Cyanide phytoremediation by water hyacinths (Eichhornia crassipes)

Although cyanide is highly toxic, it is economically attractive for extracting gold from ore bodies containing only a few grams per 1000 kg. Most of the cyanide used in industrial mining is handled without observable devastating consequences, but in informal, small-scale mining, the use is poorly regulated and the waste treatment is insufficient. Cyanide in the effluents from the latter mines could possibly be removed by the water hyacinth Eichhornia crassipes because of its high biomass production, wide distribution, and tolerance to cyanide (CN) and metals. We determined the sodium cyanide phytotoxicity and removal capacity of E. crassipes. Toxicity to 5-50 mg CN L(-1) was quantified by measuring the mean relative transpiration over 96 h. At 5 mgCNL(-1), only a slight reduction in transpiration but no morphological changes were observed. The EC(50) value was calculated by probit analysis to be 13 mgCNL(-1). Spectrophotometric analysis indicated that cyanide at 5.8 and 10 mgL(-1) was completely eliminated after 23-32 h. Metabolism of K(14)CN was measured in batch systems with leaf and root cuttings. Leaf cuttings removed about 40% of the radioactivity from solution after 28 h and 10% was converted to (14)CO(2); root cuttings converted 25% into (14)CO(2) after 48 h but only absorbed 12% in their tissues. The calculated K(m) of the leaf cuttings was 12 mgCNL(-1), and the V(max) was 35 mg CN(kg fresh weight)(-1)h(-1). Our results indicate that E. crassipes could be useful in treating cyanide effluents from small-scale gold mines.     

Utilization of two invasive free-floating aquatic plants (Pistia stratiotes and Eichhornia crassipes) as sorbents for oil removal

Free-floating aquatic plants Pistia stratiotes and Eichhornia crassipes are well-known invasive species in the tropics and subtropics. The aim of this study was to utilize the plants as cost-effective and environmentally friendly oil sorbents. Multilevel wrinkle structure of P. stratiotes leaf (PL), rough surface of E. crassipes leaf (EL), and box structure of E. crassipes stalk (ES) were observed using the scanning electron microscope. The natural hydrophobic structures and capillary rise tests supported the idea to use P. stratiotes and E. crassipes as oil sorbents. Experiments indicated that the oil sorption by the plants was a fast process. The maximum sorption capacities for different oils reached 5.1–7.6, 3.1–4.8, and 10.6–11.7 g of oil per gram of sorbent for PL, EL, and ES, respectively. In the range of 5–35 °C, the sorption capacities of the plants were not significantly different. These results suggest that the plants can be used as efficient oil sorbents.     

水葫芦对萘的降解作用研究

分别在静态和动态两种条件下 ,以水葫芦为对象 ,对水生植物净化塘处理萘污水进行研究。结果表明 ,在静态试验中 ,水葫芦净化塘对浓度为 2 5、6 5和 16 1mg L萘污水的 7d净化率分别为 97 1%、93 7%和 90 4 %。动态试验中 ,相同浓度萘污水 7d后的出水净化效率分别为 99 2 %— 99 9%、97 3%— 98 6 %和 94 6 %— 96 7%。进水浓度分别为1 2mg L和 6 5mg L萘污水在水葫芦净化塘中的最佳停留时间分别为 5d和 7d ,水葫芦净化塘动态过程的净化效率高于静态过程     

Bio-absorption of Ni and Cd on Eichhornia crassipes root thin film

Release of heavy metals into waterways without treatment can cause a significant threat to the environment. In this paper, we present a method of improving the removal of heavy metals by using Eichhornia crassipes roots (ECR) supported on a polymethyl methacrylate (PMMA) thin film. The functional groups of the synthesized PMMA sample were identified by Fourier transform infrared spectroscopy. ECR roots dried fine powder has a small size and large surface area. They contain many polyfunctional metal-binding sites for both cationic and anionic metal complexes. The results show that using 0.1 g of ECR, about 70 % of Cd present in the water was removed in 4 h; while under the same conditions, about 55 % of Ni was removed. The concentrations of Ni and Cd were measured by laser-induced breakdown spectroscopy, a promising technique for the elemental analysis of heavy metals.     

