Copper Removal Efficiency Research Articles

Removal of copper, cadmium, and chromium from wastewater by modified wheat bran using Box–Behnken design: Kinetics and isotherm

ABSTRACTIn this work, copper, cadmium, and chromium were removed using hydrochloric acid-treated wheat bran as an adsorbent. Experiments were carried out in batch adsorption mode. Box–Behnken design of response surface methodology was used to determine the effect of initial metal concentration, pH, temperature, and adsorbent dose on removal efficiency of copper, cadmium, and chromium. Analysis of variance results are shown for all the three heavy metal, and the effect of the parameters is discussed. The optimum initial metal concentration, pH, temperature, and adsorbent dose were found to be 90.58 mg/L, 6, 35.9°C, and 2.39 g, respectively. Pseudo-second-order kinetic model was found to be the best suitable model for adsorption rate. The isotherms of adsorption data were analysed using various adsorption isotherm models such as Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherms. It was found that Langmuir and Temkin isotherms represent the equilibrium data for these heavy metal removals.

Modelization and Statistical Optimization of Coagulation-Flocculation Treatment of an Old Leachate.

Coagulation/flocculation process was studied using the response surface methodology (RSM) and central composite design (CCD), to design the experiments, develop models, evaluate the relationship between operating factors (FeCl3 dose [m] and pH), and provide an efficient method for the treatment of old leachates. The quadratic polynomial models developed for chemical oxygen demand (COD) and turbidity responses indicated that the optimum conditions were m of 0.82 g/L at pH 5.33 with coefficient of determination R2 of 98.88 and 99.84%, and adjusted R2 of 98.09 and 99.73% for both COD and turbidity. The experimental data and model predictions agreed well. Chemical oxygen demand, turbidity, lead and copper removal efficiency of 76.4, 98.9, 99 and 99%, respectively, were reached.

Purification Effect of Piggery Wastewater with Chlorella pyrenoidosa by Immobilized Biofilm-Attached Culture

Piggery wastewater treatment with microalgae is a biological recycling technology. To evaluate the purification effect, this study investigated the treatment of piggery wastewater at different dilution ratios with Chlorella pyrenoidosa by attached cultivation and lipid production of algae cells and explored the tolerance of Chlorella pyrenoidosa to the piggery wastewater, which has high ammonia nitrogen. The piggery wastewater was diluted with purified water 1-, 2-, 5-, and 10-fold in culture media. The removal efficiencies of COD, ammonia nitrogen, total nitrogen, and total phosphorus and the enrichment effect of the heavy metals copper, zinc, and iron were measured. Meanwhile, we investigated the lipid production of Chlorella pyrenoidosa in variously diluted wastewater (1-, 2-, 5-, and 10-fold). It turned out that the purification effects of COD, ammonia nitrogen, total nitrogen, and total phosphorus were best when the piggery wastewater was diluted 5-fold, and the removal efficiencies were 86.8%, 94.1%, 85.2%, and 84.3%, respectively. Correspondingly, the lipid content was as high as 32.7%, and the removal efficiencies of the heavy metals copper, zinc, and iron were 72.9%, 70.0%, and 73.0%, respectively. The biomass productivity was 4.21 g·(m2·d)-1 at the end of the experiment. This research makes an effective connection between microalgae and piggery wastewater, which is difficult to purify deeply, and provides a theoretical basis for achieving algal biofuel production and decreasing the cost of wastewater treatment.

Buoyant ALG/HA/HGMs composite adsorbents for highly efficient removal of copper from aqueous solution and contaminated kaolin soil

