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1.
J Hazard Mater ; 423(Pt B): 127158, 2022 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-34555765

RESUMO

Nanotechnology has provided a new opportunity for water decontamination from trace heavy metals, yet the relatively poor acidic stability remains a major obstacle for the nano-adsorbents, given that acidic treatment is frequently used to regenerate the heavy metal-saturated adsorbents. Zirconium phosphate (ZrP) is very promising for water treatment due to its absolute insoluble nature, though it interacts with heavy metals mainly through the non-specific electrostatic attraction. Herein, we prepared the ultrafine ZrP (~3.9 nm) inside the commercially available gel-type cation exchanger (N001), i.e., the sulfonated poly(styrene-co-divinylbenzene) bead. The resultant nanocomposite ZrP@N001 contained the amorphous nanoparticles (NPs) with metastable γ-ZrP structure as the main phase, unlike the layered α-ZrP formed inside the macroporous cation exchanger D001 (referred to as ZrP@D001). As a result, ZrP@N001 could selectively adsorb heavy metals through inner-sphere coordination, possessing a much stronger adsorption affinity than ZrP@D001, as confirmed by XPS analysis. In both batch and column assays on the Pb(II)-polluted water, ZrP@N001 exhibited superior adsorption performance over ZrP@D001. After adsorption, the exhausted ZrP@N001 was fully refreshed by acidic treatment for a 5-cyclic adsorption-regeneration run with constant removal efficiencies. This study may open a door for the rational design of highly efficient water purifiers for heavy metal control.

2.
Artigo em Inglês | MEDLINE | ID: mdl-34799948

RESUMO

Metal-organic frameworks (MOFs) membranes with high pore density and tunable pore size down to the subnanoscale exhibit great potential in ion separation when appropriately designed and prepared. By a washing-assisted secondary growing method, a well intergrown UiO-67 membrane with preferential growth along the [022] direction was synthesized on a polyvinylpyrrolidone (PVP)-modified AAO substrate. Because of the oriented growth of UiO-67 nanocrystals, highly interconnected ion-transporting channels are created throughout the UiO-67/AAO membrane capable of achieving an ultrahigh Li+ permeance of 27.01 mol m-2 h-1 as well as very decent Li+ /Mg2+ selectivity of up to 159.4. Molecular dynamics simulations reveal that the high selectivity is associated with the large disparity of the transport energy barrier between Li+ and Mg2+ , which is caused by different extents of ion dehydration in unique bimodal and oriented membrane channels.

3.
Nanotechnology ; 33(7)2021 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-34763330

RESUMO

Controllable synthesis, proper dispersion, and feasible functionalization are crucial requirements for the application of nanomaterials in many scenarios. Here, we report an all-in-one approach for the synthesis and functionalization of gold nanoparticles (AuNPs) with the simplestß-diketone, acetylacetone (AcAc). With this approach, the particle size of the resultant AuNPs was tunable by simply adjusting the light intensity or AcAc dosage. Moreover, owing to the capping role of AcAc, the resultant AuNPs could be stably dispersed in water for a year without obvious change in morphology and photochemical property. Formation of ligand to metal charge transfer complexes was found to play an important role in the redox conversion of Au with AcAc. Meanwhile, the moderate complexation ability enables the surface AcAc on the AuNPs to undergo ligand exchange reactions (LER). With the aid of Ag+, the AuNPs underwent LER with glutathione and exhibited enhanced photoluminescence (PL) with a maximum of 22-fold increase in PL intensity. The PL response was linear to the concentration of glutathione in the range of 0-500µM. Such a LER makes the obtained AuNPs being good imaging probes. To the best of our knowledge, this is the first work on illustrating the roles of AcAc as a multifunctional ligand in fabrication of NPs, which sheds new light on the surface modulation in synthesis of nanomaterials.

