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1.
J Hazard Mater ; 402: 123498, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32712366

RESUMO

N-doped nanoporous carbon (NC) with two-dimensional structure derived from Zn-ZIF-L via KCl exfoliation and carbonization at different temperature were prepared for adsorptive removal of tetracycline (TC). Characterizations revealed the effective dopant of N atoms and low degree of graphitization with more defects related to the enhanced adsorption capacity of the NC materials. Benefiting from the huge surface area (2195.57 m2 g-1), high porosity (1.34 cm3 g-1) and accessible sheeting structure, the NC-800 exhibited its fast and efficient adsorption of TC in 60 min. Meantime, the maximum adsorption of TC could reach 347.06 mg g-1. Effects of pH, humic acid (HA) and ionic strength (Na+, Ca2+) were studied along with the interactions among influencing factors investigated by response surface model (RSM). By optimizing experimental conditions from RSM, the adsorption capacity could increase to 427.41 mg g-1. Additionally, electrostatic interaction and hydrogen bond interaction might play a dominating role in adsorption reaction. The NC-800 could maintain a high adsorption level after four cycles. Therefore, the NC-800 with great adsorptive property and reusability could be considered as an effective adsorbent with promising potential in applications for water treatment.

2.
J Colloid Interface Sci ; 581(Pt A): 195-204, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32771731

RESUMO

Compared with the transition metal induced homogeneous catalytic system, the heterogeneous catalytic system based on transition metal-doped metal organic frameworks (MOFs) were stable for the efficient utilization of transition metal and avoiding the metal leaching. The aim of this work is to synthesize Co-doped MIL-53(Al) by one-step solvent thermal method and use it to activate peroxymonosulfate (PMS) to remove tetracycline (TC) in water. The successful synthesis of Co-MIL-53(Al) samples was demonstrated by XDR, SEM and FTIR characterizations. The 25% Co-MIL-53(Al)/PMS system showed the optimal TC removal effect compared to the PMS alone and MIL-53(Al)/PMS system. The catalytic performances of Co-MIL-53(Al)/PMS system in conditions of different pH, co-existing substances and water bodies were investigated. Quenching experiment and electron paramagnetic resonance (EPR) showed that the degradation mechanism by Co-MIL-53(Al) activation PMS was mainly attributed to sulfate radical (SO4•-) and singlet oxygen (1O2) non-radical. The degradation intermediates of TC were also identified and the possible degradation pathways were proposed. Co-MIL-53(Al) showed good activity after four cycles. These findings demonstrated that Co-MIL-53(Al) can be a promising heterogeneous catalyst for activating PMS to degrade TC.

3.
J Colloid Interface Sci ; 580: 470-479, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32711198

RESUMO

Herein, Mn-doped MIL-53(Fe) were fabricated via one-pot solvothermal method and used for peroxymonosulfate (PMS) activation towards tetracycline (TC) degradation from aqueous solution. The characterizations of SEM, FTIR and XRD were utilized to reveal the morphology and structure of the materials. The results showed that Mn-MIL-53(Fe)-0.3 displayed the optimal catalytic performance, the removal efficiency of TC could reach 93.2%. Moreover, the catalytic activity of Mn-MIL-53(Fe) towards TC under different initial pH values, co-existing anions (Cl-,CO32- and SO42-) and humic acid (HA) were investigated. The results of thermodynamic experiment suggested that the catalytic process was endothermic. In addition, integrated with capture experiments results and the characterization results of electron paramagnetic resonance (EPR), which revealed that SO4·- and HO- were the reactive radicals involving in the reaction. More importantly, the possible activation mechanism was discussed in detail based on the X-ray photoelectron spectroscopy results. The active species were generated by the active sites of Fe(II) and Mn(II) on Mn-MIL-53(Fe) effectively activated PMS. Furthermore, the degradation intermediates and possible degradation pathway were investigated by LC-MS. Finally, the catalyst also showed good performance in actual wastewater and demonstrated good recyclability. The Mn-MIL-53(Fe)/PMS system exhibited a promising application prospect for antibiotic-containing waste water treatment.

4.
Sci Total Environ ; 724: 138248, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32247117

RESUMO

In this work, we investigated the impact of iron nanoparticle, including magnetite nanoparticles (Fe3O4 NPs) and nanoscale zero-valent iron (nZVI), on the anaerobic digestion (AD) performance. Moreover, the evolutions of antibiotic resistance genes (ARGs), class 1 integrons-integrase (intI1) and potential hosts of ARGs were also investigated. The optimal addition of Fe3O4 NPs and nZVI to promote methane production was 0.5 g/L and 1 g/L, which led to 22.07% and 23.02% increase in methane yield, respectively. The degradation rate of organic matter was also enhanced with the addition of Fe3O4 NPs or nZVI. The results of high-throughput sequencing showed that the reactors with iron NPs exhibited significant differences in microbial community structure, compared to the reactors with the non­iron NPs. Iron NPs have caused the relative abundance of the dominant bacteria (Proteobacteria, Firmicutes and Actinobacteria) generally decreased, while the dominant archaea (Euryarchaeota) increased in AD sludge. Quantitative PCR results revealed that iron NPs accelerated the reductions in total absolute abundance of ARGs, especially a beta-lactamase resistance encoded gene (blaOXA). Network analysis displayed that the attenuation of ARGs was mainly attributed to the decline of potential hosts (Proteobacteria, Firmicutes and Actinobacteria). Meanwhile, environmental factors (such as pH, soluble chemical oxygen demand and heavy metals) were also strongly correlated with ARGs.


