有机菌肥对铅、镉、锌污染土壤和水体联合修复研究

为了研究液体有机菌肥在矿区周边农田污染土壤重金属去除效果，以重金属污染为研究对象，开展液体有机菌肥吸附混合液重金属试验和土壤重金属浸出毒性吸附实验，分析液体有机菌肥对重金属离子去除作用。结果表明：随着液体有机菌肥用量的增加，水体重金属铅、镉和锌含量浓度呈显著下降，液体有机菌肥容易吸附铅，吸附量高达到1667mg/kg,其次是镉和锌。在1%质量比添加量下，经过液体有机菌肥修复后的土壤镉、锌和铅含量下降率分别是29.62%、23.94%和11.66%,土壤重金属TCLP浸出毒性去除率效果显著。有机菌肥处理可改善土壤环境，对土壤和水体的铅、镉、锌重金属有一定修复作用。     

重金属离子在二氧化锰上竞争/络合吸附行为的模拟

通过实验考察了Cu2+、Co2+、Cd2+、Zn2+和Ni2+五种重金属离子共存时各自在二氧化锰上的吸附边以及EDTA存在时Cu2+在二氧化锰上的吸附边。在改良型金属匹配模型的基础上,发展了多种重金属离子共存的竞争吸附模型和EDTA存在时的重金属离子络合吸附模型,利用所建立的吸附模型可以较好地模拟重金属离子的吸附行为,且利用模拟所得的参数可以预测EDTA存在时Cu2+在二氧化锰上的吸附边。     

壳聚糖吸附处理废水的研究进展

壳聚糖吸附处理废水的研究包括其对废水吸附性能和吸附机理的研究两个方面。壳聚糖表现出了良好的吸附废水中重金属离子、染料分子和其它易引起变异物质的能力;壳聚糖对金属离子和染料的吸附机理模型研究理论意义重大,它将进一步推动壳聚糖的实际工程应用。     

NaCl改性沸石去除水中低浓度铅的研究

实验研究了NaCl改性沸石去除水中铅的效果,比较了沸石改性前后对铅的静态平衡吸附量变化,着重考察了吸附时间、pH值、竞争离子以及有机物对去除铅效果的影响。结果表明:NaCl改性沸石吸附铅速度快,对铅有很好的去除效果,平衡吸附量由改性前的28.57mg/g提高到了32.26mg/g。pH值对NaCl改性沸石去除水中铅的效果有较大影响,在pH=6～7时,去除效果最佳。水中竞争阳离子和有机物的存在,在一定程度上会降低铅的去除效果;随干扰物质浓度的升高,NaCl改性沸石对铅去除率出现了明显的下降,但当干扰物质和水样中铅浓度相当时,NaCl改性沸石可对铅保持很高的去除率。     

酸雨中的硫酸根在土壤中的吸附实验

1 前言降水中的硫酸根等阴离子在被土壤吸附的同时,土壤中可交换的氢氧根离子就会被置换出来。这一氢氧根离子将会消耗降水中的氢离子,通过对土壤中硫酸根离子的吸咐量的测定,就可以得知以交换性氢氧根为基     

罗布麻茶叶渣对水中金属离子吸附效果的研究

本文主要研究新疆特色罗布麻茶的茶叶渣对水中锰、铁、锌三种金属离子的吸附能力。通过优化吸附效率的影响因素,制备的废茶渣吸附剂,在不同的加入量、吸附时间、反应温度及模拟废水初始金属离子浓度等条件下,分析其对水中金属离子的吸附率和吸附量,建立废茶渣作为吸附剂对工业废水中金属离子进行去除的方法。结果表明,吸附剂的使用量在30 g/500 mL、吸附温度20℃、吸附时间60 min,罗布麻茶渣对实际废水中锰、铁、锌三种金属离子的吸附效率在71.6%～81.6%。通过本次研究可以发现在试验条件下对废水中三种金属离子有较好的吸附作用,作为废弃茶叶渣回收与制备的生物吸附剂产品,具有较好的应用前景。     

