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1.
Nat Commun ; 12(1): 2009, 2021 03 31.
Artículo en Inglés | MEDLINE | ID: mdl-33790294

RESUMEN

Microorganisms play crucial roles in water recycling, pollution removal and resource recovery in the wastewater industry. The structure of these microbial communities is increasingly understood based on 16S rRNA amplicon sequencing data. However, such data cannot be linked to functional potential in the absence of high-quality metagenome-assembled genomes (MAGs) for nearly all species. Here, we use long-read and short-read sequencing to recover 1083 high-quality MAGs, including 57 closed circular genomes, from 23 Danish full-scale wastewater treatment plants. The MAGs account for ~30% of the community based on relative abundance, and meet the stringent MIMAG high-quality draft requirements including full-length rRNA genes. We use the information provided by these MAGs in combination with >13 years of 16S rRNA amplicon sequencing data, as well as Raman microspectroscopy and fluorescence in situ hybridisation, to uncover abundant undescribed lineages belonging to important functional groups.


Asunto(s)
Genoma Bacteriano/genética , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Metagenoma/genética , Metagenómica/métodos , ARN Ribosómico 16S/genética , Aguas del Alcantarillado/microbiología , Bacterias/clasificación , Bacterias/genética , Reactores Biológicos/microbiología , Dinamarca , Microbiota/genética , Filogenia , ARN Ribosómico 23S/genética , ARN Ribosómico 5S/genética , Aguas Residuales/microbiología , Purificación del Agua/métodos
2.
Nat Commun ; 12(1): 1871, 2021 03 25.
Artículo en Inglés | MEDLINE | ID: mdl-33767189

RESUMEN

Naturally-occurring membranes in the xylem tissue of gymnosperm sapwood enable its use as an abundantly-available material to construct filters, with potential to facilitate access to safe drinking water in resource-constrained settings. However, the material's behavior as a filter is poorly understood, and challenges such as short shelf life have not been addressed. Here, we characterize the operational attributes of xylem filters and show that the material exhibits a highly non-linear dependence of flow resistance on thickness upon drying, and a tendency for self-blocking. We develop guidelines for the design and fabrication of xylem filters, demonstrate gravity-operated filters with shelf life >2 years, and show that the filters can provide >3 log removal of E. coli, MS-2 phage, and rotavirus from synthetic test waters and coliform bacteria from contaminated spring, tap, and ground waters. Through interviews and workshops in India, we use a user-centric approach to design a prototype filtration device with daily- to weekly-replaceable xylem filters, and uncover indicators of social acceptance of xylem as a natural water filter. Our work enhances the understanding of xylem as a filtration material, and opens opportunities for engineering a diverse range of low-cost, biodegradable xylem-based filtration products on a global scale.


Asunto(s)
Cedrus/fisiología , Filtración/métodos , Ginkgo biloba/fisiología , Pinus/fisiología , Purificación del Agua/métodos , Bacteriófagos/aislamiento & purificación , Agua Potable/análisis , Escherichia coli/aislamiento & purificación , Filtración/instrumentación , Humanos , Rotavirus/aislamiento & purificación , Purificación del Agua/instrumentación , Xilema/fisiología
3.
Artículo en Inglés | MEDLINE | ID: mdl-33560900

RESUMEN

Removal of hexavalent chromium [Cr(VI)] from water was evaluated using a low-cost coated sand adsorbent for potential application in a flow-through filter system using permeable adsorption media. Manganese-aluminum coated sand (MACS) was investigated as a hybrid metal oxide based adsorbent due to the potential efficacy of manganese oxide and aluminum oxide for adsorption of Cr(VI) from water. Adsorbent characterization was performed using XRD, SEM/EDX, XPS and BET. Adsorption experiments were performed to determine adsorption capacity and kinetics. The effect of pH, common co-existing ions found in natural water, and the recyclability of adsorbent were investigated. Adsorbent characterization showed that the MACS sorbent contained aluminum oxide, manganese (III) oxide and manganese (IV) oxide. Adsorption followed the Langmuir and Freundlich adsorption equations, indicating favorable adsorption of Cr(VI) onto the MACS sorbent, while results from the Dubinin-Radushkevich equation were suggestive of physical adsorption of Cr(VI). Cr(VI) adsorption onto the MACS sorbent followed pseudo-second order kinetics. The adsorbent was effective in removing Cr(VI) over a broad pH range from 3 to 9.5, while surface charge analysis confirmed the adsorption of Cr(VI) onto the acidic surface of the MACS sorbent with a pHPZC of 9.72. The presence of co-existing ions bicarbonate, sulfate and phosphate in water resulted in a decrease in Cr(VI) uptake in the following order: phosphate > bicarbonate > sulfate. The presence of calcium resulted in a slight increase in Cr(VI) uptake. The MACS sorbent is a recyclable sorbent for adsorption and removal of Cr(VI) from water within 30 minutes of contact time.


