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1.
Small ; 20(11): e2306569, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38095443

ABSTRACT

The use of 2D materials to produce hydrogen (H2 ) fuel via photocatalytic water splitting has been intensively studied. However, the simultaneous fulfillment of the three essential requirements-high photon utilization, rapid carrier transfer, and low-barrier redox reactions-for wide-pH-range production of H2 still poses a significant challenge with no additional modulation. By employing the first-principles calculations, it has been observed that the Janus ZnXY2 structures (X = Si/Ge/Sn, Y = S/Se/Te) exhibit significantly enhanced built-in electric fields (0.20-0.36 eV Å-1 ), which address the limitations intrinsically. Compared to conventional Janus membranes, the ductile ZnSnSe2 and ZnSnTe2 monolayers have stronger regulation of electric fields, resulting in improved electron mobility and excitonic nature (Ebinding = 0.50/0.35 eV). Both monolayers exhibit lower energy barriers of hydrogen evolution reaction (HER, 0.98/0.86 eV, pH = 7) and resistance to photocorrosion across pH 0-7. Furthermore, the 1% tensile strain can further boost visible light utilization and intermediate absorption. The optimal AC-type bilayer stacking configuration is conducive to enhancing electric fields for photocatalysis. Overall, Janus ZnXY2 membranes overcome the major challenges faced by conventional 2D photocatalysts via intrinsic polarization and external amelioration, enabling efficient and controllable photocatalysis without the need for doping or heterojunctions.

2.
Environ Res ; 234: 116607, 2023 10 01.
Article in English | MEDLINE | ID: mdl-37429402

ABSTRACT

With the development of industry, heavy metal (HM) pollution of soil has become an increasingly serious problem. Using passivators made of industrial by-products to immobilize HMs in contaminated soil is a promising in-situ remediation technology. In this study, the electrolytic manganese slag (EMS) was modified into a passivator (named M-EMS) by ball milling, and the effects of M-EMS on adsorption of As(V) in aquatic samples and on immobilization of As(V) and other HMs in soil samples were investigated under different conditions. Results demonstrated that M-EMS had a maximum As(V) adsorption capacity of 65.3 mg/g in the aquatic samples. Adding M-EMS to the soil reduced the leaching of As (from 657.2 to 319.8 µg/L) and other HMs after 30 d of incubation, reduced the bioavailability of As(V) and improved the quality and microbial activity of the soil. The mechanism for M-EMS to immobilize As in the soil are complex reactions, ion exchange reaction with As and electrostatic adsorption. This work provides new ideas of using waste residue matrix composites for sustainable remediation of Arsenic in the aquatic environment and soil.


Subject(s)
Arsenic , Environmental Restoration and Remediation , Metals, Heavy , Soil Pollutants , Arsenic/analysis , Manganese , Soil/chemistry , Soil Pollutants/analysis , Metals, Heavy/chemistry , Electrolytes , Water Pollution , Water
3.
Int J Mol Sci ; 24(18)2023 Sep 14.
Article in English | MEDLINE | ID: mdl-37762387

ABSTRACT

The pursuit of superhydrophilic materials with hierarchical structures has garnered significant attention across diverse application domains. In this study, we have successfully crafted Ni-Mn LDHs@CuC2O4 nanosheet arrays on a copper mesh (CM) through a synergistic process involving chemical oxidation and hydrothermal deposition. Initially, CuC2O4 nanosheets were synthesized on the copper mesh, closely followed by the growth of Ni-Mn LDHs nanosheets, culminating in the establishment of a multi-tiered surface architecture with exceptional superhydrophilicity and remarkable underwater superoleophobicity. The resultant Ni-Mn LDHs@CuC2O4 CM membrane showcased an unparalleled amalgamation of traits, including superhydrophilicity, underwater superoleophobicity, and the ability to harness photocatalytic forces for self-cleaning actions, making it an advanced oil-water separation membrane. The membrane's performance was impressive, manifesting in a remarkable water flux range (70 kL·m-2·h-1) and an efficient oil separation capability for both oil/water mixture and surfactant-stabilized emulsions (below 60 ppm). Moreover, the innate superhydrophilic characteristics of the membrane rendered it a prime candidate for deployment as a supercapacitor cathode material. Evidenced by a capacitance of 5080 mF·cm-2 at a current density of 6 mA cm-2 in a 6 M KOH electrolyte, the membrane's potential extended beyond oil-water separation. This work not only introduces a cutting-edge oil-water separation membrane and supercapacitor electrode but also offers a promising blueprint for the deliberate engineering of hierarchical structure arrays to cater to a spectrum of related applications.


