Evaluation of zeolites synthesized from fly ash as potential adsorbents for wastewater containing heavy metals

The pure-form zeolites （A and X） were synthesized by applying a two-stage method during hydrothermal treatment of fly ash prepared initial Cu and Zn gel. The difference of adsorption capacity of both synthesized zeolits was assessed using Cu and Zn as target heavy metal ions. It was found that adsorption capacity of zeolite A showed much higher value than that of zeolite X. Thus, attention was focused on investigating the removal performance of heavy metal ions in aqueous solution on zeolite A, comparing with zeolite HS （hydroxyl-solidate） prepared from the residual fly ash （after synthesis of pure-form zeolite A from fly ash） and a commercial grade zeolite A. Batch method was used to study the influential parameters of the adsorption process. The equilibrium data were well fitted by the Langmuir model. The removal mechanism of metal ions followed adsorption and ion exchange processes. Attempts were also made to recover heavy metal ions and regenerate adsorbents.

Acid mine drainage and heavy metal contamination in groundwater of metal sulfide mine at arid territory (BS mine,Western Australia)

The issues of acid mine drainage （AMD） and heavy metals contamination in the metal sulfide mine in the add district were explored, through studying the acidification and the heavy metals distribution and evolution of groundwater in the black swan （BS） nickel sulfide mine （Western Australia）. The groundwater samples were collected from the drilling holes situated in the vicinity of tailings storage facility （TSF） and in the background of the mine （away from TSF）, respectively, and the pH and electric conductivity （Ec） were measured in site and the metal contents were analysed by ICP-MS and ICP-AES, quarterly in one hydrological year. The results disclose that the TSF groundwater is remarkably acidified （.pHmean=5, pHmin=3）, and the average contents of heavy metals （Co, Cu, Zn, Cd） and Al, Mn are of 1-2 orders of magnitude higher in TSF groundwater than in background groundwater. It may be due to the percolation of tailings waste water from miU process, which leads the tailings to oxidize and the deep groundwater to acidify and contaminate with heavy metals. Besides, the heavy metals concentration in groundwater may be controlled by pH mainly.

Extraction of metals from complex sulfide nickel concentrates by low-temperature chlorination roasting and water leaching

The recovery of valuable metals from complex sulfide concentrates was investigated via chlorination roasting followed by water leaching. A reaction process is proposed on the basis of previous studies and the results of our preliminary experiments. During the process, various process parameters were studied, including the roasting temperature, the addition of NH4Cl, the roasting time, the leaching time, and the liquid-to-solid ratio. The roasted products and leach residues were characterized by X-ray diffraction and vibrational spectroscopy. Under the optimum condition, 95% of Ni, 98% of Cu, and 88% of Co were recovered. In addition, the removal of iron was studied in the water leaching stage. The results demonstrate that this process provides an effective approach for extracting multiple metals from complex concentrates or ores. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

RECOVERY OF CADMIUM AND NICKEL FROM SCRAP Ni-Cd BATTERIES

Several typical methods for the recovery of Ni-Cd batteries are described in detail. Based on the comparison between the hydrometallurgical process and the pyrometallurgical process, the latter is selected as the suitable method for recycling Ni-Cd batteries in China.

Nanoscale Zero-Valent Iron(nZVI)for Heavy Metal Wastewater Treatment:A Perspective

Industries such as non-ferrous metal smelting discharge billions of gallons of highly toxic heavy metal wastewater(HMW)worldwide annually,posing a severe challenge to conventional wastewater treatment plants and harming the environment.HMW is traditionally treated via chemical precipitation using lime,caustic,or sulfide,but the effluents do not meet the increasingly stringent discharge standards.This issue has spurred an increase in research and the development of innovative treatment technologies,among which those using nanoparticles receive particular interest.Among such initiatives,treatment using nanoscale zero-valent iron(nZVI)is one of the best developed.While nZVI is already well known for its site-remediation use,this perspective highlights its application in HMW treatment with metal recovery.We demonstrate several advantages of nZVI in this wastewater application,including its multifunctionality in sequestrating a wide array of metal(loid)s(>30 species);its capability to capture and enrich metal(loid)s at low concentrations(with a removal capacity reaching 500 mg·g^(-1)nZVI);and its operational convenience due to its unique hydrodynamics.All these advantages are attributable to nZVI’s diminutive nanoparticle size and/or its unique iron chemistry.We also present the first engineering practice of this application,which has treated millions of cubic meters of HMW and recovered tons of valuable metals(e.g.,Cu and Au).It is concluded that nZVI is a potent reagent for treating HMW and that nZVI technology provides an eco-solution to this toxic waste.