Assuntos
Integrons , Nanopartículas , Anaerobiose , Antibacterianos/farmacologia , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Genes Bacterianos/efeitos dos fármacos , Integrases/farmacologia , Ferro/farmacologia , Esgotos
5.
Sci Rep ; 9(1): 8880, 2019 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-31222038

RESUMO

In this study, the adsorption and UV photocatalytic degradation of atrazine using nano-TiO2 particles were studied systematically, and the colloidal stability of nano-TiO2 particles in solution was also investigated to reveal the removal mechanism. Experiments which contained the first 6.0 hours darkness and 4.0 hours UV illumination later were conducted at different concentrations of Ca2+ and/or fulvic acids (FA) at pH = 7.0. Results showed that the adsorption rate of atrazine onto nano-TiO2 particles decreased with the increase of Ca2+ and/or FA concentrations, which could be explained well by the colloidal stability of nanoparticles. When the solution contained Ca2+ or Ca2+-FA, the nanoparticles were aggregated together leading to the decrease of the contact surface area. Besides, there existed competitive adsorption between FA and atrazine on the particle surface. During photocatalytic degradation, the increase of Ca2+ and/or FA concentration accelerated the aggregation of nano-TiO2 particles and that reduced the degradation efficiency of atrazine. The particle sizes by SEM were in accordance with the aggregation degree of nanoparticles in the solutions. Sedimentation experiments of nano-TiO2 particles displayed that the fastest sedimentation was happened in the CaCl2 and FA coexistent system and followed by CaCl2 alone, and the results well demonstrated the photodegradation efficiency trends of atrazine by nano-TiO2 particles under the different sedimentation conditions.

6.
Huan Jing Ke Xue ; 30(1): 120-6, 2009 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-19353868

RESUMO

The difference of sequencing batch biofilm reactor (SBBR) performance and nitrogen transformation mechanism which caused by four different influent patterns were researched. Through variance analysis of SBBR performance, microbial community structure and nitrogen transformation, the results indicated that, on the one hand the dispersed influent pattern displayed higher anti-load ability than the centralized one, under the same efficiency, COD and ammonia load of the dispersed M4 reached 2540 mg x (L x d)(-1) and 540 mg x (L x d)(-1) respectively compared with 2000 mg x (L x d)(-1) and 420 mg x (L x d)(-1) by the centralized M1; on the other hand, considering the dispersed influent pattern, the closer influent mood was to the cycle mood of operation, the higher the nitrogen transformation efficiency was, which finally led residual nitrogen concentration declined.


Assuntos
Bactérias Anaeróbias/metabolismo , Reatores Biológicos , Nitrogênio/metabolismo , Eliminação de Resíduos Líquidos/métodos , Bactérias Anaeróbias/genética , Biofilmes , Nitrogênio/química
7.
Huan Jing Ke Xue ; 29(7): 1860-6, 2008 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-18828367

RESUMO

At the high level of dissolved oxygen (DO) in sequencing batch biofilm reactor (SBBR), the approach and mechanism for realizing shortcut nitrification were researched. Landfill leachate was used as handling of object, the mainly environment parameters of the reactor were controlled as follow: DO 5 mg/L, pH 7.0, temperature 25 degrees C, adopted all drainage mode and 12-hour cycle influent. Through mathematical derivation and modeling analysis, determined free ammonia (FA), CO2 and HNO2 as the direct control factors, whereas the influent cycle time was the indirect one, shortcut nitrification was achieved effectively in SBBR. When the volume load of ammonia (NH4(+) -N) was 0.52 kg/(m3 x d) and NaHCO3 was 1.5 mg/L in the reactor, the shortcut nitrification effect was apparent as NH4(+) -N conversion rate was 89% and NO2(-) -N accumulation rate achieved 83% at the same time. With adequate oxygen supply, the key factors of achieving NO2(-) -N accumulation is FA concentration, and as the carbon source of ammonia-oxidizing bacteria, CO2 can upgrade the reactor performance further.


Assuntos
Amônia/isolamento & purificação , Reatores Biológicos/microbiologia , Nitrogênio/isolamento & purificação , Oxigênio/metabolismo , Amônia/química , Bactérias Aeróbias/metabolismo , Bactérias Aeróbias/fisiologia , Biodegradação Ambiental , Biofilmes , Nitrobacter/metabolismo , Nitrobacter/fisiologia , Nitrogênio/química , Eliminação de Resíduos Líquidos/métodos
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