Asunto(s)
Aluminio/química , Cromo/química , Manganeso/química , Arena/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Adsorción , Concentración de Iones de Hidrógeno , Cinética , Compuestos de Manganeso/química , Concentración Osmolar , Óxidos/química
4.
Ecotoxicol Environ Saf ; 213: 112032, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33582409

RESUMEN

Swine wastewater (SW) treatment by Myriophyllum aquaticum is an important biotechnology for its resource utilization. However, some knowledge gaps remain in compound-pollutant removal in SW, especially in practical applications. To clarify the responses of M. aquaticum to the compound pollutants as well as the related operational parameters in SW treatment, three initial doses (0.5, 1.0, and 1.5 kg per pond in 150 L simulated SW) of M. aquaticum and a control (no plant; CK) were allocated to 12 ponds under a plastic roof in Nanjing city of Eastern China during 75 days in the summer of 2019. Results showed that M. aquaticum could be used as a pioneer plant to efficiently remove compounded pollutants of nitrogen (N), phosphorus (P), and especially for heavy metals in simulated SW. Compared with CK, M. aquaticum assisted in improving the total N, NH4+-N, NO3--N, NO2--N, and dissolved organic N by 30.1%, 100%, 100%, 97.6%, 20.2%, 39.8% whereas Cu, Zn, and Cd by 50.4%, 36.4% and 47.9% on average during the 75-day experiment in summer, respectively. Moreover, concentrations of Cu and Cd at day 75 were in the ranges of 1.92-2.82 and 0.64-1.47 g kg-1 DW, respectively, exceeding the corresponding limits of the heavy-metal hyperaccumulator. For the operational parameters, the optimized initial dose was 1.0 kg per pond with M. aquaticum harvested after 45 summer days, respectively. Given that M. aquaticum has been widely used as animal feed in recent years and limit values for Cu and Zn in animal feed are not set in China, the toxicities of Cu and Zn should be assessed and the guideline of their limit values needs to be established for safe feed production. Interestingly, NH4+-N could dominate the removal of heavy metals especially Cd in the simulated SW, however, related mechanisms are needed for further study.


Asunto(s)
Metales Pesados/análisis , Saxifragales/fisiología , Aguas Residuales/química , Contaminantes Químicos del Agua/análisis , Animales , China , Contaminantes Ambientales , Nitrógeno/análisis , Nutrientes , Fósforo , Porcinos , Purificación del Agua/métodos
5.
Ecotoxicol Environ Saf ; 213: 112003, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33588188

RESUMEN

A green rust-coated expanded perlite (GR-coated Exp-p) microelectrode was synthesized and incorporated into a column-mode three-dimensional electrokinetic (3D-EK) platform to effectively pursue a continuous Cr(VI) removal from the aqueous solution. Brucite-like layers of GR were decorated onto the Exp-p material. The molar ratio of Fe(II) to Fe(III) played a most vital role among the three synthesis factors in influencing the performance of the particle electrode. For the equilibrium adsorption experiments, the target maximum adsorption capacity of 122 mg/g was predicted by a target optimizer and desirability function at the conditions following the pH of 4.7, the initial concentration of 172.4 mg/L, the dosage of 0.28 g/L, and the temperature of 28.96 °C, respectively. SO42-, Cl-, and NO3- fiercely competed with Cr(VI) anions in the acidic conditions for the locally positive sites. A low concentration and a slow flow were favored in the column-mode 3D-EK platform. The pseudo-first-order and Langmuir models were suitable for describing the kinetics and isotherms of the adsorption process, respectively. Cr(VI) anions were electrostatically attracted to the silanol groups and GR surface of the adsorbent, subsequently reduced in both heterogeneity and homogeneity, and finally immobilized by coordinating with silanediol groups and silanetriol groups.