Two buoyant ALG/HA/HGMs composite adsorbents, AHG(acid) and AHG(base), were prepared by encapsulating hollow glass microspheres and humate within alginate gel beads in this study. Both AHG(acid) and AHG(base) were characterized and their adsorption properties for removal of copper(II) ions from aqueous solution and kaolin soil were investigated. In aqueous solution, the maximum adsorption capacities of copper on AHG(acid) and AHG(base) were 34.8 and 40.4mgg−1, respectively, and the adsorption kinetics for AHG(acid) and AHG(base) followed the mechanism of the pseudo-second order kinetic model, and their equilibrium data were well fitted with the Langmuir isothermal model. The removal of copper from contaminated kaolin by AHG(acid) and AHG(base) was conducted by soil washing with deionized water containing buoyant adsorbents. As AHG(acid) could release hydrogen ions and reduce the pH value of the system consisting of adsorbent, water and kaolin, while AHG(base) could release hydroxide ions and increase the pH value of the system, the removal efficiency of copper from kaolin soil by AHG(acid) was much higher than that by AHG(base). Under soil washing conditions of the dosage of AHG(acid) of 3%, water/soil ratio of 3/1, and washing time of 48h, the removal efficiency of copper from kaolin by AHG(acid) was 72.8%, and after 5 times reuse of AHG(acid) it was kept at 70%, while the pH value of kaolin soil was maintained in the pH range of 4.60–4.80. The results indicate that AHG(acid) has a potential application prospect in removing heavy metals from soil compared with AHG(base).

Synthesis of Cu(II) ion-imprinted polymers as solid phase adsorbents for deep removal of copper from concentrated zinc sulfate solution

Novel copper (II) ion imprinted polymers (Cu(II)-IIPs) were designed and synthesized as solid phase absorbents for the selective deep removal of Cu2+ from concentrated zinc sulfate solution. Salicylaldoximes, used as chelating ligands, were anchored onto the polymer networks through quaternary ammonium cation spacers. The effect of pH, temperature, contact time, and swelling on the adsorption selectivity and the copper removal efficiency of Cu(II)-IIPs were investigated in a laboratory-scale cell. The results showed that the adsorption of Cu2+ increased significantly with increasing pH from 1 to 7, and increased with decreasing operation temperature. The equilibrium Cu2+ adsorption capacity of Cu(II)-IIPs from the zinc sulfate aqueous solution was 96mg·g−1 at 25°C in pH5.0 for 10min. Under optimized processing conditions, the copper removal efficiency reached 99.9%, and the concentration of the residual copper (II) ions in the purified ZnSO4 aqueous solution is 35μg·L−1, significant lower than the maximum acceptable value as 100μg·L−1 in the hydrometallurgical zinc process.

Cascade sulfidation and separation of copper and arsenic from acidic wastewater via gas-liquid reaction

Copper and arsenic in acidic wastewater were separated by cascade sulfidation followed by replacement of arsenic in the precipitates by copper in the solution which was realized by recycling precipitates obtained in the first stage into the initial solution. The effects of reaction time, temperature and H2S dosage on copper and arsenic removal efficiencies as well as the effects of solid-to-liquid ratio, time and temperature on the replacement of arsenic by copper were investigated. With 20 mmol/L H2S at 50 °C within 0.5 min, more than 80% copper and nearly 20% arsenic were precipitated. The separation efficiencies of copper and arsenic were higher than 99% by the replacement reaction between arsenic and copper ions when solid-to-liquid ratio was more than 10% at 20 °C within 10 min. CuS was the main phases in precipitate in which copper content was 63.38% in mass fraction.

