Effect of dissolved metal ions on PCE decomposition by gamma-rays

This study investigates the effect of initial tetrachloroethylene (PCE) concentration, irradiation dose and dissolved metal ions such as Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+ on removal of PCE by gamma irradiation. The amount of removed PCE decreased with increase in initial PCE concentration and increased with increase in irradiation dose. PCE removal reached a maximum in the presence of Fe3+, while Cu2+ strongly hindered PCE decomposition. Except for Cu2+, the amount of removed PCE in the presence of metal ions was linearly dependent on the standard reduction potential of the metal ions. The extraordinary inhibition of Cu2+ in PCE removal was caused by the action of Cu2+ as a strong *OH scavenger, that was directly confirmed by electron paramagnetic resonance spectroscopy.     

Cu~(2+)、Zn~(2+)对生物脱氮系统的影响

Cu2+和Zn2+是污水处理工艺中经常遇到的金属离子.在驯化好的活性污泥系统中,研究了金属离子Cu2+和Zn2+在0～100 mg/L浓度下对活性污泥牛物脱氮系统的影响.试验发现Cu2+＞5 mg/L、Zn2+＞30 ms/L时,对硝化过程具有明显的抑制作用,在同样浓度的试验条件下Cu2+对硝化过程的抑制作用比Zn2+大.Cu2+≤0.5 mg/L时对反硝化过程具有一定的促进作用,有助于提高TN的去除效果;Cu2+＞0.5 mg/L时,对反硝化产牛抑制作用,随着浓度的增加,TN去除率逐渐下降.Zn2+不影响反硝化过程,仅在大于30 mg/L时,对硝化过程产生抑制作用.重金属Cu2+对生物脱氮系统的影响明显强于Zn2+.     

Evaluation of pectin binding of heavy metal ions in aqueous solutions

Evaluation of adsorption performance of several industrially manufactured pectins towards some toxic heavy metals was carried out. Adsorption isotherms for divalent cations in simulant aqueous solutions were measured and corresponding distribution coefficients were calculated. The following selectivity sequences we found for pectins: Pb2+ > Cu2+ > Co2+ > Ni2+ > Zn2+ > Cd2+. It was shown that a beet pectin exhibits a high affinity for Pb2+ and Cu2+ ions, an apple pectin for Co2+ ion and a citrus pectin for Ni2+ ion. The binding properties of all pectins towards Zn2+ and Cd2+ ions are extremely poor. The quantitative data on adsorption performance of pectins suggest their applicability as food additives or remedies for efficient removal of Pb2+, Cu2+, Co2+, and Ni2+ ions from different biological systems, including human and animal organisms.     

Simultaneous heavy metal removal mechanism by dead macrophytes

The use of dead, dried aquatic plants, for water removal of metals derived from industrial activities as a simple biosorbent material has been increasing in the last years. The mechanism of simultaneous metal removal (Cd2+, Ni2+, Cu2+, Zn2+ and Pb2+) by 3 macrophytes biomass (Spirodela intermedia, Lemna minor and Pistia stratiotes) was investigated. L. minor biomass presented the highest mean removal percentage and P. stratiotes the lowest for all metals tested. Pb2+ and Cd2+ were more efficiently removed by the three of them. The simultaneous metal sorption data were analysed according to Langmuir and Freundlich isotherms. Data fitted the Langmuir model only for Ni and Cd, but Freundlich isotherm for all metals tested, as it was expected. The K(F) values showed that Pb was the metal more efficiently removed from water solution. The adsorption process for the three species studied followed first order kinetics. The mechanism involved in biosorption resulted ion exchange between monovalent metals as counter ions present in the macrophytes biomass and heavy metal ions and protons taken up from water. No significant differences were observed in the metal exchange amounts while using multi-metal or individual metal solutions.     

