UV/H_2O_2协同光降解处理酒石酸镍废水

含镍电镀废水中酒石酸的存在,使得废水中总镍无法通过化学沉淀法去除,无法满足达标排放要求。采用UV/H_2O_2光降解法处理酒石酸镍体系废水,考察了不同反应p H值、过氧化氢投加量、光照时间对酒石酸镍体系络合废水的处理效果。实验结果表明:UV/H_2O_2法对酒石酸镍体系废水有很好的协同处理效果,光降解过程呈拟一级动力学过程;优化的酒石酸镍废水处理工艺为反应p H值3.0,30%过氧化氢投加量2 m L·L~(-1),15 W功率紫外灯光照下反应120 min,在优化的工艺条件下,采用化学沉淀法去除水中镍,处理后电镀废水中总镍可满足《电镀污染物排放标准》(GB 21900-2008)中0.5 mg·L~(-1)要求。     

复配Na_2S-DDTC处理高浓度含Ni电镀废水

为降低实际工程中二硫代氨基甲酸盐(DTC)类螯合剂用药成本,以某电镀厂高浓度含络合Ni电镀漂洗废水作为处理对象,研究了一种有机巯基类螯合剂(简称DDTC)复配Na_2S去除Ni离子的效果与机理,并重点对反应pH、DDTC与Na_2S单独、复配投加量、含Ni初始浓度等几个因素的影响进行探究。实验结果表明:反应pH值对Ni的去除有较大影响,pH=9.0时Na_2S-DDTC对Ni的去除效果最好;Na_2S-DDTC对电镀络合Ni具有很好的捕集功能,优于Na_2S、DDTC单独使用,其中当pH=9.0,nNa_2S/nNi=1.5,ρ(DDTC)=200 mg·L~(-1)时,Ni的剩余浓度为0.062 mg·L~(-1),达到《电镀污染物排放标准》(GB 21900-2008)中关于Ni污染物特别排放限值要求(0.1 mg·L~(-1));Na_2S-DDTC处理不同初始浓度的含Ni废水具有较宽的应用范围,其中Na_2S对Ni的用量存在nNa_2S/nNi=1.5的化学计量关系,DDTC存在不同的最佳投药量;Na_2S与DDTC复配使用具有一定的协同作用。     

镁铝类水滑石原位共沉淀法处理含镍模拟废水的研究

通过原位共沉淀法处理含镍模拟废水,探讨了反应时间、体系pH、镍与镁的摩尔比(Ni/Mg)、二价离子与三价离子的摩尔比((Ni+Mg)/Al)和Ni 2+初始浓度对Ni 2+去除效果的影响。实验结果表明,Ni 2+能通过镁铝类水滑石原位共沉淀法被除去。体系pH、Ni/Mg、(Ni+Mg)/Al和Ni 2+初始浓度均对Ni 2+去除率影响较大,而反应时间对其影响不大。在反应时间为1～2h、pH=8.5、Ni/Mg=0.25、(Ni+Mg)/Al=2.0时,可获得最高的Ni 2+去除率(99.84%),产物经X射线衍射(XRD)分析确定具有层状双氢氧化物(LDHs)结构。     

络合-陶瓷膜耦合技术资源化处理模拟低浓度含铜废水

以聚丙烯酸(PAA)和壳聚糖(CTS)作为络合剂,耦合孔径200 nm的陶瓷膜处理模拟低浓度含铜废水,采用ICP-MS、TOC、SEM表征与Darcy膜污染模型对处理效果和膜污染情况进行表征;对比研究不同络合剂对Cu~(2+)截留效果与资源化回用效率的影响;并探讨对应的膜污染机理。结果表明:溶液pH通过影响聚合物络合活性位点对Cu~(2+)截留率起决定性作用;在pH=6、P/M≥5或C/M=10的优化条件下,Cu~(2+)截留率接近100%;PAA相对于CTS对Cu~(2+)的络合效率更高,而CTS具备更好的抗杂质离子干扰能力;酸解、循环回用的PAA与CTS对Cu~(2+)截留率稳定在99%以上。膜污染阻力分布计算和SEM、EDX微观表征表明,滤饼污染为膜污染主要形式,CTS更易造成不可逆的膜孔堵塞污染。     