诱导结晶法同时去除铜、锌离子

考察投药量、水力负荷、停留时间等因素,对诱导结晶反应器去除Cu2+、Zn2+效果的影响,确定最佳运行参数为：水力负荷40 m3·（m2·h）-1,结晶药剂投药量2：1,停留时间90 min。在最佳运行参数下,结晶反应器处理含铜20 mg·L-1,含锌10 mg·L-1、pH为5.5~6.0的混合重金属废水。反应器连续运行40 d,出水中铜离子和锌离子平均浓度分别为1.31 mg·L-1和4.57 mg·L-1,铜离子和锌离子平均去除率分别是93.4%和51.3%。诱晶载体粒径由0.568 mm长至0.617 mm,平均生长速度为0.001 23 mm·d-1。研究表明,该诱导结晶工艺可以用作同时去除废水中的Cu2+、Zn2+。     

水葫芦圈养对星云湖富营养化水体水质的影响

为了研究水葫芦圈养对富营养化水域的影响,对星云湖14个实验区的采样点及8个对照区采样点的水质各理化性质指标、化学需氧量（COD）、生化需氧量（BOD5）、不同形态氮浓度进行测定,分析了紫根水葫芦圈养对星云湖水质的影响,结果表明：在紫根水葫芦生长发育期,星云湖中圈养的紫根水葫芦能够显著增加水体中的溶解氧含量,可以有效吸收星云湖湖水中的氨氮、总氮、总磷,降低了水体中BOD5和COD含量。总磷、总氮和氨氮三者之间显著正相关,总磷、氨氮、总氮以及BOD5都与水体的pH呈显著负相关,然而溶解氧与pH显著正相关,BOD5与水温、总磷、COD、氨氮和总氮显著正相关。科学的水葫芦圈养模式可以有效的降低富营养化水体中的营养物质,改善水质。     

Bioconcentration of cadmium in water hyacinth (Eichhornia crassipes) in relation to thiol group content

To study the bioconcentration of cadmium in water hyacinth, the plants were exposed to water containing 2 microg Cd2+/ml for extended periods of time. Three strains from several exposures during a 30-day period were sampled for the analyses of cadmium and thiol group. The data showed that the plant concentrates cadmium mainly in the roots and that the cadmium uptake is proportional to the increase of the thiol group content. The latter suggests the possibility of using the thiol group content to assess the bioconcentration of heavy metal ions in water hyacinth and as a general parameter for monitoring the heavy metal pollution of water. A simple two-compartmental model was used to simulate the kinetics of cadmium uptake. The calculated bioconcentration factor matches the one derived directly from experimental data, indicating the adequacy of the model.     

Eichhornia crassipes capability to remove naphthalene from wastewater in the absence of bacteria

The aim of the current study was to investigate the potential of an aquatic plant, the water hyacinth (Eichhornia crassipes) devoid rhizospheric bacteria, to reduce naphthalene (a polyaromatic hydrocarbon) present in wastewater and wetlands.The capability of sterile water hyacinth plants to remove naphthalene from water and wastewater was studied in batch systems. Water hyacinths enhance the removal of pollutants through their consumption as nutrients and also through microbial activity of their rhizospheric bacteria.Experimental kinetics of naphthalene removal by water hyacinth coupled with natural rhizospheric bacteria was 100% after 9 d. Plants, decoupled of rhizospheric bacteria, reduced naphthalene concentration up to 45% during 7 d. Additionally, naphthalene uptake by water hyacinth revealed a biphasic behavior: a rapid first phase completed after 2.5 h, and a second, considerably slower rate, phase (2.5-225 h). In conclusion, water hyacinth devoid rhizospheric bacteria reduced significantly naphthalene concentration in water, revealing a considerable plant contribution in the biodegradation process of this pollutant.     

