Order Of Cu Research Articles

Effect of pyrolysis condition on the adsorption mechanism of lead, cadmium and copper on tobacco stem biochar

Abstract To promote the application of biochar in environmental pollution decontamination especially the heavy metals amendment, the relationship between the adsorption mechanism and biochar pyrolysis conditions was investigated. Tobacco stem was pyrolyzed at 300–700 °C for various residence time of 2 h, 4 h and 6 h. The adsorption of lead, cadmium and copper in single solute was then analyzed for as-obtained biochars. The change of the crystal structures, the related functional groups, and the exchanged cations were determined to reveal the effect of pyrolysis conditions on the adsorption mechanisms of these three heavy metals. The change of crystal structure confirmed that precipitation was the main mechanism of lead adsorption and that the tobacco stem biochar obtained at 700 °C for around 2 h was excellent adsorbent for lead clearance, since high temperature pyrolysis could promote the formation of carbonates but they would be decomposed under long-time exposure. The alteration of surface functional groups and exchanged cations of both original and demineralized biochars followed an affinity order of Cu(II)>Cd(II)>Pb(II) to oxygen functional groups. The surface complexation should be the primary mechanism of copper adsorption. Thus, the tobacco stem biochars pyrolyzed at 400 °C for 4 h could be effective adsorbents for copper amendment. Despite of the important role of precipitation in its removal, cadmium favores the cation-π interaction best, and the biochars derived from tobacco stem at 700 °C for the residence time of 4–6 h are good adsorbents for cadmium decontamination.

Ecological and Health Risks of Trace Heavy Metals in Atmospheric PM2.5 Collected in Wuxiang Town, Shanxi Province

The pollution of atmospheric PM2.5 and ambient air quality were investigated in Wuxiang Town, Shanxi Province, China, and the ecological and health risks of the trace heavy metals in PM2.5 were analyzed. The PM2.5 samples were collected every day using a medium-volume PM2.5 sampler in autumn (from Oct. 22 to Nov. 19, 2014) and in winter (from Jan. 12 to Feb. 13, 2015) on the roof of a building at the Wuxiang Environmental Protection Agency (EPA). The mass concentrations of PM2.5 were determined gravimetrically, and the contents of seven trace heavy metals (i. e., As, Cd, Cr, Cu, Ni, Pb, and Zn) in PM2.5 were obtained using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The pollution extent, sources, and potential ecological and health risks of the trace heavy metals in PM2.5 were identified and assessed using the geo-accumulation index, ecological risk index, a correlation and principle component analysis, and the exposure risk models of US EPA. Results showed that the average concentration of PM2.5 in winter, approximately three times higher than that in autumn, exceeded the national secondary standard of ambient air quality (GB 3095-2012) on 65% of the sampling days. The heavy metals in PM2.5 mainly originated from anthropogenic activities, with contributions of 58.38% and 18.73% from coal combustion and vehicular emission, respectively. In general, the levels of the heavy metals in PM2.5 followed the order of Cu > Zn > Pb > Cr > As > Ni > Cd, with higher ecological risks from Cd and Cu and higher non-carcinogenic and carcinogenic risks from Cr compared with other metals. It is suggested that greater coal combustion in winter under the adverse geographical conditions for air diffusion in Wuxiang Town were responsible for the increased atmospheric PM2.5 concentration and their ecological and health risks in heavy metals.

Two-phase homogeneous diffusion model for the fixed bed sorption of heavy metals on natural zeolites

In this work, the fixed bed removal kinetics of Pb2+, Zn2+, Mn2+, Cr3+, Fe3+ and Cu2+ from aqueous solutions on natural zeolites was studied. For this aim, a non-dimensional two-phase homogeneous solid diffusion model including axial dispersion and equipped with a universal double-selectivity equilibrium model is developed and applied. In total 9 isotherms, representing 128 experimental points and 25 breakthrough curves, representing 764 experimental points are used in modeling. The application of the model is satisfactory resulted in an average deviation from the experimental data of 11.19 ± 5.53%. The solid phase diffusion coefficients are between 10−7 and 10−9 cm2/s depending on the metal, flow rate and particle size in the decreasing order of Cu > Fe, Cr > Zn, Pb > Mn. The study is supplemented by an extended literature review on fixed bed models and experimentally derived solid phase diffusion coefficients in zeolites.

