Copper Extraction from Low-Grade Chalcopyrite in a Bioleaching Column Assisted by Bioelectrochemical System

Abstract Low-grade ores, tailings and solid wastes contain small amounts of valuable heavy metals. Improper disposal of these results in the waste of resources and contamination of soil or groundwater. Accordingly, the treatment and recycling of low-grade ores, tailings and solid wastes attracted much attention recently. Bioelectrochemical system, an innovative technology for the removal and recovery of heavy metals, has been further developed and applied in recent years. In current study, the low-grade chalcopyrite was bioleached with the assistance of microbial fuel cells. Copper extraction along with electricity generation from the low-grade chalcopyrite were achieved in the column bioleaching process assisted by MFCs. Results showed that after 197 days bioleaching of low-grade chalcopyrite, 423.9 mg copper was extracted from 200 g low-grade chalcopyrite and the average coulomb production reached 1.75 C/d. The introduction of MFCs into bioleaching processes promoted the copper extraction efficiency by 2.7 times (3.62% vs. 1.33%), mainly via promoting ferrous oxidation, reducing ORP and stimulating bacterial growth. This work provides a feasible method for the treatment and recycling of low-grade ores, tailings and solid wastes. But balancing energy consumption of aeration and circulation frequency and chemicals consumption of acid to improve the copper extraction efficiency need further investigation.

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Multi-walled carbon nanotubes as electrode material for microbial fuel cells

Water Science & Technology ◽

10.2166/wst.2012.956 ◽

2012 ◽

Vol 65 (7) ◽

pp. 1208-1214 ◽

Cited By ~ 20

Author(s):

N. Thepsuparungsikul ◽

N. Phonthamachai ◽

H. Y. Ng

Keyword(s):

Carbon Nanotubes ◽

Surface Area ◽

Microbial Fuel Cells ◽

Electricity Generation ◽

Electrode Materials ◽

Innovative Technology ◽

Carbon Paper ◽

Carbon Cloth ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

The microbial fuel cell (MFC) is a novel and innovative technology that could allow direct harvesting of energy from wastewater through microbial activity with simultaneous oxidation of organic matter in wastewater. Among all MFC parts, electrode materials play a crucial role in electricity generation. A variety of electrode materials have been used, including plain graphite, carbon paper and carbon cloth. However, these electrode materials generated only limited electricity or power. Recently, many research studies have been conducted on carbon nanotubes (CNTs) because of their unique physical and chemical properties that include high conductivity, high surface area, corrosion resistance, and electrochemical stability. These properties make them extremely attractive for fabricating electrodes and catalyst supports. In this study, CNT-based electrodes had been developed to improve MFC performance in terms of electricity generation and treatment efficiency. Multi-walled carbon nanotubes (MWCNTs) with carboxyl groups have been employed to fabricate electrodes for single-chamber air-cathode MFCs. The quality of the prepared MWCNTs-based electrodes was evaluated by morphology, electrical conductivity and specific surface area using a field emission scanning electron microscope, four-probe method and Brunauer–Emmerr–Teller method, respectively. The performance of MFCs equipped with MWCNT-based electrodes was evaluated by chemical analysis and electrical monitoring and calculation. In addition, the performance of these MFCs, using MWCNTs as electrodes, was compared against that using commercial carbon cloth.

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Recovery of heavy metals from industrial sludge using various acid extraction approaches

Water Science & Technology ◽

10.2166/wst.2009.859 ◽

2009 ◽

Vol 59 (2) ◽

pp. 289-293 ◽

Cited By ~ 13

Author(s):

C. H. Wu ◽

C. Y. Kuo ◽

S. L. Lo

Keyword(s):

Heavy Metals ◽

Particle Size ◽

Organic Matter ◽

Extraction Efficiency ◽

Copper Extraction ◽

Acid Extraction ◽

Industrial Sludge ◽

Microwave Assisted ◽

Sludge Particle ◽

Experimental Findings

Heavy metals were removed from industrial sludge by traditional and microwave-assisted acid extraction approaches. The effects of acid concentration, extraction time, sludge particle size and solid/liquid (S/L) ratio on copper-extraction efficiency were assessed. Leaching with increased acid concentrations increased the yield of heavy metals from the industrial sludge. In microwave-assisted acid extraction, reducing the S/L ratio and sludge particle size increased copper-extraction efficiency. These experimental findings indicate that S/L ratio most strongly influenced microwave-assisted acid extraction. Both traditional and microwave-assisted acid extraction demonstrate that sulfuric acid was an effective extractant, and the copper fraction in extracted sludge shifted from being primarily bound to Fe–Mn oxides and organic-matter partition, to being mostly bound to organic matter, remaining as a residue during acid extraction.