Removal of Heavy Metals from Aqueous Solutions Using Bacteria

The accumulation of heavy metals by microbial biomass with high surface area to volume ratio holds great potential for heavy metal removal in both soluble and paritcular forms, especially when the heavy metal concentrations are low (<50 mg/L). E. coli and B. subtilis are effective agents for metal removal. We further investigated the effect of pH, temperature, equilibration time, and pre treatment reagents on the removal of Pb(Ⅱ), Cd(Ⅱ) and Cr(Ⅵ) from aqueous solutions by E. coli and B. subtilis. E. coli and B. subtilis were cultivated for 60 hours, the experimentally determined optimal cultivation time before they were used in metal removal experiments. Under the optimal conditions of pH 6.0, equilibration temperature 30 °C and equilibration time 1 hour, 63.39% and 69.90% Cd(Ⅱ) can be removed by E. coli and B. subtilis. Under the optimal conditions of pH 5.5, equilibration temperature 30 °C and equilibration time 1 hour, 68.51% and 67.36% Pb(Ⅱ) can be removed by E. coli and B. subtilis. And under the optimal conditions of pH 5.5, equilibration temperature 30 °C, and equilibration time 1 hour, 60.26% and 54.56% Cr(Ⅵ) can be removed by E. coli and B. subtilis. Chemical treatment of cultivated bacteria (0.1 mol/L NaOH, 0.1 mol/L HCl, 30% ethanol, and distilled water) affects the efficiency of metal removal by E. coli and B. subtilis. Pretreatment of biomass by NaOH enhanced Cd(Ⅱ), Pb(Ⅱ) and Cr(Ⅵ) removal, while pretreatment by HCl, ethanol and distilled water reduced Cd(Ⅱ), Pb(Ⅱ) and Cr(Ⅵ) removal. For metal removal from industrial waste discharges, pretreated biomass of E. coli can remove 68.5% of Cd and 58.1% of Cr from solutions, while pretreated biomass of B. subtilis can remove 62.6% of Cd and 57% of Cr from solutions.

Removal of heavy metals（Cr^（6＋），Ni^（2＋）） from polluted water using decaying leaves of plane（Plantanus orientalis）

plane decaying leaves have been found capable of removing chromium and nickel ions from aqueous solutions. The removal efficiency depends upon the pH conditions, ions components and concentrations, and concentrations of leaves in media. The maximum removal for unique Cr6+ is about 7.5-8.0g/kg leaves at pH 4. 0, for unique Ni2+ about 2. 6g/kg at the region of PH5. 0-5.5. Under the described conditions nickel increases chromium uptake by plane decaying leaves from solution.

Heavy Metals, Metalloids, Their Toxic Effect and Living Systems

Pollution of the biosphere by heavy metals is a global hazard that has accelerated since the beginning of the industrial revolution. Toxic heavy metals are harmful to living organisms even at low concentrations whereas heavy metals that are essential trace elements are required by plants at low concentrations but can become toxic at high concentrations. Heavy metals released from different sources accumulate in soil and, where bioavailability is high enough;can adversely affect soil biological functioning and other properties, leading to the loss of soil and ecosystem fertility and health. It is important that heavy metal contaminated sites are remediated as heavy metals do not decompose into less harmful substances like organic contaminants, and thus are retained in the soil. In this review, we survey and analysis our current knowledge and understanding of the abundance of heavy metals in soil, their phytoavailability, their toxicity, their uptake and transport, role of rhizobia and other microbes and overall rhizosphere processes.

Nickel solvent extraction from cold purification filter cakes of Angouran mine concentrate using LIX984N

Cold purification filter cakes generated in the hydrometallurgical processing of Angouran mine zinc concentrate commonly contain significant amounts of Zn, Cd, and Ni ions and thus are valuable resources for metal recovery. In this research, a nickel containing solution that was obtained from sulfuric acid leaching of the filter cake following cadmium and zinc removal was subjected to solvent extraction experiments using 10vol%LIX984N diluted in kerosene. Under optimum experimental conditions （pH 5.3, volume ratio of organic/aqueous （O：A） = 2：1, and contact time -5 min）, more than 97.1% of nickel was extracted. Nickel was stripped from the loaded organic by contacting with a 200 g/L sulfuric acid solution, from which 77.7% of nickel was recovered in a single contact at the optimum conditions （pH 1-1.5, O：A =5：1, and contact time =15 min）.

