牡蛎粉中砷、铅、汞、镉有害金属含量的测定研究

采用微波消解法处理的样品,用原子荧光法来分析测定样品中的痕量Hg,用等离子原子发射光谱法来分析测定样品中As、Pb、Cd的含量。研究了测定不同金属元素的最佳仪器的工作条件,并对方法的准确度和精密度进行考察。结果表明,牡蛎粉中的砷、铅、镉、汞含量分别为9.65μg/g,1.00μg/g,11.1μg/g,0.0511μg/g,加标回收率为89.0%~106.9%,相对标准差为0.50%~4.76%。测定方法简单易行,方便快捷。     

牡蛎粉中砷、铅、汞、镉有害金属含量的测定研究

采用微波消解法处理的样品,用原子荧光法来分析测定样品中的痕量Hg,用等离子原子发射光谱法来分析测定样品中As、Pb、Cd的含量。研究了测定不同金属元素的最佳仪器的工作条件,并对方法的准确度和精密度进行考察。结果表明,牡蛎粉中的砷、铅、镉、汞含量分别为9．65μg／g,1．00μg/g,11．1μg/g,0．0511μg/g,加标回收率为89．0％～106．9％,相对标准差为0．50％～4．76％。测定方法简单易行,方便快捷。     

火焰原子吸收光谱法测定载银沸石中银

研究了载银沸石中银含量的火焰原子吸收光谱测定方法.样品在低温下用硝酸溶解,试液过滤后直接用火焰原子吸收方法进行测定.实验结果表明:大量沸石对银的测定产生干扰,可通过配制沸石基质标准工作溶液消除干扰.在最佳实验条件下,银的质量浓度在0.40～15.00 g/ml与10.00～100.00g/ml范围内分别符合比尔定律,检出限为0.11g/ml,样品加标回收率为97%～103%.该方法可用于载银沸石中银含量的测定.     

微波消解-原子荧光光谱法测定脱硝催化剂中微量砷

采用酒石酸+氢氟酸+硝酸体系微波消解处理脱硝催化剂试样,以氢化物发生-原子荧光光谱法(HG-AFS)对其中的砷进行测定。试验探讨试样消解方法、消解体系各酸用量、仪器测量条件选择以及基体和共存元素的干扰。试验结果表明,试样在1.0 mL酒石酸+2.0 mL氢氟酸+3.0 mL硝酸的混合消解体系中消解完全,在经优化仪器分析参数后,校准溶液及试样溶液均获得一个完整正态峰型,达到最佳积分效果。通过干扰试验得知,基体钛对砷测定无干扰,样品溶液中100 mg/L以内的共存元素钼、钨、硅、钒、钡、镁、钙不干扰砷的测定。砷的浓度在0～20μg/L范围内线性相关系数为0.999 5,方法检出限为0.04μg/g。方法用于实际样品分析,相对标准偏差(RSD,n=5)小于3.0%,加标回收率为95%～103%。     

微波消解—原子吸收法连续测定天然胶乳中铜和锰

实验采用微波消解法消解样品,用原子吸收法在同一体系溶液中连续测定天然胶乳中铜和锰,传统方法采用干灰法或酸消化法消解样品,分光光度法测定,实验证明本法较传统方法节约时间、提高灵敏度和准确度,对人员及环境污染减少,该方法是一种比较好的测定天然胶乳中铜和锰的方法。通过试验测出铜和锰检出限分别为0.28μg/mL和0.15μg/mL,测定精密度的RSD值分别为1.17%和1.05%,铜加标回收率在94.43%～103.40%,锰加标回收率在91.30%～113.64%。     

氢化物-原子荧光法测定矿泉水中的砷和汞

采用AFS-820双通道原子荧光光度计建立了氢化物—原子荧光法同时测定矿泉水中砷和汞的方法。矿泉水用溴酸钾—溴化钾消解,通过原子荧光法光度计同时测定样品中砷和汞。研究了仪器条件、酸度、KBH4浓度等因素对测定的影响,在最佳工作条件下,砷和汞的检出限分别为0.02μg/L、03μg/L,回收率分别为(95.0~100.5)%(、97.4~105.0)%,相对标准偏差分别为0.98%、0.79%。方法简便、准确、灵敏度高。     