Distribution, bioavailability and probabilistic integrated ecological risk assessment of heavy metals in sediments from Honghu Lake, China

Abstract Heavy metals (Cr, Cu, Zn, Pb, Cd) concentrations and fractions in surface sediments from Honghu Lake were detected by an atomic absorption spectrophotometer and Simple Bioavailability Extraction Test (SBET) from 11 typical sites to explore their spatial distribution, bioavailability and sources. Results showed the mean Igeos and ecological risk degrees decreased in the order of Cd>Cu>Cr>Pb>Zn and Cd>Cu>Pb>Cr>Zn. The metals’ bioavailability estimated by SBET decreased in the general order of Cu>Pb>Cd>Zn>Cr. Under integrated consideration of metal enrichment, ecological risk and bioavailability, it obviously made the decision-makers confused to identify final priority pollutants and priority areas. Thus, a probabilistic integrated ecological risk assessment method (PIERA) was formulated based on the potential ecological risk index (PER), SBET and triangular fuzzy numbers for synthetically assessing metal enrichment, ecotoxicity and bioavailability. With the help of PIERA, Cd was finally regarded as the risk priority metal due to the integrated potential eco-risk of Cd made the average contribution of 86.4% to the integrated RIs. Moreover, the areas around S5 and S2 were regarded as the risk priority areas. The case application of PIERA revealed that this improved method is of a better resolving ability which scientifically supplies the integrated information of enrichment, bioavailability and systematic uncertainty for decision-makers compared with the other prevalent indexes (SQGs, Igeo, PER). The consequence of the Pearson correlation analysis, distribution analysis and field investigation indicated that Cd mainly originated from both non-point agricultural and industrial pollution sources.

Synthesis, molecular docking and DNA binding studies of phthalimide-based copper(II) complex: In vitro antibacterial, hemolytic and antioxidant assessment

In the present research work, we prepared N-substituted phthalimide, 2-(-(2-(2-(2-(1,3-dioxoisoindoline-2-yl-ethylamino)ethylamino)ethyl)isoindoline-1,3-dione (DEEI) and its copper(II) complex. The ligand (DEEI) and its Cu(II) complex were structurally identified using absorption, FTIR, NMR, electron spin resonance, X-ray diffraction spectral studies, thermogravimetric and elemental analyses. The electronic spectrum and magnetic moment value proposed that Cu(II) complex has square planar geometry. The DNA interaction ability of the ligand (DEEI) and Cu(II) complex was studied by means of absorption and fluorescence spectrophotometer, viscosity measurements, cyclic voltammetery, and circular dichroism methods. The extent of DNA binding (Kb) with Calf thymus (Ct-DNA) follows the order of Cu(II) complex (1.11 × 106 M−1) > DEEI (1.0 × 105 M−1), indicating that Cu(II) complex interact with Ct-DNA through groove binding mode and more sturdily than ligand (DEEI). Interestingly, in silico predictions were corroborated with in vitro DNA binding studies. The antibacterial evaluation of these compounds was screened against a panel of bacterial strains Pseudomonas aeruginosa (MTCC 2453), Salmonella enterica (MTCC 3224), Streptococcus pneumoniae (MTCC 655), Enterococcus faecalis (MTCC 439), Klebsiella pneumonia and Escherichia coli (ATCC 25922). The results showed that the copper(II) complex has significant antibacterial potential (IC50 = 0.0019 μg/mL) against Salmonella enteric comparable with ligand (DEEI) and standard drug ciprofloxacin. Growth curve study of Cu(II) complex against only three bacterial strains S. enterica, E. faecalis and S. pneumoniae showed its bactericidal nature. Cu(II) complex showed less than 2% hemolysis on human RBCs indicating its non toxic nature. The results of antioxidant assay demonstrated that scavenging activity of Cu(II) complex is higher as compared to ligand and ascorbic acid as standard.

The Correlation of Adsorption Behavior between Ciprofloxacin Hydrochloride and the Active Sites of Fe-doped MCM-41.

