Removal and recovery of copper and nickel ions from aqueous solution by poly(methacrylamide-co-acrylic acid)/montmorillonite nanocomposites

Nanocomposite hydrogels based on poly(methacrylamide-co-acrylic acid) and nano-sized montmorillonite were prepared by aqueous dispersion and in situ radical polymerization. Optimum sorption conditions were determined as a function of montmorillonite content, contact time, pH, and temperature. The equilibrium data of Cu²⁺ and Ni²⁺ conformed to the Freundlich and Langmuir isotherms in terms of relatively high regression values. The maximum monolayer adsorption capacity of the nanocomposite hydrogel (with 3 wt% montmorillonite content), as obtained from the Langmuir adsorption isotherm, was found to be 49.26 and 46.94 mg g^?1 for Cu²⁺ and Ni²⁺, respectively, at contact time?=?60 min, pH?=?6.8, adsorbent dose?=?100 mg/ml, and temperature?=?318 K. Kinetic studies of single system indicated that the pseudo-second order is the best fit with a high correlation coefficient (R ²?=?0.97–0.99). The result of five times sequential adsorption–desorption cycle shows a good degree of desorption and a high adsorption efficiency.     

Selective separation of copper(II) and nickel(II) from aqueous media using the complexation-ultrafiltration process

The polyethylenimine (PEI) as complexing agent was used to study the complexation-ultrafiltration (CP-UF) process in the selective removal of Cu(II) from Ni(II) contained in aqueous media. Preliminary tests showed that optimal chemical conditions for Cu(II) and Ni(II) complexation by the PEI polymer were pH>6.0 and 8.0, respectively, and polymer/metal weight ratio of 3.0 and 6.0, respectively. The effect of some important operating parameters on process selectivity was studied by performing UF tests at different parameters: pH, polymer/metal weight ratio, transmembrane pressure (TMP), and membrane cut-off in a batch experimental set-up. It was observed that process selectivity was achieved by choosing the pH value for obtaining a preferential copper complexation (pH 6.0), and the polymer/metal ratio needed to bound only the copper ion (3.0). The selective separation by UF tests was performed by using both a laboratory aqueous solution and a real aqueous effluent (water from Emoli torrent, Rende (CS)). The Iris 30 membrane at TMP of 200 kPa (2 bar) for both aqueous media gave the best results. A complete nickel recovery was reached, and copper recovery was the highest for this membrane (94% and 92%). Besides at this pressure, a lower water amount was needed to obtain total nickel recovery by diafiltration. A little higher membrane fouling was obtained by using the river effluent due to the presence of dissolved organic and inorganic matter.     

Sensitivity of Mediterranean woody seedlings to copper, nickel and zinc

The restoration of heavy metal contaminated areas requires information on the response of native plant species to these contaminants. The sensitivity of most Mediterranean woody species to heavy metals has not been established, and little is known about phytotoxic thresholds and environmental risks. We have evaluated the response of four plant species commonly used in ecological restoration, Pinus halepensis, Pistacia lentiscus, Juniperus oxycedrus, and Rhamnus alaternus, grown in nutrient solutions containing a range of copper, nickel and zinc concentrations. Seedlings of these species were exposed to 0.048, 1 and 4 microM of Cu; 0, 25 and 50 microM of Ni; and 0.073, 25 and 100 microM of Zn in a hydroponic silica sand culture for 12 weeks. For all four species, the heavy metal concentration increased in plants as the solution concentration increased and was always higher in roots than in shoots. Pinus halepensis and P. lentiscus showed a higher capacity to accumulate metals in roots than J. oxycedrus and R. alaternus, while the allocation to shoots was considerably higher in the latter two. Intermediate heavy-metal doses enhanced biomass accumulation, whereas the highest doses resulted in reductions in biomass. Decreases in shoot biomass occurred at internal concentrations ranging from 25 to 128 microg g-1 of Zn, and 1.7 to 4.1 microg g( -1) of Cu. Nickel phytoxicity could not be established within the range of doses used. Rhamnus alaternus and J. oxycedrus showed higher sensitivity to Cu and Zn than P. halepensis and, especially, P. lentiscus. Contrasted responses to heavy metals must be taken into account when using Mediterranean woody species for the restoration of heavy metal contaminated sites.     

