Removal Efficiency Of Cu Research Articles

Performance of composite mineral adsorbents for removing Cu, Cd, and Pb ions from polluted water

This study evaluated the efficiency of the removal of heavy metals from contaminated water via adsorption isotherm and kinetic experiments on two composite mineral adsorbents, CMA1 and CMA2. The developed CMA1 (zeolite with clinoptilolite of over 20 weight percent and feldspar of ~10 percent, with Portland cement) and CMA2 (zeolite with feldspar of over 15 weight percent and ~9 percent clinoptilolite, with Portland cement) were applied to remove Cu, Cd, and Pb ions. Based on the adsorption isotherm and kinetic experiments, the adsorbents CMA1 and CMA2 exhibited high removal efficiency for Cu, Cd, and Pb ions in solution compared to other adsorbents. In the adsorption kinetic experiment, CMA2 demonstrated better adsorption than CMA1 with the same initial concentration and reaction time, and Cu, Cd, and Pb ions almost reached equilibrium within 180 min for both CMA1 and CMA2. The results of the adsorption kinetic experiments with pseudo-first-order (PFO) and pseudo-second-order (PSO) models indicated that the PSO model was more suitable than the PFO model. Comparing the Langmuir and Freundlich adsorption isotherm models, the former showed a very slightly higher correlation coefficient (r2) than the latter, indicating that the two models can both be applied to heavy metal solutions on a spherical monolayer surface with a weak heterogeneity of the surface. Additionally, the adsorbents CMA1 and CMA2 demonstrated different removal abilities depending on which heavy metals were used.

Bioremoval of heavy metals from metal mine tailings water using microalgae biomass

The copper industry generates large quantities of mine tailings water. Thus, this study aims to select a microalgae species that is both tolerant and capable of the bioremoval of heavy metals from metal mine tailings water as well as the potential biorefinery of this microalgae biomass. Chlorella vulgaris and Scenedesmus spinosus were tested for tolerance to metal mine tailings water (MTW) in northern Chile and synthetic treatments of Cu and Mo (0.1 and 0.5 mg/L). Additionally, the biomass generated was characterized to evaluate its potential applications. The main results showed greater tolerance of C. vulgaris cultured in MTW treatment. In fact, high removal efficiency of Cu and Mo was detected for this microalgae in MTW: 64.7% and 99.9%, respectively. Similarly, Cu (55%) and Mo (80.3%) removal was observed at 0.5 mg/L synthetic concentration treatments after 72 h. However, cell wall fluorescence and chlorophyll parameters were mainly affected by 0.5 mg/L Cu synthetic concentration, where the mean fluorescence intensity (MFI) was 878, compared with the other treatments (≥1800). Morphological cell changes in the MTW treatment were observed using SEM images. The presence of Mo on the microalgae surface was detected by 0.47% and 0.82% in both Mo synthetic treatments exposed. Additionally, the characterization of microalgae biomass exposed to MTW showed a higher protein content and a minor difference of lipid content compared with the control treatment, which could be used in biorefinery processes. This study reveals the capability of C. vulgaris to remove heavy metals from this mine tailings water and the effect that occurs in microalgae cells.

Removal Efficiency of Cu2+ and Zn2+ from Industrial Wastewater by Using Microbial Desalination Cell

The removal of Cu2+ and Zn2+ from industrial wastewater using the microbial desalination cell is studied. Both synthetic and industrial samples were haracterised in accordance with standard methods recommended for examination of water and wastewater. Synthetic samples used for the analysis were prepared with concentration 5; 25; 50; 75; 100 mg/L Cu2+ and Zn2+ in deionized water. The removal efficiency of each metal was analyzed after 30; 60; 90; 120; 150 min; psychrophilic, mesophilic, thermophilic and 2–3; 3–4; 4–5; 5–6 and 6–7 mg/L dissolved oxygen were monitored. The experiments were done on wastewater of electroplating industries in Isfahan, Iran, in optimum conditions. For data analysis, SPSS version 16 software was used. Optimum condition for removing Cu2+ and Zn2+ were found to be: 100 mg/L, 4.4 mg/L dissolved oxygen, 26°C and 120 min.