Recovery time of macroinvertebrate community from Cd pollution in Longjiang River,Guangxi,China

Estimating recovery times from pollution incident is an important issue of targeted biomonitoring programs.In the present study,the impact and recovery of macroinvertebrate communities from a cadmium wastewater discharge in the Longjiang River,Guangxi,China,in early January 2012 were studied based on 83 samples collected in fi ve surveys within 20 months after the incident.The pollution aff ected seriously the local aquatic biota,and consequently,the invertebrate abundance and species richness were reduced considerably.Twelve months later,the taxonomic number of macroinvertebrates began to increase.However,sensitive taxa remained rare.Twenty months later,the taxon richness and abundance of macroinvertebrates increased signifi cantly compared to those in the previous four time points.To explore the possible time-scale over which pre-disturbance conditions might occur,we chose four diff erent typical metrics of taxa richness(total taxa number,cumulative taxa number,taxa number per samples,and the Shannon-Wiener diversity index)and extrapolated modeled recovery trajectories.Target values for the four metrics were set at average values for sites from the nearby Lijiang River,which were used as a reference.Assuming a continued linear trajectory,the recovery times were estimated to be 52,39,39,and 31 months,respectively,which was roughly 3-5 years.This is consistent with results from recovery times from other studies of acute pollution cases,but contrasted strongly to the much longer recovery times associated with chronic pollution from groundwater contamination and mine-tailing runoff.

Core-shell design of UiO66-Fe_(3)O_(4) configured with EDTA-assisted washing for rapid adsorption and simple recovery of heavy metal pollutants from soil

The coupling of washing with adsorption process can be adopted for the treatment of soils contaminated with heavy metals pollution.However,the complex environment of soil and the competitive behavior of leaching chemicals considerably restrain adsorption capacity of adsorbent material during washing process,which demands a higher resistance of the adsorbents to interference.In this study,we synthesized strongly magnetic,high specific surface area(573.49 m^(2)/g)UiO66 composites(i.e.,UiO66-Fe_(3)O_(4))using hydrothermal process.The UiO66-Fe_(3)O_(4) was applied as an adsorbent during the ethylene diamine tetraacetic acid(EDTA)-assisted washing process of contaminated soil.The incorporation of UiO66-Fe_(3)O_(4)results in rapid heavy metal removal and recovery from the soil under low concentrations of washing agent(0.001 mol/L)with reduced residual heavy metal mobility of soil after remediation.Furthermore,UiO66-Fe_(3)O_(4)can quickly recollect by an external magnet,which offers a simple and inexpensive recovery method for heavy metals from contaminated soil.Overall,UiO66-Fe_(3)O_(4)configuration with EDTA-assisted washing process showed opportunities for heavy metals contaminated sites.

Antimicrobial Degradation Performance of Novel Polyacrylamide Derivatives by Microbial Consortia for Enhanced Oil Recovery

The pursuit of high oil recovery rate has been a persistent objective for oil industry. Pseudomonas sp. LP-7 and Bacillus sp. PAH-2 were isolated from oil-contaminated surface soil samples of an oilfield. The antimicrobial degradation rates(ADRs) of polymers achieved by LP-7 and PAH-2 were evaluated at a temperature of 35 °C in the mineral salt media during the shaken flask trial. The ADRs of copolymer synthesized by using a surfactant with a concentration of 5% could reach 8.4% for PAH-2 and 15.3% for LP-7. The ADRs of copolymer could reach 10.4% for PAH-2 and 21.3% for LP-7,when the polymer concentration was 2 g/L. All results confirmed that the ADRs of copolymers increased with an increasing content of HDDE(capsaicin derivative monomer) in the polymer. The copolymers also manifested excellent antimicrobial degradation performance in the presence of Cu^(2+), Zn^(2+), and Pb^(2+) ions, respectively, which had great potential for applications in enhanced oil recovery.