两种模型模拟重金属离子在二氧化锰上吸附行为的比较

本文通过实验考查了Cu2＋、Co2＋、Cd2＋、Zn2＋和Ni25种重金属离子在二氧化锰上的吸附边.在改良型金属分配模型（MMP模型）的基础上,作者考虑了水解态重金属离子吸附的贡献,构建了MMP-1模型,并分别利用这两种模型去模拟了重金属离子在二氧化锰上的吸附边.两个模型模拟各金属吸附边效果很好且相关系数均达到0.99以上.在pH4.0～6.0范围内,MMP-1模型模拟Cu2＋、Co2＋吸附边效果要明显优于MMP模型.     

镍离子印迹吸附剂的制备和性能研究

以镍离子为模板离子,纳米二氧化硅为载体,异烟酸为功能单体,结合表面印迹技术和溶胶凝胶法制备对Ni~(2+)具有专一性吸附的镍离子印迹吸附剂。通过吸附过程中pH、温度、吸附时间、Ni~(2+)初始浓度等因素对吸附性能的影响。确定最佳吸附条件为:pH=7,温度为25℃,吸附时间为2.0h,Ni~(2+)溶液浓度为30mg/L。同时研究了镍离子印迹吸附剂对Ni~(2+)的选择吸附性能和印迹吸附剂的回用性,发现印迹吸附剂对Ni~(2+)的吸附有很好的选择吸附性,且吸附剂可回用3~4次。     

自然水体多相体系中重金属离子在生物膜上的竞争吸附

在实验室中模拟松花江水体,研究了在表层沉积物和悬浮颗粒物存在的条件下,铅、镉和铜3种重金属离子在生物膜上竞争吸附的热力学规律。对重金属在自然水体多相体系中的迁移规律进行了探究,以期为重金属污染的治理提供理论依据。     

含羧基和吡啶基两性离子交换纤维的交换吸附性能研究

采用原子吸收光谱等手段研究羧基／吡啶基弱酸弱碱两性纤维对水溶液中各种离子的交换吸附性能，实验结果表明所制两性离子交换纤维对Cu^2 ,Cr^3 和Mg^2 离子有良好的吸附能力，酸碱基团比例接近时两性纤维的吸附容量最高。     

Prediction of metal-adsorption behaviour in the remediation of water contamination using indigenous microorganisms

In recent years, the adsorption of heavy metal cations onto bacterial surfaces has been studied extensively. This paper reports the findings of a study conducted on the heavy metal ions found in mine effluents from a mining plant where Co²⁺ and Ni²⁺ bearing minerals are processed. Heavy metal ions are reported to be occasionally present in these mine effluents, and the proposed microbial sorption technique offers an acceptable solution for the removal of these heavy metals. The sorption affinity of microorganisms for metal ions can be used to select a suitable microbial sorbent for any particular bioremediation process. Interactions of heavy metal ions (Co²⁺ and Ni²⁺) and light metal ions (Mg²⁺ and Ca²⁺) with indigenous microbial cells (Brevundimonas spp., Bacillaceae bacteria and Pseudomonas aeruginosa) were investigated using the Langmuir adsorption isotherm, pseudo second-order reaction kinetics model and a binary-metal system. Equilibrium constants and adsorption capacities derived from these models allowed delineation of the effect of binding affinity and metal concentration ratios on the overall adsorption behaviour of microbial sorbents, as well as prediction of performance in bioremediation systems. Although microbial sorbents used in this study preferentially bind to heavy metal ions, it was observed that higher concentrations (>90 mg/?) of light metal ions in multi-metal solutions inhibit the adsorption of heavy metal ions to the bacterial cell wall. However, the microbial sorbents reduced Ni²⁺ levels in the mine-water used (93–100% Ni²⁺ removal) to below the maximum acceptable limit of 350 μg/?, established by the South African Bureau of Standards. Competition among metal ions for binding sites on the biomaterial surface can occur during the bioremediation process, but microbial sorption affinity for heavy metal ions can enhance their remediation in dilute (<5 mg/? heavy metal) wastewaters.     

