Flow-electrode capacitive deionization (FCDI) provides the opportunity for continuous desalination operation of high concentration saline water. In this study, we firstly report the application of a ...battery material (a Prussian blue analogue, copper hexacyanoferrate, CuHCF) as flowable electrode in FCDI system, where it is coupled with activated carbon (AC). Its desalination performance under different voltage is evaluated when dealing with 10 g L−1 NaCl solution. Results show that the salt removal rate and salt removal efficiency of the designed FCDI is enhanced as increasing in applied voltage from 1.2 to 2.8 V. Moreover, benefiting from the high capacity of CuHCF material, the novel FCDI based on CuHCF-AC pair shows superiority over conventional FCDI with AC-AC pair when operates at high voltage over 2.0 V (e.g. salt removal rate of 0.12 vs. 0.11 mg cm−2 min−1, salt removal efficiency of ~91 vs. 84% and current efficiency of ~96 vs. 95% at 2.8 V), even though the pH of the concentrated water changes more significantly. The results indicate that FCDI based on CuHCF-AC electrode pair is effective in dealing with high saline water at high voltage. Other sodium ion intercalation material may also be applied in FCDI.
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•Copper hexacyanoferrate (CuHCF) is firstly used as flowable electrode in FCDI.•FCDI with CuHCF-AC pair works better than that with AC-AC pair at high voltage.•Desalination performance in FCDI was enhanced as increase in voltage from 1.2 to 2.8 V.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Three-dimensional superhydrophobic membranes were fabricated via one-step electrospinning.•Silica nanoparticles decorated on PVDF fiber formed superhydrophobic structure.•Doping of ...silica nanoparticles improved the mechanical properties of the membrane.•The prepared membranes show durable wetting-resistance and high water vapor flux.
The practical applications of membrane distillation (MD) are hindered by the absence of effective membranes with high porosity, sufficient strength, and durable wetting repellency for long term operation. In this study, we developed a facile method to construct composite membranes with high MD performance via one-step electrospinning of PVDF solutions blended with hydrophobic silica nanoparticles (NPs). The characterizations reveal that the incorporation of silica NPs have altered the membrane surface morphology and endowed the composite membrane with hierarchical structure on both surface and bulk layers (three-dimensional (3D) superhydrophobic membrane). The hydrophobicity of the membranes can be easily tailored by the dosage of silica NPs, and the water contact angle (WCA) of the membranes can be optimized to be 157±1°, which was close to that of the lotus leaf (160°). Furthermore, the incorporation of silica NPs have promoted the mechanical strength, salt rejection, and water permeation flux of the membranes. The composite membrane containing 7.47wt% silica NPs (designated as SIL40) can achieve a high MD performance with a water flux of 25.73kgm−2h−1 and a permeate conductivity below 5.0μScm−1 during a 100h test-period. The SIL40 also shows a tensile strength and a Young’s modulus of 3.18 and 12.8MPa, respectively; the values surpassed those of the pristine PVDF membrane (1.5 and 5.4MPa, respectively). In addition, the MD test indicates that the 3D superhydrophobic membrane exhibits a more durable wetting resistance and a more stable MD performance than the surface-modified superhydrophobic membranes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Microbial methods are promising and environmentally friendly methods for remediating heavy metal contamination. In this study, a Cr(VI)-resistant bacterial strain, DC-B3, which was identified as
...Pseudomonas
sp. by 16S rDNA gene sequencing, was isolated from heavy metal-contaminated mine soil, and its performance in Cr(VI) removal from wastewater in terms of Cr(VI) reduction and total Cr adsorption was assessed. This strain exhibited a high capability to reduce Cr(VI) to less toxic Cr(III) without the addition of an external electron donor at low pH (2.0). The Cr(VI) reduction capacity and rate both increased linearly with increasing Cr(VI) concentration, with a reduction capacity of 32.0 mg Cr(VI)·g
−1
achieved at an initial concentration of 135.0 mg L
−1
over 75 h. In addition, 41.0% of the total Cr was removed from the solution by biosorption, and equilibrium was reached within approximately 5 h. The total Cr sorption process was well described by the pseudo-second-order kinetic and Langmuir isotherm models. Desorption assays indicated that NaOH was the most efficient agent for total Cr desorption, and Cr(VI) and generated Cr(III) were both loaded on the DC-B3 biomass. The bacterial cells after Cr treatment were characterized by scanning electron microscopy-energy dispersive X-ray spectrometer and Fourier transform infrared spectroscopy analyses. Strain DC-B3 showed high potential for possible application in the remediation of Cr(VI) contamination in mine areas.