Asunto(s)
Cromo/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Adsorción , Óxido de Aluminio , Aniones , Electrodos , Compuestos Férricos , Concentración de Iones de Hidrógeno , Cinética , Dióxido de Silicio , Temperatura , Agua , Contaminantes Químicos del Agua/análisis
6.
Ecotoxicol Environ Saf ; 210: 111866, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33387906

RESUMEN

A novel composite electrospun fiber with high photocatalytic efficiency, good stability, strong hydrophobicity, good pollution resistance, and easy separation and recovery was synthesized. The TiO2@g-C3N4 (TCN) with special core-shell structure (5-10 nm shell) facilitated the separation of photogenerated electron-holes and had high photocatalytic performance. The poly (vinylidene fluoride) (PVDF) electrospun fiber immobilized with TCN was successfully fabricated (PVDF-TCN) with uniform distribution and size of nanofibers by using electrospinning, which was used for degrading tetracycline under visible-light irradiation (> 400 nm). A special rougher surface of electrospun fiber obtained by washing of sacrificial PVP increased the specific surface area, which became more conducive to the adhesion of the catalyst. The water contact angle and FTIR results demonstrated that the electrospun fiber became extremely hydrophilic after adding TCN catalyst, which could effectively mitigate the fiber pollution. The PVDF-TCN-0.2g electrospun fiber exhibited excellent photocatalytic performance and the degradation efficiency of tetracycline was up to 97% in 300 min under visible-light irradiation. The mechanism of PVDF-TCN electrospun fiber degradation of tetracycline in the photocatalytic process was also proposed. In addition, the PVDF-TCN-0.2g exhibited a stable activity after 4 cycles experiments since the degradation efficiency remained about 90%. Therefore, we believed this study provided a new strategy in catalyst immobilization and wastewater treatment.


Asunto(s)
Antibacterianos/química , Nanofibras/efectos de la radiación , Nitrilos/efectos de la radiación , Polivinilos/efectos de la radiación , Tetraciclina/química , Titanio/efectos de la radiación , Contaminantes Químicos del Agua/química , Catálisis , Luz , Nanofibras/química , Nitrilos/química , Procesos Fotoquímicos , Polivinilos/química , Titanio/química , Purificación del Agua/métodos
7.
Ecotoxicol Environ Saf ; 210: 111885, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33421714

RESUMEN

Antibiotic resistance genes (ARGs) have attracted extensive attention as an emerging environmental contaminant potentially threatening humans. One of the main emission sources of ARGs is swine wastewater. In this study, integrated membrane filtration including ultrafiltration and two-stage reverse osmosis was conducted for swine wastewater treatment. The abundances of 16 target ARGs, which accounted for 72.64% of the total ARGs in swine wastewater according to metagenomic sequencing, were quantified by quantitative real-time PCR (qPCR) during each stage of the membrane filtration process. The results showed that integrated membrane filtration could reduce more than 99.0% of conventional pollutants and 99.79% of ARGs (from 3.02 × 108 copy numbers/mL to 6.45 × 105 copy numbers/mL). Principal component analysis (PCA) indicated that the removal efficiency of ARGs subtype by membrane filtration did not depend on ARGs type. However, strong correlations were found between ARGs and the wastewater quality indicators TP, SS and EC according to Cooccurrence patterns, indicating that ARG removal was closely associated with insoluble solid particles and soluble ions in swine wastewater. These results showed that membrane filtration could not only remove conventional pollutants such as nitrogen and phosphorus but also reduce the emerging pollutant of ARGs and decrease the risk of ARGs flowing into natural water.


Asunto(s)
Farmacorresistencia Microbiana/genética , Filtración/métodos , Genes Bacterianos , Purificación del Agua/métodos , Crianza de Animales Domésticos , Animales , Nitrógeno , Fósforo , Reacción en Cadena en Tiempo Real de la Polimerasa , Porcinos , Aguas Residuales/microbiología , Contaminantes del Agua
8.
Ecotoxicol Environ Saf ; 210: 111862, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33429321

RESUMEN

Microcystin-leucine arginine (MC-LR) is a carcinogenic toxin, produced by cyanobacteria. The release of this toxin into drinking water sources can threaten public health and environmental safety. Therefore, effective MC-LR removal from water resources is necessary. In the present study, the hydrothermal method was used to synthesize a novel ternary BiVO4/TiO2/NaY-Zeolite (B/T/N-Z) nanocomposite for MC-LR degradation under visible light. FESEM, FTIR, XRD, and DRS were performed for characterizing the nanocomposite structure. Also, the Response Surface Methodology (RSM) was applied to determine the impact of catalyst dosage, pH, and contact time on the MC-LR removal. High-performance liquid chromatography was performed to measure the MC-LR concentration. Based on the results, independent parameters, including contact time, catalyst dosage, and pH, significantly affected the MC-LR removal (P < 0.05). In other words, increasing the contact time, catalyst dosage, and acidic pH had positive effects on MC-LR removal. Among these variables, the catalyst dosage, with the mean square and F-value of 1041.37 and 162.84, respectively, had the greatest effect on the MC-LR removal efficiency. Apart from the interaction between the catalyst dosage and contact time, the interaction effects of other parameters were not significant. Also, the maximum MC-LR removal efficiency was 99.88% under optimal conditions (contact time = 120 min, catalyst dosage = 1 g/L, and pH = 5). According to the results, the B/T/N-Z nanocomposite, as a novel and effective photocatalyst could be used to degrade MC-LR from polluted water.