4.
Environ Sci Technol ; 55(21): 14494-14514, 2021 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-34669394

RESUMO

The presence of diverse pollutants in water has been threating human health and aquatic ecosystems on a global scale. For more than a century, chemical oxidation using strongly oxidizing species was one of the most effective technologies to destruct pollutants and to ensure a safe and clean water supply. However, the removal of increasing amount of pollutants with higher structural complexity, especially the emerging micropollutants with trace concentrations in the complicated water matrix, requires excessive dosage of oxidant and/or energy input, resulting in a low cost-effectiveness and possible secondary pollution. Consequently, it is of practical significance but scientifically challenging to achieve selective oxidation of pollutants of interest for water decontamination. Currently, there are a variety of examples concerning selective oxidation of pollutants in aqueous systems. However, a systematic understanding of the relationship between the origin of selectivity and its applicable water treatment scenarios, as well as the rational design of catalyst for selective catalytic oxidation, is still lacking. In this critical review, we summarize the state-of-the-art selective oxidation strategies in water decontamination and probe the origins of selectivity, that is, the selectivity resulting from the reactivity of either oxidants or target pollutants, the selectivity arising from the accessibility of pollutants to oxidants via adsorption and size exclusion, as well as the selectivity due to the interfacial electron transfer process and enzymatic oxidation. Finally, the challenges and perspectives are briefly outlined to stimulate future discussion and interest on selective oxidation for water decontamination, particularly toward application in real scenarios.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Ecossistema , Humanos , Oxirredução , Poluentes Químicos da Água/análise , Abastecimento de Água
5.
Environ Sci Technol ; 55(20): 14173-14184, 2021 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-34590827

RESUMO

Selective inhibition of photosynthesis is a fundamental strategy to solve the global challenge caused by harmful cyanobacterial blooms. However, there is a lack of specificity of the currently used cyanocides, because most of them act on cyanobacteria by generating nontargeted oxidative stress. Here, for the first time, we find that the simplest ß-diketone, acetylacetone, is a promising specific cyanocide, which acts on Microcystis aeruginosa through targeted binding on bound iron species in the photosynthetic electron transport chain, rather than by oxidizing the components of the photosynthetic apparatus. The targeted binding approach outperforms the general oxidation mechanism in terms of specificity and eco-safety. Given the essential role of photosynthesis in both natural and artificial systems, this finding not only provides a unique solution for the selective control of cyanobacteria but also sheds new light on the ways to modulate photosynthesis.


Assuntos
Cianobactérias , Microcystis , Proliferação Nociva de Algas , Ferro , Oxirredução , Fotossíntese
6.
Langmuir ; 37(32): 9793-9801, 2021 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-34351154

RESUMO

Temporal and spatial segregations are two fundamental requirements for the successful synthesis of nanoparticles (NPs). To obtain colloidally stable selenium nanospheres (SeNSs), surfactants or polymers are generally needed as structure-directing agents or stabilizers in the reduction approaches for SeNP synthesis. The addition of such chemicals sacrifices the purity of the obtained SeNPs and, therefore, is detrimental to the applications. Here, for the first time, we report that low-molecular weight (less than six carbons) diketones are excellent photoreductants for green and tunable synthesis of SeNPs, owing to their merits in temporal and spatial control. With simple diketones as the photoreductants, the resultant SeNPs were pure and colloidally stable with nice photoelectronic properties. This finding not only provides a useful strategy for the synthesis of SeNPs but also might be a milestone in the development of ketone photochemistry.


Assuntos
Nanopartículas , Nanosferas , Selênio , Cetonas , Peso Molecular
7.
Anal Chem ; 93(32): 11116-11122, 2021 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-34346203

RESUMO

The presence of per- and poly-fluoroalkyl substances (PFASs) even at trace levels poses a potential threat to ecological safety and human health. PFASs often require an extraction pretreatment for enrichment before detection and analysis, which is still challenged by the relatively low efficiency because of the limited specific interactions involved. Here, we deliberately introduced multiple interactions into the solid-phase microextraction (SPME) process via a dual-functional modification of MIL-101(Cr), i.e., amination and subsequent fluorination, which is then used as an adsorbent for the efficient enrichment of PFASs. In combination with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), ultrasensitive quantitative analysis is available for nine selected PFASs with high linearities above 0.9941 in the ranges of 0.5-1500 ng/L, low limits of detection of 0.004-0.12 ng/L, satisfactory repeatability and reproducibility with a relative standard deviation (RSD) < 11.6%, as well as excellent performance in complicated real water samples (recovery ratio of 76.2-108.6%). This work represents a rational design of a solid extractant with the desired structure and functionality for the selective enrichment and analysis of PFASs at trace concentrations in real applications.