Subject(s)
Copper , Pulmonary Surfactants , Electric Capacitance , Electrodes , Phenotype
4.
J Environ Manage ; 321: 115855, 2022 Nov 01.
Article in English | MEDLINE | ID: mdl-35994962

ABSTRACT

Nutrients and heavy metals (HM) in the sediment have an impact on microbial diversity and community structure. In this study, the distribution characteristics of nutrients, HM, and microbial community in the sediments along the Longsha River, a tributary of the Pearl River (or Zhu Jiang), China were investigated by analyzing samples from 11 sites. On the basis of the HM-contamination level, the 11 sampling sites were divided into three groups to explore the changes in microbial communities at different ecological risk levels. Results indicated that nutrient concentrations were higher near farmlands and residential lands, while the ecological risk of HM at the 11 sampling sites was from high to low as S10 > S2 > S9 > S6 > S11 > S7 > S5 > S8 > S3 > S4 > S1. Among these HM, Cu, Cr, and Ni had intense ecological risks. In addition, the results of Variance Partitioning Analysis (VPA) revealed a higher contribution of HM (35.93%) to microbial community variation than nutrients (12.08%) and pH (4.08%). Furthermore, the HM-tolerant microbial taxa (Clostridium_sensu_stricto_1, Romboutsia, norank_o__Gaiellales, and etc.) were the dominant genera, and they were more dynamic around industrial lands, while microbes involved in the C, N, and S cycles (e.g., Smithella, Thiobacillus, Dechloromonas, Bacter oidetes_vadinHA17, and Syntrophorhabdus) were inhibited by HM, while their abundance was lower near industrial lands and highway but higher around residential lands. A three-unit monitoring program of land-use types, pollutants, and microbial communities was proposed. These results provide a new perspective on the control of riparian land-use types based on contaminants and microbes, and different microbial community response patterns may provide a reference for contaminant control in sediments with intensive industrial activities.


Subject(s)
Metals, Heavy , Microbiota , China , Environmental Monitoring/methods , Geologic Sediments/chemistry , Metals, Heavy/analysis , Nutrients , Risk Assessment , Rivers/chemistry
5.
J Environ Manage ; 305: 114384, 2022 Mar 01.
Article in English | MEDLINE | ID: mdl-34991022

ABSTRACT

Due to the drawbacks of using fossil fuels and the need to mitigate global warming caused by increasing greenhouse gas emissions, agricultural biomass for bioenergy production is gaining great interest around the world. This work presented a study at a biochemical plant in Lianyungang, Jiangsu Province, China to maximize methane production from cassava distiller wastewater. The plant's annual production of cassava distiller wastewater is more than 3 million tons and currently was treated using a series of 5000 m3 Internal Circulation (IC) reactors. Modification was applied at No.19 IC reactor by connecting it to two 1 m3 automatic biological incubators called Information Bio-Booster (IBB). The effluent of the IC reactor was fed into the IBBs and iron, cobalt and nickel were added directly in the IBBs. The function of the IBBs was to regulate the microbial community. Afterwards, the microorganisms in the IBBs were pumped back into the IC reactor to participate in the methane production reaction. Daily net increase of methane content and COD removal reached 8.02% and 33% respectively in No.19 IC reactor comparing to the unadjusted reactors. Preliminary lab experiments found that improvements of biogas production, enhanced COD removal and VS removal was closely related to the enhancement of anaerobic microbial communities' diversity and the promotion of enzyme activity through the addition of the metal salts. Daily economic value could be estimated to be $218 which indicated the application potential of using the proposed system to enhance anaerobic digestion at industrial plants for bioenergy production.