나노버블수에 의한 구리 오염 토양의 정화에 관한 기초 연구

본 연구에서는 중금속 오염지반을 정화하기 위한 향상제로 친환경 재료인 나노버블수를 적용하기 위한 기초 연구를 수행하였다. 수소 나노버블을 제조하여 입도분석과 제타 포텐셜 측정을 통해 장기 생존성을 평가하였다. 제조된 나노버블수를 회분식 탈착실험에 적용하여 구리 오염토양에 대한 나노버블수의 정화 효과를 증류수와 비교하여 분석하였다. 가압용해식 나노버블 제조 장치를 통해 제조한 나노버블은 최소 14일간 존재함을 알 수 있었다. 또한 구리 오염 토양에 대한 회분식 탈착실험을 수행한 결과, 토양 종류에 관계없이 나노버블수의 제거효율은 전반적으로 증류수보다 높았으며 고액비와 반응시간에 비례하여 증가하였다. pH 변화에 따라 사질토는 산성 측에서 제거 효율이 높게 나타났으나 점성토는 그 차이가 다소 낮았다. 실험 결과를 통해 나노버블의 구리 탈착 효과는 나노버블의 큰 비표면적과 제타 포텐셜에 기인하여 전반적으로 우수하게 나타난 것으로 판단된다. 따라서 본 연구를 바탕으로 나노버블수의 중금속 제거 효과를 확인하였으며 이를 토양정화의 향상제로 적용하여 친환경적인 정화공법으로 활용될 수 있을 것으로 기대된다. The fundamental study for an application of nanobubble as a soil remediation enhancer on heavy metal contaminated soil was carried out. The existence and long-term stability of hydrogen nanobubbles were investigated by particle analysis and zeta-potential analysis. And the removal efficiency of copper using nanobubble water(NBW) and distilled water(DW) were compared and analyzed through a batch desorption test. As a result, it is confirmed that nanobubble which was fabricated by compression-dissolution type generator can exist for more than 14 days. The results of batch test show that copper removal of NBW was higher than that of DW irrespectively to soil type and increased as solid-liquid ratio and contact time increased, respectively. According to the pH change, the removal of copper on sand was higher on the acid side but the removal difference was slightly lower on the clay. It is considered that a high efficiency of NBW in copper removal is due to the large surface area and high zeta-potential of nanobubbles. Therefore, the nanobubble can be applied to soil remediation for heavy-metal contaminated soil as an eco-friendly enhancer.

Copper recovery via polyelectrolyte enhanced ultrafiltration followed by dithionite based chemical reduction: Effects of solution pH and polyelectrolyte type

Abstract A chemical reduction process was proposed to recover copper from the retentate of polyelectrolyte enhanced ultrafiltration (PEUF). Three polyelectrolytes (PSS, PAA, and PEI) containing various functional groups and molecular weights were studied to explore their effects on the copper removal in PEUF and on the copper recovery by chemical reduction under various pH conditions. With PSS which contains sulfonic group, copper was removed reasonably well (ca. 75%) by PEUF even under acidic pH value of 3. With PAA which contains carboxylic group, copper removal was a bit low (∼60%) under pH 3.0 but increased substantially at pH 4.0. A branched PEI having amine group achieved the highest Cu removal of 94% at pH 3. The copper removal efficiency decreased slightly with increasing pH due to the high permeation of PEI through membrane. Chemical reduction achieved the complete copper recovery for solution containing PSS. The copper recovery efficiencies were more than 95% for PAA solution with pH values ranging from 3 to 9 at reaction time of one hour. For PEI, the recovery efficiencies ranged from 20 to 96% and were pH dependent. Aggregated and settled readily copper particles were produced by chemical reduction in PSS solution. XRD analysis identified cuprous oxide in all of the samples. Dependent of pH and polyelectrolytes, additional peaks matching those of elemental copper were identified. TGA analysis showed that solids produced from PSS and PAA systems contained no polyelectrolytes while solid collected from PEI system contained 32% of polyelectrolyte.

Two-sectional struvite formation process for enhanced treatment of copper–ammonia complex wastewater

Mg2+ and PO43+ were added into the synthetic wastewater, leading to the dissociation of the complex ions in the wastewater, and resulting in removal of copper and ammonia therein. The effects of agents addition amount, pH, and reaction time on the removal efficiency of copper and ammonia were investigated. In particular, two-sectional struvite formation (TSSF) process was established for copper and ammonia removal. MgCl2 and Na2HPO4 were added by following 90% addition in the first section and remained 10% in the second during the TSSF process. Compared with one sectional struvite formation, TSSF possessed much better performance. Under condition of n(NH3-N):n(Mg):n(P)=1:1.2:1.5 (molar ratio), pH=9, and reaction time of 30 min, the removal efficiencies of copper and ammonia were 98.9% and 99.96%, respectively. The enhanced performance of TSSF is explained by the competition of ammonia by copper–ammonia complexes and struvite. The dissociation of copper–ammonia complexes is further demonstrated by thermodynamic equilibrium analysis, on the basis of calculations and establishment of predominance phases diagram. Moreover, XRD and EDS analyses further confirmed the formation of struvite and precipitation of copper, which prove the transmission of copper and ammonia from liquid phase into solid phase.