Studies on the ability of water hyacinth (Eichhornia crassipes) to bioconcentrate and biomonitor aquatic mercury

Water hyacinth (Eichhornia crassipes, Mart solms) plants were employed to assess bioconcentration and genotoxicity of aquatic mercury. Plants were exposed to water contaminated with mercuric chloride (MC) or phenyl mercuric acetate (PMA) at 0.001 to 1.0 mg litre(-1), or mercury contaminated effluent from a chloralkali plant for various periods of 4 t0 96 h. Root samples taken after 4, 8, 12, 24, 48, 72 and 96 h of exposure were analysed for bioconcentration of mercury spectrophotometrically, and the root meristems were fixed in aceto-ethanol for cytological analysis to determine the frequencies of cells with micronuclei (MNC). Ethyl methane sulfonate and tap water served as positive and negative controls, respectively. The results indicated that bioconcentration of mercury in root tissue was both time- and concentration-dependent, providing evidence that water hyacinth is a good absorbant of aquatic mercury. The frequency of root meristematic cells with MNC followed a concentration-response. The findings indicate the potential of water hyacinth plants for in situ monitoring and for mitigation of aquatic mercury pollution.     

凤眼莲去除垃圾渗滤液中的COD、NH3-N和TP

在静态水培实验条件下,对不同浓度垃圾渗滤液条件下凤眼莲的生长状况及其净化效果进行了研究。结果表明,在高浓度(COD 3 546.7 mg/L、NH3-N 527.5 mg/L、TP 8.02 mg/L)垃圾渗滤液条件下(HCL)凤眼莲全部被毒害致死,在中浓度(COD 1 233.3 mg/L、NH3-N 182.9 mg/L、TP 2.83 mg/L)垃圾渗滤液条件下(MCL)生长状况差,生物量减少为实验前的32.6%。在低浓度(COD 660.0 mg/L、NH3-N 99.7 mg/L、TP 1.59 mg/L)垃圾渗滤液条件下(LCL)能够正常生长,且对低浓度垃圾渗滤液有较好的净化效果。24 d后COD、NH3-N和TP的去除率分别为85.9%,99.8%和84.8%。COD与NH3-N均达到《生活垃圾填埋场污染控制标准(GB16889-2008)》排放标准,TP达到《地表水环境质量标准(GB 3838-2002)》Ⅳ类排放标准。     

凤眼莲去除垃圾渗滤液中的COD、NH_3-N和TP

在静态水培实验条件下,对不同浓度垃圾渗滤液条件下凤眼莲的生长状况及其净化效果进行了研究。结果表明,在高浓度（COD 3 546.7 mg/L、NH3-N 527.5 mg/L、TP 8.02 mg/L）垃圾渗滤液条件下（HCL）凤眼莲全部被毒害致死,在中浓度（COD 1 233.3 mg/L、NH3-N 182.9 mg/L、TP 2.83 mg/L）垃圾渗滤液条件下（MCL）生长状况差,生物量减少为实验前的32.6%。在低浓度（COD 660.0 mg/L、NH3-N 99.7 mg/L、TP 1.59 mg/L）垃圾渗滤液条件下（LCL）能够正常生长,且对低浓度垃圾渗滤液有较好的净化效果。24 d后COD、NH3-N和TP的去除率分别为85.9%,99.8%和84.8%。COD与NH3-N均达到《生活垃圾填埋场污染控制标准（GB16889-2008）》排放标准,TP达到《地表水环境质量标准（GB 3838-2002）》Ⅳ类排放标准。     

高分子重金属螯合剂PATD的制备及其去除Cu~(2+)、Ni_(2+)性能

以丙烯酸,四乙烯五胺,二硫化碳和氢氧化钠为原料合成了一种二硫代氨基甲酸盐类高分子重金属螯合剂,PATD,采用红外光谱对其结构进行了表征。研究了PATD的投加量、体系pH对Cu2+和Ni2+模拟废水的处理效果的影响。结果表明,PATD高分子重金属螯合剂处理浓度为50 mg/L的Cu2+和Ni2+模拟重金属废水时,当PATD/重金属离子质量比分别大于6(Cu2+)和12(Ni2+)时,处理后废水中残留的重金属离子浓度均低于国家污水综合排放一级标准。PATD在较宽p H范围内均可有效去除重金属Cu2+和Ni2+离子;对Cu2+的去除效果要好于Ni2+。对低浓度(1.0 mg/L)的Cu2+和Ni2+废水的处理同样具有很好的效果。     