HIGHLIGHTS Fe incorporation significantly accelerated the adsorption of CPX on MCM-41.Fe leaching can be ignored when pH was higher than 4.0.pH played an important role in CPX adsorption on Fe-MCM-41.Co-effect of CPX and metal cations on Fe-MCM-41 was investigated.Fe-MCM-41s with various molar ratios of silicon to iron (20, 40, 80, and 160) were prepared to investigate adsorption properties of ciprofloxacin hydrochloride (CPX) in aqueous solutions. Fe-MCM-41s were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption/desorption isotherms, and infrared spectroscopy (FT-IR). Effects of silicon-iron ratio, adsorbent dosage, pH, and temperature were conducted to explore the adsorption mechanism of CPX on Fe-MCM-41. The results showed that the introduction of iron facilitated the absorption quantity for CPX from 20.04 to 83.33 mg g−1 at 120 min of reaction time, which was mainly attributed to surface complexation. The promotion of hydrophobic effect, electrostatic interactions, and π-π electron donor-acceptor interaction also played coordinate roles in the adsorption process. The experimental kinetic data followed both the pseudo-second-order and intra-particle diffusion models, while the adsorption isotherm data fit well to Freundlich model at high temperature. Thermodynamic study showed that the adsorption was spontaneous. Under the effect of electrostatic interaction, pH of the solution strongly affected CPX adsorption. Five representative metal cations (Ca, Cu, Ni, Pb, and Cd) were chosen to study the effects on CPX adsorption and their complexation. The inhibiting effect of metal cations on CPX adsorption was sequenced in the order of Cu > Ni > Pb > Cd > Ca, which followed the same order as the complexation stability constants between CPX and cations. The Fe-MCM-41 adsorbent possessed excellent reusability for 4 cycles use, suggesting a potential applicability of Fe-MCM-41 to remove CPX in water.

Heavy metals contamination and human health risk assessment in soils of an industrial area, Bandar Abbas – South Central Iran

ABSTRACTThe purpose of this study was to determine the contamination level, distribution, health risk and potential sources of Cr, Cd, Pb, Zn, Cu, Ni and As in 66 topsoil samples from industrial areas in Bandar Abbas County. The geoaccumulation index, pollution index and pollution load index were calculated to assess the pollution level in the industrial soils. The hazard index and carcinogenic risk were used to assess human health risk of heavy metals. Results showed that the contamination levels of heavy metals were in the descending order of Cu> Cd> Pb> Zn> As> Ni> Cr. Moreover, based on principal component analysis, Cd, Zn, Cu, and Pb originated mainly from anthropogenic sources, including power plants, oil and gas refinery, steel and zinc production factories and municipal waste landfills. For non-carcinogenic effects, hazard index of studied metals decreased in the order of Cr> As> Cd> Pb> Ni > Cu> Zn. Arsenic, chromium and cadmium were regarded as the priority pollutants. Carcinogenic risks due to Cd and As in suburban soils were within tolerable risk to human health; however, children faced more health risk in their daily life than adults via their unconscious ingestion and dermal contact pathway.

The crystal structure of cesbronite, Cu3TeO4(OH)4: a novel sheet tellurate topology

The crystal structure of cesbronite has been determined using single-crystal X-ray diffraction and supported by electron-microprobe analysis, powder diffraction and Raman spectroscopy. Cesbronite is orthorhombic, space group Cmcm, with a = 2.93172 (16), b = 11.8414 (6), c = 8.6047 (4) Å and V = 298.72 (3) Å3. The chemical formula of cesbronite has been revised to CuII 3TeVIO4(OH)4 from CuII 5(TeIVO3)2(OH)6·2H2O. This change has been accepted by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association, Proposal 17-C. The previously reported oxidation state of tellurium has been shown to be incorrect; the crystal structure, bond valence studies and charge balance clearly show tellurium to be hexavalent. The crystal structure of cesbronite is formed from corrugated sheets of edge-sharing CuO6 and (Cu0.5Te0.5)O6 octahedra. The structure determined here is an average structure that has underlying ordering of Cu and Te at one of the two metal sites, designated as M, which has an occupancy Cu0.5Te0.5. This averaging probably arises from an absence of correlation between adjacent polyhedral sheets, as there are two different hydrogen-bonding configurations linking sheets that are related by a ½a offset. Randomised stacking of these two configurations results in the superposition of Cu and Te and leads to the Cu0.5Te0.5 occupancy of the M site in the average structure. Bond-valence analysis is used to choose the most probable Cu/Te ordering scheme and also to identify protonation sites (OH). The chosen ordering scheme and its associated OH sites are shown to be consistent with the revised chemical formula.