聚合物强化超滤处理含铜废水

聚合物强化超滤工艺（PEUF）是一种将高分子聚合物和超滤技术结合的新型、高效的重金属废水治理方法。以壳聚糖（CTS）为聚合物去除水中的铜离子。考察了吸附络合和超滤过程中影响铜去除率的多种因素。结果表明,溶液pH值为6.0、CTS浓度为0.15 g/L和反应时间为60 min时,通过超滤系统后效果最佳。装载比一定时,铜初始浓度的变化对铜的去除率没有明显影响。CTS对铜的吸附过程符合Langmuir吸附等温方程。还研究了超滤膜的污染情况和膜清洗方法,结果表明,酸清洗效果较好,可使膜通量恢复达87%左右。     

电芬顿法去除化学镀镍废水中的镍、总磷和COD

采用电芬顿法处理化学镀镍废水,分别考察了电流密度、初始pH和H_2O_2投加量对镍离子、总磷和COD去除效果的影响。结果表明:随着电流密度的增大,镍离子和COD的去除率提高,总磷去除率也逐渐增加;当初始pH为3时,对镍离子、COD和总磷的去除效果最好;随着H_2O_2投加量的增加,镍离子去除率并没有明显的提高,总磷和COD的去除率表现为先增大后减小。优化所得的最佳工艺参数:电流密度为10 mA·cm~(-2)、初始pH为3、 30%H_2O_2投加量为6 mL·L~(-1)、反应40 min,镍离子、总磷和COD的去除率分别达到96.6%、91.5%和84.7%。此外,随着电化学反应的进行,反应体系不断升高的pH导致生成的正磷酸盐沉淀溶出,总磷去除率降低。镍离子主要是通过电絮凝作用去除,总磷和COD主要通过芬顿氧化后吸附沉淀而被去除。以上研究证明,采用电芬顿方法处理化学镀镍废水具有较好的应用前景。     

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。     

新型过滤回收设备

香港特区生产力促进局开发成功新型聚合过滤回收设备，其原理是利用大分子的水溶性聚合物吸收金属离子形成复合物，再以超滤方式将其和污水分离与浓缩，然后凋整pH值，99％以上的金属离子从聚合物中释放出来，从而回收绝大部分金属离子，聚合物能无限循环利用。该技术与传统离子交换技术建设费用相当，但是运行成本下降1／2，污水达到排放标准，设备占地面积也下降1／2，操作简便，可使电镀行业减少成本，大大减轻污染排放，提高竞争力。     

破络-Fenton法处理化学镀镍废水并回收水中的磷酸盐

以电镀厂化学镀镍的混合清洗水为处理对象,采用CaO破络吸附联合Fenton氧化的多级物化技术去除废液中的镍离子和磷酸盐,研究CaO投加量和反应时间对镍离子去除效率的影响以及Fenton试剂投加量、反应初始pH对废液中磷处理效果的影响。结果表明,通过两段式反应,当CaO投加量为2 g·L~(-1)、反应时间1 h;反应初始pH为4、H_2O_2投加量9.18 mg·L~(-1)、m(H_2O_2)/m(Fe~(2+))为5∶1、反应时间180 min时,镍离子和总磷(TP)含量由原来的64.6和90.2 mg·L~(-1)分别降低至0.43和0.46 mgl·L~(-1),均达到国家《污水综合排放标准》(GB 8978-1996)。处理后沉淀物经测试符合Fe_2(PO_4)_3晶体及其形貌特征,达到了资源回收的目的。     

离子浮选法处理电镀废水实验研究

进行离子浮选法处理电镀废水的研究,对影响因素pH、CA∶CMe(摩尔比)、离子强度、浮选时间和通气量等进行了实验研究。实验结果表明:离子分离选择性递减顺序为:Cd2+Zn2+Fe2+Cu2+Ni2+。当CA∶CMe为2.5～3∶1,pH为8.5～9,离子强度不高于0.0001 mol/L时,离子浮选对镉、锌、铜、镍等金属离子均有很高的去除率,Cd2+、Zn2+、Fe2+、Ni2+、Cu2+残余浓度最低分别可达0.05、0.20、0.22、0.28和0.33 mg/L,处理后的电镀废水各污染物浓度均达到排放标准。泡沫产品中镉、锌、铜、镍品位分别达到3.2%、9.3%、18.1%和13.2%,具有极高的资源回收价值。     

Chloroaromatic pollutants in mussels incubated in two finnish watercourses polluted by industry