Pregnancy complications effect on the nickel content in maternal blood,placenta blood and umbilical cord blood during pregnancy

BACKGROUND Nickel(Ni)may accumulate in the human body and has biological toxicity and carcinogenicity.Ni has an extensive impact on the health of pregnant women and fetuses during gestation.AIM To evaluate Ni exposure in pregnant women in Kunming,Yunnan Province,China;to describe the distribution of Ni in the maternal-fetal system and placental barrier function;and to investigate the effect of Ni exposure on fetal health in mothers with pregnancy complications.METHODS Seventy-two pregnant women were selected using a case-control design.The women were divided into two groups:The control group(no disease;n=29)and the disease group[gestational diabetes(GDM),hypertensive disorder complicating pregnancy(HDCP),or both;n=43].The pregnant women in the disease group were further divided as follows:14 cases with GDM(GDM group),13 cases with HDCP(HDCP group)and 16 cases with both GDM and HDCP(disease combination group).Basic information on the pregnant women was collected by questionnaire survey.Maternal blood,placenta blood and cord blood were collected immediately after delivery.The Ni content in paired samples was determined using inductively coupled plasma mass spectrometry.RESULTS Compared to the control group,age was higher and body mass index was greater in pregnant women in the disease groups(28.14±2.54 vs 28.42±13.89,P<0.05;25.90±3.86 vs 31.49±5.30,P<0.05).The birth weights of newborns in the HDCP group and the control group were significantly different(2.52±0.74 vs 3.18±0.41,P<0.05).The content of Ni in umbilical cord blood in the entire disease group was higher than that in the control group(0.10±0.16 vs 0.05±0.07,P<0.05).CONCLUSION In the maternal-fetal system of women with pregnancy complications,the barrier effect of the placenta against Ni is weakened,thus affecting healthy growth of the fetus in the uterus.

Recovery and Upgrading of Phosphorus from Digested Sewage Sludge as MAP by Physical Separation Techniques

Physical separation apparatuses;a vibrating screen, a 4-inch hydrocyclone and a Multi-Gravity Separator (MGS) were used to recover phosphorus as MAP (magnesium ammonium phosphate, MgNH4PO4.6H2O) from anaerobic digested sludge of two sewage-treatment plants A and B. For plant A, the MAP grade increased from 0.08% to 88.9% with 90.4% recovery and for plant B, the grade increased from 0.11% to 73.8 with 93.2% recovery. The collected MAP products containing impurities such as organic materials and heavy metals were further upgraded through dry and wet magnetic separation tests at different magnetic flux densities. A dry magnetic separator was tested on both MAP products (MAP-A and MAP-B), while the wet magnetic separation process was exclusively experimented for the removal of impurities from MAP-B. Feed samples, as well as magnetic and nonmagnetic products were analyzed by absorption spectroscopy, XRD, ICP-AES, polarizing microscope observation, and SEM-EDX. The grade of MAP products could be improved by about 4% - 9% after magnetic separation (the most appropriate magnetic force being 15,000 Gauss). During both dry and wet magnetic separation processes, not only heavy metals have been removed, but also nonmagnetic constituents like Al, Ba, and Ca. This may be attributed to the attachment of fine magnetic particles on the nonmagnetic surfaces, rendering them magnetic properties.

Producing High Purity Nickel Metal Powder from Nickel Wastes through Acidic Leaching by Sulfuric Acid

Nickel has found increasing application in electronic,automobile manufacturing,plating,and metal industries and so on.Producing high quality metal powders to satisfy increasing demand for advanced materials is of very high importance.There are a few numbers of standard powder production techniques.An acidic leaching has been applied in present research.Sulfuric acid has been used to leach nickel wastes of plating industry.To produce nickel oxide powder furnaces with no protecting atmosphere and to produce pure nickel powder,tube furnace with hydrogen atmosphere has been applied.Variables performed in the research are time,density of sulfuric acid,and amount of hydrogen peroxide.To analyze powders produced,EDS element analysis and to determine size of powder particles,SEM has been applied.It was shown by the results that the highest amount of nickel dissolution in sulfuric acid(98%)has taken place during one hour and there is a direct relationship between hydrogen peroxide amount and nickel dissolution in sulfuric acid.