Sorption of Pb(II), Cu(II), Fe(II) and Cr(VI) metal ions onto cross-linked graft copolymers of chitosan with binary vinyl monomer mixtures

Novel adsorbents for sorption of Pb(II), Cu(II), Fe(II) and Cr(VI) metal ions from waste water were synthesized by simultaneous cross-linking and graft copolymerization of chitosan (Ch) with N-isopropyl acrylamide (NIPAM) and its binary comonomers acrylic acid, acrylamide and acrylonitrile in presence of azo-bis(isobutyronitrile) (AIBN) as free radical initiator and N,N′-methylene bisacrylamide (MBA) cross-linker. FTIR, XRD, SEM and TGA/DTA techniques were used to describe the structural aspects of cross-linked graft copolymers. The improvement in swelling properties of the synthesized hydrogels was utilized to explore their potential for sorption of toxic metal ions from aqueous solutions. Metal ion sorption by synthesized cross-linked adsorbents was studied as a function of the change in contact time, pH, temperature and concentration of metal ions from a solution of individual metal ions. Selective sorption of metal ions was performed by immersing polymeric samples in a solution containing four metal ions in the same concentration. Candidate polymers showed preferential sorption of metal ions in order of Cu(II)>Pb(II)>Fe(II)>Cr(VI) ions. Cross-Ch-g-poly(NIPAM-co-AAc), Cross-Ch-g-poly(NIPAM-co-AAm) and Cross-Ch-g-poly(NIPAM), showed best results for sorption of all ions from single and four component solutions.

Accumulation and Potential Ecological Risk Assessment of Heavy Metals in surface sediments of Han River Estuary, Da Nang City

Deposited sediments contain toxic metals which can pollute surface water as well as aquatic eco-systems. Accumulation of heavy metals in sediment was assessed based on the geoaccumulation index (Igeo), the degree of contamination (Cd value) and potential ecological risk was also proposed based on ecological risk index (RI). The surface sediments collected at Han river estuary, Da Nang city were digested with a mixture of HNO3 nd H2O2, and analyzed for five heavy metals Cd, Cr, Cu, Pb and Zn sing inductively coupled plasma-atomic emission spectroscopy (ICP-AES), separately using the AAS method for AS . Results showed that all of metals were detected in sediment samples with mean concentration of As, Cd, Cr, Cu, Pb and Zn were 9.16; 0.083; 52.5; 45.4; 23.2 and 41.1 mg/kg dw, in respective. Cd values were smaller than 8 suggested that surface sediments of Han river estuary were moderately polluted by this metal. Besides, the results of potential ecological risk factor show that the risks of heavy metals are in the decreasing order of Cu>Pb>As>Cr>Cd>Zn.

PROX reaction of CO in H2/H2O/CO2 Water–Gas Shift (WGS) feedstocks over Cu–Mn/Al2O3 and Cu–Ni/Al2O3 catalysts for fuel cell applications

Abstract Catalytic conversion performance of the γ-Al2O3-supported Cu-, Mn- and Ni-based materials for the selective preferential oxidation of CO was investigated. The influence of CO2 and H2O in the reactor feed gas on activity and selectivity was lastly investigated for copper bimetallic catalysts containing manganese and nickel. Cu/Al2O3 proved to be optimal among the monometallic examined. It was observed that even in the absence of H2, CO was effectively converted. Upon H2 presence, a fraction of oxygen is utilized for the latter, which results in the decrease of CO turnover. Cu–Mn/Al2O3 surpassed other single and mixed metal oxide catalysts which could be due to a combination of surface desorption capacity and redox properties. The oxygen storage capacities (OSC) were in the order of Cu–Mn/Al2O3 > Cu–Ni/Al2O3 > Cu/Al2O3 > Mn/Al2O3 > Ni/Al2O3, in an agreement with reactivity. The efficiency at low process temperatures was enhanced by adding H2O vapors, nonetheless, decreased at high-end range due to the reverse water–gas shift (RWGS). Also, the rate of CO conversion was high utilizing Cu–Mn/Al2O3; furthermore, even upon applying H2O and CO2. CO2 notably affected CO conversion, and ultimately, decreased the activity, which, conversely, remained stable upon time-on-stream.

