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1.
ACS Chem Neurosci ; 11(18): 2786-2788, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32870651

RESUMO

Herein, we propose the use of novel adsorbents, namely micelle clay complexes comprising the clay montmorillonite, coupled with activated carbon for effective eradication of neuropathogenic microbes such as SARS-CoV-2 and Naegleria fowleri from water supplies for ablution/nasal irrigation. These can be incorporated easily to water collection devices, i.e., taps and water bottles, in the domestic setting. These filters are low cost, easy to install, and ideal disinfection systems. Such strategies are particularly useful for communities who have lack of access to safe water supplies, rely heavily on water storage tanks, or lack adequate water sanitation facilities, especially in developing countries.


Assuntos
Infecções por Coronavirus/prevenção & controle , Filtração/métodos , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Purificação da Água/métodos , Bentonita , Betacoronavirus , Infecções Protozoárias do Sistema Nervoso Central/prevenção & controle , Carvão Vegetal , Argila , Filtração/instrumentação , Humanos , Naegleria fowleri , Lavagem Nasal , Purificação da Água/instrumentação
2.
Chemosphere ; 260: 127586, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32693257

RESUMO

Removing contaminants from wastewater is critical towards resolving global water pollution problems. However, the variety of oily contaminants composition, and the unsatisfactory performance and efficiency of current separation systems are still big challenges, thus developing efficient and scalable oil-water separation (OWS) methods is needed. Here, the performance of a novel pilot-scale oil-water separator skimmer (OWSS) prototype is fully investigated using an upflow fixed bed column system packed with polypropylene (PP) fibrous sorbent materials for dual continuous OWS and in situ oils/organic solvents recovery. The mechanism of oil sorption by the PP fibrous sorbents, as well as capillary and vacuum assisted oil flow within the inter-fiber voids is fully explored. A series of pilot-scale column experiments were performed with different bed heights (7.5-30 cm) and using different types of oil/solvent in order to determine their influence on the oil flux, OWS efficiency and recovered organic solvent purity. The OWSS provided excellent and stable performance. A trade-off relationship between oil flux and OWS efficiency can be obtained: The maximum flux was attained at the lowest sorbent bed height (7.5 cm), while the maximum OWS efficiency (>99%) was achieved at the highest sorbent bed height (30 cm). The materials' morphology and wettability were examined showing outstanding stability and recyclability, which demonstrates their efficient integration into the overall OWSS. This study is expected to provide significant insights into the feasibility and scalability of an advanced, environmentally friendly, and relatively cost-effective OWS system, towards promising industrial implementation to overcome large-scale oil spill cleanup and oily wastewater treatment shortcomings.


Assuntos
Poluição por Petróleo/análise , Polipropilenos/química , Solventes/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Desenho de Equipamento , Interações Hidrofóbicas e Hidrofílicas , Projetos Piloto , Purificação da Água/instrumentação , Molhabilidade
3.
Chemosphere ; 258: 127179, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32554002

RESUMO

Hydrophobic membranes for desalination and toxic organic pollutant removal have been fabricated using polyamide - PDMS (polydimethylsiloxane) chemistries in a one-step protocol. The curing of polyamide and PDMS are orthogonal and co-curing both networks imparts hydrophobicity to the thin film composite membranes. The membranes exhibit increased adsorption of pesticides from the feed water along with maintaining excellent salt rejection capability (97% NaCl rejection), thus giving the membranes a multifunctional character. Three toxic pesticides have been used in this study to demonstrate the viability of combining osmosis desalination technology with organic matter adsorption. The membranes also show excellent resistance to fouling by toxic pesticides (85% salt rejection vs 67% for commercial membranes in the presence of pesticides) and significantly improved chlorine tolerance (93.8% salt rejection vs 86.5% for commercial membranes after 20 h of exposure to sodium hypochlorite solution).