Urban soil quality of Raipur,Chhattisgarh, India

Soil quality in urban areas in India is degraded due to multiple anthropogenic activities. The objectives of this work are to determine the concentration variations, toxicity, and sources of carbons, metals, and ions in the surface soil of Raipur, the industrialized capital city of Chhattisgarh state, India. High concentrations of Al, K, Ca, Ti, Fe, and elemental carbon (EC) were registered. Relatively lower concentrations of V, Cr, Mn, Ni, Cu, Zn, Sr, Ba, Pb, organic carbon (OC), and carbonate carbon (CC), as well as ions (viz. F^–, Cl^–, NO₃^–, SO₄^2–, Na⁺, K⁺, Mg²⁺, and Ca²⁺), were also recorded. EC was found to be one of the major pollutants, although enrichment factors pointed to high contamination with SO₄^2–, K⁺, Mg²⁺_, Cr, Mn, and Pb; and extreme contamination with NO₃^– and Ca²⁺. The spatial and temporal variations, enrichment factors, toxicity, and sources of the chemical species detected in the soil are discussed.     

Metal bioavailability and speciation in a wetland tailings repository amended with biosolids compost,wood ash,and sulfate

Lead poisoning of waterfowl from direct ingestion of wetland mine tailings has been reported at the Coeur d'Alene River basin in Idaho. A greenhouse study was conducted to evaluate the effects of surface applications of amendments on lead bioavailability in the tailings. Treatments included sediment only, and sediment with three different surface amendments: (i) biosolids compost plus wood ash, (ii) compost + wood ash + a low SO4(2-) addition as K2SO4, and (iii) compost + wood ash + a high SO4(2-) addition. Measured variables included growth and tissue Pb, Zn, and Cd concentration of arrowhead (Sagittaria latifolia Willd.) and cattail (Typha latifolia L.) and soil pH, redox potential (Eh), pore water Pb, Pb speciation by X-ray absorption spectroscopy, and in vitro Pb bioavailability. The compost + ash amendment alleviated phytotoxicity for both plant species. Bioavailability of Pb as measured by a rapid in vitro extract decreased by 24 to 34% (over control) in the tailings directly below the amendment layer in the compost + SO4 treatments. The ratio of acid volatile sulfide (AVS) to simultaneously extracted metals (SEM) also indicated a reduction in Pb bioavailability (1:40 control, 1:20 compost, 1:8 compost + low SO4, and 1:3 compost + high SO4). Extended X-ray adsorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopy data indicated that lead sulfide was greater after 99 d in the treatments that included additions of sulfate. These results indicated that, under reducing conditions, surface amendments of compost + wood ash (with or without sulfate) decreased the bioavailability of Pb in metal-contaminated mine tailings.     

An efficient technology to treat heavy metal--lead--contaminated soil by microwave radiation

Microwave (MW) technology can be used to vitrify contaminated soil wastes and immobilize heavy metal ions in soils. More than 93% of the Pb(II)-contaminated soil was vitrified to a glass/ceramic formation after 30 min of MW radiation. In a 6-year study, the Pb(II) concentration of the vitrified soil in the leaching test was less than 1.0 mg/l, which is substantially below the USEPA regulatory limit of 5.0 mg/l.     