电感耦合等离子质谱法测定镀锌液中的杂质元素

为了研究镀锌液中杂质元素的测定方法,用氢氧化钇共沉淀分离富集锌,用电感耦合等离子体质谱(ICP-MS)法同时测定镀锌液样品中Cu,Fe,Pb,Cd,Cr.对影响其测量的各种因素进行了较为详细的研究,确定了试验的最佳测定条件.结果表明,方法的检出限为0.001～0.117μg/L,回收率为93.3%～110.0%,RSD小于2.51%.该法准确、快速、简便,应用于镀锌液中杂质元素的测定,效果较好.     

工业废盐中杀虫单残留量的GC-MS测定

针对工业含杀虫单废盐的特殊基质,通过对样品前处理条件以及仪器条件优化建立一种适合工业废盐中杀虫单残留量检测的气质联用分析方法。样品经盐酸提取、衍生,乙酸乙酯萃取浓缩后,用气质联用仪测定。结果表明在0.01～2.5μg/mL范围内峰面积与浓度呈良好线性关系,方法检出限为1.01μg/kg,加标回收率在96.0%～111.0%之间。该方法简便、快速,适用于工业废盐中杀虫单残留的检测。     

用火焰原子吸收光谱法测中草药中的金属元素

在微波消解罐内用硝酸消化样品,采用火焰原子吸收光谱法对9种中草药中的K、Na、Mg、Mn、Fe、Zn、Cu七种金属元素进行分析测定,并研究了最佳实验条件。在选定条件下,钾的检测限为0.0019μg/mL,钠的检测限为0.0077μg/mL,镁的检测限为0.0024μg/mL,铁检出限为0.0047μg/mL,锌检出限为0.0032μg/mL,铜检出限为0.0052μg/mL,锰检出限为0.0028μg/mL,相对标准偏差为0.54%～3.2%,回收率为94.8%～101.7%。用于中草药中金属元素的测定,简便、省时、准确,结果满意。     

有机溶剂萃取-火焰原子吸收法测定丁基黄原酸

研究用火焰原子吸收分光光度法间接测定丁基黄原酸的方法,依据铜试剂亚铜分光光度法的萃取原理,直接将萃取后的有机溶剂进原子吸收雾化器进行测定.通过优化仪器条件,选取最佳的萃取溶剂为环己烷、萃取体积为4 mL,并向萃取后的环己烷以体积比2/1加入MIBK,增加提升量;硫离子干扰实验表明Cs2-＜1 μg/L不对测定产生干扰.应用最优条件对实际样品进行加标回收实验,回收率良好,结果表明与铜试剂亚铜分光光度法相比,该方法可以有效避免样品本体颜色的干扰,且操作简便,可用于地表水及水源水中丁基黄原酸测定.     

Preconcentration and separation of copper, nickel and zinc in aqueous samples by flame atomic absorption spectrometry after column solid-phase extraction onto MWCNTs impregnated with D2EHPA-TOPO mixture

A solid phase extraction method has been developed for the determination of copper, nickel and zinc ions in natural water samples. This method is based on the adsorption of copper, nickel and zinc on multiwalled carbon nanotubes (MWCNTs) impregnated with di-(2-ethyl hexyl phosphoric acid) (D2EHPA) and tri-n-octyl phosphine oxide (TOPO). The influence of parameters such as pH of the aqueous solution, amount of adsorbent, flow rates of the sample and eluent, matrix effects and D2EHPA-TOPO concentration have been investigated. Desorption studies have been carried out with 2 mol L(-1) HNO(3). The copper, nickel and zinc concentrations were determined by flame atomic absorption spectrometry. The results indicated that the maximum adsorption of copper, nickel and zinc is at pH 5.0 with 500 mg of MWCNTs. The detection limits by three sigma were 50 μg L(-1) for copper, 40 μg L(-1) for nickel and 60 μg L(-1) zinc. The highest enrichment factors were found to be 25. The adsorption capacity of MWCNTs-D2EHPA-TOPO was found to be 4.90 mg g(-1) for copper, 4.78 mg g(-1) for nickel and 4.82 mg g(-1) for zinc. The developed method was applied for the determination of copper, nickel and zinc in electroplating wastewater and real water sample with satisfactory results (R.S.D.'s <10%).     