Chelator-assisted washing for the extraction of lead, copper, and zinc from contaminated soils: A remediation approach

Chelators have proven to be effective extractants in soil washing and represent a suitable remediation technology for potentially toxic elements (PTEs) from contaminated sites. In this paper, the extraction of lead (Pb), copper (Cu), and zinc (Zn) from contaminated real and reference soils using both biodegradable (EDDS and HIDS) and persistent (EDTA and DTPA) chelators was investigated. Different metal–chelator complex formation constants, pH, extraction temperature, and mechanochemical energy were tested. The PTEs were extracted at a relatively higher rate under acidic to neutral conditions (pH 5 and 7), with the greatest extraction being observed at pH 5. The metal extraction efficiencies of the chelators for the real sample at pH 5 were as follows: Pb – EDTA > DTPA > EDDS > HIDS; Cu – DTPA > EDTA > EDDS > HIDS; and Zn – DTPA > EDTA > HIDS > EDDS. The data suggested that EDDS was more effective than HIDS for Cu and Zn extraction in neutral to slightly alkaline solutions, as well as at raised temperature. Furthermore, EDTA washing using mechanochemical agitation was found to enhance the removal efficiency of Cu and Zn. Sequential chemical extraction showed that the apparent metal mobilities were reduced by soil washing. EDTA and DTPA appeared to offer greater potential than the biodegradable chelators in extracting metals from the relatively mobile carbonate- and Fe–Mn oxide-bound fractions. The residual fraction of Pb displayed considerable stability (≥70%), and was not entirely amenable under washing treatments, and hence could be considered non-bioavailable and non-toxic.

Mechanism and performance of trace metal removal by continuous-flow constructed wetlands coupled with a micro-electric field

Constructed wetlands coupled with a micro-electric field (CW-MEF) is a novel and efficient water treatment technology. The objective of this study was to investigate the mechanism and performance of trace metals (TMs) removal for CW-MEF systems during summer and winter. The mass distribution of TMs in plants and biofilms, physiological indices of wetland plants, and bacterial community structures on electrodes and in the rhizospheres were analyzed as well as to explore further the TM removal mechanism. Results show that the electric field intensities (EFI) of 100 and 200 mV cm−1 had a significantly promoting effect on TM removal. Maximum removal efficiencies for Cu, Zn, Cd, Co, Ni and Pb were 95.6, 80.1, 74.0, 67.1, 69.8 and 99.6%, respectively, in summer with a 5d-hydraulic retention time (HRT). An EFI of 100 mV cm−1 could alleviate the oxidative damage in plant cells by promoting the synthesis of reduced glutathione and an activity increase of catalase, thus increasing the phytoextraction for Cu, Zn and Cd. For biofilms, the MEF caused shifts in the bacterial community structures, and an EFI of 50 to 200 mV cm−1 significantly promoted the enrichment of Cu, Zn, Cd and Co by biofilms. Moreover, microorganisms related to TM tolerance and enrichment exhibited a high abundance with an EFI of 100 and 200 mV cm−1. It can be concluded that introducing MEF to CWs could intensify the TMs removal via the biological process and result in more efficient purification for TM-containing wastewater.

Effects of biodegradable chelator combination on potentially toxic metals leaching efficiency in agricultural soils

Soil washing with chelators, a viable method for treating soils contaminated with potentially toxic metals, has drawn increasing attentions. The objective of this study was to determine a new generation of mixed degradable chelating agents from N, N-bis (carboxymethyl) glutamic acid (GLDA), [S, S]-stereoisomer of ethyleneiaminedisucc--inic acid (EDDS), nitrilotriacetic acid (NTA), and citric acid (CA), and to evaluate its effectiveness and feasibility to reduce toxic metals contamination in two different agricultural soils. A comparative leaching test conducted on the four individual degradable chelating agents showed that the capacity of single chelator in mobilizing copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) varied significantly. Using a combination of GLDA and NTA was more advantageous than using a single chelating agent in extracting potentially toxic metals. The removal efficiencies of Cu, Zn, Cd, and Pb reached 38.2, 9.8, 71.4, and 19.5% for soil 1, and 25.0, 5.2, 59.7, and 18.5% for soil 2, respectively, at mixed chelator (MC) concentrations of 3 mmol/L (GLDA) and 2 mmol/L (NTA), pH of 6.0, and a contact time of 4.0 h. The effects of washing conditions, chelator concentration, pH values, and contact time on the removal efficiencies of target toxic metals were investigated. The results showed that the combined chelating agent has a lower pH dependence, making it feasible for a wider range of applications. The effects of the chelating agents on the morphological distribution of potentially toxic metals and the soil enzyme activity before and after the treatments were also studied. After washing, the content of the water-soluble, acid-soluble, reducible, and oxidizable target metals showed a certain degree of decrease. Although the activities of catalase, urease, and invertase appeared to be inhibited during a short period of time, their activities were stimulated and later promoted with the degradation of the chelating agent. In general, the chelating agent combination has a great potential for toxic metals leaching.