Cu2+沉淀-氧化法脱除H2S废气回收硫磺研究

开发了一种用含Cu2 的溶液吸收H2S,并用Cu2 自氧化CuS制取硫磺的新工艺,Cu2 的还原产物CuCl2-由空气氧化再生,实现循环.考察了Cu2 浓度与净化效率的关系,研究了Cu2 、H 、助剂N的浓度和温度对Cu2 氧化CuS效率的影响及H 、助剂N的浓度、空塔气速和温度对Cu2 空气氧化再生效率的影响.结果表明,该技术对H2S废气净化效率100%,Cu2 氧化CuS及Cu2 空气氧化再生条件温和、效果好,终产物硫磺纯度高.     

改性水葫芦粉对水体中Hg2+的吸附

通过二硫化碳（CS2）对水葫芦粉进行改性,研究吸附时间、吸附剂浓度和溶液pH对改性前后水葫芦吸附溶液二价汞（Hg2+）的影响,并探讨其吸附动力学、热力学行为和除汞机理。结果表明：吸附剂浓度为2 g·L-1,溶液pH值为6,吸附时间180 min,改性水葫芦粉对Hg2+浓度为2.0 mg·L-1时的去除率大于93%;改性前后水葫芦粉对Hg2+的吸附过程均符合拟二级动力学方程,化学吸附在整个吸附过程中起重要作用。吸附过程能够很好地用Langmuir方程拟合,吸附自由能变（ΔG）H）>0、吸附熵变（ΔS）>0,表明改性水葫芦粉对Hg2+的吸附过程是自发的吸热过程;动力学拟合和热力学研究表明改性水葫芦粉对Hg2+的吸附既有物理吸附又有化学吸附。     

Physiological responses of Alternanthera philoxeroides (Mart.) Griseb leaves to cadmium stress

Aquatic macrophytes were found to be the potential scavengers of heavy metals from aquatic environment. In this study, several physiological responses of Alternanthera philoxeroides (Mart.) Griseb leaves to elevated concentrations of cadmium (up to 10mM) were investigated. It was found that A. philoxeroides was able to accumulate cadmium in its leaves. The pigment contents decreased with the increase of the Cd concentrations. The Cd could induce rise of the activity of peroxidase (POD) at lower concentration (<5mM), however, when the concentration of Cd rose up to 10mM, the POD activity declined. The changes of superoxide dismutase (SOD) and Catalase (CAT) activities were exactly opposite to that of POD. In the leaves of Cd-treated fronds, the amounts of three polypeptides with apparent molecular weights 80, 39 and 28kDa, respectively, were became visible in SDS-PAGE. The nature of these polypeptides remains to be determined.     

滇池凤眼莲种养水域水体理化指标24小时变化规律

在滇池水域选择3个实验点,分别是外草海、老干鱼塘和龙门村,构建围栏控制性种养凤眼莲,用于吸收富集水体氮磷。于凤眼莲旺盛生长期内(2010年8月),每隔3小时监测种养区与对照区水体理化指标,包括气温、水温、pH、溶解氧(DO)、总氮(TN)、氨氮(NH4+-N)、硝氮(NO3--N)、总磷(TP)和磷酸根(PO43--P),分析24 h内水体理化指标的变化规律。结果显示,(1)昼夜变化使得3个实验点水体pH和DO白天高于夜晚。由于气泡浮力机制影响,龙门村水体Chl-a浓度在中午12:00达到最高,在日落后21:00又出现一个高值;(2)外草海种养区NO3--N浓度与TN浓度呈显著的正相关关系,与NH4+-N浓度呈显著的负相关关系,推测是因为凤眼莲可以促进富营养化水体的硝化、反硝化、硝化-反硝化反应的耦合过程。老干鱼塘水体由于pH过高,使得水体NH4+-N浓度明显高于NO3--N浓度;(3)昼夜变化对水体氮、磷浓度并未表现出显著的影响。在野外大水面种养相对小面积的凤眼莲,种养水域内部的氮磷浓度均高于相对较远的对照水域;规模化种养凤眼莲方可有效降低整个水体的氮磷浓度。     