Lead,mercury, cadmium,chromium, nickel,copper, zinc,calcium, iron,manganese and chromium (VI) levels in Nigeria and United States of America cement dust

This study was aimed at investigating the relative abundance of heavy metals in cement dust from different cement dust factories in order to predict their possible roles in the severity of cement dust toxicity. The concentrations of total mercury (Hg), copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), manganese (Mn), lead (Pb), iron (Fe) and chromium (VI) (Cr (VI)) levels in cement dust and clinker samples from Nigeria and cement dust sample from the United States of America (USA) were determined using graphite furnace atomic absorption (GFAAS), while Zn and Ca were measured by flame atomic absorption spectrophotometry (FAAS), and Cr (VI) by colorimetric method. Total Cu, Ni and Mn were significantly higher in cement dust sample from USA (p < 0.05), also, both total Cr and Cr (VI) were 5.4–26 folds higher in USA cement dust compared with Nigeria cement dust or clinker (p < 0.001). Total Cd was higher in both Nigeria cement dust and clinker (p < 0.05 and p < 0.001), respectively. Mercury was more in both Nigeria cement dust and clinker (p < 0.05), while Pb was only significantly higher in clinker from Nigeria (p < 0.001). These results show that cement dust contain mixture of metals that are known human carcinogens and also have been implicated in other debilitating health conditions. Additionally, it revealed that metal content concentrations are factory dependent. This study appears to indicate the need for additional human studies relating the toxicity of these metals and their health impacts on cement factory workers.     

Determination of cadmium, zinc, copper, chromium and arsenic in crude oil cargoes

One of the sources of trace heavy metal elements in air is emission by the oil industry, either directly through stack emissions from refineries or indirectly from emissions of combustion of hydrocarbons. Emission estimates are based mainly on the trace metal content of the crude oil processed. From a literature study carried out at the beginning of the 1990s it became clear that data on the trace metal content of crudes were scarce and showed a very large scatter. For this reason a measurement programme to assess the occurrence and concentrations of a number of trace metals, i.e. Cadmium (Cd), Zinc (Zn), Copper (Cu), Chromium (Cr), and arsenic (As), in crudes which are regularly processed in the Netherlands, was set up. By drafting strict sampling protocols and by constructing a special sampling device, as many as possible of the additional contamination sources were avoided. The study suggests that sample contamination may explain a significant amount of the scatter and some of the high concentrations reported in the literature for certain metals. The measured variation in the concentrations of Cd, Zn, and Cu is thought to be due to associated water and/or sediment particles from the producing wells or that picked up during transport. The greater consistency in our measurements for Cr and As suggests that these metals are predominantly associated with the hydrocarbon matrix. Based on the results of this work, it can be concluded that emissions of Cd, Zn, Cu, Cr, and As by the oil industry in the Netherlands are most probably significantly lower than hitherto assumed.     

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.     

Nitric acid recycling and copper nitrate recovery from effluent

The recycling of nitric acid and copper nitrate contained in an industrial effluent was studied. The experiments conducted on such a medium showed that the presence of copper nitrate significantly improves nitric acid-water separation during distillation in an azeotropic medium. At the temperature of the azeotrope, however, this metal salt starts to precipitate, making the medium pasty, thus inhibiting the nitric acid extraction process. The optimisation of parameters such as column efficiency and adding water to the boiler at the azeotrope temperature are recommended in this protocol in order to collect the various components while avoiding the formation of by-products: NO_x compounds. Thus, the absence of column, along with the addition of a small volume of water at a temperature of 118 °C, significantly increases the yield, allowing 94 % nitric acid to be recovered at the end of the process, along with the residual copper nitrate. The resulting distillate, however, is sufficiently dilute to not be used as is. Rectification is required to obtain concentrated nitric acid at 15 mol·l^?1, along with a weakly acidic distillate from the distillation front. This latter is quenched using potassium hydroxide and is used as a fertiliser solution for horticulture or sheltered market gardening. This process thus allows complete recycling of all the medium’s components, including that of the distillate resulting from the nitric acid rectification operation.     

Soil mobility of sewage sludge-derived dissolved organic matter, copper, nickel and zinc

A soil (sandy loam) column leaching study aimed to determine the extent of mobility and co-mobility of Cu, Ni, Zn and dissolved organic matter (DOM) released from a surface-application (equivalent to 50 t ds ha(-1) of anaerobically-digested sewage sludge. Leaching of DOM through the soil column was found to be almost un-retarded. Decidedly similar behaviour was exhibited by Ni suggesting that it migrated as organic complexes. Whilst Cu was also found to be leached, significant retardation was evident. However, the importance of DOM in promoting the mobility of both Cu and Ni was evidenced by their lack of mobility when added to the soil column as inorganic forms. The presence of DOM did not prevent Zn from becoming completely adsorbed by the soil solid phase. In relation to WHO drinking water guidelines, only Ni concentrations showed potential environmental significance, due to the relatively poor retention of Ni by the sludge solid phase.     