Health risk assessment of heavy metal variability in sachet water sold in Ado-Odo Ota, South-Western Nigeria.

The sales of sachet water (SW), also known as "pure water" (PW), in Nigeria is a lucrative business. It serves many people, especially low-income earners, by providing a more affordable access to safe drinking water when compared with table water. However, some of the producers of SW do not effectively treat raw water before packaging them for sale. This study investigates the presence and concentrations of heavy metals, such as chromium (Cr), iron (Fe), manganese (Mn), copper (Cu), aluminum (Al), and zinc (Zn) in some samples of SW sold within Ota, Ogun State, Nigeria. Samples of SW from nine different producers were purchased for four consecutive weeks and analyzed to determine the concentrations of these heavy metals in them. Furthermore, health risk indicators, such as chronic daily intake (CDI) and health risk indices (HRI) for children and adults, were calculated separately. The metal concentrations were compared with allowable limits set by the World Health Organization (WHO), Nigerian Industrial Standard (NIS), and the United States Environmental Protection Agency (US EPA). High concentrations of Cr, Fe, and Al were found in all the nine samples and exceeded the maximum allowable limits (MAL) of all the standards considered. However, the concentrations of Zn, Mn, and Cu were within permissible limits. The HRIs of heavy metals were in the order of Cu>Fe>Zn>Mn>Al>Cr, but since the standard limits set for some metals were exceeded, proper and effective treatment is required to safeguard the health of consumers.

Risk assessment and interpretation of heavy metal contaminated soils on an urban brownfield site in New York metropolitan area.

In this study, soil samples were collected at 22 sites in Liberty State Park, New Jersey, in 2005, for metal enrichment and potential ecological risk assessment. The geoaccumulation index (I geo) showed that enrichment levels of trace metals followed an order of Cu>Pb>Zn>As>Cr>Hg while the potential ecological risk factor ([Formula: see text]) indicated that the potential ecological risk of the metals was in the order of Cu>Pb>As>Hg>Zn>Cr. Among these 22 sites, this investigation identified 9 sites at moderate ecological risk, 3 sites at considerable ecological risk, and 4 sites at high ecological risk according to the potential ecological risk index (RI). Hierarchical cluster analysis (CA) of soil metal concentrations separated the study sites into four groups, which are supported by the significant difference in RI values. Geographically, three regions in the Liberty State Park brownfield site were determined based on the CA results and RI values. Subarea 1 had low ecological risk while subareas 2 and 3 had a greater potential for ecological risk. Significant correlations of Pb with Cr and Zn were observed in subareas 2 and 3, respectively. This study shows that statistical approaches coupled with a risk assessment index provide a more comprehensive interpretation of land contamination than a single approach in support of planning land redevelopment.

Transfer of Heavy Metals from Soils to Vegetables and Associated Human Health Risks at Selected Sites in Pakistan.

Contamination of the food chain with heavy metals is considered as one of the major environmental pathways of human exposure to metals leading to potential health risks. This study aimed to investigate the concentrations of heavy metals such as copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni), and manganese (Mn) in agricultural soils and food crops (fruit, leaf, and root vegetables), and their associated health risks to the local population in selected southern districts of Khyber Pakhtunkhwa Province, Pakistan. The concentrations of the selected metals in soil varied over a wide range, in the following decreasing order: Mn > Zn > Cr > Ni > Cu. The bioaccumulation of metals in vegetables was within the permissible risk limits, except for Cr which showed higher contamination in all the tested food crops. The trend of metal transfer factors for different vegetables was in the order of Cu > Ni > Cr > Mn > Zn, while the calculated daily intake of metals (DIM) in adults and children through consumption of food crops was in the decreasing order of Mn > Zn > Ni > Cr > Cu. The health risk index (HRI) values for the heavy metals for both adults and children were less than 1. Therefore, no significant health risk is anticipated for the local consumers through ingestion of these food crops.

