色概率统计理论为基础,引入灰色-随机风险率方法,通过计算并分析2006年、2007年和2008年入湖断面各水质参数存在的超标风险性,反映不同水质参数的污染强度和污染历时的变化过程。结果表明,入湖水体总氮总磷浓度超标风险率呈现逐年上升的趋势;总氮浓度超过Ⅴ类标准值的上限风险率达96.4%,下限风险率达87.7%;总磷浓度超过Ⅴ类标准值的上限风险率达96.2%,下限风险率达86.9%;BOD5浓度超过Ⅴ类标准值的平均风险率达55%;COD浓度超过Ⅴ类标准值的平均风险率达85%。乌梁素海入湖水体污染程度已十分严重,源头水污染防治已刻不容缓。     

磷和柠檬酸共存对高岭石和针铁矿吸附铅的影响

通过平衡吸附试验及矿物电动电位(Zeta电位)的变化分析,研究了磷(P)和柠檬酸(CA)共存对针铁矿和高岭石吸附铅的影响。结果表明:(1)针铁矿和高岭石对铅的吸附量随柠檬酸浓度的升高呈现"峰形"曲线变化,铅吸附量达到峰值的柠檬酸浓度均为0.5 mmol L~(-1),不同浓度磷存在下柠檬酸对矿物吸附Pb2+量有不同程度增加。(2)随着磷添加浓度的增加,两种矿物对铅吸附量均呈增加趋势,磷添加浓度分别为1 mmol L~(-1)和0.6 mmol L~(-1)时,针铁矿和高岭石吸附铅量达到平衡;当处理中添加不同浓度柠檬酸,两种矿物均表现为对铅的吸附量增加,且随着柠檬酸浓度增加促进铅吸附的作用增强,说明在磷及试验浓度柠檬酸存在下促进了矿物对铅的吸附。(3)高岭石体系中,加入磷或(和)柠檬酸后,Zeta电位-pH曲线向负值方向位移,降低程度大小顺序为1.0 mmol L~(-1) P+0.5mmol L~(-1) CA0.5 mmol L~(-1) CA1.0 mmol L~(-1) P,说明高岭石表面增加的负电荷也部分增加了其对铅的电性吸附;添加磷和柠檬酸处理针铁矿的Zeta电位显著降低,且随着体系pH的升高其Zeta电位没有明显变化,表明磷和柠檬酸均主要是通过吸附到针铁矿表面而增加对铅的专性吸附。     

Deformation of humic acid by acid treatment

In our previous report (1) we had proposed the method to fractionate humic acid into three parts using organic solvents, and had advocated the new theory on the process of humification in volcanic ash soils from the results of the fractionation.     

Anaerobic biotransformation of organo-arsenical pesticides monomethylarsonic acid and dimethylarsinic acid

Monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV) are extensively utilized as pesticides, introducing large quantities of arsenic into the environment. Once released into the environment, these organo-arsenicals are subject to microbial reactions. Aerobic biodegradation of MMAV and DMAV has been evaluated, but little is known about their fate in anaerobic environments. The objective of this study was to evaluate the biotransformation of MMAV and DMAV in anaerobic sludge. Biologically mediated conversion occurred under methanogenic or sulfate-reducing conditions but not in the presence of nitrate. Monomethylarsonous acid (MMAIII) was consistently observed as an important metabolite of MMAV degradation, and it was recovered in molar yields ranging from 5 to 47%. The main biotransformation product identified from DMAV metabolism was MMAV, which was recovered in molar yields ranging from 8 to 65%. The metabolites indicate that reduction and demethylation are important steps in the anaerobic bioconversion of MMAV and DMAV, respectively.     

Nonenzymatic antioxidative and antiglycative effects of oleanolic acid and ursolic acid