Assuntos
Cloro/química , Dimetilpolisiloxanos/química , Membranas Artificiais , Praguicidas/isolamento & purificação , Purificação da Água/instrumentação , Varredura Diferencial de Calorimetria , Interações Hidrofóbicas e Hidrofílicas , Nylons/química , Osmose , Espectrometria por Raios X , Termogravimetria , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos
4.
J Water Health ; 18(2): 106-117, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32300085

RESUMO

Nanofibers of polyacrylonitrile (PAN)/boehmite were prepared by electrospinning a homogeneous solution of PAN/DMF (dimethyl formamide). Enhancing the amount of boehmite nanoparticles (NPs) led to increase in the nanofibers' diameter. Samples had high pure water flux, which did not change significantly with boehmite concentration, but decreased with increasing electrospinning duration. Escherichia coli bacteria removal was remarkably more efficient, as it was enhanced from 72.33% to 97.37% with increase in the boehmite NPs' concentration from 0 to 10% wt. High bacterial removal efficiency could be attained by the large surface area of NPs, as well as the electrostatic force of attraction between NPs and microorganisms. The increase in boehmite concentration from 10 to 30 and 50% did not noticeably affect bacterial removal. Prolonging electrospinning time significantly enhanced bacteria removal. Hence, it was shown that 6-hour electrospinning of PAN/boehmite nanofiber layers composed of 50% boehmite led to 99.7%, 99.39%, 99.8%, and 74% E. coli, Staphylococcus aureus bacteria removal, particles' separation efficiency of 2 µm and cadmium adsorptivity, respectively, which were better than those obtained by using pure PAN nanofibers. E. coli bacterial removal efficiency of the sample was increased to 99.99% by repeating filtering four times. Considering the results, this PAN/boehmite nanofibers' membrane has potential application to purification of drinking water.


Assuntos
Resinas Acrílicas , Hidróxido de Alumínio , Óxido de Alumínio , Bactérias/isolamento & purificação , Cádmio/isolamento & purificação , Nanofibras , Purificação da Água/instrumentação , Escherichia coli , Nanopartículas , Água , Microbiologia da Água
5.
Am J Trop Med Hyg ; 103(1): 465-471, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32274986

RESUMO

Diarrheal illness remains a leading cause of morbidity and mortality in children < 5 years in developing countries, and contaminated water contributes to diarrhea risk. To address this problem, a novel hollow fiber ultrafilter (HFU) was developed for household water treatment. To test its impact on water quality and infant health, we conducted a cluster-randomized longitudinal evaluation in 10 intervention and 10 comparison villages in Kenya, attempting to enroll all households with infants (< 12 months old). We conducted a baseline survey, distributed HFUs to intervention households, made biweekly home visits for 1 year to assess water treatment practices and diarrhea in infants, and tested water samples from both groups every 2 months for Escherichia coli. We enrolled 92 infants from intervention households and 74 from comparison households. During the 1-year study period, 45.7% of intervention households and 97.3% of comparison households had at least one stored water sample test positive for E. coli. Compared with comparison households, the odds of E. coli contamination in stored water was lower for intervention households (odds ratio [OR]: 0.42, 95% CI: 0.24, 0.74), but there was no difference in the odds of reported diarrhea in infants, adjusting for covariates (OR: 1.19, 95% CI: 0.74, 1.90). Although nearly all water samples obtained from unprotected sources and filtered by the HFU were free of E. coli contamination, HFUs alone were not effective at reducing diarrhea in infants.


Assuntos
Água Potável/microbiologia , Disenteria/epidemiologia , Escherichia coli/isolamento & purificação , Microbiologia da Água , Purificação da Água/instrumentação , Adolescente , Adulto , Idoso , Feminino , Humanos , Lactente , Quênia/epidemiologia , Masculino , Pessoa de Meia-Idade , Razão de Chances , Aceitação pelo Paciente de Cuidados de Saúde , População Rural , Purificação da Água/métodos , Adulto Jovem
6.
Rev Environ Health ; 35(2): 211-217, 2020 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-32304315

RESUMO

The work described is motivated by an inability to extend central infrastructure for power and water to low-population-density areas of the Navajo Nation and elsewhere. It is estimated that 35% of the Navajo population haul water for household use, frequently from unregulated sources of poor initial quality. The proposed household-scale, solar-driven nanofiltration (NF) system designs are economically optimized to satisfy point-of-use water purification objectives. The systems also provide electrical energy for a degree of nighttime household illumination. Results support rational design of multiple-component purification systems consisting of solar panels, a high-pressure pump, NF membranes, battery storage and an electrical control unit subject to constraints on daily water treatment and excess energy generation. The results presented are conditional (based on initial water quality, membrane characteristics and geography) but can be adapted to satisfy alternative treatment objectives in alternate geographic, etc. settings. The unit costs of water and energy from an optimized system that provides 100 gpd (1 gallon is 3.78 L) and 2 kWh/day of excess electrical energy are estimated at $0.16 per 100 gallons of water treated and $0.26 per kWh of nighttime electrical energy delivered. Methods can be used to inform dispersed infrastructure design subject to alternate constraint sets in similarly remote areas.