Effect of the size of Cu clusters on selectivity and activity of acetylene selective hydrogenation

In order to probe into the size effect of Cu catalyst on the selectivity and activity of ethylene formation in acetylene selective hydrogenation, different sizes of Cu catalysts including Cu13, Cu38, Cu55 clusters and the periodic Cu(111) surface have been employed to systematically investigate the selective hydrogenation of C2H2 using density functional theory calculations. The results show that the adsorption ability of C2H2 is stronger than that of C2H4 on different sizes of Cu catalysts, which is in favor of C2H2 activation and hydrogenation. On Cu13 and Cu38 clusters, C2H2 easily undergoes over-hydrogenation to form ethane via CHCH2 and CHCH3 intermediates, namely, both clusters exhibit a poor selectivity towards C2H4 formation. However, on Cu55 cluster, C2H2 is easily hydrogenated to form C2H4via CHCH2 intermediate, and C2H4 prefers desorption over its hydrogenation, suggesting that Cu55 cluster exhibits a good selectivity towards C2H4 formation. Further, the periodic Cu(111) surface regarded as the large Cu particle sizes has the same results with Cu55 cluster. Therefore, among different sizes of Cu cluster, the size of Cu cluster affects the preferred pathway of C2H2 selective hydrogenation, and alters the selectivity towards C2H4 formation; moreover, beginning with Cu55 cluster, Cu cluster is beneficial to C2H2 hydrogenation to C2H4. The activity of C2H4 formation follows the order of Cu(111) > Cu38> Cu55 >> Cu13, which corresponds to the d-band center of these catalysts. The identifications about the relationship of the intrinsic selectivity and activity with cluster size effect would provide a clue for designing highly-efficient Cu-based catalysts in C2H2 hydrogenation to C2H4.

Point defects in Cu2ZnSnSe4 (CZTSe): Resonant X‐ray diffraction study of the low‐temperature order/disorder transition

The interest in Cu2ZnSn(S,Se)4 (CZTS) for photovoltaic applications is motivated by similarities to Cu(In,Ga)Se2 while being comprised of non‐toxic and earth abundant elements. However, CZTS suffers from a Voc deficit, where the Voc is much lower than expected based on the band gap, which may be the result of a high concentration of point‐defects in the CZTS lattice. Recently, reports have observed a low‐temperature order/disorder transition by Raman and optical spectroscopies in CZTS films and is reported to describe the ordering of Cu and Zn atoms in the CZTS crystal structure. To directly determine the level of Cu/Zn ordering, we have used resonant‐XRD, a site, and element specific probe of long range order. We used CZTSe films annealed just below and quenched from just above the transition temperature; based on previous work, the Cu and Zn should be ordered and highly disordered, respectively. Our data show that there is some Cu/Zn ordering near the low temperature transition but significantly less than high chemical order expected from Raman. To understand both our resonant‐XRD results and the Raman results, we present a structural model that involves antiphase domain boundaries and accommodates the excess Zn within the CZTS lattice.

Sorption and desorption of potentially toxic metals (Cd, Cu, Ni and Zn) by soil amended with bentonite, calcite and zeolite as a function of pH

Sorption and desorption studies of cadmium (Cd), copper (Cu), nickel (Ni) and zinc (Zn) were carried out at the pH range of 2 to 9 by a soil amended with three sorbents including bentonite, calcite and zeolite. A geochemical computer model was used to simulate the sorption of metals by control and amended soils as influenced by pH. Metals sorption on control and amended soils was dependent on pH, and increased with increasing equilibrium pH. Furthermore, metals sorption on soil amended by sorbents was greater than control, indicating the increase of soil sorption capacity by adding sorbents, while their desorption decreased. The modeling results indicated that the sorption of metals was modeled successfully using the ion exchange and surface complexation reactions. In general, the maximum sorption of metals was observed by bentonite-amended soil and calcite-amended soil, whereas the maximum desorption of all metals obtained in zeolite-amended soil, suggesting that the sorption of metals on zeolite was based on the reversible mechanism. In general, the sequence of metals sorption at pH2 to 9 for all treatments was in order of Cu>Zn>Cd≥Ni. In addition, this sequence was observed mostly for metals activity and desorption (occasionally an exchange in the positions of Cd and Ni) but with an inverse trend. Results indicated that distribution coefficient (Kd) increased with increasing pH and, in particular, had a sharp increase at the neutral to alkaline pH.