Subject(s)
Manihot , Wastewater , Anaerobiosis , Bioreactors , Methane , Waste Disposal, Fluid
6.
Molecules ; 27(1)2022 Jan 02.
Article in English | MEDLINE | ID: mdl-35011500

ABSTRACT

Developing an ideal and cheap adsorbent for adsorbing heavy metals from aqueous solution has been urgently need. In this study, a novel, effective and low-cost method was developed to prepare the biochar from lettuce waste with H3PO4 as an acidic activation agent at a low-temperature (circa 200 °C) hydrothermal carbonization process. A batch adsorption experiment demonstrated that the biochar reaches the adsorption equilibrium within 30 min, and the optimal adsorption capacity of Cd(II) is 195.8 mg∙g-1 at solution pH 6.0, which is significantly improved from circa 20.5 mg∙g-1 of the original biochar without activator. The fitting results of the prepared biochar adsorption data conform to the pseudo-second-order kinetic model (PSO) and the Sips isotherm model, and the Cd(II) adsorption is a spontaneous and exothermic process. The hypothetical adsorption mechanism is mainly composed of ion exchange, electrostatic attraction, and surface complexation. This work offers a novel and low-temperature strategy to produce cheap and promising carbon-based adsorbents from organic vegetation wastes for removing heavy metals in aquatic environment efficiently.


Subject(s)
Cadmium/chemistry , Charcoal/chemistry , Lactuca/chemistry , Water Pollutants, Chemical/chemistry , Water Purification , Phosphoric Acids/chemistry
7.
Chemistry ; 27(29): 7908-7914, 2021 May 20.
Article in English | MEDLINE | ID: mdl-33778989

ABSTRACT

It is highly desirable to design advanced heteroatomic doped porous carbon for wide application. Herein, N-doped porous carbon (NPC) was developed via the fabrication of high nitrogen cross-linked triazine polymers followed by pyrolysis and activation with controllable porous structure. The as-synthesized NPC at the pyrolysis temperature of 700 °C possessed rich nitrogen content (up to 11.51 %) and high specific surface area (1353 m2 g-1 ), which led to a high CO2 adsorption capability at 5.67 mmol g-1 at 298.15 K and 5 bar pressure and excellent stability. When the activation temperature was at 600 °C, such NPC exhibited a superior electrochemical performance as anode for supercapacitors with a specific capacitance of 158.8 and 113 F g-1 in 6 M KOH at a current density of 1 and 10 A g-1 , respectively. Notably, it delivered an excellent stability with capacity retention of 97.4 % at 20 A g-1 after 6000 cycles.

8.
Phys Chem Chem Phys ; 23(24): 13623-13632, 2021 Jun 23.
Article in English | MEDLINE | ID: mdl-34115084

ABSTRACT

Vacancy defects are inevitable when synthesizing two-dimensional (2D) materials, and vacancy defects greatly affect the physical properties, such as magnetism and electronic properties. Currently, sufficient information is not available on whether and how the interaction of vacancy defects affects material properties and how to control these defects and their associated interaction for the development of new materials. In this study, the interaction between two adjacent vacancy defects of the gallium sulfide (GaS) monolayer is investigated using first-principles calculations based on density functional theory (DFT). The results indicate that the localized size of a Ga vacancy defect is the area within the S atoms second nearest to the neighboring vacancy defect. When the localized sizes of Ga vacancy defects intersect, a non-negligible interaction exists between the Ga vacancy defects. The interaction generally has been ignored by the traditional defect concentrations model but would affect the magnetic and electronic properties of the defective GaS monolayer. A vacancy defect cluster model (VDCM) is developed based on the system clustering method and then used to evaluate the interactions between vacancy defects. In order to check the reliability of the model, this research studies a defective MoS2 monolayer as an example and compares the band gap and density of states (DOS) calculated by using different vacancy defect models, including VDCM. The results indicate that VDCM has good accuracy relative to the traditional vacancy concentration model. This means that with the help of VDCM the properties of the defective system could be calculated more accurately considering some extent of nonuniform distribution of defects based on DFT.