Assuntos
Estruturas Metalorgânicas , Poluentes Químicos da Água , Cromatografia Líquida de Alta Pressão , Humanos , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem , Poluentes Químicos da Água/análise
8.
Water Res ; 202: 117397, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34246991

RESUMO

The increased release of phosphonates to natural waters causes global concern due to their potential threat to the aquatic environment. It is curial to mineralize phosphonates to orthophosphate (PO43-) before they are thoroughly removed from wastewater via conventional biological treatment. In this study, we systematically investigated the performance and mechanism of degradation of phosphonates in Co(II)-triggered peroxymonosulfate (PMS) activation process. The degradation efficiency of various phosphonates is highly dependent on their coordination with Co(II). Using 1-hydroxyethane 1,1-diphosphonic acid (HEDP) as a target pollutant, the Co(II)/PMS process is effective in a broad solution pH range from 5.0 to 10.0. Multiple experimental results imply that Co(II)-PMS complex is the primary reactive species, while hydroxyl radicals (HO•), sulfate radicals (SO4•-), singlet oxygen (1O2) and Co(III) play as the secondary reactive species for the degradation of HEDP. The presence of Cl-, HCO3-, and natural organic matters (NOM) inhibits the degradation of HEDP. However, in real water samples, the selectivity and efficiency for HEDP removal in the Co(II)/PMS process are higher than that in free radicals-mediated advanced oxidation processes. This study not only sheds new lights on the mechanism of Co(II)-triggered PMS activation process, but also provides feasible technology for the degradation of phosphonates in wastewater.


Assuntos
Organofosfonatos , Poluentes Químicos da Água , Oxirredução , Peróxidos , Águas Residuárias , Poluentes Químicos da Água/análise
9.
Huan Jing Ke Xue ; 42(8): 3847-3857, 2021 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-34309271

RESUMO

As an emerging advanced oxidation technology, UV/chlorine treatment is capable of effectively oxidizing various organic pollutants. Till now, the transformation of dissolved effluent organic matter (dEfOM) in real wastewater during UV/chlorine treatment remains unclear. In this study, ultraviolet and fluorescence spectroscopy were combined with Fourier transform ion cyclotron resonance mass spectrometry to probe the transformation of dEfOM in two municipal secondary effluents during UV/chlorine treatment. Meanwhile, the newly formed chlorinated byproducts (Cl-BPs) are particularly concerned. Generally, aromatic compounds and fluorescent components could be readily removed after UV/chlorine treatment, and most of the dEfOM underwent transformation rather than mineralization. Protein-like components, which accounted for the largest proportion of fluorescent components, were subject to a preferential reaction. UV/chlorine treatment could result in the degradation of CHOS compounds and the formation of CHO compounds. During this process, unsaturated and reduced compounds of large molecules were preferentially removed, whereas saturated and oxidized compounds with low molecular weight were produced. Moreover, the concentrations of trihalomethanes and haloacetic acids increased substantially after UV/chlorine treatment. In total, 255 and 133 Cl-BPs were detected in the respective effluents after UV/chlorine treatment. In addition, 12 and 43 possible precursor-Cl-BPs pairs were identified, respectively, based on electrophilic substitution and addition reactions by means of mass difference analysis. This study is expected to provide fundamental information for practical application of the UV/chlorine treatment process.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Cloro/análise , Desinfecção , Trialometanos , Raios Ultravioleta , Águas Residuárias , Poluentes Químicos da Água/análise
10.
Nat Commun ; 12(1): 3508, 2021 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-34108484