Removal of potentially toxic elements from aqueous solutions and industrial wastewater using activated carbon

Water contamination with potentially toxic elements (PTEs) has become one of the key issues in recent years that threatens human health and ecological systems. The present study is aimed at removing PTEs like cadmium (Cd), chromium (Cr), copper (Cu) and lead (Pb) from aqueous solutions and industrial wastewater using activated carbon (AC) as an adsorbent through different batch and column experiments. Results demonstrated that the removal of PTEs from aqueous solutions was highly pH dependent, except for Cr, and the maximum removal (>78%) was recorded at pH 6.0. However, maximum Cr removal (82.8%) was observed at pH 3.0. The adsorption reached equilibrium after 60 min with 2 g of adsorbent. Coefficient (R2) values suggested by the Langmuir isotherm model were 0.97, 0.96, 0.93 and 0.95 for Cd, Cr, Cu and Pb, respectively, indicating the fit to this model. In column experiments, the maximum removal of PTEs was observed at an adsorbent bed height of 20 cm with the optimal flow rate of 3.56 mL/min. Furthermore, PTEs removal by AC was observed in the order of Cu > Cd > Pb > Cr. Findings from this study suggest that AC could be used as a promising adsorbent for simultaneously removing several PTEs from wastewaters.

Status of heavy metal in sediment of Saguling Lake, West Java

The quality of water in the Saguling lake has been monitored since 1990 by the state agency for environmental control. However, no data on heavy metal in sediment had been reported. Metal pollutans have receives considerable attention due to their persistence, biogeochemical recycling, and environmental risk. The objective of this study was to assess the level contamination of heavy metals (Cd, Cr, Cu, and Pb) in the surface sediment of the Saguling Lake West Java. Surface sediment samples were collected from 10 location of the Saguling Lake on July and November 2015. The concentration of heavy metals in the surface sediment on July and November 2015 decreased in the order of Cu>Cr>Pb>Cd and Cr>Cu>Pb>Cd respectively. Mean metals concentrations (mg/kg) in July 2015 were in the range of: Cd: 10.69-16.65, Cr: 76.67-138.38, Cu:106.02-229.54, Pb: 23.93-80.17. Mean metals concentrations (mg/kg) in November 2015 were in the range of Cd: 18.64-23.25, Cr: 152.16-197.98, Cu: 63.32-152.53, Pb: 20.31-32.74. Geochemical approaches such as contamination factor, and pollution load index were exploited for the assessment of the contamination and enrichment level of heavy metals in the lake sediment. Contamination factor and pollution load index values indicated that surface sediments around Saguling Lake were polluted with heavy metals. The finding of this study would help in formulating guidelines to control the pollution and suggested for Saguling lake revitalization.

Investigation of the Leaching Characteristics of Heavy Metals from Waste Printed Circuit Boards through Column Testing with Simulated Acid Rain

Waste printed circuit boards (PCBs) contain various heavy metals; hence, randomly discarded PCBs in open fields induce probable environmental risks when precipitation occurs, particularly acid rain (AR). We applied the column leaching method under simulated AR leaching to study the leaching characteristics of Cu, Pb and Zn in waste PCBs. Cu and Pb were easily leached by AR (pH 2 and 3) but not by distilled water (pH 5.6; CK treatment). By contrast, Zn could be leached readily even in CK treatment. AR with low pH exerted good leaching effects on Cu, Pb, and Zn. The heavy metal contents in the leachates were in the order of Cu > Pb > Zn. The maximum leaching concentrations of Cu, Pb, and Zn were 34.7, 4.06, and 1.15 mg/L, respectively, which are higher than drinking water standard set by the US Environmental Protection Agency. Therefore, waste PCBs can be considered a new source of heavy metal and pose potential environmental risks.