9.
Environ Res ; 202: 111659, 2021 11.
Article in English | MEDLINE | ID: mdl-34246642

ABSTRACT

Electrolytic manganese residue (EMR) is a kind of solid waste with a high silicon content. Most of the silicon in EMR, however, exist in the state of SiO2, which cannot be directly absorbed by plants. Currently, it is very challenge to recover the silicon from EMR. In this study, a preliminary screening of strains with silicon-activating ability was conducted, and four strains were screened out and isolated from the soil around the tailings pond of EMR. Then, single factor experiments were conducted to obtain the optimal growth conditions of the four strains, and the results indicated that the Ochrobactrum sp. T-07 had the best silicon-activating ability from EMR after nitrosoguanidine mutagenesis (Ochrobactrum sp. T-07-B). The available silicon (in terms of SiO2) in the leaching solution was up to 123.88 mg L-1, which was significantly higher than that produced by Bacillus circulans and Paenibacillus mucilaginosus, the two commercial available pure culture strains. Results of direct/indirect contact experiments between Ochrobactrum sp. T-07-B and EMR revealed that bioleaching was promoted under the synergistic effect of bacteria growth on the surface of and metabolism within EMR. The newly isolated strains with silicon-activating effect are different from the existing-known silicate bacteria and may be used for more efficient silicon activation in silicate minerals.


Subject(s)
Manganese , Paenibacillus , Bacillus , Silicon , Silicon Dioxide
10.
J Environ Manage ; 296: 113246, 2021 Oct 15.
Article in English | MEDLINE | ID: mdl-34271353

ABSTRACT

Nitrogen and phosphorous are indispensable for growth and vitality of living beings, hence termed as nutrients. However, discharge of nutrient rich waste streams to aquatic ecosystems results in eutrophication. Therefore, nutrient removal from wastewater is crucial to meet the strict nutrient discharge standards. Similarly, nutrient recovery from waste streams is vital for the realization of a circular economy by avoiding the depletion of finite resources. This manuscript presents analysis of existing information on different conventional as well as advanced treatment technologies that are commonly practiced for the removal of nutrient from domestic wastewater. First, the information pertaining to the biological nutrient removal technologies are discussed. Second, onsite passive nutrient removal technologies are reviewed comprehensively. Third, advanced nutrient removal technologies are summarized briefly. The mechanisms, advantages, and disadvantages of these technologies along with their efficiencies and limitations are discussed. An integrated approach for simultaneous nutrient removal and recovery is recommended. The fifth section of the review highlights bottlenecks and potential solutions for successful implementation of the nutrient removal technologies. It is anticipated that the review will offer an instructive overview of the progress in nutrient removal and recovery technologies and will illustrate necessity of further investigations for development of efficient nutrient removal and recovery processes.


Subject(s)
Ecosystem , Wastewater , Bioreactors , Denitrification , Nitrogen , Nutrients , Phosphorus , Waste Disposal, Fluid
11.
Ecotoxicol Environ Saf ; 191: 110145, 2020 Mar 15.
Article in English | MEDLINE | ID: mdl-31954214