Equilibrium and kinetic studies on biosorption of Hg(II), Cd(II) and Pb(II) ions onto microalgae Chlamydomonas reinhardtii

The microalgae Chlamydomonas reinhardtii was used for the biosorption of Hg(II), Cd(II) and Pb(II) ions. The maximum adsorption of Hg(II) and Cd(II) ions on Chlamydomonas reinhardtii biomass was observed at pH 6.0 and the corresponding value for Pb(II) ions was 5.0. The biosorption of Hg(II), Cd(II) and Pb(II) ions by microalgae biomass increased as the initial concentration of Hg(II), Cd(II) and Pb(II) ions increased in the biosorption medium. The maximum biosorption capacities of microalgae for Hg(II), Cd(II) and Pb(II) ions were 72.2+/-0.67, 42.6+/-0.54 and 96.3+/-0.86 mg/g dry biomass, respectively. The affinity order for algal biomass was Pb(II)>Hg(II)>Cd(II). FT-IR analysis of algal biomass revealed the presence of amino, carboxyl, hydroxyl and carbonyl groups, which were responsible for biosorption of metal ions. Biosorption equilibrium was established in about 60 min and the equilibrium was well described by the Freundlich biosorption isotherms. Temperature change in the range of 5-35 degrees C did not affect the biosorption capacity. The microalgae could be regenerated using 0.1 M HCl, with up to 98% recovery, which allowed the reuse of the biomass in six biosorption-desorption cycles without any considerable loss of biosorption capacity.     

Biosorption of heavy metals by activated sludge and their desorption characteristics

The biosorption of different metals (Cu2+, Cd2+, Zn2+, Ni2+ and Pb2+) was investigated using activated sludge. The optimum pH was 4 for Cd, Cu and Pb sorption and 5 for Ni and Zn. Biomass metal uptake clearly competed with protons present in the aqueous medium, making pH an important variable in the process. Protons consumed by biomass in control tests versus protons exchange in biosorption tests confirmed a maximum exchange between metal cations and protons at pH 2. The study of the influence of biomass concentration revealed that the amount of protons released from biomass increased with biomass concentration. This would confirm the hypothesis of ion exchange between both types of ions. The application of the Langmuir and Freundlich models showed a better fitting of experimental data to the first model. The maximum sorption uptake of the studied metals by the activated sludge showed the following decreasing order: Pb>Cu>CdZn>Ni. Desorption experiments showed that HCl was a good eluent for the five metals tested, particularly at low pH values (1 and 2). At pH 3 or 4 the desorption yield was significantly lower. However, its use did not allow the reuse of biomass in subsequent loading and unloading cycles. EDTA was also a good desorption agent, achieving the total recovery for the five metals tested at a concentration of 1mM, with the advantage that biomass could be reused for three sorption-desorption cycles.     

Removal of Pb(II) ions from aqueous solution using activated tea waste: Adsorption on a fixed-bed column

An inexpensive and effective adsorbent was developed from waste tea leaves for the dynamic uptake of Pb(II). Characterization of the adsorbents showed a clear change between physico-chemical properties of activated tea waste and simply tea waste. The purpose of this work was to evaluate the potential of activated tea waste in continuous flow removal of Pb(II) ions from synthetic aqueous effluents. The performance of the system was evaluated to assess the effect of various process variables, viz., of bed height, hydraulic loading rate and initial feed concentration on breakthrough time and adsorption capacity. The shape of the breakthrough curves was determined for the adsorption of Pb(II) by varying different operating parameters like hydraulic loading rate (2.3–9.17 m³/h m²), bed height (0.3–0.5 m) and feed concentration (2–10 mg/l). An attempt has also been made to model the data generated from column studies using the empirical relationship based on the Bohart–Adams model. There was an acceptable degree of agreement between the data for breakthrough time calculated from the Bohart–Adams model and the present experimental study with average absolute deviation of less than 5.0%. The activated tea waste in this study showed very good promise as compared with the other adsorbents available in the literature. The adsorbent could be suitable for repeated use (for more than four cycles) without noticeable loss of capacity.     