Performance of Grass Filter Strip in Copper and Zinc Removal in Surface and Subsurface Runoff

Three filter strips were conducted on self-designed soil bins. Taking a filter strip with no vegetation as contrast, the effectiveness of vegetation and soil conditions on heavy metals (including copper and zinc) removal efficiencies were investigated by simulated runoff experiment. The results showed that the adsorbed state is the main existing form of heavy metal. For surface runoff, most of total copper and total zinc are trapped in first 4m and it is ineffective to increase the distance beyond 4m for removal. Vegetation has no significant effect on total copper and total zinc removal, while the soil with higher content of organic matter is contributing to total Zn interception. For subsurface runoff, the removal efficiencies of total copper and total zinc can reach to above 95.38% and both vegetation and soil conditions have no significant effects. Vegetation is contributing to copper ion and zinc ion removal significantly. Soil condition is only a significant factor to zinc ion, with higher content of organic matter as a contributing factor.

Editors' Choice—Efficiency of a CMP Pad at Removing Protective Material from Copper during CMP

The efficiency of a pad asperity and abrasives embedded between the asperity and wafer at removing the protective material on the surface of copper (removal efficiency) during chemical mechanical planarization (CMP) was determined experimentally using current densities from in situ electrochemical measurements while polishing with a slurry containing BTA. The removal efficiency was insentitive to the pressure and sliding velocity, but was dictated by the pad surface topography parameters and abrasive concentration in the slurry. An analytical estimate was derived by comparing the trajectories of a pad asperity and the abrasives embedded in the asperity. Comparison of the experimental and analytical estimate suggests that the asperities are deformed enough by the embedded abrasives to contact the surface of copper at abrasive concentrations up to 1 wt%. At higher concentrations up to 5 wt%, the asperities deflected to a lesser amount, making the force exerted on the copper increase. At these higher concentrations, some of the copper interacting with the squeezed abrasives was plastically deformed, yielding higher removal efficiency than when elastically deformed. The removal efficiency can be used as a standard metric for assessing the material removal ability of various consumables such as slurry, CMP pad and pad conditioner.

Optimization of copper removal from aqueous solutions in a continuous electrochemical cell divided by cellulosic separator.

Copper, as an inseparable part of many industrial discharges, threatens both public and environmental health. In this work, an electrochemical cell utilizing a cellulosic separator was used to evaluate Cu removal using graphite anodes and stainless steel cathodes in a continuous-flow mode reactor. In the experimental matrix, Cu concentration (1-5 mg L-1), electrolysis time (20-90 min), and current intensity (0.1-0.4 A) were employed. Results showed that the maximum removal efficiency of copper was obtained as 99%. The removal efficiency was independent of initial copper concentration and directly related to electrolysis time and current intensity. Energy consumption was more dependent on current intensity than electrolysis time. Under optimal conditions (75.8 min electrolysis time, 0.18 A current intensity, and 3 mg L-1 copper concentration), the removal efficiency was obtained as 91% while 7.05 kWh m-3 electrical energy was consumed. The differences between the actual and predicted data under optimal conditions were 0.42% for copper removal and 0.23% for energy consumption, which signify the performance and reliability of the developed models. The results exhibited the suitability of the electrochemical reduction for copper removal from aqueous solutions, which was facilitated under alkaline conditions prevailing in the cathodic compartment due to applying a cell divided by a cellulosic separator.

Remediation of chromium and copper on water hyacinth (E. crassipes) shoot powder

Tannery effluent characterization and removal efficiency of Chromium (Cr) and Copper (Cu) on water hyacinth has been observed by filtration process. The effluent was contaminated by deep blue color, acidic pH, higher value of total dissolve solid (TDS), electrical conductivity (EC), chemical oxygen demand (COD) and lower value of dissolve oxygen (DO). After filtration, the effluent shows that the permissible limit of investigated metals. Adsorbent capacity of water hyacinth shoot powder for Cr and Cu ion was found to be 99.98% and 99.96% for standard solution (SS) and 98.83% and 99.59% for tannery effluent (TE), respectively.