Concentrations of different chlorinated compounds were measured in mussels incubated in two polluted watercourses, a river (the River Kymijoki) and a lake (Lake Vanaja) for four weeks in summer 1995. The sum concentrations of polychlorinated phenols (PCP) and biphenyls (PCB) were both about 1 μg/g lipid weight (lw) in Lake Vanaja mussels, while in the River Kymijoki mussels PCPs were non-detectable and PCBs were measured 120 ng/g lIw. The concentrations of toxic polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners ranged between <17 and 370 pg/g Iw in Lake Vanaja mussels and between <38 and 11,000 pg/g lw in the River Kymijoki mussels. Polychlorinated diphenyl ethers (PCDE) were detected in the mussels incubated in the River Kymijoki (0.4–1.1 ng/g Iw), but not in those incubated in Lake Vanaja. Polychlorinated phenoxyanisoles (PCPA) were measured 33 ng/g lw and polychlorinated phenoxyphenols (PCPP) 300 ng/g lw in the mussels incubated in the River Kymijoki. PCPAs were also detected in reference samples, which were sediment and pike from the River Kymijoki and Baltic salmon, seal and white-tailed sea eagle.     

Evaluation of trichloroethene recovery processes in heterogeneous aquifer cells flushed with biodegradable surfactants

The ability of two biodegradable surfactants, polyoxyethylene (20) sorbitan monooleate (Tween 80) and sodium dihexyl sulfosuccinate (Aerosol MA), to recover a representative dense non-aqueous-phase liquid (DNAPL), trichloroethene (TCE), from heterogeneous porous media was evaluated through a combination of batch and aquifer cell experiments. An aqueous solution containing 3.3% Aerosol MA, 8% 2-propanol and 6 g/l CaCl(2) yielded a weight solubilization ratio (WSR) of 1.21 g TCE/g surfactant, with a corresponding liquid-liquid interfacial tension (IFT) of 0.19 dyn/cm. Flushing of aquifer cells containing a TCE-DNAPL source zone with approximately two pore volumes of the AMA formulation resulted in substantial (>30%) mobilization of TCE-DNAPL. However, a TCE mass recovery of 81% was achieved when the aqueous-phase flow rate was sufficient to displace the mobile TCE-DNAPL toward the effluent well. Aqueous solutions of Tween 80 exhibited a greater capacity to solubilize TCE (WSR=1.74 g TCE/g surfactant) and exerted markedly less reduction in IFT (10.4 dyn/cm). These data contradict an accepted empirical correlation used to estimate IFT values from solubilization capacity, and indicate a unique capacity of T80 to form concentrated TCE emulsions. Flushing of aquifer cells with less than 2.5 pore volumes of a 4% T80 solution achieved TCE mass recoveries ranging from 66 to 85%, with only slight TCE-DNAPL mobilization (<5%) occurring when the total trapping number exceeded 2 x 10(-5). These findings demonstrate the ability of Tween 80 and Aerosol MA solutions to efficiently recover TCE from a heterogeneous DNAPL source zone, and the utility of the total trapping number as a design parameter for a priori prediction of DNAPL mobilization and bank angle formation when flushing with low-IFT solutions. Given their potential to stimulate microbial reductive dechlorination at low concentrations, these surfactants are well-suited for remedial action plans that couple aggressive mass removal followed by enhanced bioremediation to treat chlorinated solvent source zones.     

Book review

The Pesticide Manual ‐ A World Compendium, 8th Edition, C.R. Worthing, Editor and S.B. Walker, Assistant Editor, British Crop Protection Council, BCPC Publications Sales, Bear Farm, Binfield, Bracknell, Berkshire RG12 5QE, England. 1987, 1100 pp., UK £50; Overseas £56. ISBN 0–948404–01–9.     

Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.     

Organochlorine compounds in a three-step terrestrial food chain

The concentrations of 15 organochlorine chemicals (PCBs and pesticides) were studied in a Central European oak wood food chain system: Great tit (Parus major), caterpillars (Tortrix viridana, Operophtera brumata, Erannis defoliaria), and oak-leaves (Quercus robur). Juvenile tits receive organochlorines from the mother via egg transfer and, eventually to a greater extent, from the caterpillar food source during nestling period. The concentrations of PCB 153 (2,2′,4,4′,5,5′-hexachlorobiphenyl, the most abundant in this study) was found in leaf material at ca. 1 ng/g, in caterpillars 10 ng/g, and in bird eggs 170 ng/g on an average and on a dry mass basis.     