4A沸石对复合污染水体中Pb2+、Cu2+和Cd2+的去除

采用静态吸附法以4A沸石为吸附剂研究其对复合污染水体中Pb2+、Cu2+和Cd2+的竞争吸附特性,并探讨了影响吸附的环境因素。实验表明,在室温条件下,溶液pH5～6,4A沸石15 mg对10 mL复合污染溶液(Pb2+、Cu2+和Cd2+浓度分别为100 mg/L)吸附20 min时,对溶液中3种重金属的吸附去除率均可达99.8%以上。反应过程中4A沸石对3种重金属的吸附速率大小为Pb2+>Cu2+>Cd2+。复合污染水体中4A沸石对Pb2+、Cu2+和Cd2+的吸附符合Langmuir和Fre-undlich等温吸附方程,相关系数分别为0.9981、0.9901、0.9916和0.9638、0.9194、0.9689。经计算,4A沸石对Pb2+、Cu2+和Cd2+的饱和吸附量分别为129.9 mg/g、107.5 mg/g和99.0 mg/g。4A沸石吸附重金属离子达到吸附平衡的时间较短,对溶液pH值的适应性较好。吸附后的4A沸石可以再生利用,对铅离子洗脱重复利用性较铜离子和镉离子强。     

Heavy metal ion influence on the photosynthetic growth of Rhodobacter sphaeroides

The potential of purple non-sulphur bacteria for bioremediation was assessed by investigating the ability of Rhodobacter sphaeroides strain R26.1 to grow photosynthetically in heavy metal contaminated environments. Bacterial cultures were carried out in artificially polluted media, enriched with the transition metal ions Hg2+, Cu2+, Fe2+, Ni2+, Co2+, MoO4(2-), and CrO4(2-) in millimolar concentration range. For each investigated ion the effect on growth parameters was evaluated. The analysis of concentration-effect curves revealed a differentiated response, indicating that diverse mechanisms of tolerance and/or resistance are involved. Adaptation or selection procedures were not applied, leading to assess intrinsic abilities of coping with these contaminants. The microorganism proved to be highly tolerant to heavy metal exposure, especially towards Co2+, Fe2+ and MoO4(2-). In addition Ni2+ and Co2+ were found to decrease the cellular content of light harvesting complexes. A characteristic behavior was observed with mercuric ions, which produced a significant increase of the lag-phase.     

Multi-component adsorption of copper,nickel and zinc from aqueous solutions onto activated carbon prepared from date stones

The removal of Cu²⁺, Ni²⁺, and Zn²⁺ ions from their multi-component aqueous mixture by sorption on activated carbon prepared from date stones was investigated. In the batch tests, experimental parameters were studied, including solution pH, contact time, initial metal ions concentration, and temperature. Adsorption efficiency of the heavy metals was pH-dependent and the maximum adsorption was found to occur at around 5.5 for Cu, Zn, and Ni. The maximum sorption capacities calculated by applying the Langmuir isotherm were 18.68 mg/g for Cu, 16.12 mg/g for Ni, and 12.19 mg/g for Zn. The competitive adsorption studies showed that the adsorption affinity order of the three heavy metals was Cu²⁺?>?Ni²⁺?>?Zn²⁺. The test results using real wastewater indicated that the prepared activated carbon could be used as a cheap adsorbent for the removal of heavy metals in aqueous solutions.     

基因工程菌E.coli BL21-NiCoT吸附镍的性能研究

以表达Staphylococcus aureus ATCC6538镍钴转运酶NiCoT基因的基因工程菌E.coli BL21-NiCoT作为生物吸附剂处理含镍废水.结果表明:基因工程菌在pH为4～9时有比较好的吸附效果,30 min就达到了吸附平衡;基因工程菌对Ni2 的富集容量比原始宿主菌有很大的提高,最大平衡富集量从3.76 mg/g增加到11.33 mg/g,增幅达3倍多,溶液中Ni2 的最大去除率也从原来的35.62%增加到91.23%;Cu2 、Cr6 、Zn2 等的存在对吸附没有很大的影响.镍进入细胞内后与羟基和酰胺基团发生结合,蛋白类物质和含羟基类物质在细胞内富集镍的过程中起到重要作用;基因工程菌转接10、20、30、40、50次,重组质粒保持良好的结构稳定性,基因工程菌对镍的富集能力也具有较好的稳定性.     