ABSTRACT

Arsenic (As) and antimony (Sb) are listed as the priority pollutants by the U.S. Environmental Protection Agency (EPA) and the European Union (EU) due to their toxicity and potential carcinogenicity. It is necessary to investigate their adsorption over soil as such a behavior affects their mobility and bioavailability. In this study, the effect of pH on the adsorption of As(V) and Sb(V) by the black soil was investigated with three systems: the Single system, Binary system, and Sequence system. The operating pH was set at 4.0, 7.0 and 10.0. Based on the Langmuir isothermal and the pseudo-second-order kinetic models, the adsorption for As(V) was always better than Sb(V) in the whole pH range; the best adsorption performance for the two sorbates was achieved at pH of 4.0, followed by 7.0 and 10.0 in the three systems. The reasons could be that the atomic radius of arsenic is smaller than that of antimony, and the positively charged functional groups carried by the inorganic colloids in the soil contributed to binding with the negatively charged As(V)/Sb(V). A lower pH promoted the inorganic colloids to carry more positive charges. Compared to Single system, the maximum adsorption capacity (qm) and the initial adsorption rates (k2qe,cal2) of As(V) and Sb(V) in Binary system decreased obviously, suggesting competitive adsorption occurred when As(V) and Sb(V) coexisted. The findings of this workimprove the understanding of As(V)/Sb(V) adsorption behavior in soil under different situations and would facilitate a comprehensive evaluation on the risk assessment of arsenic and antimony.


Subject(s)
Antimony/analysis , Arsenic/analysis , Soil Pollutants/analysis , Adsorption , Hydrogen-Ion Concentration , Kinetics , Soil/chemistry
12.
Water Sci Technol ; 80(5): 892-901, 2019 Sep.
Article in English | MEDLINE | ID: mdl-31746796

ABSTRACT

Characteristics of Chlorella sorokiniana treating wastewater with consideration of HRT (6 d, 16 h, 8 h), hydraulic conditions, light or dark culture were evaluated and compared with activated sludge. Results showed that optimal HRT was 8 h; if longer, effluent chemical oxygen demand (COD) and NH4 +-N in the dark began to rebound. Mixing was beneficial to COD removal of algae, while aeration was suitable for nutrient removal. Growth of C. sorokiniana in the light was mixotrophic growth and 1.3-1.7 times more than that of dark heterotrophic growth. The maximum specific growth rate (µmax), productivity, and biomass yields on COD (YCOD), N (YNH4), P (YP) of algae were higher in the light than that in the dark. COD assimilation capacity of algae was similar to activated sludge but with different dynamics. N and P assimilation capacity of algae was 1.4, 1.2-2.5 times more than activated sludge; N and P removal efficiency of algae was 5%-10%, 10%-55% respectively higher than activated sludge. This study confirmed the advantage of algae over activated sludge and reveal why algae could assist the activated sludge process.


Subject(s)
Chlorella , Wastewater , Biological Oxygen Demand Analysis , Bioreactors , Heterotrophic Processes , Sewage , Waste Disposal, Fluid
13.
J Environ Manage ; 223: 825-833, 2018 Oct 01.
Article in English | MEDLINE | ID: mdl-29986330

ABSTRACT

The present article reports the treatment of resorcinol using a catalytic wet peroxidation (CWPO) process in the presence of copper impregnated granular activated carbon (Cu/GAC) with a bench-scale batch reactor. The typical physico-chemical properties of synthesized catalyst were characterized with different equipment and methods. 90% resorcinol removal and 81% of TOC removal was achieved at optimum conditions (pH = 6, the stoichiometric ratio of H2O2/resorcinol = 1.2, catalyst dose = 0.5 g/L, initial concentration of resorcinol = 100 mg/L, temperature = 70 °C and time t = 4 h). Fourier-transform infrared spectroscopy (FTIR) measurements revealed that GAC posses various conjugated hydrocarbon groups including aromatic hydrocarbons, carboxylic groups, carboxyl and carbonate. Cu/GAC catalyst has a surface smoother than that of pristine GAC. At neutral or natural pH (∼6.4) of resorcinol, CWPO of resorcinol is favorable by Cu/GAC catalyst. Catalyst stability study revealed that Cu/GAC sustain its catalytic reactivity to over 76% in the five cycles without any regeneration. The thermogravimetric analysis confirmed that 350 °C temperature found to be optimum for calcination of Cu/GAC without any major losses. The mineralization mechanism was proposed based on intermediates identified during CWPO reaction.