Assuntos
Fontes de Energia Elétrica/provisão & distribução , Filtração , Luz Solar , Purificação da Água/métodos , Filtração/instrumentação , Purificação da Água/instrumentação
7.
Chemosphere ; 248: 126028, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32018109

RESUMO

As increasing demand of global reuse water, microbial desalination cell (MDC) is developed as a potential desalination approach to drive ion migration and separation through biodegradation without any additional energy. A novel, efficient, stable reactor coupled stacked MDC with upflow MDC was constructed, which was named as upflow-stacked MDC (USMDC). Compared with the traditional stacked MDC and upflow MDC, the desalination and generation performance of the USMDC was evaluated. Results showed that, after 24 h, the desalination ratio of USMDC can reach 91.9% when the external resistance was 1.5 Ω, which was 1.18 and 1.48 times higher than SMDC and UMDC, respectively. The long-term performance of the desalination efficiency was tested, which was maintained at 87.2-96.0% and stable for consecutive 120 days. Then, it was also the investigated that the relationship between desalination rate and external resistance during every period. The USMDC produced a maximum power density of 32.91 W m-3. In addition, the difference of current density between USMDC and SMDC indicates the turbulence generated by cylindrical structure could effectively decrease the internal resistance. It was also corroborated that salt concentration gradient and bipolar electrodialysis would decline the charge transfer efficiency. Accordingly, USMDC was verified having the superior desalination performance thus providing the possibility for application in wastewater reuse.


Assuntos
Purificação da Água/instrumentação , Purificação da Água/métodos , Biodegradação Ambiental , Fontes de Energia Bioelétrica , Desenho de Equipamento , Salinidade , Cloreto de Sódio , Águas Residuárias
8.
Chemosphere ; 248: 126027, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32032875

RESUMO

In this study, an activation treatment for recycled anion exchange membranes is proposed. Following the circular economy approach, these membranes were prepared by using end-of-life reverse osmosis membranes as mechanical support. The end-of-life membrane was previously used and discarded by desalination plants after overcoming its lifespan. The activation treatment was based on the subsequent immersion of the membranes in diluted acid and alkali solutions. This treatment promoted the complete dissociation of the functional groups in the membrane, making them more reactive to the counter ions. The effects of acid and alkali concentrations and exposition times on the electrochemical properties were studied and the best combination was selected. In such a way, a decrease of 37% in membrane electrical resistance was achieved. The performance of activated and non-activated membranes in brackish water desalination by electrodialysis was compared. The results showed that the proposed activation treatment increased the flux of fresh water more than four-fold (from 1.2 to 4.9 L h-1·m-2), with a considerable reduction of energy consumption (from 5.2 to 3.0 kWh·m-3) and a great improvement in current efficiency (from 38% to 71%). In conclusion, this work shows a simple and low cost methodology for the improvement of the electrochemical properties of recycled electromembranes and thus, their performance in electrodialysis.


Assuntos
Diálise/métodos , Purificação da Água/instrumentação , Diálise/instrumentação , Filtração/instrumentação , Água Doce , Concentração de Íons de Hidrogênio , Membranas Artificiais , Reciclagem , Purificação da Água/métodos
9.
Ecotoxicol Environ Saf ; 192: 110307, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32070781

RESUMO

An increasing concern for natural resources preservation and environmental safety is the removal of heavy metals from contaminated water. It is essential to develop simple procedures that use ecofriendly materials with high removal capacities. In this context, we have synthesized a new hybrid material in which eggshell membranes (ESMs) act as nucleation sites for magnetite nanoparticles (MNPs) precipitation in the presence of an external magnetic field. As a result, ESM was transformed into a magnetic biomaterial (MESM) in order to combine the Pb adsorption abilities of both MNPs and ESM and to facilitate collection of the bioadsorbant using an external magnetic field. This green co-precipitation method produced long strands of bead-like 50 nm superparamagnetic MNPs decorating the ESM fibers. When MESM were incubated in Pb(NO3)2 solutions, the hybrid material displayed a 2.5-fold increase in binding constant with respect to that of ESM alone, and a 10-fold increased capacity to remove Pb ions from aqueous solution. The manufactured MESMs present a maximum loading capacity of 0.066 ± 0.009 mg Pb/mg MNPs at 25 °C, which is increased up to 0.15 ± 0.05 mg Pb/mg MNPs at 45 °C. Moreover, the MESM system is very stable, since incubation in 1% HCl solution resulted in rapid Pb desorption, while MNP release from the MESM during the same period was negligible. Altogether, these results suggest that MESM could be utilized as an efficient nanoremediation agent for separation/removal of heavy metal ions or other charged pollutants from contaminated waters, with facile recovery for recycling.