电镀行业铜、镍、锌产排污系数的核算

针对现有国家《产排污系数手册》中电镀行业重金属产排污系数的不完整问题,以深圳市电镀企业分布较多的宝安区和龙岗区为研究对象,采用全面调研和个案实测的方法,将电镀行业典型镀种铜、镍、锌划分为18组四同组合。根据调研数据计算获得了每组四同组合的产排污系数,并通过个案实测验证了产排污系数的合理性及适用性。结果表明,产排污系数法计算的产污量误差在16%以内,排污量误差在30%以内,所以产排污系数能够推广应用于电镀行业重金属污染排放量核算。     

Development of an environmentally benign process for the production of fatty acid methyl esters

The production of fatty acid methyl esters (FAME) is an important intermediate step in oleochemistry. The oleochemical production route starts with the renewable raw materials fat and oil and ends at fatty alcohols and different special products. Fatty acid methyl esters can be formed at mild reaction temperatures by transesterification of natural triglycerides (fats and oils). This contribution will show the development of a continuous process which is considering the main principles of production integrated environmental protection. The main advantages of this process are low energy consumption and minimal waste production. The process alternatives are shown and a scope on future problems which have to be solved to reach a real additional improvement of the fatty acid methyl esters production is given.     

Effects of copper, chromium and nickel on growth, photosynthesis and chlorophyll a synthesis of Chlorella pyrenoidosa 251

Individual and combined effects of three heavy metals; namely, copper, chromium and nickel, on growth, photosynthesis and chlorophyll a synthesis of the unicellular green alga, Chlorella pyrenoidosa 251, were determined. Within the concentration range of 0.1 to 1.0 mg litre(-1) of the three heavy metals tested on growth, photosynthesis and chlorophyll a synthesis of the alga, the order of toxicity of the three heavy metals was copper > chromium > nickel. The presence of one of the three heavy metals interacted synergistically with the other two heavy metals in various bimetallic combinations on growth, photosynthesis and chlorophyll a synthesis of the alga.     

Evaluation of the critical factors controlling stability of chromium, copper, arsenic and zinc in iron-treated soil

Various environmental factors are expected to affect the mobility of elements in chemically stabilized soils. The aim of this study was to evaluate the effects of pH, oxidizing-reducing potential (Eh), liquid-to-solid ratio (L/S), presence of organic matter (OM) and microbial activity (MA) on the mobility of chromium, copper, arsenic and zinc in zerovalent iron (Fe(0))-stabilized soil. A 2(5) full factorial design was applied to assess the leaching of the elements from the treated soil. The factor having the most impact on the mobility of Cr, Cu and Zn was pH; low pH (3) led to the release of these elements. Arsenic remobilization was controlled by L/S and MA, whilst Eh, though also significant, had less influence. In the identified worst-case scenarios, more than half of the total Zn and Cu and 14% of As can be expected to remobilize from the treated soil. The leaching procedure concerning sample agitation and type of filtration showed to substantially affect the results of As leaching, especially in OM rich soil.     

Field-scale leaching of arsenic, chromium and copper from weathered treated wood

Earlier studies documented the loss of wood preservatives from new wood. The objective of this study was to evaluate losses from weathered treated wood under field conditions by collecting rainfall leachate from 5 different wood types, all with a surface area of 0.21 m². Wood samples included weathered chromate copper arsenate (CCA) treated wood at low (2.7 kg/m³), medium (4.8 kg/m³) and high (35.4 kg/m³) retention levels, new alkaline copper quat (ACQ) treated wood (1.1 kg/m³ as CuO) and new untreated wood. Arsenic was found to leach at a higher rate (100 mg in 1 year for low retention) than chromium and copper (<40 mg) in all CCA-treated wood samples. Copper leached at the highest rate from the ACQ sample (670 mg). Overall results suggest that metals' leaching is a continuous process driven by rainfall, and that the mechanism of release from the wood matrix changes as wood weathers.     

Source identification of copper, lead, nickel, and zinc loading in wastewater reclamation plant influents from corrosion of brass in plumbing fixtures

A natural experiment indicated that a link between the presence and concentration of four elements, copper, lead, nickel, and zinc in the influent to two wastewater reclamation plants to the presence and concentrations of the same four elements in the tap water of residential properties. There were 36 populations of results that were assessed for the normality of their distribution, the difference in their median concentrations, the similarity in the ratios of their median concentrations, and the correlations of the concentrations. The results of this study suggest that brass corrosion is the major source of these four elements in the water reclamation plants influent and that there are two distinct populations of brass sources, those in the early stages of dezincification where the release of the non-copper elements is dominant and those in the later stages where the release of copper dominates and the type of brass that is corroding.     