Subject(s)
Copper/chemistry , Resorcinols/chemistry , Water Pollutants, Chemical/chemistry , Adsorption , Carbon , Charcoal , Hydrogen Peroxide , Oxidation-Reduction
14.
Water Sci Technol ; 78(11): 2338-2348, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30699085

ABSTRACT

Effects of different C/N (NO2 -N) ratios on nitrogen removal and microbial community structure were investigated using an anaerobic baffled reactor (ABR). Results indicated that the C/N ratio exerted an important effect on nitrogen removal in the anammox-coupling-denitrification process associated with the ABR. When the C/N ratio was 1.29, the ABR could achieve the highest total nitrogen (TN) removal efficiency of 99.9%. Most of TN was removed in the 1st and 2nd compartment, accounting for about 81.0-97.6% of total TN removal. The nitrogen removal resulted from the interaction among anammox, heterotrophic denitrificans, and other microbes within the ABR. The contribution of anammox to nitrogen removal varied from 6.8% to 32.4%. High-throughput MiSeq sequencing analyses revealed that the C/N ratio was one of the most important factors regulating the microbial community structure, and the predominant phylum changed from Proteobacteria to Chloroflexi with the elevated C/N ratio. In addition, the Candidatus Brocadia was the major anammox bacterium, and its percentage varied from 1.0-2.9% at day 9 to 2.8-9.1% at day 46.


Subject(s)
Bioreactors , Microbiota , Waste Disposal, Fluid/methods , Bacteria , Carbon , Denitrification , Nitrogen/analysis , Oxidation-Reduction
15.
Water Environ Res ; 89(1): 43-50, 2017 Jan 01.
Article in English | MEDLINE | ID: mdl-28236827

ABSTRACT

Effects of hydraulic retention time (HRT) and nitrogen loading rate (NLR) on performance of anammox UASBs amended with spherical plastic and bamboo charcoal carriers were investigated. During the experimental period, the performance of reactors was continuously evaluated by monitoring ammonium-N, nitrite-N, and nitrate-N at HRT of 48, 36, 24, and 12 hours. With HRTs between 24 and 48 hours, the ammonium-N and nitrite-N removal efficiency was higher than 99%, while the total nitrogen (TN) removal efficiency was almost higher than 90%. When HRT decreased to 12 hours with NLR increasing to 0.16 kg N m-3 d-1, ammonium-N, and TN removal efficiency decreased to 87 and 80%, respectively. Moreover, phylogenetic analysis revealed anammox community still existed at the HRT of 12 hours and was most closely related to C. Brocadia sp.40. In addition, different types of carriers had no significant influence on the anammox community.


Subject(s)
Ammonium Compounds/metabolism , Bacteria/metabolism , Nitrates/metabolism , Nitrites/metabolism , Nitrogen/metabolism , Anaerobiosis , Bacteria/classification , Bioreactors , Oxidation-Reduction , Phylogeny , Time Factors
16.
Water Sci Technol ; 76(11-12): 2895-2906, 2017 Dec.
Article in English | MEDLINE | ID: mdl-29210677

ABSTRACT

In this study, surfactant modified zeolite-clinoptilolite (SMZ) by CPB (cetylpyridinium bromide) was used for simultaneous removal of ammonium, nitrate and phosphate in synthetic wastewater, and the sorption properties of SMZ were determined and compared with natural zeolite. Results showed that natural clinoptilolite had good affinity for ammonium (8.940 mg/g), but not for nitrate (0.427 mg/g) and phosphate (0.801 mg/g). With the increase of surfactant loading from 5 g/L to 40 g/L, the sorption capacity for nitrate increased from 0.462 mg/g to 4.661 mg/g. when the surfactant loading is 40 g/L, the SMZ has a phosphate adsorption capacity of 2.119 mg/g. The SMZ had a significant enhancement on nitrate and phosphate sorption, could simultaneously remove ammonium, nitrate and phosphate at specific conditions, with removal efficiency up to 85.2%, 83.1% and 56.7%, respectively. Orthogonal experiments showed that ammonium concentration was the most important factor for ammonium sorption on SMZ. Surfactant loading was the major factor for nitrate and phosphate sorption. With the increase of surfactant loading from 5 g/L to 40 g/L, the sorption capacity for nitrate increased from 0.462 mg/g to 4.661 mg/g. When the surfactant loading is 40 g/L, the SMZ has the best phosphate adsorption capacity 2.119 mg/g. Samples were characterized by X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET). Semi-empirical quantum mechanics molecular simulation indicated that electrostatic attraction existed between CPB and dihydrogen phosphate ion. Results indicate that SMZs might have great potential of removing cations and anions simultaneously in the aquatic environment, which is good for eutrophication control and nutrients removal.