Effect of chloride ions on the oxidation of aniline by Fenton's reagent

The objective of this study was to experimentally probe the mechanism of chloride ions specifically affecting aniline oxidation by Fenton's reagent. Batch experiments were carried out to investigate the effects of pH, Fe2+, H2O2 and chloride concentration on the oxidation reaction. Results show that the inhibition caused by chloride ions can be overcome by extending the reaction time if the concentration of chloride ions is low. At a high concentration of chloride ions, however, the oxidation of aniline was inhibited, and actually ceased due to the complexation of Fe-Cl. In this study, the chloride ion concentration was kept at 0.2 M in the experiments when studying the effect of ferrous ion concentration on the Fenton reaction. If the ratio of [Cl-]/[Fe2+] was < or = 200, the inhibition effect was very significant. In other words, adding more ferrous ions rather than hydrogen peroxide can break the inhibition originating from the chloride ions at an initial stage of pH 3. The inhibition effect of chloride ions on the aniline reaction depended on the reaction pH; the extent of inhibition decreased with increasing the initial pH as long as the pH was less than 5. Consequently, the inhibition effect by chloride ions was primarily due to the complexation of iron species and chloride ions. The influence of chloride ions on aniline oxidation due to the competition of hydroxyl radicals was not significant.     

Spectroscopic speciation and quantification of lead in phosphate-amended soils

The immobilization of Pb in contaminated soils as pyromorphite [Pb(5)(PO(4))(3)Cl, OH, F] through the addition of various phosphate amendments has gained much attention in the remediation community. However, it is difficult to fully determine the speciation and amount of soil Pb converted to pyromorphite by previously employed methods, such as selective sequential extraction procedures and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, which often lead to erroneous results in these non-equilibrated and heterogeneous systems. Statistical analysis by linear combination fitting (LCF) applied to X-ray absorption fine structure (XAFS) spectroscopic data of Pb-contaminated soil samples relative to known Pb reference material provides direct, in situ evidence of dominate Pb species in the amended soils without chemical or physical disruption to the Pb species as well as a weighted quantification output. The LCF-XAFS approach illustrated that pyromorphite concentration ranged from 0% (control soil) to 45% (1% phosphoric acid amendment, residence time of 32 mo) relative to the total Pb concentration. The Pb speciation in the nonamended control soil included Pb-sulfur species (galena + angelsite = 53%), adsorbed Pb (inner-sphere + outer-sphere + organic-bound = 45%), and Pb-carbonate phases (cerussite + hydrocerussite = 2%). The addition of P promoted pyromorphite formation and the rate of formation increased with increasing P concentration (up to 45%). The supplemental addition of an iron amendment as an iron-rich byproduct with triple superphosphate (TSP) enhanced pyromorphite formation relative to independent TSP amendment of like concentrations (41 versus 29%). However, the amendment of biosolids and biosolids plus TSP observed little pyromorphite formation (1-16% of total Pb), but a significant increase of sorbed Pb was determined by LCF-XAFS.     

Binding of heavy metal contaminants onto chitosans--an evaluation for remediation of metal contaminated soil and water

The binding efficiency of chitosan samples for Ag(+), Cd(2+), Cu(2+), Pb(2+) and Zn(2+) has been evaluated in order to consider their application to remediate metal contaminated soil and water. The sorption behaviour of metal ions was assessed using a batch technique at different contact time and initial metal concentration with different background electrolytes. The kinetics followed a pseudo-second-order model, while the equilibrium data correlated well with the Freundlich and Langmuir isotherm models. For example, the maximum sorption capacity (Q) for chitosan was estimated as 1.93 mmol/g for Ag(+), 1.61 mmol/g for Cu(2+), 0.94 mmol/g for Zn(2+), 0.72 mmol/g for Cd(2+) and 0.64 mmol/g for Pb(2+). Covalent interaction between metal ions and functional groups (amino and hydroxyl) of the chitosans was the main binding mechanism. Ion exchange is not an important process. Chitosan and cross-linked chitosans were able to bind metal ions in the presence of K(+), Cl(-) and NO(3)(-). The nature of Cl(-) and NO(3)(-) ions did not affect Zn(2+) binding by the chitosans. Even at 11x dilution, the chitosans were able to retain metal ions on their surfaces.