Effects of Copper and pH on the Growth and Physiology of Desmodesmus sp. AARLG074.

Copper (Cu) is a heavy metal that is widely used in industry and as such wastewater from mining or industrial operations can contain high levels of Cu. Some aquatic algal species can tolerate and bioaccumulate Cu and so could play a key role in bioremediating and recovering Cu from polluted waterways. One such species is the green alga Desmodesmus sp. AARLG074. The aim of this study was to determine how Desmodesmus is able to tolerate large alterations in its external Cu and pH environment. Specifically, we set out to measure the variations in the Cu removal efficiency, growth, ultrastructure, and cellular metabolite content in the algal cells that are associated with Cu exposure and acidity. The results showed that Desmodesmus could remove up to 80% of the copper presented in Jaworski’s medium after 30 min exposure. There was a decrease in the ability of Cu removal at pH 4 compared to pH 6 indicating both pH and Cu concentration affected the efficiency of Cu removal. Furthermore, Cu had an adverse effect on algal growth and caused ultrastructural changes. Metabolite fingerprinting (FT-IR and GC-MS) revealed that the polysaccharide and amino acid content were the main metabolites affected under acid and Cu exposure. Fructose, lactose and sorbose contents significantly decreased under both acidic and Cu conditions, whilst glycerol and melezitose contents significantly increased at pH 4. The pathway analysis showed that pH had the highest impact score on alanine, aspartate and glutamate metabolism whereas Cu had the highest impact on arginine and proline metabolism. Notably both Cu and pH had impact on glutathione and galactose metabolism.

Mobilization of Cu and Pb from multi-metal contaminated soils by dissolved humic substances extracted from leonardite and factors affecting the process

The aim of the research was to determine the potential of dissolved humic substances extracted from leonardite to mobilize Cu and Pb from multi-metal contaminated soils with the scope of finding an efficient washing solution as a possible substitute for conventional washing agents used to extract heavy metals from polluted soils around mining areas. The efficiency of dissolved humic substances extracted from leonardite to extract Cu and Pb from multi-metal contaminated soil collected from “Larga de Sus” mine (Romania) was determined under batch conditions by single-step extraction. All extraction experiments were conducted in a stirrer with orbital rotation-oscillation and thermostat cupola at 100 oscillations/min and oscillation amplitude of 32 mm. The influence of stirring time (120, 240, 360, 720, 1440, 2400 min), concentration of humic solution (2% and 5%), and soil:solution ratio (mass:volume (m/V)) of 1:8, 1:10, and 1:16 on the Cu and Pb removal efficiency was investigated. The heavy metal concentration from soil and extractant solution was determined through atomic absorption spectrometry. The Cu and Pb removal process from soil using dissolved humic substances proceeded relatively quickly. In investigated experimental conditions, the best Cu and Pb removal efficiencies were observed after 360 min of stirring when 60.3% of Cu and 48% of Pb were extracted from soil (2% humic washing solution). The removal efficiency of Cu increased with increasing the soil:solution ratio and humic solution concentration, at shorter stirring times. In the case of Pb, an important improvement of the mobilization with an increasing soil:solution ratio or humic solution concentration was not observed, along with investigated stirring time. A soil:solution ratio of 1:8 was sufficient to reduce the Cu concentration in the studied soil below the intervention threshold established by Romanian legislation, after 360 min of stirring. The mobilization of Cu and Pb from multi-metal contaminated soil using dissolved humic substances is strongly dependent on stirring time, soil:solution ratio, and concentration of humic washing solution. Nevertheless, the results of the present study demonstrate that dissolved humic substances extracted from leonardite are fairly effective washing agents for soils polluted with Cu, Pb, multiple heavy metals, and other pollutants in high concentrations.