重金属离子在腐植酸上吸附的研究

对4种代表性重金属离子在腐植酸上吸附、pH对竞争吸附的影响及其吸附机理进行了研究。结果表明，Cu2＋、Pb2＋、Zn2＋的吸附等温线为F型，而Cd2＋等温线为L型；2．5＜pH＜3．5时，竞争吸咐次序为Cu2＋＞Pb2＋＞Cd2＋＞Zn2＋；pH＞5．0时，Cd2＋＞Cu2＋＞Zn2＋＞Pb2＋；Cu2＋在腐植酸上的吸附主要是以与腐植酸形成配合物的方式相互结合。     

Predictions of binary sorption isotherms for the sorption of heavy metals by pine bark using single isotherm data

The adsorption of three heavy metal ions by pine bark was studied. The study was divided into two parts; single component adsorption of the metals Cu2+, Cd2+ and Ni2+ and bisolute adsorption of the three binary systems Cu2+-Cd2+, Cu2+-Ni2+ and Cd2+-Ni2+. Extended Langmuir model, extended Freundlich model. Sips model and ideal adsorption solution theory (IAST) models were used to predict the equilibrium uptake for Cu2+, Cd2+ and Ni2+ in the binary diluted solutions using the single adsorption constants. The experimental data of single isotherm adsorption process were found to follow Langmuir isotherm model with less accuracy than Freundlich and Sips models. Whereas, the predictions of bisolute adsorption isotherms of the mentioned three systems, Cu2+-Cd2+, Cu2+-Ni2+ and Cd2+-Ni2+, showed good agreement with experimental data when using Extended-Langmuir, Extended-Freundlich and IAST. However, the only good fit of the Sips model was with the Cu2+-Cd2+ system.     

酸洗废液制取复合亚铁的研制及应用

介绍了利用酸洗废液为原料制备复合亚铁型混凝剂的新方法 ,并用制得的产品应用于电镀和印染废水治理工程。工程应用及实验结果表明 ,对含Ni2 + 、Cu2 + 和Cr6+ 的电镀废水 ,能使Ni2 + 、Cu2 + 出水浓度 <0 .1mg/L ,Cr6+ 未检出 ,还能处理数种化学镀废液。对印染废水 ,COD去除率和脱色率可分别达到 84 %和 98%以上 ,值得进一步研究和推广     

Microbial enhancement of Cu2+ removal capacity of Eichhornia crassipes (Mart.)

Bacteria resistant to Cu2+, Ni2+ or Zn2+ were isolated from the rhizosphere of water hyacinth (Eichhornia crassipes (Mart.)) and their metal ion removal capacities (RCs) were determined. The Ni2+ and Zn2+ RCs of the respective metal ion-resistant bacteria were less than 4.1 mg g(-1), while one of the Cu2+-resistant bacteria (Strain CU-1) showed a significant high Cu2+ RC of 10.6 mg g(-1). The effect of inoculating water hyacinth with Strain CU-1 on its Cu2+ RC was further studied. Water hyacinths were treated with an antibiotic, oxytetracycline (OTC), to remove most rhizospheric bacteria of plant roots. Inoculation of Strain CU-1 increased the Cu2+ RC of the plant root by 1.91 (OTC-treated) and 1.56 (OTC-untreated) folds respectively when compared with the control. Results also showed that Strain CU-1 colonized onto the plant root and led to the increase of Cu2+ RC of the roots of water hyacinth.     

利用芦竹修复重金属污染湿地的研究

研究了芦竹(Arundodonaxlinn)对Cu2+、Ni2+、Cr6+重金属污染湿地的响应和对该污染湿地的影响。实验结果表明,芦竹对这3种重金属离子有一定的耐受性,并有不同程度的吸收,Cu2+、Ni2+和Cr6+去除率分别为63.8%,42.3%和34.4%。芦竹在100mg/kg浓度的Cu2+、Ni2+污染湿地中生长正常,在低浓度(55mg/kg)Cr6+污染中能存活,但生长速度较慢。在100mg/kg浓度Cr6+污染湿地中,出现急性中毒现象,半月后致死。在重金属污染环境中,芦竹普遍出现失绿现象,但除高浓度Cr6+(100mg/kg)以外,都能正常存活,表现出较强的适应性。     