Removal of lead and zinc ions from aqueous solution using Amasya zeolites from Turkey

A 3-D Eulerian-Lagrangian approach to moving vehicles is presented that takes into account the traffic-induced flow rate and turbulence. The method is applied to pollutant dispersion in an individual street canyon and a system of two street canyons forming a perpendicular intersection. The approach is based on computational fluid dynamics (CFD) calculations using a Eulerian approach for continuous phase and a Lagrangian approach for moving vehicles. The wind speed was assigned values of 4, 7 and 12 m/s. One-way and two-way traffic with different traffic rates per lane is considered. In the case of the intersection, a longitudinal wind direction was assumed. Predictions show differences in the pollutant dispersion in the case of one-way and two-way traffic.     

电镀污泥中铜镍回收方法及工艺的研究

研究了电镀污泥中铜、镍的回收方法及工艺,采用硫酸浸出,浸出液在电压为2.4 V时电解3.5 h,铜的总回收率在99%以上,同时将Fe2 氧化成Fe3 ,电解余液(电解铜之后的溶液)加热至90℃,用磷酸盐调节pH至3.0,磷酸钠投加倍数为形成磷酸盐沉淀理论用量的1.4倍,99%的铁、铝、铬被去除.镍的总回收率约在97%以上.     

The effects of pH and soil type on concentrations of zinc, copper and nickel extracted by calcium chloride from sewage sludge-treated soils

The effects of pH on concentrations of zinc, copper and nickel extracted by calcium chloride from a clay loam and two sandy loam soils that had been treated with sewage sludge were studied. Concentrations of all the metals increased rapidly as pH decreased below a threshold value ranging from 6.2 to 7.0 for Zn, 6.2 to 7.2 for Ni and 4.7 to 5.7 for Cu. Both the total concentrations and the threshold pH values were influenced by differences in soil texture and (between the two light-textured soils) by differences in soil cation exchange capacity. The amount of zinc and copper extracted from the mixtures was considerably less than that extracted from the same quantity of sludge alone.     

Effect of mixed cadmium,copper, nickel and zinc at different pHs upon alfalfa growth and heavy metal uptake

Alfalfa plants were grown in soil-pots contaminated with a mixture of Cd(II), Cu(II), Ni(II), and Zn(II), (at 50 mg/kg each) at pHs of 4.5, 5.8, and 7.1. The plants were fertilized using a nutrient solution, which was adjusted appropriately to the same pH. Plants in the control treatment were grown in the absence of the heavy metals mixture. The growth of the control plants was the same at the three pHs studied and the heavy metal stressed plants also showed similar behavior at each pHs. There were statistically significant differences (P<0.05) between the shoot length of the control treatment plants and the length of plants grown in the presence of the heavy metal mixture. Under the effects of the heavy metal mixture, nickel was the most accumulated element in the shoot tissue, with 437, 333, and 308 ppm at pH 7.1, 5.8, and 4.5, respectively. Cadmium was found to be second in accumulated concentrations with 202 ppm, 124 ppm, and 132 ppm at pH 7.1, 5.8, and 4.5, respectively, while zinc was third, followed by copper. The maximum relative uptakes (element in plant/element in soil-water-solution) were found to be 26 times for nickel, 23 times for cadmium, 12 times for zinc. and 6 times for copper. We considered these relations as indicative of the ability of alfalfa plants to take up elements from a soil matrix contaminated with a mixture of cadmium, copper, nickel, and zinc.     

Risks of using membrane filtration for trace metal analysis and assessing the dissolved metal fraction of aqueous media--a study on zinc, copper and nickel

Membrane filtration is commonly performed for solid-liquid separation of aqueous solutions prior to trace metal analysis and when assessing “dissolved” metal fractions. Potential artifacts induced by filtration such as contamination and/or adsorption of metals within the membrane have been investigated for different membrane materials, metals, applied pressures and pre-cleaning steps. Measurements have been conducted on aqueous solutions including well-defined metal standards, ultrapure water, and on runoff water from corroded samples.Filtration using both non-cleaned and pre-cleaned filters revealed contamination and adsorption effects, in particular pronounced for zinc, evident for copper but non-significant for nickel. The results clearly show these artifacts to be non-systematic both for non-cleaned and pre-cleaned membranes. The applied pressure was of minor importance.Measurements of the labile fraction by means of stripping voltammetry clearly elucidate that membrane filtration followed by total metal analysis cannot accurately assess the labile or the dissolved metal fraction.