Subject(s)
Cetylpyridinium/chemistry , Nitrogen/chemistry , Phosphorus/chemistry , Zeolites/chemistry , Adsorption , Ammonium Compounds/chemistry , Nitrates , Surface-Active Agents , Water Pollutants, Chemical/chemistry , Water Purification/methods , X-Ray Diffraction
17.
Water Sci Technol ; 72(11): 1931-9, 2015.
Article in English | MEDLINE | ID: mdl-26606086

ABSTRACT

In this study, surfactant (hexadecyltrimethylammonium, HDTMA) modified zeolite (clinoptilolite) (SMZ) was used for simultaneous removal of ammonium and nitrate in wastewater, and the sorption properties of SMZ were determined. Results showed that natural clinoptilolite had good affinity for ammonium, but low sorption ability for nitrate, and the ammonium sorption process was well described by the pseudo-second order kinetic model. The SMZ had a significant enhancement on nitrate sorption and could simultaneously remove ammonium and nitrate at specific conditions, with removal efficiency up to 93.6% and 81.8%, respectively. The sorption process fitted well with the Langmuir isotherm. Orthogonal experiments showed that ammonium concentration was the most important factor for ammonium sorption on SMZ. However, surfactant loading was the major factor for nitrate sorption. Meanwhile, phosphate did not interfere with nitrate removal. Semi-empirical quantum mechanics molecular simulation indicated that electrostatic attraction existed between HDTMA and nitrate. Results of this study demonstrated that SMZs may have great potential for removing cations and anions simultaneously in the aquatic environment.


Subject(s)
Ammonium Compounds/chemistry , Environmental Restoration and Remediation/methods , Nitrates/chemistry , Zeolites/chemistry , Adsorption , Environmental Restoration and Remediation/instrumentation , Kinetics , Polymethacrylic Acids , Quaternary Ammonium Compounds , Surface-Active Agents/chemistry
18.
Water Environ Res ; 96(2): e10993, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38348629

ABSTRACT

Effects of total vermibed depth, as well as the ratio of aerobic (the unsubmerged) to anaerobic (the submerged) zone on the performance of the horizontal subsurface flow macrophyte-assisted vermifilters (HSSF-MAVFs) treating synthetic brewery wastewater at a higher hydraulic loading rate (HLR), were investigated for the first time. Results showed that the HSSF-MAVF with a 50 cm total and 18 cm submerged vermibed depth yielded the optimum removal of the pollutants, ensuring a (91.2 ± 1.7)%, (81.8 ± 1.9)%, (67.4 ± 3.9)%, and (63.1 ± 2.3)% removal of chemical oxygen demand (COD), ammonium N (NH4 + -N), total N (TN), and organic N, respectively, whereas there was an increase of (142 ± 6.3)% in the effluent nitrate-N (NO3 - -N) than that in the influent. At the optimum condition, the effluent concentrations of all the pollutants including COD, NH4 + -N, NO3 - -N, TN, and organic N were well below the surface water discharge standards specified by the Central Pollution Control Board (CPCB), and thus, the effluent of the HSSF-MAVF could be safely discharged into the surface water bodies. PRACTITIONER POINTS: Total vermibed depth of HSSF-MAVFs was optimized for organic and nitrogen removal. HSSF-MAVFs were subjected to the higher HLR of synthetic brewery wastewater. Removal of COD and NH4 + -N was decreased with the increase in submerged bed depth. Removal of organic N and TN was increased with the increase in submerged bed depth. Total/unsubmerged bed depth had a positive impact on the organic and N removal.