Removal of arsenic from groundwater by granular titanium dioxide adsorbent

A novel granular titanium dioxide (TiO2) was evaluated for the removal of arsenic from groundwater. Laboratory experiments were carried out to investigate the adsorption capacity of the adsorbent and the effect of anions on arsenic removal. Batch experimental results showed that more arsenate [As(V)] was adsorbed on TiO2 than arsenite [As(III)] in US groundwater at pH 7.0. The adsorption capacities for As(V) and As(III) were 41.4 and 32.4 mgg(-1) TiO2, respectively. However, the adsorbent had a similar adsorption capacity for As(V) and As(III) (approximately 40 mgg(-1)) when simulated Bangladesh groundwater was used. Silica (20 mgl(-1)) and phosphate (5.8 mgl(-1)) had no obvious effect on the removal of As(V) and As(III) by TiO2 at neutral pH. Point-of-entry (POE) filters containing 3 l of the granular adsorbent were tested for the removal of arsenic from groundwater in central New Jersey, USA. Groundwater was continuously passed through the filters at an empty bed contact time (EBCT) of 3 min. Approximately 45,000 bed volumes of groundwater containing an average of 39 microgl(-1) of As(V) was treated by the POE filter before the effluent arsenic concentration increased to 10 microgl(-1). The total treated water volumes per weight of adsorbent were about 60,000 l per 1 kg of adsorbent. The field filtration results demonstrated that the granular TiO2 adsorbent was very effective for the removal of arsenic in groundwater.     

可渗透反应复合电极法对土壤重金属的电动去除

将零价铁(Fe0)、沸石等活性材料附着在电极上形成可渗透反应层并构成可渗透反应复合电极,采用不同的复合电极对Cd2+、Ni 2+、Pb2+和Cu2+等4种阳离子型重金属污染土壤进行了电动力学修复。研究了不同可渗透反应复合电极对土壤pH的控制效果以及对重金属的去除作用,分析了迁移到复合电极中的重金属形态变化。结果表明,复合电极中添加酸、碱性沸石并适时更换,可有效中和、截留阴阳极电解产生的OH-和H+,避免或减缓土壤酸碱迁移带的形成,防止重金属离子的过早沉淀及土壤过度酸化,极大提高了重金属的去除率。复合电极中Fe0可将迁移进来的重金属离子进行还原稳定,实现重金属污染物的捕获与固定,与迁移到沸石复合电极中的4种重金属不稳定态相比,"Fe0+沸石"复合电极中重金属不稳定态分别下降了61.4、60.5、61.4、57.1百分点。结果还显示,阴极采用"Fe0+沸石"复合电极并适时进行更换,施加1.5V/cm的直流电压修复10d后,土壤中Cd、Ni、Pb、Cu的总去除率分别为44.5%、41.5%、33.5%和36.7%,且进一步延长修复时间和持续更换电极可获得更为理想的修复效果。     

Cu2+、Zn2+对生物脱氮系统的影响

Cu²⁺和Zn²⁺是污水处理工艺中经常遇到的金属离子。在驯化好的活性污泥系统中,研究了金属离子Cu²⁺和Zn²⁺在0～100 mg/L浓度下对活性污泥生物脱氮系统的影响。试验发现Cu²⁺＞5 mg/L、Zn²⁺＞30 mg/L时,对硝化过程具有明显的抑制作用,在同样浓度的试验条件下Cu²⁺对硝化过程的抑制作用比Zn²⁺大。Cu²⁺≤0.5 mg/L时对反硝化过程具有一定的促进作用,有助于提高TN的去除效果;Cu²⁺＞0.5 mg/L时,对反硝化产生抑制作用,随着浓度的增加,TN去除率逐渐下降。Zn²⁺不影响反硝化过程,仅在大于30 mg/L时,对硝化过程产生抑制作用。重金属Cu²⁺对生物脱氮系统的影响明显强于Zn²⁺。     

Persulfate oxidation for in situ remediation of TCE. I. Activated by ferrous ion with and without a persulfate-thiosulfate redox couple