Assuntos
Casca de Ovo/química , Chumbo/isolamento & purificação , Fenômenos Magnéticos , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/instrumentação , Adsorção , Animais , Conservação dos Recursos Naturais , Chumbo/química , Nanopartículas de Magnetita/química , Membranas Artificiais , Poluentes Químicos da Água/química , Purificação da Água/métodos
10.
J Agric Food Chem ; 68(10): 3050-3060, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32069040

RESUMO

Industrial wastewater has brought great disaster to water bodies and soils and seriously affected the growth of crops. It is necessary to prepare a stable, effective, and sustainable treatment agent to control water pollution to obtain clean water. The adsorption effect of a lignosulfonate-lysine hydrogel (CLS-Lys adsorbent) on heavy metal ions (Cu2+ and Co2+) in water is studied. In the synthesis experiment, a response surface method is used to optimize the content of sodium lignosulfonate, lysine, initiator, and cross-linker. The CLS-Lys adsorbent is characterized by Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, thermal analysis, and zeta potential analysis. The performance of the CLS-Lys adsorbent under different influencing factors is studied. The kinetic and isothermal models of the CLS-Lys adsorbent are established. The results show that the main adsorption model of the CLS-Lys adsorbent is chemical adsorption, accompanied by electrostatic adsorption. These two ions have a competitive adsorption relationship, and when the two ions are present at the same time, they inhibit each other. In addition, the CLS-Lys adsorbent has good adsorption and analytical regeneration performance. It is an economic and effective adsorbent and has a broad application prospect.


Assuntos
Hidrogéis/química , Lignina/análogos & derivados , Lisina/química , Metais Pesados/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Hidrogéis/síntese química , Cinética , Lignina/química , Águas Residuárias/química , Purificação da Água/instrumentação
11.
Molecules ; 25(3)2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32041149

RESUMO

Plant phytochemicals have potential decontaminating properties, however, their role in the amelioration of hydrophobic water filtration membranes have not been elucidated yet. In this work, phytochemicals (i.e., cannabinoids (C) and terpenes (T) from C. sativa) were revealed for their antibacterial activity against different Gram-positive and Gram-negative bacteria. As such, a synergistic relationship was observed between the two against all strains. These phytochemicals individually and in combination were used to prepare polyethersulfone (PES) hybrid membranes. Membrane characterizations were carried out using scanning electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy. Moreover, contact angle, water retention, surface roughness, mechanical testing, and X-ray florescence analysis were also carried out. According to results, the CT-PES hybrid membrane exhibited the lowest contact angle (40°), the highest water retention (70%), and smallest average pore size (0.04 µm). The hybrid membrane also exhibited improved water flux with no surface leaching. Quantitative bacterial decline analysis of the CT-PES hybrid membranes confirmed an effective antibacterial performance against Gram-positive and Gram-negative bacteria. The results of this study established cannabinoids and terpenes as an inexpensive solution for PES membrane surface modification. These hybrid membranes can be easily deployed at an industrial scale for water filtration purposes.


Assuntos
Antibacterianos/farmacologia , Canabinoides/farmacologia , Terpenos/farmacologia , Antibacterianos/química , Canabinoides/química , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Membranas Artificiais , Microscopia Eletrônica de Varredura , Compostos Fitoquímicos/química , Compostos Fitoquímicos/farmacologia , Polímeros , Sulfonas , Terpenos/química , Purificação da Água/instrumentação
12.
Molecules ; 25(3)2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32041154

RESUMO

A composite membrane based on polycaprolactone (PCL) and cellulose nanofibers (CNF) with different compositions was prepared using the electro-spinning method, with the objective of developing organic membranes with good mechanical properties to remove contaminants from water. Water is a resource of primary importance for life and human activities. In this sense, cellulose obtained from agave bagasse and polycaprolactone nanofibers was used to prepare membranes that were tested by filtering tap water. The membranes obtained presented a porosity and structure on a nanometric scale. The water quality variables evaluated after filtration with the PCL/CNF membranes showed 100% turbidity removal, 100% conductivity, and heavy metal removal of the order of 75% to 99% for iron and chromium. CNF comprises biowaste derived from tequila production, and it has added value. Electro-spun CNF and PCL membranes can be applied as a "green" and eco-friendly filtration system for water purification.