Asunto(s)
Luz , Toxinas Marinas/química , Microcistinas/química , Nanocompuestos/efectos de la radiación , Titanio/efectos de la radiación , Vanadatos/efectos de la radiación , Contaminantes Químicos del Agua/química , Itrio/efectos de la radiación , Zeolitas/efectos de la radiación , Bismuto/química , Catálisis , Nanocompuestos/química , Procesos Fotoquímicos , Titanio/química , Vanadatos/química , Purificación del Agua/métodos , Itrio/química , Zeolitas/química
9.
Ecotoxicol Environ Saf ; 208: 111669, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396179

RESUMEN

In this study, one lab-scale EGSB reactor (1.47 L volume) was designed to treat the antibiotic wastewater under different environmental factors, including the addition of cephalexin (CFX), Temperature (T) and Hydraulic Retention Time (HRT). The microbial community structure in EGSB reactor was analyzed with high-throughput sequencing technology to investigate their response to environmental factors changes, and then the random-matrix-theory (RMT)-based network analysis was used to investigate the microbial community's molecular ecological network in EGSB systems treating antibiotics wastewater. Moreover, the explanatory value of each environmental factor on the change of microbial community structure was obtained through the result of redundancy analysis (RDA). The results showed that the addition of cephalexin (CFX), decline of T and decline of HRT (8 h) would decrease the removal efficiency of COD decreasing. And the removal efficiency of CFX would not be affected by decline of T and HRT, except the producing and degrading process of CFX by-products was changed obviously. The result of RDA analysis suggested the environmental factors mainly affected bacterial and fungal microbial community structure but not archaeal ones. The result of high-throughput sequencing showed the relative abundance (RA) of Firmicutes had been obviously affected by T and HRT, which might be main reason leading to the decrease of COD removal efficiency. In addition, molecular ecological network analysis showed the growth of Bacteroidetes occupied the niche of functional microorganism and led to the unstable operation of EGSB when T declined. What's more, the molecular ecological network analysis revealed that Exophiala which belonged to fungi Ascomycota phylum was the hub genus to degrade complex refractory organic pollutants, and Aceticlastic methanogens Methanosaeta was the core functional archaea genus.


Asunto(s)
Antibacterianos/aislamiento & purificación , Reactores Biológicos/microbiología , Microbiota , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Antibacterianos/metabolismo , Archaea/clasificación , Archaea/genética , Archaea/crecimiento & desarrollo , Archaea/metabolismo , Bacterias/clasificación , Bacterias/genética , Bacterias/metabolismo , Hongos/clasificación , Hongos/genética , Hongos/crecimiento & desarrollo , Hongos/metabolismo , Temperatura , Aguas Residuales/química , Contaminantes Químicos del Agua/metabolismo
10.
Ecotoxicol Environ Saf ; 211: 111912, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33493727

RESUMEN

The reuse of the sewage is an effective way to solve the shortage of water resources, but disinfection by-products (DBPs) caused by chlorination may bring potential ecological and health risks to the supplied water. In this study, the occurrence and potential ecological risk of DBPs in SH River in Beijing were evaluated. Four kinds of DBPs were detected in 84 samples by GC-MS, including THM, CH, CTC and TCAN, whose detection rates were 100%, 100%, 100% and 2.38%, respectively. Combining with the relevant standard limitation and corresponding threshold values in China, and the reported concentration in domestic and foreign literatures, the results showed that the number of samples which [THM], [CTC] and [CH] exceeded the threshold values in relevant standard for 23.81%, 100.00% and 89.29%, respectively. CTC showed the highest excess times than the threshold value with [CTC]max was 356.46 µg/L. In addition, the temporal and spatial characteristics of identified DBPs were studied. [THM], [CTC] and [CH] all exhibited the highest concentration in Aug., which was as the same as the variation trend of air and water temperature. With the increase of sampling distance, [THM] and [CTC] fluctuated greatly, and the background values in SH River were higher due to the supplement of the reclaimed water. [CH] and [TCAN] gradually decreased, which may be due to that they were more prone to volatilize in the channel and be degraded by aquatic microorganisms. In addition, the occurrence situation in S2 and S7, were in the order of CTC > CH > THM. Hence, the rank of the occurrence situation of identified DBPs was CTC > CH > THM > TCAN. Multivariate analysis showed that THM was significantly positively correlated with CTC and their sources were similar. Moreover, they were all affected by solution pH and DO. Potential ecological risk assessment indicated that the rank of identified DBPs ecological risk was CTC > THM > CH > TCAN. Among them, the risk level of CTC and THM were high in both daily and extreme situations. Therefore, the potential ecological risk caused by DBPs should be fully considered in the process of reclaimed water supplying landscape water, such as urban river. If a higher level of the ecological risk management is needed, THM, CTC and CH, especially CTC, should be considered firstly.