Non-carbon materials in capacitive deionization (CDI) can help to enhance the capacity of removed ions. Here, we report for the first time the removal of chloride ions (Cl
−
) with a bismuth (Bi) ...anode when coupled with an activated carbon (AC) cathode in CDI. The effects of carbon black in the Bi electrode, applied voltage, electrode mass loading and initial concentration on Cl
−
removal are investigated. Moreover, its cycle performance is also tested. Results show that addition of carbon black to a Bi electrode (Bi@CB) significantly improves Cl
−
removal. The declining trend of Cl
−
concentration and appearance of peaks assigned to products of bismuth oxychloride (BiOCl) in XRD patterns confirm Cl
−
storage by the Bi electrode, which is enhanced with an increase in voltage. When coupled with AC in a fixed mass, increasing the Bi mass does not contribute to more Cl
−
removal. Although the cycle performance is not excellent (the attenuation rate is 74% after 10 cycles), its chloride removal capacity is ∼2-3 times the value of AC (
e.g.
0.95
vs.
0.32 mmol g
Bi
−1
at 1.2 V in 500 mg L
−1
NaCl solution). Besides, the Bi-AC electrode pair in CDI is more suitable to remove Cl
−
from a solution with a Cl
−
concentration of below 600 mg L
−1
.
A bismuth-activated carbon (Bi-AC) electrode pair is innovatively packed into a capacitive deionization (CDI) cell to remove chloride ions. Cl removal performance under different voltages and storage-release cycle performance are mainly discussed.
We developed a kind of macropore- and micropore-dominated carbon (HPAC) derived from poly(vinyl alcohol) and polyvinylpyrrolidone for electric double-layer capacitive (EDLC) applications, e.g., ...supercapacitors and capacitive deionization (CDI). By comparing the EDLC performance of HPAC with those of ordered mesoporous carbon (OMC) and commercial activated carbon (AC), we evaluated the pore size effects. Cyclic voltammetry (CV) was employed for static and flowing CDI processes to identify the disparities between supercapacitors and CDI. HPAC exhibits a specific capacitance of 309 F g–1 at a specific current of 0.5 A g–1 (6 M KOH) in a three-electrode half-cell and has a salt removal capacity of 16.3 mg g–1 (1.2 V, 500 mg L–1 NaCl), which is better than those of AC and OMC. Cycling tests of HPAC in supercapacitors and CDI show excellent stability. The properties of HPAC, fine, hydrophilic, macroporous, and microporous, endow HPAC with the promising possibility of use in supercapacitors and capacitive deionization. The disparities of supercapacitors and CDI include ionic species and concentrations and solution hydromechanics. CV analysis of static and flowing CDI equipped with HPAC electrodes suggests that increasing the salt concentration in CDI is beneficial for the carbon electrode to show high capacitance and to reduce the pumping energy during the CDI process.
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IJS, KILJ, NUK, PNG, UL, UM
The research interest on the critical role of macrophytes in aquatic ecosystems has been mounting in recent years. Whereas the selection of plant species and restoration pattern still need further ...evaluations for better understanding of their relationship with aquatic ecosystem. In this study, two popular submerged macrophytes, Ceratophyllum demersum L. and Myriophyllum verticillatum L., were chosen and manipulated growing in mimic systems. Their individual and combined planting effects on water quality and sediment biogeochemistry were assessed, and their overall performance was ranked. The results showed that water quality was significantly improved, especially more than 70% reductions in turbidity and Chlorophyll a (Chl. a) concentration (P<0.05). No significant effect of the macrophytes was detectable on total phosphorus (TP), organic phosphorus (OP), inorganic phosphorus (IP), total nitrogen (TN) and organic matter (OM) contents in the sediments (P>0.05). Overall, the differences among three experimental systems were slight; however, considering C. demersum having better potential in removing the nutrients from waters and other factors, such as the importance of species richness, their ranking performance is in the order of: combined plants (C. demersum and M. verticillatum)>C. demersum>M. verticillatum.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Constructed wetlands (CWs) are well recognized as a cost-effective and environmentally friendly eco-technology for contaminated water remediation, especially in decentralized communities and rural ...areas. As a critical component in CWs, the substrate determines the wastewater treatment performance and ecological effects of CW systems. Biochar, a versatile and green carbonaceous biomaterial produced by carbonization of various biomasses, has recently been amended into CWs or biofilters (BFs) as a novel alternative substrate for wastewater treatment. In this paper, the performance of biochar amendment in CWs/biofilters with respect to the removal of nitrogen, phosphorus, organic contaminants, heavy metals and pathogens and its concurrent ecological benefits in improving macrophyte growth and mitigating greenhouse gas (GHG) emissions are summarized and evaluated. Furthermore, the mechanisms involved in these benefits, which are considerably different from those in batch tests, are analysed and elucidated, especially highlighting the roles of microorganisms. The high potential for recycling spent biochar media in CWs/BFs as a soil ameliorant/remediator is proposed. Collectively, it is highly promising to apply biochar as a substrate in CW/BF treatment systems, and more relevant research and practical applications of biochar substrates in CWs/BFs, especially the durability, recycling and possible negative effects of biochar, are required in the future.