The chemical stability of formulations of some hydrolyzable insecticides in aqueous mixtures with hydrolysis catalysts

Abstract

The active ingredients in commercial formulations of malathion, oxamyl, carbaryl, diazinon, and chlorpyrifos diluted to “spray tank”; concentrations with buffered distilled or natural water of pH 4–9 were stable for at least 24 hr. Formulations of trichlorfon were not stable at pH 7 or above but disappearance rates were slower than for the pure chemical in homogeneous solution. Cupric ion was observed to be an effective catalyst for the hydrolysis of a variety of pure organophosphorus insecticides but did not catalyze hydrolysis of the active ingredients of the formulations examined. Increasing the dilution of the formulation increased the susceptibility of malathion, oxamyl, and carbaryl to hydrolysis.     

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalystequipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.     

Teratological effects of pesticides in vertebrates: a review

Abstract

In the last decades, the use and misuse of pesticides in the agriculture have increased, having a severe impact on ecosystems and their fauna. Although the various effects of pesticides on biodiversity have been already documented in several studies, to our knowledge no consistent overview of the impact of pesticides in vertebrates, both terrestrial and aquatic, is available. In this review, we try to present a concise compilation of the teratogenic effects of pesticides on the different classes of vertebrates – mammals, birds, reptiles, amphibians and fish.     

Radionuclides in pinon pine (Pinus edulis) nuts from los alamos national laboratory lands and the dose from consumption

Abstract

One of the dominant tree species growing within and around the eastern portion of Los Alamos National Laboratory (LANL), Los Alamos, NM, lands is the pinon pine (Pinus edulis). Pinon pine is used for firewood, fence posts, and building materials and is a source of nuts for food—the seeds are consumed by a wide variety of animals and are also gathered by people in the area and eaten raw or roasted. This study investigated the (1) concentration of ³H, ¹³⁷Cs, ⁹⁰Sr, ^totU, ²³⁸Pu, ^{239, 240}Pu, and²⁴¹ Am in soils (0‐ to 12‐in. [31 cm] depth underneath the tree), pinon pine shoots (PPS), and pinon pine nuts (PPN) collected from LANL lands and regional background (BG) locations, (2) committed effective dose equivalent (CEDE) from the ingestion of nuts, and (3) soil to PPS to PPN concentration ratios (CRs). Most radionuclides, with the exception of ³H in soils, were not significantly higher (p < 0.10) in soils, PPS, and PPN collected from LANL as compared to BG locations, and concentrations of most radionuclides in PPN from LANL have decreased over time. The maximum net CEDE (the CEDE plus two sigma minus BG) at the most conservative ingestion rate (10 lb [4.5 kg]) was 0.0018 mrem (0.018 μSv); this is far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem (1000 μSv). Soil‐to‐nut CRs for most radionuclides were within the range of default values in the literature for common fruits and vegetables.     

Degradation and sorption of imidacloprid in dissimilar surface and subsurface soils

Degradation and sorption/desorption are important processes affecting the leaching of pesticides through soil. This research characterized the degradation and sorption of imidacloprid (1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine) in Drummer (silty clay loam) and Exeter (sandy loam) surface soils and their corresponding subsurface soils using sequential extraction methods over 400 days. By the end of the incubation, approximately 55% of imidacloprid applied at a rate of 1.0 mg kg^?1 degraded in the Exeter sandy loam surface and subsurface soils, compared to 40% of applied imidacloprid within 300 days in Drummer surface and subsurface soils. At the 0.1 mg kg^?1 application rate, dissipation was slower for all four soils. Water-extractable imidacloprid in Exeter surface soil decreased from 98% of applied at day 1 to > 70% of the imidacloprid remaining after 400 d, as compared to 55% in the Drummer surface soil at day 1 and 12% at day 400. These data suggest that imidacloprid was bioavailable to degrading soil microorganisms and sorption/desorption was not the limiting factor for biodegradation. In subsurface soils > 40% of ¹⁴C-benzoic acid was mineralized over 21 days, demonstrating an active microbial community. In contrast, cumulative ¹⁴CO₂ was less than 1.5% of applied ¹⁴C-imidacloprid in all soils over 400 d. Qualitative differences in the microbial communities appear to limit the degradation of imidacloprid in the subsurface soils.