Biosorption of copper ions from aqueous solution by Codium vermilara: Optimization,kinetic, isotherm and thermodynamic studies

In this investigation, the efficiency of Codium vermilara for copper ions removal from aqueous solution was studied. Central Composite Design has been used for the Response Surface Methodology and has been found to be an effective method for investigating the influences of various variables and their interactions on the efficiency of Cu²⁺ ions removal. The interactive impacts of four variables: algal dose, pH, initial concentrations of copper and contact time on the copper removal efficiency were assessed. Algal dose 0.75 g/L, pH 5.28, contact time 70.51 min, and copper concentration 48.75 mg/L were found to be the conditions of optimum biosorption. The efficiency of copper removal was found to be 85.5% under these optimum conditions. Copper removal on the biomass of C. vermilara followed well the kinetics of pseudo-first-order, Elvoish and Intraparticle diffusion. Compared to the other models, Dubinin-Radushkevich isotherm best suited the experimental data revealing that the adsorption mechanism was physical adsorption. Thermodynamic parameters exhibited non-spontaneous, randomness and endothermic biosorption of Cu²⁺ ions. Additionally, the biosorbent characterization was estimated by scanning electron microscopy and Fourier transform infrared analysis. Thus, C. vermilara could be used as possible biosorbent for removing heavy metals and other pollutants from the environment.     

Removal of copper from industrial sludge by traditional and microwave acid extraction

This work elucidates the removal of copper from industrial sludge by traditional and microwave acid extraction. The effects of acid concentration, extraction time, sludge particle size and solid/liquid (S/L) ratio on copper removal efficiency were evaluated. Leaching with more concentrated acid yielded greater copper content from the industrial sludge. The experimental findings reveal that the most economical traditional extraction conditions were the use of 1N sulfuric or nitric acid for 60 min at an S/L ratio of 1/20; however, at an S/L ratio of 1/6, the extraction time needed to achieve the same copper removal efficiency was increased to 36 h. Increasing the microwave power and reducing the S/L ratio increased the copper extraction efficiency and the effect in the larger S/L ratio system was more significant. A comparison of the results of microwave-assisted (microwave only) and microwave-enhanced (microwave with addition of active carbon) acid extraction demonstrated that under both conditions, S/L ratio = 1/6 and 1/20; adding active carbon shortened the extraction time required to achieve 80% copper extraction efficiency from 20 to 10 min. These experimental results indicate that the most important factors that most strongly affected microwave acid extraction were the addition of a microwave absorber, the microwave power input and the S/L ratio. The sludge particle size did not significantly affect the copper extraction. The results reveal that sulfuric acid was an effective extractant and that the copper fraction in the extracted sludge shifted from being mostly bound to the Fe–Mn oxides and organic matter, to being mostly bound to organic matter and remaining as a residue during acid extraction.     