A Study on the Removal of Copper (II) from Aqueous Solution Using Lime Sand Bricks

Heavy metals such as Cu(II), if ubiquitous in the runoff, can have adverse effects on the environment and human health. Lime sand bricks, as low-cost adsorbents to be potentially applied in stormwater infiltration facilities, were systematically investigated for Cu(II) removal from water using batch and column experiments. In the batch experiment, the adsorption of Cu(II) to bricks reach an equilibrium within 7 h and the kinetic data fits well with the pseudo-second-order model. The sorption isotherm can be described by both the Freundlich and Langmuir model and the maximum adsorption capacity of the bricks is 7 ± 1 mg/g. In the column experiment, the best removal efficiency for Cu(II) was observed at a filler thickness of 20 cm, service time of 12 min with a Cu(II) concentration of 0.5 mg/L. The Cu(II) removal rate increases with the increasing bed depth and residence time. The inlet concentration and residence time had significant effects on the Cu(II) removal analyzed by the Box–Behnken design (BBD). The Adams-Bohart model was in good agreement with the experimental data in representing the breakthrough curve. Copper fractions in the bricks descend in the order of organic matter fraction > Fe-Mn oxides fraction > carbonates fraction > residual fraction > exchangeable fraction, indicating that the lime sand bricks after copper adsorption reduce the long-term ecotoxicity and bioavailability to the environment.

The use of Artificial Neural Network (ANN) for modeling of Cu (II) ion removal from aqueous solution by flotation and sorptive flotation process

Abstract A three-layer artificial neural network model was developed to predict the removal of copper ions from simulated wastewater by flotation and sorptive flotation systems using Sodium Dodecyl Sulfate (SDS) as surface active agent and sunflower seed husk as low-cost locally available adsorbent based on 197 experimental data. The effect of initial copper ion concentration, flow rate, sunflower seed husk dosage and surfactant concentration at 40 min contact time, pH of 5 and at room temperature, were investigated. The best value of these parameters that achieved maximum removal efficiency of Cu(II) ion were 30 g/l initial Cu(II) ion concentration, 500 cm3/min flow rate for both systems and 7 g/l sunflower seed husk for sorptive flotation while the SDS concentration was 60 mg/L for flotation and 30 mg/L for sorptive flotation. The present model was capable to predict the removal efficiency with a tangent sigmoid transfer function (tansig) at hidden layer with 20 neurons and a linear transfer function (purelin) at output layer. The linear regression between the corresponding targets and network outputs was confirmed to be satisfactory with a correlation coefficient of 0.99955 and 0.99549 in flotation and sorptive flotation system, respectively. Sensitivity analysis shows that the time and pH was found to be most significant parameters of relative importance 24.22 and 23.02% in flotation system, and the sunflower seed husk dosage and time with relative importance of 26.86 and 24.23% were found to be the most affected one for sorptive flotation system.

Capacity of Absorption and Removal of Heavy Metals from <i>Scirpus californicus</i> and Its Potential Use in the Remediation of Polluted Aquatic Environment

The research aimed to evaluate the absorption and removal capacity of Cu, Pb, Fe and Zn from Scirpus californicus for potential use in the remediation of polluted aquatic environments. Initially, Scirpus californicus plants were conditioned in 1.5 liters of 10 ppm Cu solution at a pH of 2.3 as well as Pb, Fe and Zn. Subsequently, the concentration of heavy metals in the root-rhizome, submerged stem and aerial stem was determined; the solution and pH were also analyzed. The greatest capacity of absorption and accumulation occurred in the root-rhizome reaching values for Cu of 491.84, Pb of 739.43, Zn of 830.71 and Fe of 2624.72 mg/kg dry followed by the submerged stem and low values for the aerial stem. The removal efficiency of Cu from the solution was 52.10%, Pb 53.50%, Fe 48.00% and Zn 50.20%. It is concluded that the contact time has a significant effect on the absorption and removal capacity of the metals under study.

Investigation of adsorption efficiency of Cu2+ and Zn2+ by red soil and activated bentonite from acid copper mine drainage