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Conditioning of oily sludges with municipal solid wastes incinerator fly ash

Water Science & Technology ◽

10.2166/wst.1997.0318 ◽

1997 ◽

Vol 35 (8) ◽

pp. 231-238 ◽

Cited By ~ 7

Author(s):

Tay Joo Hwa ◽

S. Jeyaseelan

Keyword(s):

Heavy Metals ◽

Fly Ash ◽

Specific Resistance ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Solid Wastes ◽

Municipal Solid Wastes ◽

Capillary Suction ◽

Optimum Dosage

Conditioning of sludges improves dewatering characteristics and reduces the quantity of sludge to be handled. Anaerobic digested sludge collected from a sewage treatment plant contained 1.8% to 8% oil. The increase of specific resistance and capillary suction time (CST) with increasing oil content observed in these samples indicates the interference of oil in dewatering. It has been found that addition of municipal solid wastes incinerator fly ash decreases the specific resistances and capillary suction times of oily sludges rapidly up to 3% dosage. Beyond 3% fly ash, the decrease is less significant and the solids content in the sludge cake increases. This optimum dosage remains the same for sludges with varying oil contents from 1.8% to 12%. The total suspended solids of filtrate decreases with fly ash dosage but the toxic concentrations of heavy metals increases considerably. However at the optimum dosage of 3%, concentrations of heavy metals are within the limits for discharging into the sewers. The correlations of CST with the dewatering characteristics such as specific resistance, filter yield and corrected filter yield are established. These correlations can be used to obtain a quick prediction on dewaterability.

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Combined Influence of Low-Grade Metakaolins and Natural Zeolite on Compressive Strength and Heavy Metal Adsorption of Geopolymers

Minerals ◽

10.3390/min11050486 ◽

2021 ◽

Vol 11 (5) ◽

pp. 486

Author(s):

Alcina Johnson Sudagar ◽

Slávka Andrejkovičová ◽

Fernando Rocha ◽

Carla Patinha ◽

Maria R. Soares ◽

...

Keyword(s):

Heavy Metals ◽

Heavy Metal ◽

Compressive Strength ◽

Natural Zeolite ◽

Metal Adsorption ◽

Low Grade ◽

Heavy Metal Adsorption ◽

Adsorption Model ◽

X Ray ◽

Adsorption Capacities

Metakaolins (MKs) prepared from low-grade kaolins located in the Alvarães (A) and Barqueiros (B) regions of Portugal were used as the aluminosilicate source to compare their effect on the compressive strength and heavy metal adsorption of geopolymers. Natural zeolite, an inexpensive, efficient adsorbent, was used as an additive in formulations to enhance geopolymers’ adsorption capacities and reduce MK utilization’s environmental footprint. Geopolymers were synthesized with the replacement of MK by zeolite up to 75 wt.% (A25, B25—25% MK 75% zeolite; A50, B50—50% MK 50% zeolite; A75, B75—75% MK 25% zeolite; A100, B100—100% MK). The molar ratios of SiO2/Al2O3 and Na2O/Al2O3 were kept at 1 to reduce the sodium silicate and sodium hydroxide environmental impact. Geopolymers’ crystallography was identified using X-ray diffraction analysis. The surface morphology was observed by scanning electron microscopy to understand the effect of zeolite incorporation. Chemical analysis using X-ray fluorescence spectroscopy and energy dispersive X-ray spectroscopy yielded information about the geopolymers’ Si/Al ratio. Compressive strength values of geopolymers obtained after 1, 14, and 28 days of curing indicate high strengths of geopolymers with 100% MK (A100—15.4 MPa; B100—32.46 MPa). Therefore, zeolite did not aid in the improvement of the compressive strength of both MK-based geopolymers. The heavy metal (Cd2+, Cr3+, Cu2+, Pb2+, and Zn2+) adsorption tests exhibit relatively higher adsorption capacities of Barqueiros MK-based geopolymers for all the heavy metals except Cd2+. Moreover, zeolite positively influenced divalent cations’ adsorption on the geopolymers produced from Barqueiros MK as B75 exhibits the highest adsorption capacities, but such an influence is not observed for Alvarães MK-based geopolymers. The general trend of adsorption of the heavy metals of both MK-based geopolymers is Pb2+ > Cd2+ > Cu2+ > Zn2+ > Cr3+ when fitted by the Langmuir isotherm adsorption model. The MK and zeolite characteristics influence geopolymers’ structure, strength, and adsorption capacities.

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