Asunto(s)
Desinfectantes/análisis , Monitoreo del Ambiente , Contaminantes Químicos del Agua/análisis , Beijing , China , Desinfectantes/química , Desinfección/métodos , Cromatografía de Gases y Espectrometría de Masas , Halogenación , Medición de Riesgo , Ríos , Eliminación de Residuos Líquidos , Aguas Residuales/análisis , Purificación del Agua/métodos , Abastecimiento de Agua
11.
Ecotoxicol Environ Saf ; 208: 111712, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396043

RESUMEN

The photocatalytic process is an environmentally-friendly procedure that has been well known in the destruction of organic pollutants in water. The multiple semiconductor heterojunctions are broadly applied to enhance the photocatalytic performances in comparison to the single semiconductor. Polymeric semiconductors have received much attention as inspiring candidates owing to their adjustable optical absorption features and simply adaptable electronic structure. The shortcomings of the current photocatalytic system, which restricts their technical applications incorporate fast charge recombination, low-utilization of visible radiation, and low immigration capability of the photo-induced electron-hole. This paper indicates the novel fabrication of new CuI/g-C3N4 nanocomposite by hydrothermal and ultrasound-assisted co-precipitation methods. The structure, shape, and purity of the products were affected by different weight percentages and fabrication processes. Electron microscope unveils that CuI nanoparticles are distributed on g-C3N4. The bandgap of pure carbon nitride is estimated at 2.70 eV, and the bandgap of the nanocomposite has increased to 2.8 eV via expanding the amount of CuI. The CuI/C3N4 nanocomposite has a great potential to degrade cationic and anionic dyes in high value because of its appropriate bandgap. It can be a great catalyst for water purification. The photocatalytic efficiency is affected by multiple factors such as types of dyes, fabrication methods, the light sources, mass ratios, and scavengers. The fabricated CuI/C3N4 nanocomposite exposes higher photocatalytic performance than the pure C3N4 and CuI. The photocatalytic efficiency of nanocomposite is enhanced by enhancing the amount of CuI. Besides, the fabricated CuI/C3N4 revealed remarkable reusability without the obvious loss of photocatalytic activity. The antibacterial activity of the specimens reveals that the highest antimicrobial activities are revealed against P. aeruginosa and E. coli. These results prove that the nanocomposite possesses high potential for killing bacteria, and it can be nominated as a suitable agent against bacteria.


Asunto(s)
Antibacterianos/farmacología , Cobre/química , Grafito/química , Yoduros/química , Compuestos de Nitrógeno/química , Contaminantes Químicos del Agua/aislamiento & purificación , Antibacterianos/química , Catálisis , Colorantes/química , Colorantes/aislamiento & purificación , Colorantes/metabolismo , Cobre/farmacología , Grafito/farmacología , Yoduros/farmacología , Luz , Nanocompuestos/química , Compuestos de Nitrógeno/farmacología , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos
12.
Arch Environ Contam Toxicol ; 80(1): 248-258, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33398394

RESUMEN

Arsenic contamination in drinking water is a great concern in different regions of the world as well as in India. Several technologies have been investigated to remove arsenic from water, such as coagulation and co-precipitation, ion exchange, adsorption, and reverse osmosis. In the present research, electrocoagulation with iron electrodes has been assessed as a treatment technology for arsenic removal from groundwater to reach concentrations below 0.01 mg/L (WHO limit) and which is technically effective, affordable for the local area, and easy to operate and maintain. Electrochemically generated iron is converted to hydrated ferric oxide within the contaminated water, which takes up the arsenic from water. A downstream filtration unit (sand or activated alumina) is applied to remove ferric hydroxide flocs produced during the process. The laboratory experiments were conducted in a batch reactor using iron plates as electrodes with monopolar configuration to study the effects of initial pH and electro-charge loading (ECL) on arsenic removal. The optimum operating condition was observed for an electro-charge loading of 25-30 Coulombs/L at pH 7.0 and an initial arsenic concentration of 0.2 mg/L. Two field trials were implemented in West Bengal after suitably designing the electrocoagulation system. Arsenic removal was significant (75-80%) delivering safe water with arsenic below 0.01 mg/L (acceptable limit). Passivation of the electrodes occurred during the operation and calcium-based (including iron) deposition was observed on the cathodes. Passivation is avoidable after running regular polarity reversal of the electrodes.