The objective of the laboratory study is to examine the conditions under which transition metal ions (e.g., ferrous ion, Fe2+) could activate the persulfate anion (S2O8(2)-) to produce a powerful oxidant known as the sulfate free radical (SO4-*) with a standard redox potential of 2.6 V. The SO4-* is capable of destroying groundwater contaminants in situ such as trichloroethylene (TCE). Experiments using Fe2+ as an activator under various molar ratios of S2O8(2)-/Fe2+/TCE in an aqueous system indicated that partial TCE degradation occurred almost instantaneously and then the reaction stalled. Either destruction of SO4-* in the presence of excess Fe2+ or the rapid conversion of all Fe2+ to Fe3+ limited the ultimate oxidizing capability of the system. Sequential addition of Fe2+ in small increments resulted in an increased TCE removal efficiency. Therefore, it appeared that Fe2+ played an important role in generating SO4-*. An observation of oxidation-reduction potential (ORP) variations revealed that the addition of sodium thiosulfate (Na2S2O3) to the ferrous ion activated persulfate system could significantly decrease the strong oxidizing conditions. It was hypothesized that the thiosulfate induced reducing conditions might convert Fe3+ to a lower valence state of Fe2+, making the Fe2+ available to activate persulfate decomposition. The sequential addition of thiosulfate (S2O3(2)-), after the initial stalling of ferrous ion activated persulfate oxidation of TCE, resulted in an improvement in TCE removal. The ferrous ion activated persulfate-thiosulfate redox couple resulted in fairly complete TCE degradation in aqueous systems in a short time frame. In soil slurry systems, TCE degradation was slower in comparison to aqueous systems.     

芘降解菌DY-1的条件优化及降解动力学特性分析

选用已筛选出以芘为唯一碳源的假单胞菌DY-1(Pseudomonas sp.)作为芘降解菌,采用摇瓶振荡培养方法,研究了不同环境条件对菌DY-1降解芘效率的影响以及降解动力学特性。结果表明,在含芘50 mg/L的条件下培养9 d,降解率达83.2%。最适宜温度为30℃,pH值为7.5,摇床转速为120 r/min,接种量为1.5 mL;在不同培养条件下芘的降解符合一级动力学模型;低浓度Zn2+,Cd2+,Cr6+的存在对芘降解效果影响较小,Cu2+,Pb2+对芘的降解有较强的毒性;加入低浓度有机物质,蔗糖可提高DY-1芘的降解;低浓度萘或蒽的存在可促进芘的降解。     

皂化改性橘子皮生物吸附剂对重金属离子的吸附

以生物废料橘子皮(OP)为原料,经乙醇、氢氧化钠处理,得到改性橘子皮生物吸附剂SOP,将其用于对重金属离子Cu2+、Pb2+、Cd2+、Zn2+和Ni2+的吸附。研究了溶液pH、吸附时间和重金属离子初始浓度对SOP吸附性能的影响。结果表明,重金属离子在生物吸附剂上的吸附速率快,符合准二级动力学方程。SOP对重金属离子的吸附等温线符合Lang-muir模型,根据Langmuir模型计算SOP对Cu2+、Pb2+、Cd2+、Zn2+和Ni2+的饱和吸附量分别为56.82、152.4、66.27、33.90和23.02 mg/g,均高于改性前。常见阳离子的存在对重金属离子吸附的影响较小,改性后的橘子皮生物吸附剂可以再生重复使用4次以上,是性能良好的重金属离子吸附剂。     

Thermochemical studies of the toxic actions of heavy metal ions on Rhizopus nigricans

By using a LKB2277 BioActivity Monitor (heat conduction microcalorimeter), stopped-flow method, the thermogenetic curves of Rhizopus nigricans growth at 25 degrees C inhibited by four kinds of heavy metal ions are determined, parameters such as growth rate constants k, inhibitory ratio I, half inhibitory concentration IC50 et al. are obtained. The experimental results show that heavy metal ions can inhibit Rhizopus nigricans growth obviously, low concentration of Cu2+ has promoting action. The inhibitory sequence is Cd2+ > Hg2+ > Pb2+ > Cu2+, half inhibitory concentration of them are Cd+ 0.8 micro g x ml(-1), Hg2+ 1.7 micro g x ml(-1), Pb2+ 48.0 micro g x ml(-1), Cu2+ 110 micro g x ml(-1). This microclorimetric bioassay for acute cellular toxicity is based on metabolic heat evolution from cultured cells. The assay is quantitative, inexpensive, and versatile; moreover, toxicological information can be obtained with cell from other species of interest.