RESUMO

Controlled generation of reactive oxygen species (ROS) is essential in biological, chemical, and environmental fields, and piezoelectric catalysis is an emerging method to generate ROS, especially in sonodynamic therapy due to its high tissue penetrability, directed orientation, and ability to trigger in situ ROS generation. However, due to the low piezoelectric coefficient, and environmental safety and chemical stability concerns of current piezoelectric ROS catalysts, novel piezoelectric materials are urgently needed. Here, we demonstrate a method to induce polarization of inert poly(tetrafluoroethylene) (PTFE) particles ( ~ 1-5 µm) into piezoelectric electrets with a mild and convenient ultrasound process. Continued ultrasonic irradiation of the PTFE electrets generates ROS including hydroxyl radicals (•OH), superoxide (•O2-) and singlet oxygen (1O2) at rates significantly faster than previously reported piezoelectric catalysts. In summary, ultrasonic activation of inert PTFE particles is a simple method to induce permanent PTFE polarization and to piezocatalytically generate aqueous ROS that is desirable in a wide-range of applications from environmental pollution control to biomedical therapy.

11.
Water Res ; 199: 117158, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33975087

RESUMO

Ultraviolet-based advanced oxidation processes (UV-AOPs) are very promising in advanced treatment of municipal secondary effluents. However, the transformation of dissolved effluent organic matter (dEfOM) in advanced treatment of real wastewater, particularly at molecular level, remains unclear. In this study, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) coupled with multiple statistical analysis were performed to better understand the transformation of dEfOM in UV/H2O2, UV/persulfate (UV/PS), and UV/chlorine treatments. An obvious increase in oxygen content of dEfOM was observed after every UV-AOPs treatment, and the detailed oxygenation processes were further uncovered by mass difference analysis based on 24 types of typical reactions. Generally, UV/H2O2 process was subjected to the most oxygenation reactions with the typical tri-hydroxylation one (+3O), whereas di-hydroxylation reaction (+H2O2) was dominant in UV/PS and UV/chlorine processes. Additionally, the three UV-AOPs shared the majority of precursors, and more proportions of unique products were identified for each process. The precursors with lower H/C and higher aromaticity were readily degraded by UV/chlorine over UV/H2O2 and UV/PS, with the products featuring lower molecular weight. Moreover, dEfOM of high aromaticity tended to produce chlorinated byproducts through addition reactions in chlorination and UV/chlorine processes. Among these UV-AOPs, the highest reduction of both acute toxicity and specific UV absorbance at 254 nm (SUVA254) was observed for UV/chlorine, implying the potential for UV/chlorine process in advanced treatment of wastewater. In addition, acute toxicity was highly correlated with SUVA254 and CHOS compounds. This study is believed to help better understand the different fates of dEfOM in real wastewater during UV-AOPs treatment.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Cloro , Peróxido de Hidrogênio , Espectrometria de Massas , Oxirredução , Raios Ultravioleta , Poluentes Químicos da Água/análise
12.
Environ Sci Technol ; 55(12): 8299-8308, 2021 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-34032409

RESUMO

The Fenton reaction is limited by a narrow acidic pH range, the slow reduction of Fe(III), and susceptibility of the nonselective hydroxyl radical (HO•) to scavenging by water constituents. Here, we employed the biodegradable chelating agent picolinic acid (PICA) to address these concerns. Compared to the classical Fenton reaction at pH 3.0, PICA greatly accelerated the degradation of atrazine, sulfamethazine, and various substituted phenols at pH 5.0 in a reaction with autocatalytic characteristics. Although HO• served as the principal oxidant, a high-spin, end-on hydroperoxo intermediate, tentatively identified as PICA-FeIII-OOH, also exhibited reactivity toward several test compounds. Chloride release from the oxidation of 2,4,6-trichlorophenol and the positive slope of the Hammett correlation for a series of halogenated phenols were consistent with PICA-FeIII-OOH reacting as a nucleophilic oxidant. Compared to HO•, PICA-FeIII-OOH is less sensitive to potential scavengers in environmental water samples. Kinetic analysis reveals that PICA facilitates Fe(III)/Fe(II) transformation by accelerating Fe(III) reduction by H2O2. Autocatalysis is ascribed to the buildup of Fe(II) from the reduction of Fe(III) by H2O2 as well as PICA oxidation products. PICA assistance in the Fenton reaction may be beneficial to wastewater treatment because it favors iron cycling, extends the pH range, and balances oxidation universality with selectivity.