Assuntos
Celulose/química , Metais Pesados/isolamento & purificação , Poliésteres/química , Poluentes Químicos da Água/isolamento & purificação , Agave/química , Cromo/isolamento & purificação , Ferro/isolamento & purificação , Membranas Artificiais , Nanofibras/química , Porosidade , Purificação da Água/instrumentação
13.
J Chromatogr A ; 1619: 460916, 2020 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-32037072

RESUMO

Disinfection by-products (DBPs) in drinking water can pose a health risk to humans. In this work, a new nitrogen-rich covalent organic frameworks (TpTt-COFs) was synthesized and applied firstly as a novel solid-phase extraction (SPE) trapping media for four ultra-trace levels of DBPs in drinking water samples. Under the optimal conditions, these DBPs were absorbed on a SPE cartridge; then, the DBPs were eluted with the optimized volume of eluent. The concentrated elution was detected and quantified by gas chromatography-mass spectrometry. Low limits of detection (0.0004-0.0063 ng mL-1), wide linearity (0.002-50 µg L-1), good reproducibility (1.54-2.88%) and repeatability (1.28-3.40%) were obtained. This novel method has been successfully applied to the analysis of ultra-trace levels DBPs in real drinking water samples. These accurate experimental results by this method indicated that the novel TpTt-COFs as a SPE trapping material was an attractive option for efficient and effective analysis of ultra-trace levels DBPs in future.


Assuntos
Desinfetantes/química , Água Potável/química , Estruturas Metalorgânicas , Extração em Fase Sólida/métodos , Purificação da Água/instrumentação , Desinfecção , Cromatografia Gasosa-Espectrometria de Massas , Nitrogênio/análise , Reprodutibilidade dos Testes , Extração em Fase Sólida/instrumentação , Poluentes Químicos da Água/isolamento & purificação
14.
Biofouling ; 36(1): 14-31, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31928216

RESUMO

The impact of feed water quality on biofilm formation during membrane distillation (MD) was investigated in this study, particularly emphasizing the interrelationship between organics, salts, and microbes. Two types of typical natural surface waters in Nanjing, China, were chosen as feed solutions for long-term MD operation, including the Qinhuai River and Xuanwu Lake. The biofilms that developed under different feed water qualities exhibited distinct Foulant compositions and structures, causing different flux decline trends for the MD system. Accordingly, two typical patterns of biofilm formation were suggested for the MD operation of the two different kinds of surface waters in this study. Organics from a primal feed solution and dead bacteria were the key to the establishment of a biofilm on the membrane, and this needs to be effectively removed from the MD system through pre-treatment and process control strategies. Finally, a feasible strategy for MD biofouling control was suggested.


Assuntos
Biofilmes/crescimento & desenvolvimento , Incrustação Biológica/prevenção & controle , Destilação , Água Doce , Membranas Artificiais , Politetrafluoretileno/química , Purificação da Água/métodos , China , Água Doce/química , Água Doce/microbiologia , Interações Hidrofóbicas e Hidrofílicas , Lagos/química , Lagos/microbiologia , Rios/química , Rios/microbiologia , Propriedades de Superfície , Purificação da Água/instrumentação , Qualidade da Água
15.
Artigo em Inglês | MEDLINE | ID: mdl-31903841

RESUMO

This study revealed the status of 2833 Kanchan Arsenic Filters (KAFs), aged 2 months to over 10 years, distributed in Nepal. Thirty percent of the filters were being used, but usage status generally declined 4 years after installation. Lack of use was mostly due to breakage or leaks (74%), which users did not know how to repair. Some 1283 filters (65%) were abandoned, and users returned to drinking arsenic-contaminated water. Water quality tests showed that the average KAF arsenic removal rate was 75%, and 87 and 62% of the samples met Nepal's drinking water quality standards and World Health Organization guidelines, respectively. The KAF arsenic removal amount was significantly influenced by the arsenic and iron concentrations of influent water and KAF type. The concrete square type showed the best performance in usage status and arsenic removal capacity, namely 57 and 83%, respectively. Long-term use of KAFs (more than 4 years) was assumed to be a cause of the decreasing capacity of iron nails to supply ferric hydroxide to influent water, which led to decreased arsenic removal capacity. Thus, replacement of older iron nails may restore the arsenic removal capacity of KAFs.