Heavy metals can be transmitted to living creatures and ultimately to humans through various ecosystems due to their accumulative properties. The entry of these compounds through acid mine drainage into the water, soil, and agricultural products has created a condition that is considered always a threat for human health. The research was carried out in order to investigate the removal of Cu2+ and Zn2+ by red soil and activated bentonite from acid copper mine drainage in Rafsanjan. Variables examined in this study were temperature, particle size, contact time, pH, and adsorbent concentration. Both adsorbents were characterized using X-ray fluorescence and Fourier transform infrared. The Cu2+ and Zn2+ concentrations of samples were determined using flame atomic absorption spectroscopy after the adsorbents were added. The results showed that increases in contact time from 5 to 45 min had a notable effect on the removal process. The Cu2+ removal rates by both adsorbents were higher than those of Zn2+. The current study showed that the process of adsorption of Cu2+ and Zn2+ ions by natural soils is a thermal reaction, and adsorption capacity and equilibrium increase with increasing temperature. With reducing adsorbent particle size from the range of 2-6.7 mm to the range of 0.5-0.8 mm, the removal efficiency of Cu2+ and Zn2+ was reduced on average by 13 using activated bentonite and red soil. The results indicated that the Cu2+ and Zn2+ of acid copper mine drainage could be reduced using activated bentonite and red soil as low-cost and available adsorbents. Results indicated that Freundlich adsorption isotherm was the best model for the metal ion adsorption onto the activated bentonite and red soil with higher R-2. The kinetic studies revealed that the adsorption process followed the pseudo-second-order kinetics model. The decrease of the adsorption efficiency in the real sample was notable compared with the synthetic sample, and this reduction was bigger for zinc metal. The results indicated that the activated bentonite and red soil achieved acceptable efficiency in removing copper and zinc metals from the acid copper mine drainage.

Green synthesis of zeolite 4A using fly ash fused with synergism of NaOH and Na2CO3

A high-purity zeolite 4A was synthesized by the hydrothermal method using fly ash as the raw material. The effects of sodium hydroxide (NaOH) or/and sodium carbonate (Na2CO3) on the activation of fly ash were studied, and the removal efficiency of Cu2+ in aqueous solution was also investigated for the synthesized zeolite. The formation process of the zeolite from fly ash was surveyed by ex situ techniques such as X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetry (TG-DCS), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDX) and Fourier transform infrared spectroscopy (FTIR). The important influential factors of energy and water consumption were analysed by orthogonal tests, and the best conditions for green synthesis were accurately determined through batch tests. The factors affecting the green synthesis of zeolite are the alkali mixture ratio, alkali melting temperatures, solid-to-liquid ratios, crystallization times and crystallization temperatures. The alkali mixture ratio was indicated to be an important factor for green synthesis according to the results of the orthogonal test. Compared with the use of alkali alone, when NaOH and Na2CO3 were mixed at a mass ratio of 1:2.8, the alkali melting temperature (760 °C) and solid-to-liquid ratios (1:5) were both lower, the crystallization time (4 h) was shorter in the zeolite synthesis process, and the relative crystallinity was the highest at 75.8%. The removal rate of 100 mg/L Cu2+ solution from pH 3 to pH 7 by 0.18 g of zeolite synthesized for 60 min was close to 100%, and the adsorption capacity was 55.5 mg/g. After the zeolite was desorbed and reused 4 times, the removal efficiency of Cu2+ was maintained at 73% at a pH of 3.

Chitosan/Ag-hydroxyapatite nanocomposite beads as a potential adsorbent for the efficient removal of toxic aquatic pollutants

In the present study, the potential of synthesized chitosan/Ag-substituted hydroxyapatite nanocomposite beads to remove basic dye, heavy metal and microbes from aqueous solutions was investigated. Beads were prepared in different ratios via embedding of Ag-hydroxyapatite (Ag-HA) into chitosan (CS) solution. The beads were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) in order to get an insight of the functional groups and morphology. Batch adsorption studies were conducted with copper ions (Cu (II)) and rhodamine B (RhB) dye by changing several parameters such as Ag-HA to Cs ratio, contact time, solution pH and initial concentration of pollutants. The antibacterial efficiency of beads was tested under dynamic contact conditions against commonly found bacteria in water, Escherichia coli. The adsorption isotherm data were best fitted with Langmuir model. The maximum Langmuir adsorption capabilities for Cu (II) ions and rhodamine B were found to be 40.11 mg/g and 127.61 mg/g, respectively. The adsorption process could be best described by pseudo-second-order kinetic model for both rhodamine B and Cu(II). The percentage removal efficiency of Cu (II) and rhodamine B from tap water and untreated river water ranged from 86.7 to 94.4% along with 99.99% of decontamination of microbial load.

Nanoscale Zero-Valent Iron Decorated on Bentonite/Graphene Oxide for Removal of Copper Ions from Aqueous Solution.