Asunto(s)
Arsénico/análisis , Técnicas Electroquímicas/métodos , Agua Subterránea/química , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Adsorción , Electrodos , Compuestos Férricos/química , India , Hierro/química , Minerales/química
13.
Ecotoxicol Environ Saf ; 209: 111858, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33385680

RESUMEN

A novel amino-functionalized magnetic adsorbent (Fe3O4@C@DETA) was developed for adsorption of Cr(III) and Cr(III)-EDTA from wastewater. Fe3O4@C@DETA were successfully prepared by modification of Fe3O4@C with diethylenediamine (DETA), which exhibits a core-shell structure and sufficient saturation magnetization. Fe3O4@C@DETA exhibits much better adsorption performance for Cr(III) and its chelates than the Fe3O4@C because of newly introduced amino active sites. The enhanced adsorption capacity of Fe3O4@C@DETA for Cr(III) is 44.74 mg g-1 (at 25 °C and pH 3.0), which is due to the surface coordination with the newly introduced amino functional sites. The Cr(III)-EDTA anions as a whole was adsorbed through the electrostatic interaction with protonated amino species of the Fe3O4@C@DETA and have maximum adsorption capacity of 47.27 mg g-1 (at 25 °C and pH 3.0). The adsorption data of free and EDTA coordinated Cr(III) were followed the Langmuir equation, while the adsorption dynamics was well explained by pseudo second order model indicating the chemical nature of adsorption process. The higher concentration of Ca2+ ions in the wastewater compete for adsorption sites and inhibit the Cr(III) removal, while on other hand Ca2+ ions promotes the adsorption of Cr(III)-EDTA, because of electrostatic interaction with adsorbent active sits. Furthermore, the adsorbent can be easily separated by external magnetic field and regenerated in acidic solution. The adsorbent is stable, recyclable and have more than 75% regeneration efficiency and can be repeatedly used in the adsorption process.


Asunto(s)
Cromo/análisis , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Adsorción , Carbono , Ácido Edético , Concentración de Iones de Hidrógeno , Fenómenos Magnéticos , Magnetismo , Aguas Salinas , Salinidad , Aguas Residuales/química , Agua/química
14.
ACS Appl Mater Interfaces ; 13(3): 4410-4418, 2021 Jan 27.
Artículo en Inglés | MEDLINE | ID: mdl-33438389

RESUMEN

For antagonizing urgent water pollution and increasing environmental consciousness, the integration of renewable resources and nanotechnologies has become a trend to improve water quality in the ecosystem. Here, we designed a green route to fabricate regenerated cellulose fibers (CFs) with 3D micro- and nanoporous structures in NaOH/urea aqueous solvent systems via a scalable wet-spinning procedure as support materials for nanoparticles (NPs). Modification of CFs with polyaniline@Ag nanocomposites through in situ reduction of the silver ion with aqueous aniline led to enhanced pollutant removal efficiency of functional cellulose-based fibers (FCFs), demonstrating both rapid hydrogenation catalytic performance for the reduction of p-nitrophenol and high antibacterial properties for in-flow water purification. Most importantly, the hierarchically porous structures of FCFs not only provided carrier space but also formed a limiting domain guaranteeing the homogeneity of FCFs even with a Ag NP content as high as 36.47 wt %. The prepared functional fibers show good behavior in in-flow water purification, representing significant advancement in the use of biomass fibers for catalytic and bactericidal applications in liquid media.