Assuntos
Ferro , Oxidantes , Peróxido de Hidrogênio , Cinética , Oxirredução , Ácidos Picolínicos , Água
13.
Environ Sci Technol ; 55(9): 6397-6406, 2021 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-33882668

RESUMO

The catalytic activation of peroxymonosulfate (PMS) is under intensive investigation with potentials as an alternative advanced oxidation process (AOP) in wastewater treatment. Among all catalysts examined, Co(II) exhibits the highest reactivity for the activation of PMS, following the conventional Fenton-like mechanism, in which free radicals (i.e., sulfate radicals and hydroxyl radicals) are reckoned as the reactive species. Herein, we report that the primary reactive species (PRS) is proposed to be a Co(II)-PMS complex (Co(II)-OOSO3-), while free radicals and Co(III) species act as the secondary reactive species (SRS) that play a minor role in the Co(II)/PMS process. This Co(II)-OOSO3- exhibits several intriguing properties including ability to conduct both one-electron-transfer and oxygen-atom-transfer reactions with selected molecules, both nucleophilic and electrophilic in nature, and strongly pH-dependent reactivity. This study provides novel insights into the chemical nature of the Co(II)-catalyzed PMS activation process.


Assuntos
Peróxidos , Purificação da Água , Radicais Livres , Oxirredução
14.
J Hazard Mater ; 414: 125505, 2021 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-33689995

RESUMO

Given high selectivity and excellent stability, zirconium oxides are very promising in selective removal of arsenic, fluorine, and phosphorus from water. Nevertheless, it remains challenging to prepare sub-10 nm zirconium oxides of ultra-high adsorptive reactivity. Herein, we prepared hydrated zirconium oxides (HZO) of 4.88 ± 1.02 nm by conducting in-situ precipitation of nanoparticles (NPs) inside the gel-type anion exchanger (GAE). GAE was swollen in water and contained lots of < 10 nm swollen pores, restricting excess growth of HZO NPs. In comparison, the NPs formed inside the macroporous anion exchanger (MAE) possessed an average diameter of 30.91 ± 8.98 nm. XPS O1s analysis indicated that the oxygen sites in the gel-type nanocomposite (HZO@GAE) possessed a much higher proportion (48.9%) of reactive terminal oxygen (-OH) than the macroporous nanocomposite (HZO@MAE, 21.2%). Thus, HZO@GAE exhibited significantly enhanced adsorption reactivity toward As(V)/As(III) than HZO@MAE. The exhausted HZO@GAE could be fully regenerated by alkali treatment for repeated use without any loss in decontamination efficiency. In column assays, the HZO@GAE column successively produced ~2400 bed volume (BV) clean water ([As]<10 µg/L) from synthetic groundwater, exceeding twice the amount produced by the HZO@MAE column. This study may shed new light on developing highly efficient nanocomposites for water decontamination.

15.
Environ Sci Technol ; 55(3): 2110-2120, 2021 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-33427455

RESUMO

Oxygen vacancies (OVs) play a crucial role in the catalytic activity of metal-based catalysts; however, their activation mechanism toward peroxydisulfate (PDS) still lacks reasonable explanation. In this study, by taking bismuth bromide (BiOBr) as an example, we report an OV-mediated PDS activation process for degradation of bisphenol A (BPA) employing singlet oxygen (1O2) as the main reactive species under alkaline conditions. The experimental results show that the removal efficiency of BPA is proportional to the number of OVs and is highly related to the dosage of PDS and the catalyst. The surface OVs of BiOBr provide ideal sites for the inclusion of hydroxyl ions (HO-) to form BiIII-OH species, which are regarded as the major active sites for the adsorption and activation of PDS. Unexpectedly, the activation of PDS occurs through a nonradical mechanism mediated by 1O2, which is generated via multistep reactions, involving the formation of an intermediate superoxide radical (O2•-) and the redox cycle of Bi(III)/Bi(IV). This work is dedicated to the in-depth mechanism study into PDS activation over OV-rich BiOBr samples and provides a novel perspective for the activation of peroxides by defective materials in the absence of additional energy supply or aqueous transition metal ions.