The removal efficiency of Cu(II) in aqueous solution by bentonite, graphene oxide (GO), and nanoscale iron decorated on bentonite (B-nZVI) and nanoscale iron decorated on bentonite/graphene oxide (GO-B-nZVI) was investigated. The results indicated that GO-B-nZVI had the best removal efficiency in different experimental environments (with time, pH, concentration of copper ions, and temperature). For 16 hours, the removal efficiency of copper ions was 82% in GO-B-nZVI, however, it was 71% in B-nZVI, 26% in bentonite, and 18% in GO. Bentonite, GO, B-nZVI, and GO-B-nZVI showed an increased removal efficiency of copper ions with the increase of pH under a certain pH range. The removal efficiency of copper ions by GO-B-nZVI first increased and then fluctuated slightly with the increase of temperature, while B-nZVI and bentonite increased and GO decreased slightly with the increase of temperature. Lorentz-Transmission Electron Microscope (TEM) images showed the nZVI particles of GO-B-nZVI dispersed evenly with diameters ranging from 10 to 86.93 nm. Scanning electron microscope (SEM) images indicated that the nanoscale iron particles were dispersed evenly on bentonite and GO with no obvious agglomeration. The qe,cal (73.37 mg·g−1 and 83.89 mg·g−1) was closer to the experimental value qe,exp according to the pseudo-second-order kinetic model. The qm of B-nZVI and GO-B-nZVI were 130.7 mg·g−1 and 184.5 mg·g−1 according to the Langmuir model.

Removal of cadmium and copper from water by a magnetic adsorbent of PFM: Adsorption performance and micro-structural morphology

In this study, a novel magnetic composite of polyacrylamide-modified Fe3O4/MnO2 (PFM) was successfully synthesized and introduced to remove cadmium and copper ions from water. The characterization methods of vibrating sample magnetometry, X-ray diffraction, scanning electron microscopy with energy dispersive spectrometer, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller were applied to examine the ferromagnetism, to compare the crystal structure, to examine the crystal shape change and elemental composition change, to examine the composition change, and to compare the specific surface area, respectively. The effects of various factors, including adsorbent dosage, initial ion concentration, and adsorption time, were evaluated. Under the condition of 50 mg/L Cu2+ or Cd2+ concentration, 1.6 g/L nano-PFM, and pH 6, the adsorption equilibrium was considered to have been reached when the solution has been adsorbed for an adsorption time of 400 min. Using the condition of 50 mg/L Cu2+ or Cd2+ solution as an example, the removal efficiency of Cu2+ and Cd2+ reached 96.91% and 78.10% and the adsorption capacity of them reached 30.285 mg/g and 39.052 mg/g, respectively. Additionally, a competing ions adsorption experiment was carried out to determine which ion’s adsorption capacity is larger in aqueous solution of both Cd2+ and Cu2+ ions. The result indicated that Cu2+ binds more easily with the active sites on the surface of the nano-PFM. An experiment of five consecutive adsorption–regeneration cycles confirmed that the adsorbent can be reused successfully for Cd2+ and Cu2+ adsorption and that it has promising potential for practical application.

Phosphate-solubilizing bacteria improve the phytoremediation efficiency of Wedelia trilobata for Cu-contaminated soil

ABSTRACTIn a controlled experiment, we assessed the effect of phosphate-solubilizing bacterium (PSB) on the soil metal (Cu2+) phytoremediation by Wedelia trilobata and examined the effect of the interaction of Cu contamination and PSB on the growth of W. trilobata. We also explored the effect of the interaction of Cu contamination and PSB on the soil microflora. The results showed that the removal efficiency of Cu from soil by W. trilobata increased with an increase in the concentration of PSB, and the translocation factors of Cu (i.e., leaf:root and stem:root) were both significantly upregulated by PSB. The PSB significantly promoted the growth of W. trilobata; however, the effect of the Cu–PSB interaction on the leaf net photosynthetic rate (Pn) of W. trilobata was not significant, whereas copper contamination had a significant negative influence on the soil microflora, PSB had a significant positive influence on the soil microflora. Thus, PSB improved the phytoremediation efficiency of W. trilobata in Cu-contaminated soil because of the positive influence on the soil microflora, improving soil quality, which then increased the growth of W. trilobata in Cu-contaminated soil. The vigorous growth of W. trlobata led to higher of Cu absorption and translocation from soil as the ultimate result.