Asunto(s)
Compuestos de Anilina/química , Celulosa/química , Plata/química , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Agua/análisis , Nanocompuestos/química , Nanofibras/química
15.
Int J Biol Macromol ; 172: 299-308, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33418048

RESUMEN

As one of the most significant natural polymer with the highest annual yield, lignin has been applied in the treatment of wastewater to remove heavy metal ions. However, there are still some shortages, such as low reactivity, difficulties in adsorbing oxyanions and low selectivity on specific oxyanions. To improve its adsorption properties, a novel lignin-based adsorbent was prepared in this study, doped with nitrogen by Mannich reaction, using triethylenetetramine (TETA) as N source, and further modified with Ca2+. The adsorption of Ca, N-co-doped lignin (Ca@N-Lig) for As (V), Cr (VI) and P (V) was studied. The Ca@N-Lig shows high capacity, excellent selectivity and prominent regeneration ability for As (V) adsorption. The adsorption of Ca@N-Lig for As (V) followed the Langmuir isotherm model and the pseudo-second-order kinetics model, yielding a maximum adsorption capacity of 681.59 mg·g-1 and a fast adsorption equilibrium within 30 min. Ca@N-Lig has an excellent regeneration ability on the adsorption of As (V) with a decrease of about 15.60% after 5 adsorption/desorption cycles. This study offers an efficient way to remove As (V) from polluted water.


Asunto(s)
Arsénico/aislamiento & purificación , Calcio/química , Lignina/química , Nitrógeno/química , Trientina/química , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción , Equipo Reutilizado , Agua Dulce/química , Humanos , Cinética , Bases de Mannich/química , Aguas Residuales/química , Purificación del Agua/métodos
16.
Int J Biol Macromol ; 172: 197-209, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33453250

RESUMEN

This study is the first to evaluate the effects of Iron oxides (FeOx) species and their decoration on graphene oxide/chitosan (GO/CS) composites for Cr(VI) removal and the possibility of Fe secondary pollution. Results show that Fe(III) is a better decoration material than Fe(II) and decoration through immersion-evaporation shows a higher adsorption capacity of Cr(VI) (Qe) than co-precipitation. Fe2O3-GO/CS as the only eco-friendly composite for enhanced Cr(VI) removal is further used for batch adsorption experiments, characterization, kinetics, isotherms, and thermodynamic studies. It is found that Cr(VI) removal mainly includes electrostatic attraction between Cr(VI) oxyanions and surface -NH3+ and -OH2+, and the adsorbed Cr(VI) partially reduces to Cr(III). Qe increases with the increasing initial Cr(VI) concentration, contact time, and temperature, while decreases with the increasing pH and mass and volume ratio (m/v). The coexisting ions (Cl-, NO3-, SO42-, PO43-, As, Fe, and Pb) can cause an obvious decrease of Qe. The removal efficiency (Re) and Qe are 94.3% and 83.8 mg/g, respectively under the optimal conditions. After five times of regeneration, Re is still as high as 84% and Qe drops about 2.6%. Cr(VI) adsorption is spontaneous and endothermic, which is best fitted with the Sips model, and the fitted maximum Qe is 131.33 mg/g.


Asunto(s)
Quitosano/química , Cromo/aislamiento & purificación , Compuestos Férricos/química , Grafito/química , Nanocompuestos/química , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción , Agua Potable/química , Humanos , Concentración de Iones de Hidrógeno , Cinética , Temperatura , Termodinámica , Aguas Residuales/química , Purificación del Agua/métodos
17.
Int J Biol Macromol ; 172: 210-222, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33453251

RESUMEN

The recovery of gold from wastewater has received significant attention in the last years due to its high economic value and low availability. A novel chitosan-based adsorbent (CS-GTU) was successfully synthesized by using formaldehyde as a crosslinker between chitosan and guanylthiourea, and applied for selective adsorption of AuIII from an aqueous medium. Through batch experiments, the maximum adsorption capacity of CS-GTU for AuIII could reach up to 695.63 mg/g at pH 5.0, and the adsorption process followed the Pseudo-second-order kinetic and Langmuir isotherm models, indicating that the monolayer chemisorption possibly occurred on the adsorbent surfaces. The adsorption was an enthalpy driven and spontaneous chemical process based on thermodynamic analysis. Furthermore, the adsorbent has demonstrated outstanding selectivity toward AuIII from multi-metallic solutions, and five cycled experiments of adsorption-desorption showed that CS-GTU could be efficiently regenerated. Experimental breakthrough curves were successfully simulated by using the Thomas model, which can fit the experimental data with the correlated curve (R2 > 0.9) well. This improvement in adsorption was a consequence of the complexation and electrostatic attraction of gold ions with the abundant sulfur/nitrogen-containing groups. The CS-GTU beads can be considered as a suitable and efficient adsorbent for gold ions in aqueous solutions.