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•Biochar as an innovative substrate in constructed wetlands (CWs)/biofilters (BFs) for water treatment is reviewed.•Biochar substrates enhance pollutant removal and mitigate greenhouse effect of CWs/BFs.•Recycling spent biochar substrates into agrosystems can improve the sustainability of CWs/BFs.•Scaling up application of biochar substrates is needed, taking care of potential negative effects.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Dianchi Lake and Yilong Lake, two prominent plateau lakes in Yunnan Province, China, have suffered from Microcystis and Cylindrospermopsis blooms for decades. While cyanobacteria harvest boats ...utilizing cationic polyacrylamide (CPAM) flocculation and screen filtration have been proven effective for harvesting Microcystis biomass in Dianchi Lake, they struggle against Cylindrospermopsis blooms in Yilong Lake. This study systematically compared the removal of Microcystis and Cylindrospermopsis blooms using flocculation–filtration treatment, aiming to identify key factors influencing flocculation and propose enhancements to improve treatment efficiency for Cylindrospermopsis blooms. The reduction of turbidity, OD680, biovolume and phytoplankton density all revealed significantly better treatment efficiency for Microcystis blooms compared to Cylindrospermopsis blooms. In Dianchi Lake, 1 mg/L CPAM achieved a 95% turbidity reduction, while in Yilong Lake, even with 4.0 mg/L CPAM, the removal efficiency remained below 90%. Post-treatment, Dianchi Lake’s water quality showed substantial improvements, including over 50% reductions in total nitrogen, total phosphorus, permanganate index, and chemical oxygen demand. Conversely, nutrient level reductions were limited in Yilong Lake’s treated water. The average molecular weight of dissolved organic matters (DOM) in Yilong Lake was notably smaller than in Dianchi Lake. The treatment selectively removed high molecular weight, microbial-sourced, and protein-like DOM components, leading to a decrease in average molecular weight and an increase in humification index (HIX) in both lakes. Excessive humic matters in the water of Yilong Lake was found to hamper algae flocculation significantly. Introducing additional acidic polysaccharides or oxidants emerged as potential strategies to enhance Yilong Lake’s treatment efficiency.
Summary
Biological approaches are considered promising and eco‐friendly strategies to remediate Hg contamination in soil. This study investigated the potential of two ‘green’ additives, ...Hg‐volatilizing bacteria (Pseudomonas sp. DC‐B1 and Bacillus sp. DC‐B2) and sawdust biochar, and their combination to reduce Hg(II) phytoavailability in soil and the effect of the additives on the soil bacterial community. The results showed that the Hg(II) contents in soils and lettuce shoots and roots were all reduced with these additives, achieving more declines of 12.3–27.4%, 24.8–57.8% and 2.0–48.6%, respectively, within 56 days of incubation compared to the control with no additive. The combination of DC‐B2 and 4% biochar performed best in reducing Hg(II) contents in lettuce shoots, achieving a decrease of 57.8% compared with the control. Pyrosequencing analysis showed that the overall bacterial community compositions in the soil samples were similar under different treatments, despite the fact that the relative abundance of dominant genera altered with the additives, suggesting a relatively weak impact of the additives on the soil microbial ecosystem. The low relative abundances of Pseudomonas and Bacillus, close to the background levels, at the end of the experiment indicated a small biological disturbance of the local microbial niche by the exogenous bacteria.
Hg‐volatilizing bacteria and biochar can reduce soil Hg bioavailability. Combination of bacteria DC‐B2 and 4% biochar performed best to lower Hg(II) bioavailability. Soil bacterial community structure was limitedly influenced by the additives.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
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•Granular biochar was filled in CWs to treat acidic mining-impacted water (MIW).•Biochar CWs had better abiotic Cu/Zn/Cd removal and macrophyte growth and high pH.•Liquid organic ...waste (LOW) addition drove biogenic routes in CWs for MIW treatment.•Metals were predominantly deposited in CW media, with marginal uptake by macrophytes.•Functional microbial groups were stimulated by LOW for efficient MIW biotreatment.
Granular biochar made from walnut shells was layered into sand-based constructed wetlands (CWs) to treat simulated mining-impacted water (MIW). The results showed that the biochar media exhibited markedly high capacities for metal binding and acidity neutralization, supported notably better plant growth and mitigated metal transfer from the plant roots to the shoots. The addition of organic liquid wastes (domestic sewage and plant straw hydrolysation broth) stimulated biogenic sulfate reduction after 40 d of adaptation to effectively remove multiple heavy metals in the MIW. The microbial community compositions were prominently regulated by organic carbon, with desirable communities dominated by Cellulomonas and Desulfobulbus formed in the CWs for MIW biotreatment. The role of macrophytes in the CWs in MIW treatment was insignificant and was dependent on operation conditions and metal species. A biochar-packed CW system with liquid organic waste supplementation was effective in metal removal and acidity neutralization of MIW.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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