Surface Modification of Silica Spheres for Copper Removal

Efficient copper removal from water was achieved by using surface modified silica spheres with 3-mercaptopropyltrimethoxysilane (MPTMS) using base catalyst. The surface modification of silica spheres was performed by hydrolysis and condensation reactions of the MPTMS. The characteristic infrared absorption peaks at 2929, 1454, and 1343 cm^−1 represent the −CH₂ stretching vibration, asymmetric deformation, and deformation, respectively. The absorption peaks at 2580 and 693 cm^−1 corresponding the −SH stretching vibration and the C-S stretching vibration indicate the incorporation of MPTMS to the surface of silica spheres. Field emission scanning electron microscope (FESEM) image of the surface modified silica sphere (SMSS) shows nano-particles of MPTMS on the surface of silica spheres. High concentration of copper solution (1000 ppm) was used to test the copper removal efficiency and uptake capacity. The FESEM image of SMSS treated with the copper solution shows large number of copper lumps on the surface of SMSS. The copper concentration drastically decreased with increasing the amount of SMSS. The residual copper concentrations were analyzed using inductively coupled plasma mass spectrometer. The copper removal efficiency and uptake capacity with 1000 ppm of copper solution were 99.99 % and 125 mg/g, respectively.

Copper Removal with Biologcal Treatment Aided with Modified Adsorbents

The performance of a biological system was evaluated for copper removal with and without the addition of an adsorbent to the aeration compartment. Three different reactors were employed in this study. The first reactor consist of biomass alone and was used as a control reactor (CR). The second reactor consist of biomass and microwave incinerated rice husk ash (MIRHA) whereas the third reactor consist of biomass and hybrid adsorbent (HA), which is a mixture of MIRHA and groundwater treatment plant sludge (GWTPS). The reactors were operated at solid retention time (SRT) of 30 days and hydraulic retention time (HRT) of 19.8 hours. The experiment was conducted in 8 different phases consisting of various copper concentrations coming from the influent source. The first and second phase were acclimation period during which copper was not added to the influent wastewater. From the third to the eight phase, copper was fed to the reactors at different concentrations. Reactor performance was monitored every two days. Results show that copper toxicity was significant for the control reactor from phase from phase 5 to phase 8 with effluent concentration between 0.34 – 2.62 mg/L. Copper removal was significant for both MIRHA and HA reactor. Effluent copper concentration in the MIRHA reactor was 2.04 mg/L and 1.09 mg/L for HA reactor at phase 8 (copper concentration 15 mg/L). Addition of the adsorbents (MIRHA and HA) enhanced the biomass tolerance towards copper toxicity at high concentration and improved copper removal efficiency. This study, therefore demonstrates that low cost non-conventional adsorbents could be utilized as support materials to enhance biomass tolerance towards heavy metal toxicity.

Adsorption kinetic models for the removal of Cu(II) from aqueous solution by clay liners in landfills

Liners are commonly used in engineered waste disposal landfill to minimize the potential contamination of the aquatic environment. The adsorption behavior of Cu(II) from aqueous solution onto clay admixed with various mix ratios of quarry fines was investigated. The amount of Cu(II) adsorption increases with increase in contact time. The copper removal efficiencies of the composite mixture gradually decrease from 94.53 % (raw clay) to 85.59 % (20 % of quarry fines with clay), and appreciable decrease in percent removal 75.61 % was found with 25 % of quarry fines with clay. The kinetic adsorption data were analyzed by pseudo-first-order, pseudo-second-order, Bhattacharya–Venkobachar and Natarajan–Khalaf kinetic models to classify adsorption process mechanisms. Kinetic experimental data were good agreement with pseudo-second-order kinetic model with the degree of fitness of the data (R 2) 0.9999 for the adsorption of Cu(II). The results revealed that quarry fines can be used with optimum of 20 % replacement of natural clay for removal of Cu(II) as a liner material in landfills.