Electrokinetic remediation of wood preservative contaminated soil containing copper, chromium, and arsenic

As a result of wood treatment, and the recent banning of the copper, chromium, and arsenic (CCA) treated wood for residential use many CCA treatment facilities have been abandoned or being closed. Soil contamination resulting from CCA is common at these sites. In this study, the feasibility of electrokinetic technique to remove CCA from contaminated soil was investigated. To better understand the ionic mobility within the soil and to detect the generation and advancement of acid front, sampling ports were provided along the longitudinal axis of a test cell. To determine the effect of varying current, three tests were performed at different current densities of 5.9, 2.9, and 1.5mA/cm(2) for a period of 15 days. The initial concentrations of copper, chromium, and arsenic in the soil were 4800, 3100, and 5200mg/kg, respectively. Dilute nitric acid was used as an amendment to neutralize the hydroxyl ions produced at the cathode. Experiments resulted in removal efficiencies as high as 65% for copper, 72% for chromium, and 77% for arsenic. The results also indicated that the advancement of acid front favored desorption of metals from the soil and the metals were mobilized either as free cations or metal complexes. Chromium that was in its +6 valence state was transported as anion prior to its reduction. However, once the chromium was reduced to chromium(III) its transport direction reversed with transport being favored towards the cathode.     

Dispersion of chitosan on perlite for enhancement of copper(II) adsorption capacity

Chitosan coated perlite beads were prepared by drop-wise addition of slurry, made of chitosan dissolved in oxalic acid and perlite, to an alkaline bath (0.7 M NaOH). The beads that contained 32% chitosan enhanced the accessibility of OH and amine groups present in chitosan for adsorption of copper ions. The experiments using Cu(II) ions were carried out in the concentration range of 50-4100 mg/L (0.78-64.1 mmol/L). Adsorption capacity for Cu(II) was pH dependent and a maximum uptake of 104 mg/g of beads (325 mg/g of chitosan) was obtained at pH 4.5 when its equilibrium concentration in the solution was 812.5 mg/L at 298 K. The XPS and TEM data suggested that copper was mainly adsorbed as Cu(II) and was attached to amine groups. The adsorption data could be fitted to one-site Langmuir adsorption model. Anions in the solution had minimal effect on Cu(II) adsorption by chitosan coated perlite beads. EDTA was used effectively for the regeneration of the bed. The diffusion coefficient of Cu(II) onto chitosan coated beads was calculated from the breakthrough curve and was found to be 2.02 x 10(-8) cm(2)/s.     

Preconcentration and separation of trace amount of copper (II) on N, N-bis(4-fluorobenzylidene)ethane-1,2-diamine loaded on Sepabeads SP70

A sensitive and simple method for the preconcentration of copper (II) ions has been reported. The method is based on the adsorption of copper ion N¹, N²-bis(4-fluorobenzylidene)ethane-1,2-diamine loaded on Sepabeads. The sorpted copper content was eluted by 8 ml of 4 M nitric acid in acetone. The influences of the analytical parameters including pH and sample volume were investigated. The interference effects of matrix ions on the retentions of the copper (II) ions were also examined. The recovery of understudy analyte was generally higher than 95%. The method has been successfully applied to the evaluation of copper contents in some real samples including water samples, vegetable samples and milk samples.     

Recovery and reutilisation of copper from metal hydroxide sludges

Sludges generated from electroplating wastewaters contain high concentrations of metals. Studies have confirmed that the concentrations of several metals in the sludge exceed that of those found in natural ores. A very good example is in the case of copper. The natural copper ore contains less than 1% of copper, whereas copper precipitate sludges from the electroplating industry may have an average of 5–10% of copper. Thus, they are one of the largest sources of untapped metal-bearing secondary materials amenable to metals recovery. In Malaysia, most of these metal-bearing sludges are disposed in specially engineering landfills, as many of them do not have the proper incentives and recovery technology. Very less metal recovery is being carried out, and there seems to be a huge waste in these valuable metal resources. With regards to that, an experimental study was carried out to develop and optimise a method of copper recovery from metal hydroxide sludges. Sludge samples containing high concentrations of copper were obtained from a local electroplating plant for the study. A procedure based upon mineral acid leaching or solubilisation was carried out. Two different types of acids, hydrochloric acid (HCl) and sulphuric acid (H₂SO₄) were used to compare the extractability of copper. Experiments were conducted at various acid concentrations and temperatures to determine the maximum amount of copper recoverable. From the results obtained, maximum copper (95%) was solubilised using H₂SO₄ of 10 M at temperature 110°C, for a leaching period of 4 h. These copper concentrated solutions were then heated and crystallised to form CuSO₄ crystals. These crystals were then washed with water and purified. They can be then further treated and reutilised in the metallurgical industry. This study introduces a sustainable method of utilising an electroplating sludge containing valuable metals.     

