Int. J. Electrochem. Sci.

This study explores the use of MFCs to anodic dechlorination of aromatic chlorides such as 2,4,6-trichlorophenol (2,4,6-TCP). Mixed microbe, isolated from submarine sediment, was used to detect its dechlorination performance in microbial fuel cells device. Moreover, It was confirmed that exoelectrogen microbe accelerated the 2,4,6-TCP degrading in MFCs. Dechlorination efficiency of 2,4,6-TCP in the anode of MFCs could reach 86.51%, accompanying with power generation. Besides, the pathway of 2,4,6-TCP degradation in MFCs was proved. Dichlorophenol, a major intermediate product for TCP dechlorination, was degraded into CO2. This study explores the use of MFCs to anodic dechlorination of aromatic chlorides such as 2,4,6-trichlorophenol (2,4,6-TCP). Mixed microbe, isolated from submarine sediment, was used to detect its dechlorination performance in microbial fuel cells device. Moreover, It was confirmed that exoelectrogen microbe accelerated the 2,4,6-TCP degrading in MFCs. Dechlorination efficiency of 2,4,6-TCP in the anode of MFCs could reach 86.51%, accompanying with power generation. Besides, the pathway of 2,4,6-TCP degradation in MFCs was proved. Dichlorophenol, a major intermediate product for TCP dechlorination, was degraded into CO2.</p

2,4,6-TCP removal mechanism in the process of leaching manganese

2,4,6-trichlorophenol (2,4,6-TCP) was used in the leaching system of manganese/pyrite to achieve the simultaneous utilization and removal of 2,4,6-TCP. When the initial concentration of 2,4,6-TCP was 300?mgL(?1) and the weight percentage of pyrite was 12.8%, the removal of 2,4,6-TCP was 83.3%, meanwhile, the leaching efficiency of manganese was 97.6%. Fourier Transform Infrared Spectroscopy (FTIR) showed that the removal of 2,4,6-TCP mainly relied on the chemical oxidative degradation by Mn (IV) and the surface adsorption by leaching residue, including physical adsorption and chemical adsorption. Gas Chromatography?Mass Spectrometry analysis and Chemical Oxygen Demand (COD) indicated that 2,4,6-TCP was degraded to inorganic substances eventually.</p

reductiveleachingoflowgrademanganeseorewithpreprocessedcornstalk

Cornstalk is usually directly used as a reductant in reductive leaching manganese. However, low utilization of cornstalk makes low manganese dissolution ratio. In the research, pretreatment for cornstalk was proposed to improve manganese dissolution ratio. Cornstalk was preprocessed by a heated sulfuric acid solution (1.2 M of sulfuric acid concentration) for 10 min at 80℃. Thereafter, both the pretreated solution and the residue were used as a reductant for manganese leaching. This method not only exhibited superior activity for hydrolyzing cornstalk but also enhanced manganese dissolution. These effects were attributed to an increase in the amount of reductive sugars resulting from lignin hydrolysis. Through acid pretreatment for cornstalk, the manganese dissolution ratio was improved from 50.14% to 83.46%. The present work demonstrates for the first time the effective acid pretreatment of cornstalk to provide a cost-effective reductant for manganese leaching

Ocean bacteria: performance on CODCr and NH4+-N removal in landfill leachate treatment

An experiment was carried out to investigate the performance of mixed ocean bacteria, isolated from the ocean sediment, on landfill leachate treatment. In this treatment, ocean bacteria were the only constituent added to remove organics and NH4+-N. Given their considerable influence on wastewater purification, factors such as inoculum, initial pH, processing time and oxygen condition, were directly involved in this research. As indicated by laboratory test results, chemical oxygen demand (CODCr) and NH4+-N removal could reach 94.45% and 67.87%, respectively, after 3 days of treatment, in conditions of natural pH 6.3 and with the application of oxygen. The volt-ampere characteristics of the bacteria solution verified the redox-active ability of the bacteria in landfill leachate treatment.</p

Recovery of nickel and molybdate from ammoniacal leach liquor of spent hydrodesulfurization catalyst using LIX84 extraction

Ammonia leaching can achieve selective recovery of nickel and molybdenum without aluminum extraction from spent hydrodesulfurization catalyst. In this study, a method for selective nickel extraction by LIX84 from ammoniacal leach liquor is proposed. After a two-stage countercurrent extraction, 99.977% Ni was extracted, while 0.096% Mo, 0.431% Al and 2.812% P were co-extracted under LIX84 concentration of 5%, initial pH value of 11.5, and phase ratio (O/A) of 2/1.1. Then a 0.1 mol/L oxalic acid (initial pH 1.36) was used to strip Ni-loaded organic phase under the phase ratio (O/A) of 0.5. 99.91% nickel in organic phase can be stripped into aqueous phase, while 91.16% nickel in aqueous phase can be precipitated as pure nickel oxalate dihydrate, and the oxalic acid solution containing dissolved nickel can be returned to the next stripping process to achieve nickel recovery. Subsequently, ammonium molybdate product can be obtained from molybdenum-containing raffinate by evaporation and crystallization after impurity removal. In addition, thermodynamic calculations show that the nickel extraction process by LIX84 from ammoniacal solution is an endothermic reaction. The present approach may efficiently be applied to recovery of molybdenum and nickel from spent hydrodesulfurization catalyst as per the proposed schematic flow-sheet

enhanceduvibioreductionbyalginateimmobilizeduraniumreducingbacteriainthepresenceofcarbonnanotubesandanthraquinone26disulfonate

Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2, 6-disulfonate (AQDS), and carbon nanotubes (CNTs). The effects of different AQDS-CNTs contents, U(IV) concentrations, and metal ions on U(IV) reduction by immobilized beads were examined. Over 97.5% U(VI) (20 mg/L) was removed in 8 hr when the beads were added to 0.7% AQDS-CNTs, which was higher than that without AQDS-CNTs. This result may be attributed to the enhanced electron transfer by AQDS and CNTs. The reduction of U(VI) occurred at initial U(VI) concentrations of 10 to 100 mg/L and increased with increasing AQDS-CNT content from 0.1% to 1%. The presence of Fe(III), Cu(II) and Mn(II) slightly increased U(VI) reduction, whereas Cr(VI), Ni(II), Pb(II), and Zn(II) significantly inhibited U(VI) reduction. After eight successive incubation-washing cycles or 8 hr of retention time (HRT) for 48 hr of continuous operation, the removal efficiency of uranium was above 90% and 92%, respectively. The results indicate that the AQDS-CNT/AL/cell beads are suitable for the treatment of uranium-containing wastewaters. (C) 2015 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V

Enhanced U(VI) bioreduction by alginate-immobilized uranium-reducing bacteria in the presence of carbon nanotubes and anthraquinone-2,6-disulfonate

Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2, 6-disulfonate (AQDS), and carbon nanotubes (CNTs). The effects of different AQDS-CNTs contents, U(IV) concentrations, and metal ions on U(IV) reduction by immobilized beads were examined. Over 97.5% U(VI) (20 mg/L) was removed in 8 hr when the beads were added to 0.7% AQDS-CNTs, which was higher than that without AQDS-CNTs. This result may be attributed to the enhanced electron transfer by AQDS and CNTs. The reduction of U(VI) occurred at initial U(VI) concentrations of 10 to 100 mg/L and increased with increasing AQDS-CNT content from 0.1% to 1%. The presence of Fe(III), Cu(II) and Mn(II) slightly increased U(VI) reduction, whereas Cr(VI), Ni(II), Pb(II), and Zn(II) significantly inhibited U(VI) reduction. After eight successive incubation-washing cycles or 8 hr of retention time (HRT) for 48 hr of continuous operation, the removal efficiency of uranium was above 90% and 92%, respectively. The results indicate that the AQDS-CNT/AL/cell beads are suitable for the treatment of uranium-containing wastewaters. (C) 2015 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.</p

Lithium recovery from lepidolite roasted with potassium compounds

Three different potassium compounds, namely K2SO4, KOH, and K2SO4 + KOH, were used as additives to extract lithium from lepidolite by roasting and water leaching. The effect of the additive/ore mass ratio on the extraction of Li, K, Si, and Al was compared among the different additives. Efficient extraction of Li and K was obtained by roasting lepidolite with the K2SO4 and K2SO4 + KOH additives. The Li extraction and K recovery were 92.78% and 81.72% respectively under the optimum conditions: K2SO4/KOH/ore mass ratio of 1:0.5:1, roasting at 900 degrees C for 2 h, and water leaching at 90 degrees C for 3 h with a liquid to solid (L/S) ratio of 5:1. The decomposition process of lepidolite with different additives was explored. The results indicate that lepidolite is decomposed into kalsilite when roasted with KOH and mixed phases of kalsilite, leucite, K2SO4, and LiKSO4 when roasted with K2SO4 and K2SO4 + KOH additives. Li in the lepidolite is converted into soluble LiKSO4, facilitating its extraction. The addition of KOH contributes to the formation of kalsilite, which makes K recovery easier

Preparation of Vanadium Oxalate by Solvent Extraction and Purification with P507 and Its Physicochemical Properties

Vanadium oxalate is an ideal precursor used for the preparation of vanadium containing catalysts, advanced phase change material of VO2, high performance VN and other vanadium based chemical products. Currently, few research on the preparation of VOC2O4 was found to be reported. In this study, highly pure vanadium oxalate was prepared through "extraction-stripping-evaporative crystallization" method using 2-ethylhexyl dihydrogen phosphate(P507) as the extractant and H2C2O4 as the stripping reagent from a vanadium leach solution obtained by sodium roasting and water leaching of vanadium titano-magnetite slags. V(IV) stripping from the loaded P507 solution with H2C2O4 was emphatically studied and the stripping conditions were optimized. The result showed that vanadium could be almost completely (99. 98%) stripped at an A/O ratio of 1 :5 and 50 degrees C using 2. 0 mol/L oxalic acid solution in three stages (theoretical). The concentration of VOC2O4 would reach 290 g/L in the loaded strip liquor. The vanadium oxalate was characterized by X-ray diffraction (XRD), energy dispersive spectrometer(EDS), field emission scanning electron microscope (SEM) and synchronous thermal analyzer(TGA-DSC). The result showed that vanadium oxalate was VOC2O4 center dot 2H(2)O and it had high purity, good crystallinity and average particle size distribution