Assuntos
Oxigênio , Oxigênio Singlete , Catálise , Oxirredução , Peróxidos
16.
J Hazard Mater ; 409: 124920, 2021 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-33412472

RESUMO

Cobalt-mediated activation of peroxymonosulfate (PMS) has been widely used to remove the refractory organic pollutants from contaminated waters. However, the residual cobalt usually at a trace level inevitably brings about secondary pollution to be disposed of. In this study we found that the presence of phosphate could trigger a more efficient catalytic activation of PMS at trace Co2+ dosages (0.17-1.7 µM). Fast degradation of atrazine (ATZ) was observed in the Co2+/PMS/phosphate system, with the pseudo first-order kinetic rate constant as high as 5.4 and 15.4 times that in Co2+/PMS and phosphate/PMS systems respectively under otherwise similar conditions. The presence of phosphate promoted the production of sulfate radical (SO4·-), accompanying the enhanced formation of by-product 1O2 simultaneously. Using a competition reaction kinetics approach, the contribution of SO4·- to ATZ oxidation was determined as 96.5%, suggesting that SO4·- was the main reactive species responsible for ATZ removal. Such favorable effect was partially ascribed to the specific ligand structure of six coordination structure between phosphate and cobalt, which facilitated electron transfer in the CoIII/CoII reduction. In addition, it was dependent upon the aqueous phosphate levels, and low level (< 0.5 mM) was insufficient to drive the CoIII/CoII cycle, whereas the higher level (> 15 mM) showed negative effect since the excessive phosphate could quench SO4·- and·OH. This study is believed to advance the fundamental understanding of the ligand effect on the cobalt-mediated sulfate radicals-based advanced oxidation process.

17.
Ecotoxicology ; 30(7): 1446-1453, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33411164

RESUMO

The bioremoval potential of Pseudomonas plecoglossicida toward mixed contaminants was explored through the coupled biostimulation and bioaugmentation in soil microcosm. Response surface methodology was employed to optimize nutrients and innoculum size for the cometabolic removal of two representative chloroethylenes, trichloroethylene (TCE) and cis-1,2-dichloroethylene (cis-DCE), mixed with benzene, toluene, ethylbenzene, and xylenes (BTEX). The interactive effects of nutrients [nitrogen (N) and phosphorus (P)] and inoculum size toward the bioremoval of mixture of BTEX (600 mg kg-1), cis-DCE (10 mg kg-1), and TCE (10 mg kg-1) were estimated using principal component analysis and two-dimensional hierarchical cluster analysis. The optimal condition was confirmed with C:N:P ratio of 100:26.7:1.8-4.8 and higher inoculum size (≥25%), where 97.7% of benzene, 98.3% of toluene, 91.2% of ethylbenzene, 45.6% of m,p-xylene, 31.2% of o-xylene, 26.9% of cis-DCE, and 33.5% of TCE were bioremoved.


Assuntos
Cloreto de Vinil , Xilenos , Benzeno , Derivados de Benzeno , Biodegradação Ambiental , Argila , Pseudomonas , Solo , Tolueno
18.
Water Res ; 189: 116599, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33166920

RESUMO

Adsorption is a viable technology to remove trace heavy metals from wastewater, but regeneration of adsorbents in an economic and environmentally friendly manner often represents a limiting factor of its application. Compared with traditional strong acid desorption, developing a chemical-free method is of great significance to both economic and the environmental welfare. Herein, we synthesized a novel thermoresponsive absorbent, A-MIL-121, which could effectively remove trace Cu(II) (> 95 %) from a high-salinity ([Na+]/[Cu2+] = 20000) water at normal temperature. At elevated temperature, A-MIL-121 could quickly and efficiently desorb Cu(II), with over 90% desorption rate at 80°C within 3 h. Fourier transform infrared spectroscopy (FTIR) analysis revealed that two types of -COOH groups existed in the material. One was in free form and acted as the sites for Cu(II) adsorption; the other was in dimer connected by two H-bonds, which cleaved at elevated temperature. As a result, massive exchangeable protons were released to the solution, which caused the desorption of Cu(II). Similar temperature dependent adsorption-desorption behavior was also found to other heavy metals, such as Cd2+, Pb2+, Ni2+. No significant capacity loss was observed after 10 successive adsorption-desorption cycles. Finally, Column experiments using a real copper electroplating wastewater showed that a total of ~ 1650 mL of clean water was generated before breakthrough (Cu2+ < 0.5 mg/L), while less than 45 mL of 80°C water was used for regeneration. This study indicates the potential of A-MIL-121 as a novel green adsorbent to address trace heavy metals in wastewater.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Adsorção , Compostos de Alumínio , Concentração de Íons de Hidrogênio , Cinética , Prótons , Temperatura , Poluentes Químicos da Água/análise
19.
Water Res ; 189: 116673, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33276212