CONVERSION OF SLUDGE FROM A WASTEWATER TREATMENT PLANT TO A FERTILIZER

Preventing wastage of resources is an important priority for sustainability. Sludge from a wastewater treatment plant (WWTP) is such a resource that it often wasted. It is a source of nutrients and organic materials that can be used as a fertilizer. At a waste water treatment plant in Montreal, the sludge is currently incinerated and sent for disposal. Alternatives to the practice are thus desirable. Elevated concentrations of cadmium, copper, cobalt and selenium are found in the sludge and therefore a treatment process is required before use as a fertilizer according to the Province of Quebec regulations. Leaching was selected as there is potential for heavy metal removal. However, nutrient loss must be minimized to preserve its use as a fertilizer. To meet these goals, a new leaching agent (K2HPO4) was proposed, and investigated for heavy metal removal efficiency on the sludge. A correlation of heavy metal removal and preserved nutrient concentration with time and pH was found. Removal efficiencies of cadmium, copper, cobalt and selenium of 80%, 44%, 70% and 93%, respectively were determined. In addition, concentrations of nitrogen, phosphorus and potassium of 17%, 17% and 25%, respectively, resulted in the treated sludge. In conclusion, the use of dipotassium phosphate is an effective leaching method to remove heavy metals and simultaneously increase the primary macro nutrients at an acceptable cost.

A new approach to copper ion removal from water by polymeric nanocomposite membrane embedded with γ-alumina nanoparticles

The ability of alumina (Al2O3) nanoparticles in adsorption of heavy metals was employed in improving the copper removal efficiency of PES membranes. Mixed matrix membranes were prepared using PES and different amounts of alumina nanoparticles by phase inversion method. The fabricated membranes were characterized in terms of morphology and performance using scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses, water contact angle and porosity measurements, determination of pure water flux, copper ion removal, and reusability test. Mixed matrix membranes revealed higher water permeation compared with the pristine PES membrane just by adding small amounts of nanoparticles ≤1.0 wt.% as a result of increasing the membrane porosity and hydrophilicity after addition of alumina nanoparticles into the membrane matrix. Moreover, copper ion removal efficiency of alumina mixed membranes was improved. Membrane performance tests as well as adsorptive nature of alumina nanoparticles proposed that adsorption was the most possible separation mechanism by mixed matrix membranes. Reusability test of membrane confirmed the durability of removal efficiency even after four cycles of filtration.

Removal of both cationic and anionic contaminants by amphoteric starch

A novel amphoteric starch incorporating quaternary ammonium and phosphate groups was applied to investigate the efficiency and mechanism of cationic and anionic contaminant treatment. Its flocculation abilities for kaolin suspension and copper-containing wastewater were evaluated by turbidity reduction and copper removal efficiency, respectively. And the kinetics of formation, breakage and subsequent re-formation of aggregates were monitored using a Photometric Dispersion Analyzer (PDA) and characterized by flocculation index (FI). The results showed that amphoteric starch possessed the advantages of being lower-dosages-consuming and being stronger in shear resistance than cationic starch, and exhibited a good flocculation efficiency over a wide pH range from 3.0 to 11.0.

Copper and Cyanide Extraction with Emulsion Liquid Membrane with LIX 7950 as the Mobile Carrier: Part 1, Emulsion Stability

The potential use of emulsion liquid membranes (ELMs) with LIX 7950 as the mobile carrier to remove heavy metals from waste cyanide solutions has been proposed. Relatively stable ELMs with reasonable leakage and swelling can be formed under suitable mixing time and speed during emulsification. The concentration of LIX 7950 and Span 80 in the membrane phase, KOH in the internal phase and the volume ratio of membrane to internal phases are also critical to ELM formation. The efficiency of copper and cyanide removal from dilute cyanide solution by ELMs is related to ELM stability to some extent. More than 90% copper and cyanide can be removed from dilute cyanide solutions by ELMs formed under suitable experimental conditions.