Asunto(s)
Quitosano/química , Formaldehído/química , Oro/aislamiento & purificación , Guaniltiourea/química , Aguas Residuales/química , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción , Reactivos de Enlaces Cruzados/química , Humanos , Concentración de Iones de Hidrógeno , Cinética , Temperatura , Termodinámica , Purificación del Agua/métodos
18.
Int J Biol Macromol ; 172: 241-249, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33454322

RESUMEN

Silver nanoparticles (AgNPs) in surface water are highly toxic to humans and difficult to remove due to their adsorption to humic acid (HA). In this study, laminarin (LA) was used as a coagulant aid in a coagulation-ultrafiltration (C-UF) system to improve AgNPs-HA removal efficiency. C-UF efficiency, membrane flux, and flocs properties were investigated to explore the AgNPs-HA removal mechanism and membrane fouling. Results showed that when poly aluminum chloride (PAC) was dosed with LA, AgNPs-HA removal was 10-15% higher than when using PAC alone. The C-UF system using only PAC improved the AgNPs-HA removal efficiency through increased coagulation but resulted in membrane fouling. LA application helped mitigate membrane fouling, and the highest normalized permeate flux and smallest resistance values (0.573 and 2.180 × 1010 m-1, respectively) were achieved when 0.1 mg/L of LA was applied with 5 mg/L of PAC. The alleviating mechanism was related to flocs with large sizes and small fractal dimension (Df) values, generating a cake layer with porous morphology. This cake layer was easily removed by flushing and backwashing, which resulted in minimal resistance and fouling of the UF membrane.


Asunto(s)
Hidróxido de Aluminio/química , Glucanos/química , Nanopartículas del Metal/química , Plata/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Adsorción , Floculación , Agua Dulce/química , Humanos , Sustancias Húmicas/análisis , Membranas Artificiales , Nanopartículas del Metal/ultraestructura , Porosidad , Ultrafiltración/métodos , Purificación del Agua/métodos
19.
Int J Biol Macromol ; 171: 17-27, 2021 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-33412196

RESUMEN

Herein, an effective adsorbent, 3D porous tubular network-structured citric acid-chitosan/Fe/polyethyleneimine beads (CCFPB) with multifunctional active groups and strong selectivity, was prepared for the selective removal of Cu2+ from simulated wastewater. Compared with pure chitosan beads (CB), the adsorption capacity of CCFPB for Cu2+ was increased by 127 mg g-1 (238%), and the adsorption equilibrium time was shortened by 480 min. The CCFPB showed porous surface and a novel 3D porous tubular network structure in interior, which were benefit to the diffusion of Cu2+ from surface to interior of the CCFPB and the shortening of adsorption equilibrium time. The common coexisting ions in the simulated wastewater had almost no effect on the adsorption of Cu2+ by CCFPB, and the adsorption was fast and reached equilibrium within 10 h. The adsorption process followed pseudo-second-order kinetics and the Langmuir isotherm model (qm = 240.9 mg g-1 for Cu2+). The adsorption mechanism of CCFPB for Cu2+ was mainly the synergistic interaction with amino, carboxyl, and hydroxyl groups. This strategy shows great potential for developing a variety of novel, highly active, and reusable immobilized functional beads materials for effective separation of Cu2+ from multi-ion wastewater.


Asunto(s)
Quitosano/química , Ácido Cítrico/química , Cobre/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Adsorción , Cationes Bivalentes , Humanos , Concentración de Iones de Hidrógeno , Hierro/química , Cinética , Polietileneimina/química , Porosidad , Termodinámica , Aguas Residuales/química
20.
Int J Biol Macromol ; 172: 10-18, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33388320

RESUMEN

Wastewater contaminated with dyes is discharged by huge amount daily, and involved many hazardous materials. Thus, this study focused on introducing low cost, ecofriendly and available removal agent (lignin-based adsorbent). Three adsorbents, APKL-4, APKL-5 and APKL-6 were obtained using gradient acid precipitation technology and used for methylene blue (MB) removal. The samples were characterized by SEM, FT-IR and zeta potential analyzer. The results indicated that the three adsorbents exhibit significantly different adsorption behavior due to the structural differences caused by fractionation. The APKL-5 and APKL-6 have fewer hydrophilic groups in their molecules and thus have more adsorption active sites to load MB molecules. A pore structure inside of APKL-5 molecules is form in acid fractionation, which allows it to carry more MB molecules. The adsorption capacity of APKL-5 increased 3.8 times (from 345 to 1310 mg g-1) in the alkaline solution which showing excellent pH responsiveness. This paper presents a new promising approach for preparing high efficiency, low cost and eco-friendly adsorbents and builds a foundation for developing further applications of lignin-based adsorbents.


Asunto(s)
Ácidos/química , Fraccionamiento Químico/métodos , Colorantes/química , Lignina/química , Adsorción , Cinética , Azul de Metileno/química , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Aguas Residuales/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos
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