Assuntos
Arsênico/análise , Água Potável/normas , Filtração/instrumentação , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Abastecimento de Água/métodos , Água Potável/química , Falha de Equipamento , Características da Família , Compostos Férricos/química , Ferro/análise , Nepal , Purificação da Água/instrumentação , Qualidade da Água/normas , Abastecimento de Água/normas
16.
Molecules ; 25(2)2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31936177

RESUMO

Pharmaceuticals, especially antibiotics, constitute an important group of aquatic contaminants given their environmental impact. Specifically, tetracycline antibiotics (TCs) are produced in great amounts for the treatment of bacterial infections in both human and veterinary medicine. Several studies have shown that, among all antibiotics, oxytetracycline hydrochloride (OTC HCl) is one of the most frequently detected TCs in soil and surface water. The results of the photocatalytic degradation of OTC HCL in aqueous suspensions (30 mg·L-1) of 0.5 wt.% cobalt-doped TiO2 catalysts are reported in this study. The heterogeneous Co-TiO2 photocatalysts were synthesized by two different solvothermal methods. Evonik Degussa Aevoxide P25 and self-prepared TiO2 modified by the same methods were used for comparison. The synthesized photocatalysts were characterized by X-ray powder diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), UV/vis diffuse reflectance spectroscopy (DRS), and N2 adsorption (BET) for specific surface area determination. The XRD and Raman results suggest that Ti4+ was substituted by Co2+ in the TiO2 crystal structure. Uv/visible spectroscopy of Co-TiO2-R showed a substantial redshift in comparison with bare TiO2-R. The photocatalytic performance of the prepared photocatalysts in OTC HCL degradation was investigated employing Uv/vis spectroscopy and high-performance liquid chromatography (HPLC). The observed initial reaction rate over Co-TiO2-R was higher compared with that of Co-TiO2-HT, self-prepared TiO2, and the commercial P25. The enhanced photocatalytic activity was attributed to the high surface area (153 m2·g-1) along with the impurity levels within the band gap (2.93 eV), promoting the charge separation and improving the charge transfer ability. From these experimental results, it can be concluded that Co-doping under reflux demonstrates better photocatalytic performances than with the hydrothermal treatment.


Assuntos
Antibacterianos/química , Cobalto/química , Nanopartículas/química , Oxitetraciclina/química , Titânio/química , Poluentes Químicos da Água/química , Catálise , Luz , Microscopia Eletrônica de Transmissão , Nanopartículas/ultraestrutura , Oxirredução , Análise Espectral Raman , Raios Ultravioleta , Purificação da Água/instrumentação , Purificação da Água/métodos , Difração de Raios X
17.
Environ Pollut ; 259: 113902, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31918149

RESUMO

A series of phosphorus containing ZnO (P-ZnO) photocatalysts with various percentages of phosphorus were successfully synthesized using the hydrothermal method. The structural, physical and optical properties of the obtained microparticles were investigated using diverse techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible diffusion reflectance spectroscopy (UV-Vis DRS), photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and N2 adsorption-desorption analysis. The photocatalytic activities of the pure and P-ZnO samples were evaluated for the degradation of Rhodamine B (RhB) under visible light irradiation. The parameters such as pH, catalyst dosage, contaminant concentration and effect of persulfate as an oxidant were studied. It was found that the P-ZnO1.8% photocatalyst could destroy 99% of RhB (5 ppm) in 180 min at pH = 7; furthermore, it degraded ∼100% of 5 and 10 ppm of the RhB pollutant in 120 and 180 min, respectively, only by adding 0.01 g of persulfate into the reaction solution. To determine the photocatalytic mechanism, 2-propanol, benzoquinone and EDTA were used and it was indicated that hydroxyl radicals, superoxide ions and holes, all had major roles in the photocatalytic degradation but the hydroxyl radical effect was the most significant. The phenol degradation was also investigated using the P-ZnO1.8% optimum photocatalyst which could destroy 53% of the phenol (5 ppm) in 180 min. According to the reusability test, it was proved that after 5 cycles, the catalyst activity was not highly changed and it was potentially capable of pollutant degradation.