Subject(s)
Environmental Pollutants , Wastewater , Waste Disposal, Fluid/methods , Anaerobiosis , Nitrogen , Bioreactors , Water , Denitrification
19.
Sci Total Environ ; 919: 170770, 2024 Apr 01.
Article in English | MEDLINE | ID: mdl-38340823

ABSTRACT

Antibiotic resistance genes (ARGs) may be synergistic selected during bio-treatment of chromium-containing wastewater and causing environmental risks through horizontal transfer. This research explored the impact of self-screening bacterium Acinetobacter sp. SL-1 on the treatment of chromium-containing wastewater under varying environmental conditions. The findings indicated that the optimal Cr(VI) removal conditions were an anaerobic environment, 30 °C temperature, 5 g/L waste molasses, 100 mg/L Cr(VI), pH = 7, and a reaction time of 168 h. Under these conditions, the removal of Cr(VI) reached 99.10 %, however, it also developed cross-resistance to tetracycline, gentamicin, clarithromycin, ofloxacin following exposure to Cr(VI). When decrease Cr(VI) concentration to 50 mg/L at pH of 9 with waste molasses as carbon source, the expression of ARGs was down regulated, which decreased the horizontal transfer possibility of ARGs and minimized the potential environmental pollution risk caused by ARGs. The study ultimately emphasized that the treatment of chromium-containing wastewater with waste molasses in conjunction with SL-1 not only effectively eliminates hexavalent chromium but also mitigates the risk of environmental pollution.


Subject(s)
Acinetobacter , Catechols , Wastewater , Anti-Bacterial Agents/metabolism , Molasses , Carbon/metabolism , Acinetobacter/metabolism , Chromium/metabolism , Drug Resistance, Microbial , Biodegradation, Environmental
20.
Int J Biol Macromol ; 269(Pt 1): 132078, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38705332

ABSTRACT

The remarkable characteristics of porous biochar have generated significant interest in various fields, such as CO2 capture and supercapacitors. The modification of aerogel-derived porous biochar through activation and heteroatomic doping can effectively enhance CO2 adsorption and improve supercapacitor performance. In this study, a novel N, B-co-doped porous biochar (NBCPB) was synthesized by carbonating and activating the N, B dual-doped cellulose aerogel. N and B atoms were doped in-situ using a modified alkali-urea method. The potassium citrate was served as both an activator and a salt template to facilitate the formation of a well-developed nanostructure. The optimized NBCPB-650-1 (where 650 corresponded to activation temperature and 1 represented mass ratio of potassium citrate activator to carbonized NBCPB-400 precursor) displayed the largest micropore volume of 0.40 cm3·g-1 and a high specific surface area of 891 m2·g-1, which contributed to an excellent CO2 adsorption capacity of 4.19 mmol·g-1 at 100 kPa and 25 °C, a high CO2/N2 selectivity, and exceptional reusability (retained >97.5 % after 10 adsorption-desorption cycles). Additionally, the NBCPB-650-1 electrode also delivered a high capacitance of 220.9 F·g-1 at 1 A·g-1. Notably, the symmetrical NBCPB-650-1 supercapacitor exhibited a high energy density of 9 Wh·kg-1 at the power density of 100 W·kg-1. This study not only presents the potential application of NBCPB-650-1 material in CO2 capture and electrochemical energy storage, but also offers a new insight into easy-to-scale production of heteroatomic-modified porous biochar.


Subject(s)
Carbon Dioxide , Cellulose , Charcoal , Electric Capacitance , Nitrogen , Carbon Dioxide/chemistry , Charcoal/chemistry , Porosity , Cellulose/chemistry , Adsorption , Nitrogen/chemistry , Gels/chemistry , Electrodes
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