7种改性硅藻土对Cd2+、Pb2+、Cu2+的吸附性能对比

首次系统地研究了硅藻土经热活化、锰氧化物、Mg(OH)2改性、聚丙烯酰胺、氨丙基三乙氧基硅烷、微乳液和Cu2等7种方法改性后,在不同pH下对Cd2+、pb2+、Cu2+的吸附效果及其主要机理.在实验条件下,重金属吸附效果最佳的是锰氧化物和Mg(OH)2改性硅藻土.对于pb2+、Cu2+和Cd2+的吸附,前者的最大吸附量分别为98、84和78 mg/g,后者是79、76和91 mg/g.SEM、BET、XRD、FTIR结果显示,这2种改性硅藻土的比表面积大大增加,且拥有更多能提高其吸附性能的Si-O-H基团.Mg(OH)2改性硅藻土对Cd2+吸附等温线研究表明,其符合Langmuir等温吸附模型.提供的改性方法和实验结果,为硅藻土处理水体重金属污染提供了新的技术手段和理论依据.     

菌丝体-甲壳素水处理剂对重金属Ni2+离子吸附性能的研究

本文系统研究了菌丝体 -甲壳素 (甲壳素 )作为水处理剂对去除水体中Ni2 + 离子时的吸附特性 ,结果表明 ,甲壳素作为水处理剂 ,在较大pH值变化范围内 ,对Ni2 + 离子与柠檬酸镍都有较高的吸附容量 ;甲壳素在吸附金属离子的同时 ,对H+ 有吸附作用 ,且H+ 是金属离子的竞争性抑制剂。将甲壳素与市售吸附树脂相比 ,其对阳离子 (Ni2 + )和络阴离子(柠檬酸镍Ni(cit) 2 -)的吸附特性类似于阳离子交换树脂。同时 ,甲壳素不会带来二次污染 ,是一种具有广泛应用前景的环保型工业水处理剂。     

浮游球衣菌对Pb2+、Cu2+、Zn2+、Cd2+的吸附性能研究

研究了浮游球衣菌（Sphaerotilus natans）在不同吸附条件下对溶液中Pb^2＋、Cu^2＋、Zn^2＋、Cd^2＋的吸附规律。结果表明,Sphaerotilus natans对这4种重金属离子均有一定的吸附作用,并在20min内达到吸附平衡,pH对吸附过程影响较大,pH为5.5时Sphaerotilus natans对这4种金属离子的吸附效果最好,Sphaerotilus natans对它们的吸附选择性为Pb^2＋〉Cu^2＋〉Zn^2＋〉Cd^2＋,Pb^2＋、Cu^2＋能部分置换出已被菌体吸附的Zn^2＋、Cd^2＋。HCI和EDTA溶液可有效地将金属离子从菌体上解吸下来,解吸后的菌体可重复使用。     

羧基化杯[6]芳烃磷氧衍生物(HHPHC)对Cu2+、Ni2+的萃取性能

合成了萃取剂羧基化杯[6]芳烃磷氧衍生物,即5,11,17,23,29,35-六羧基-37,38,39,40,41,42-六氧磷酸二乙酯杯[6]芳烃（HHPHC）,并对其进行了红外表征,考察了溶液初始pH值、萃取时间、重金属离子初始浓度、萃取温度对HHPHC萃取重金属离子（Cu2+、Ni2+）的影响。结果表明,HHPHC萃取Cu2+和Ni2+的最佳温度均为30℃,最佳pH值均为5.0,且15 min基本达到萃取平衡,适宜处理低浓度重金属废水。准二级动力学模型（R2>0.94）和Freundlich等温模型（R2>0.999）均可拟合其萃取过程,Gibbs自由能（ΔG0）和焓变（ΔH0）值均小于0,表明萃取反应是一个自发的放热反应。