Assuntos
Luz , Fósforo , Purificação da Água/métodos , Óxido de Zinco , Nanopartículas Metálicas/química , Nanopartículas Metálicas/efeitos da radiação , Fósforo/química , Espectroscopia de Infravermelho com Transformada de Fourier , Purificação da Água/instrumentação , Óxido de Zinco/química
18.
FEMS Microbiol Ecol ; 96(2)2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31913449

RESUMO

Spatial patterns of bacterial community composition often follow a distance-decay relationship in which community dissimilarity increases with geographic distance. Such a relationship has been commonly observed in natural environments, but less so in engineered environments. In this study, bacterial abundance and community composition in filter media samples (n = 57) from full-scale rapid biofilters at 14 water treatment facilities across North America were determined using quantitative polymerase chain reaction and Illumina HiSeq high-throughput sequencing targeting the 16S rRNA gene, respectively. Bacteria were abundant on the filter media (108.8±0.3 to 1010.7±0.2 16S rRNA gene copies/cm3 bed volume) and the bacterial communities were highly diverse (Shannon index: 5.3 ± 0.1 to 8.4 ± 0.0). Significant inter-filter variations in bacterial community composition were observed, with weighted UniFrac dissimilarity values following a weak but highly significant distance-decay relationship (z = 0.0057 ± 0.0006; P = 1.8 × 10-22). Approximately 50% of the variance in bacterial community composition was explained by the water quality parameters measured at the time of media sample collection (i.e. pH, temperature and dissolved organic carbon concentration). Overall, this study suggested that the microbiomes of biofilters are primarily shaped by geographic location and local water quality conditions but the influence of these factors on the microbiomes is tempered by filter design and operating conditions.


Assuntos
Bactérias/isolamento & purificação , Água Potável/microbiologia , Microbiota , Microbiologia da Água , Bactérias/classificação , Bactérias/genética , Biodiversidade , Água Potável/química , Geografia , Microbiota/genética , América do Norte , RNA Ribossômico 16S/genética , Purificação da Água/instrumentação , Purificação da Água/métodos , Qualidade da Água
20.
Am J Trop Med Hyg ; 102(2): 458-467, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31837131

RESUMO

Household water treatment including solar disinfection (SODIS) is recognized worldwide as an important intervention for prevention and control of diarrheal and other waterborne diseases. However, in Ethiopia's countryside, SODIS is not being practiced. Therefore, the objective of this qualitative study conducted in villages of Dabat district in northwest Ethiopia was to explore barriers to and enabling factors for consistent and wider implementation of SODIS. This phenomenological study design included four focus group discussions with 25 parents of children younger than 5 years and interviews with four key informants to elicit their experiences and opinions. ATLAS.ti 8.0 software (GmbH, Berlin, Germany) was used for data organization, and the content was analyzed thematically. Enabling factors were categorized into four themes, such as supportive values for SODIS (positive attitude, advantage of SODIS, and cultural acceptance of SODIS), consistent use of SODIS (community's interest, health education, availability of bright sunlight, and simplicity of the method), participation of family and community in daily implementation of the SODIS process (controlling theft of bottles and recognizing the importance of SODIS technology), and willingness to pay for new polyethylene terephthalate (PET) bottles. On the other hand, barriers were grouped into three themes such as sociocultural (poor knowledge, hesitation to leave SODIS bottles unguarded outdoor, less attention, and unplanned social events), environmental (cloud, shadow over SODIS bottles, turbidity and leeches in source water, and geographical settings), and behavioral (mishandling of SODIS bottles and drinking water). The analysis of the data revealed that all the participants had positive attitude toward the implementation of SODIS, and it was culturally accepted. They identified the barriers to and enabling factors for the implementation of SODIS. Promoting enabling factors and mitigating barriers are substantially important for consistent implementation of SODIS as a long-term interventional measure widely in rural Ethiopia for the achievement of the goal of safe drinking water for all.


Assuntos
Desinfecção/métodos , Água Potável , Características da Família , Luz Solar , Purificação da Água/métodos , Adulto , Desinfecção/economia , Desinfecção/instrumentação , Etiópia , Feminino , Humanos , Masculino , População Rural , Microbiologia da Água , Purificação da Água/economia , Purificação da Água/instrumentação , Abastecimento de Água , Doenças Transmitidas pela Água/prevenção & controle
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