RESUMO

The efficient removal of arsenite [As(III)] from groundwater remains a great challenge. Nanoscale oxides of Fe(III), Zr(IV), and Al(III) can selectively remove arsenic from groundwater through inner-sphere complexation. However, owing to polysilicate coatings formation on nanoparticles surface, the ubiquitous silicate exerts remarkably adverse effects on As(III) removal. Herein, we propose a new strategy to enhance silicate resistance of nanoscale oxides by embedding them inside the redox polymer host. As a proof-of-concept, the nanocomposite HFO@PS-Cl was employed to remove As(III) from silicate-containing water. The polymer host (PS-Cl) contains active chlorine to oxidize As(III) into arsenate [As(V)], and the embedded Fe(III) oxides enabling specific adsorption toward arsenic. Silicate exerts negligible effects on As(III) removal by HFO@PS-Cl in pH 3-7, but increasing the residual arsenic concentration from 49 µg/L to 166 µg/L for the solutions treated by HFO@PS-N, i.e., the nanoscale Fe(III) oxides embedded inside the polymer host without active chlorine. During the six cyclic decontamination-regeneration assays, HFO@PS-Cl steadily reduces As(III) below 10 µg/L. As for HFO@PS-N, however, the residual arsenic increases to ~57 µg/L in the sixth run. In column mode, HFO@PS-Cl column generates >3200-bed volume (BV) clean water ([As]<10 µg/L) from the simulated As(III)-contaminated groundwater. In contrast, the values for As(V)-contaminated water and HFO@PS-N column are only ~650 BV and ~608 BV, respectively. The stoichiometric assays, XPS, and in-situ ATR-FTIR analysis demonstrate that silicate polymerization is intensively suppressed by the protons produced during As(III) oxidation, thus rendering HFO@PS-Cl with excellent silicate resistant properties.


Assuntos
Arsênio , Arsenitos , Nanocompostos , Poluentes Químicos da Água , Purificação da Água , Adsorção , Compostos Férricos , Oxirredução , Óxidos , Polímeros , Silicatos , Água
20.
Environ Sci Technol ; 55(1): 665-676, 2021 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-33347310

RESUMO

Lanthanum (La)-based materials are effective in removing phosphate (P) from water to prevent eutrophication. Compared to their bulky analogues, La(OH)3 nanoparticles exhibit a higher P removal efficiency and a more stable P removal ability when spatially confined inside the host. Consequently, the understanding of the nanoconfinement effects on the long-term evolution of La-P structures is crucial for their practical use in P sequestration and recycle, which, however, is still missing. Here, we describe an attempt to explore the evolution of La-P structures, the P environment, and the status of La(OH)3 nanoparticles confined in the nanopores of the D201 resin, compared to a nonconfined analogue, over a P adsorption period of 25 days in both simulated wastewater and the real bioeffluent. A combinative use of X-ray diffraction (XRD), cross-polarization nuclear magnetic resonance (CP-NMR), and X-ray photoelectron spectroscopy (XPS) techniques confirms the transition from La-P inner-sphere complexation to the formation of LaPO4·xH2O and finally to LaPO4 in both samples. Interestingly, the rate of structural transformation in the real bioeffluent is substantially reduced. Nevertheless, in both conditions, nanoconfinement results in a much faster rate and larger extent of the structural transition. Moreover, nanoconfinement also facilitates the reverse transformation of stable LaPO4 back to La(OH)3. Our work provides the scientific basis of nanoconfinement for the preferable use of La-based nanocomposites in P mitigation, immobilization, and recycle application.


Assuntos
Lantânio , Nanocompostos , Adsorção , Hidróxidos , Fosfatos
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