Electro-oxidation of Ni(Ⅱ)-citrate complexes at BDD electrode and simultaneous recovery of metallic nickel by electrodeposition

The simultaneous electro-oxidation of Ni(Ⅱ)-citrate and electrodeposition recovery of nickel metal were attempted in a combined electro-oxidation-electrodeposition reactor with a boron-doped diamond(BDD)anode and a polished titanium cathode.Effects of initial nickel citrate concentration,current density,initial p H,electrode spacing,electrolyte type,and initial electrolyte dosage on electrochemical performance were examined.The efficiencies of Ni(Ⅱ)-citrate removal and nickel metal recovery were determined to be 100%and over 72%,respectively,under the optimized conditions(10 m A/cm^(2),pH 4.09,80 mmol/L Na_(2)SO_(4),initial Ni(Ⅱ)-citrate concentration of 75 mg/L,electrode spacing of 1 cm,and 180 min of electrolysis).Energy consumption increased with increased current density,and the energy consumption was 0.032 kWh/L at a current density of 10 m A/cm^(2)(pH 6.58).The deposits at the cathode were characterized by scanning electron microscopy(SEM),energy-dispersive spectrometry(EDS),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).These characterization results indicated that the purity of metallic nickel in cathodic deposition was over 95%.The electrochemical system exhibited a prospective approach to oxidize metal complexes and recover metallic nickel.

Recovery of rare earths from acid leach solutions of spent nickel-metal hydride batteries using solvent extraction

The extraction of rare earths from acid leach solutions of spent nickel-metal hydride batteries using a primary amine ex- tractant of N 1923 was studied. The effects of feed pH, temperature, agitation rate and time on the extraction of rare earths, as well as stripping agent composition and concentration, phase ratio on the stripping were investigated. In addition, the extraction isotherm was determined. The pilot plant test results showed that the extraction of rare earths reached 99.98% after a five-stage counter current extraction. The mixed rare earths oxalates with the 99.77% purity of rare earth elements and impurity content less than 0.05% were obtained by the addition of oxalic acids in loaded strip liquors. The extractant exhibited good selectivity of rare earths over base metals of iron, nickel, copper and manganese.

Biosorption of Ni²⁺and Cd²⁺from Aqueous Solutions Using NaOH-Treated Biomass of <i>Eupenicillium ludwigii</i>: Equilibrium and Mechanistic Studies

The removal of Ni2+ and Cd2+ ions by Eupenicillium ludwigii biomass was studied in a batch system. The optimum pH for the biosorption was 6 for Ni2+ and 5 for Cd2+. Temperature changes in the range from 15oC to 40oC affected the biosorption capacity, and the nature of the reaction was found to be endothermic for both metal ions. HCl was the best desorbing agent for the desorption of both metals. Chemical modifications of the biomass demonstrated that carboxyl and amine groups played an important role in Ni2+ and Cd2+ biosorption. Ion exchange mechanism was also suggested in the biosorption process.

基于分类处理-分质利用的电子电镀废水中金属离子资源化处理新技术研究进展

随着城市化、工业化以及农业现代化进程加快,电子信息行业快速发展的同时产生了大量电子电镀重金属废水。这类型废水成分复杂、赋存稳定、危害极大且具有一定资源属性,目前较流行的混凝沉淀法处理效果不佳,污泥量大,存在二次污染且无法资源化回收。基于此,归纳总结了电子电镀重金属废水的来源与危害,归纳分析了现行主要技术存在的不足,系统介绍了基于分类处理-分质利用的电子电镀废水中金属离子资源化处理的进展与最新研究成果,为电子信息行业清洁生产、重金属废水污染防治和资源化处理提供借鉴与技术支撑。

粤港澳大湾区某镍污染场地空间分布模拟

文章以粤港澳大湾区某电镀厂场地为研究对象,为探究重金属镍在场地中的分布规律,利用场地地层勘探测绘和土壤检测数据建立三维地层模型和污染分布模型。该研究采用克里格插值法(Kriging)、反距离加权插值法(IDW-Shepard)、改进的反距离加权插值法(IDW-(Franke/Nielson))、邻近点插值法(Nearest Neighbor)和快速径向基函数(Fast Radial Basis Function)5种插值方法预测了场地中镍污染分布特征和污染方量,基于交叉验证法分析获取最优插值方法。结果显示Kriging法的平均绝对误差和均方根误差数值最小,是预测精度最高的空间插值方法。不同土层污染物浓度分布差异明显,污染物迁移性强的砂土层镍污染范围大含量高,黏土和淤泥层对污染物迁移有很好的阻隔作用,Kriging法能较真实地反映场地污染分布特征。污染物空间分布特征与生产活动和地层条件密切相关,选用合适的插值方法构建污染分布模型可为污染场地精细化修复提供参考。