Oleanolic acid and ursolic acid are two triterpenes presented in several herbs. This study analyzed the content of oleanolic acid and ursolic acid in eight locally available fresh herbs, also examined several nonenzymatic antioxidant activities of these two triterpenes, and used a liposome system to evaluate the influence of temperature and pH upon the antioxidant property of these two triterpenes. The impact of these two triterpenes on the production of nonenzymatic glycative products, pentosidine and carboxymethyllysine (CML), was also evaluated. alpha-Tocopherol was used for comparison. Results showed that the content of oleanolic acid and ursolic acid in glossy privet fruit and hawthorn fruit varied from season to season and was in the range of 200-650 microg/g of fresh weight. Both oleanolic acid and ursolic acid possessed greater antioxidant activity against 2,2'-azobis-(2-amidinopropane) dihydrochloride and less antioxidant activity against 2,2'-azobis(2,4-dimethylvaleronitrile) when compared with alpha-tocopherol at equal concentration (P <0.05). At 75 and 100 degrees C, oleanolic acid exhibited greater antioxidant activity than alpha-tocopherol and ursolic acid (P <0.05). At pH 2 and pH 4, oleanolic acid and ursolic acid showed greater antioxidant activity than alpha-tocopherol (P <0.05). These two triterpenes also exhibited a dose-dependent effect in superoxide anion scavenging activity, chelating effect, xanthine oxidase inhibition activity, and reducing power (P <0.05). Oleanolic acid significantly and dose-dependently inhibited pentosidine and CML formation (P <0.05). Ursolic acid also significantly suppressed CML formation (P <0.05). These data support that these two triterpenes possessed nonenzymatic antioxidative and antiglycative properties.     

阿魏酸与肉桂酸对杉木化感作用的生物评价

通过绿豆、大豆、黄瓜、空心菜及玉米等种子发芽的生物评价,分析研究阿魏酸和肉桂酸对杉木化感作用结果表明,阿魏酸对5种蔬菜种子作用表现为高浓度抑制萌发和生长,随浓度的降低其抑制作用逐渐减弱。肉桂酸除对空心菜发芽表现为高浓度促进生长外,对其余种子作用表现为高浓度抑制萌发和生长,随浓度的降低其抑制作用逐渐减弱。     

Some effects of replacement of metaphosphoric acid/acetic acid solvent system with trichloroacetic acid in microfluorometric determination of vitamin C

Trichloroacetic acid (TCA) is suggested as a substitute for the metaphosphoric acid/acetic acid (HPO3-HOAc) solvent system in the AOAC microfluorometric determination of vitamin C. Comparative advantages of TCA are easier handling, greater stability, and the approximate 10-fold increase in sensitivity. For both solvent systems, the influence of acid concentration on fluorescence is described. TCA provides maximum fluorescence enhancement at pH 5.5-6.0.     

Epimeric separation of L-ascorbic acid and D-isoascorbic acid by capillary zone electrophoresis

Capillary zone electrophoresis (CZE) was used for separation of L-ascorbic acid (L-AA) and D-isoascorbic acid (D-IAA) in a model system. The effects of borate buffer concentration (0.05-0.25 M) and pH (pH 7.5-9.0) on migration time, resolution (Rs), and theoretical plates (N) were investigated. The migration times of L-AA and D-IAA increased with the increasing pH of carrier electrolyte (0.2 borate buffer), and the resolutions (Rs) of L-AA and D-IAA were calculated to be 12.98 at pH 9.0. Concentrations of borate buffer (pH 9.0) increased the Rs values of L-AA and D-IAA, and buffer concentrations >0.1 M were found to be effective for separation of L-AA and D-IAA. Methanol in the carrier electrolyte was also influential in improving the separation of L-AA and D-IAA, which increased with the increasing concentrations (0-10%) of methanol. The optimal separation conditions for L-AA and D-IAA were as follows: carrier electrolyte, 0.2 M borate buffer (pH 9.0); applied voltage, 25 kV, with an uncoated fused silica capillary, 75 microm (i.d.) x 57 cm.     

Adsorption mechanisms of nicotine on humic acid and clay humic acid complex

The adsorption isotherm of nicotine on humic acid - surface was found to be multiphase according to the applied concentrations of nicotine. Each phase was characterized by its own change in free energy and represented a mechanism of interaction. At low concentrations, the isotherm showed a H-curve of high affinity between both reactants as a result of protonation of the pyrrolidine nitrogen atom of nicotine, the second phase was that of flat adsorption in which the nitrogen atoms of nicotine acted as electron donor. The third phase was that of the rearrangement of the nicotine from flat to side adsorption on the humic surface, after which the phase of multilayer formation followed. The adsorption on the surface of the humic acid-clay complex showed no distinct phases but an isotherm looks like the L-type, although it could not verify Langmuir's equation. Probably the isotherm was the resultant of two mechanisms one due to the adsorption of the humic acid part and the other due to the clay part in the complex. Comparison of the constants of Freundlich's equation showed that the capacity of the adsorption humic surface was greater than that of the complex.