Application of enteromorpha polysaccharides as coagulant aid in the simultaneous removal of CuO nanoparticles and Cu2+: Effect of humic acid concentration

Humic acid (HA) influences the aggregation and stability of nanoparticles (NPs), which determine the removal performance of NPs in coagulation. Consequently, in this study, the impact of HA concentration on the simultaneous removal of CuO NPs, Cu2+, and natural organic matter (NOM) was investigated. Enteromorpha polysaccharides (Ep), as the novel recycling coagulant aid, were integrated with polyaluminum chloride (PAC) to treat composite contaminants in this coagulation process. Removal performance, floc properties, zeta potential, scanning electron microscope (SEM) images, and Fourier Transform Infrared Spectra (FT-IR) were measured and analyzed. Results showed that PAC with Ep (PAC-Ep) was more beneficial for improving removal performances than PAC alone. Further, the coagulation performance became better with the increase in HA concentration. When the HA concentration was 10 mg/L (used PAC-Ep), the removal efficiencies of CuO NPs and Cu2+ were both more than 80%; and in particular, the highest removal efficiency of turbidity was 98%. However, excessive HA (more than 10 mg/L) reduced the removal efficiency of Cu by more than 31%. Smaller and denser flocs with better recoverability were formed as the HA concentration increased. Furthermore, because of affluent functional groups, HA was easily adsorbed on the surface of NPs and combined with dissociative Cu2+, thereby forming a composite contaminant. During the coagulation process, the colloidal system was destabilized preferentially by the charge neutralization between composite contaminants and PAC. Furthermore, a chelated reticular structure was formed by the conjunction of carboxyl and hydroxyl groups (from Ep) and Al (III) species (from PAC). Flocs were further enlarged and precipitated by bridging and sweeping of this structure.

Simultaneous decomplexation in blended Cu(II)/Ni(II)-EDTA systems by electro-Fenton process using iron sacrificing electrodes

This research explored the application of electro-Fenton (E-Fenton) technique for the simultaneous decomplexation in blended Cu(II)/Ni(II)-EDTA systems by using iron sacrificing electrodes. Standard discharge (0.3 mg L−1 for Cu and 0.1 mg L−1 for Ni in China) could be achieved after 30 min reaction under the optimum conditions (i.e. initial solution pH of 2.0, H2O2 dosage of 6 mL L−1 h−1, current density of 20 mA/cm2, inter-electrode distance of 2 cm, and sulfate electrolyte concentration of 2000 mg L−1). The distinct differences in apparent kinetic rate constants (kapp) and intermediate removal efficiencies corresponding to mere and blended systems indicated the mutual promotion effect toward the decomplexation between Cu(II) and Ni(II). Massive accumulation of Fe(Ⅲ) favored the further removal of Cu(II) and Ni(II) by metal ion substitution. Species distribution results demonstrated that the decomplexation of metal-EDTA in E-Fenton process was mainly contributed to the combination of various reactions, including Fenton reaction together with the anodic oxidation, electro-coagulation (E-coagulation) and electrodeposition. Unlike hypophosphite and citrate, the presence of chlorine ion displayed favorable effects on the removal efficiencies of Cu(II) and Ni(II) at low dosage, but facilitated the ammonia nitrogen (NH4+-N) removal only at high dosage.

Removal of Cu(II), Cd(II) and Pb(II) ions from aqueous solutions by biochars derived from potassium-rich biomass

Abstract: This work evaluated the novel application of biochars derived from potassium (K)-rich feedstock (banana peels (BB) and cauliflower leaves (CB)). The sorptive property of the produced biochars was evaluated with multi-element [Copper (Cu(II)), Cadmium (Cd(II)) and Led (Pb(II))] sorption experiments. Morphologies of the pre- and post-sorption samples were characterized using SEM/EDS and XRD spectra analyses. The produced biochar was further subjected to mono-element sorption studies to explore the effect of the pH value of the sorbate solution on the removal efficiency of Cu(II), Cd(II) and Pb(II) ions. Biochar productivity was noticeably high (61.44 and 64.66% for BB and CB, respectively) due to the catalytic action of K during the pyrolytic conversion of the feedstock. K-minerals were the predominant on the XRD patterns of both biochars. Metal sorption capacity of BB was much greater than that of CB due to its higher electrostatic attraction, which was the predominant mechanism governed sorption process. Sorption of metal ions onto BB and CB was pH-dependent as the sorption capacity increased significantly with the increase of the pH value of sorbate solutions (6.0 with Cu(II), Pb(II) and 8.0 with Cd(II)). Dynamics of metal ions sorption onto biochars showed competitive sorption following the order: Pb(II) > Cu(II) > Cd(II).