A study on the modified flotation parameters and selectivity index in copper flotation

Selectivity index (SI) and modified flotation rate constants of copper and iron were evaluated to rougher flotation circuit of the Sarcheshmeh copper ore by a series of batch flotation tests. Kinetics model of Agar was fitted to experimental data. The results indicated that first-order kinetics model of Agar presented the time–cumulative recovery curves of flotation tests quite well for Cu and Fe. Also, the results showed that the selectivity between Cu and Fe enhanced with increasing the pH, solid content, and dosage collector. In addition, performance of collectors showed that the best selectivity between Cu and Fe was in the order of combination of Z11 and MBTs > flomin C4132 > combination of MBTs and flomin C4132 > combination of Z11, MBTs, and flomin C4132 in flotation of copper. It was also found that better results for flotation kinetics were obtained at pH 11.5, solid percentage 28, and dosage collector 40 g/t (15 g/t sodium isopropyl xanthate and 25 g/t mercaptobenzothiazole [MBT]). SI value was determined as 5.12 in optimum condition.     

Solid phase extraction method for the determination of lead, nickel, copper and manganese by flame atomic absorption spectrometry using sodium bispiperdine-1,1'-carbotetrathioate (Na-BPCTT) in water samples

A novel column solid phase extraction procedure was developed for the determination of lead, nickel, copper and manganese in various water samples by flame atomic absorption spectrometry (FAAS) after preconcentration on sodium bispiperdine-1,1'-carbotetrathioate (Na-BPCTT) supported by Amberlite XAD-7. The sorbed element was subsequently eluted with 1M nitric acid and the acid eluates are analysed by Flame atomic absorption spectrometry (FAAS). Various parameters such as pH, amount of adsorbent, eluent type and volume, flow-rate of the sample solution, volume of the sample solution and matrix interference effect on the retention of the metal ions have been studied. The optimum pH for the sorption of above mentioned metal ions was about 6.0+/-0.2. The loading capacity of adsorbent for Pb, Cu, Ni and Mn were found to 28, 26, 22 and 20x10(-6) g/mL, respectively. The recoveries of lead, copper, nickel and manganese under optimum conditions were found to be 96.7-99.2 at the 95% confident level. The limit of detection was 3.0, 3.2, 2.8 and 3.6x10(-6) g/mL for lead, copper, nickel and manganese, respectively by applying a preconcentration factor 50. The proposed enrichment method was applied for metal ions in various water samples. The results were obtained are good agreement with reported method.     

The influence of thiourea on copper electrodeposition: Adsorbate identification and effect on electrochemical nucleation

The effect of thiourea on copper deposition onto a copper seed layer from an electrolyte composed of CuSO₄, H₂SO₄, deionized water, and thiourea was investigated. Even in the presence of very low concentrations of thiourea, extremely smooth and bright copper deposits were obtained. From the results of X-ray photoelectron spectroscopy, Auger electron spectroscopy, and electrochemical analyses, thiourea was found to react with copper or copper ions leading to the generation of CuS. CuS adsorption onto the copper seed layer seemed to inhibit the initial nucleation of the copper adions, resulting in the formation of smaller Cu grains compared to those forming in the absence of thiourea. CuS was observed to cover all active sites of the 1 cm² copper seed layer above 0.017 g/L thiourea. The surface roughness as well as the mean grain size of the deposits also approached minimum values above this thiourea concentration. Adsorbed CuS was incorporated into the deposits during electroplating, which was believed to be the major factor for the increased resistivity of the deposits.