A Comparison of Solar Photocatalytic Inactivation of Waterborne E. coli Using Tris (2,2′-bipyridine)ruthenium(II), Rose Bengal, and TiO2

Background. The development of alternative processes to eliminate pathogenic agents in water is a matter of growing interest. Current drinking water disinfection procedures, such as chlorination and ozonation, can generate disinfection by-products with carcinogenic and mutagenic potential and are not readily applicable in isolated rural communities of less-favored countries. Solar disinfection processes are of particular interest to water treatment in sunny regions of the Earth. Solar light may be used to activate a photocatalyst or photosensitizer that generates, in the presence of molecular oxygen dissolved in water, reactive oxygen species (ROS), such as the HO• radical, singlet oxygen (O21), or superoxide (O2•), which are toxic to waterborne microorganisms. Method of Approach. Wild and collection-type Escherichia coli have been selected as model bacteria. Inactivation of such bacteria by either TiO2 nanoparticles, water-soluble tris(2,2′-bipyridine)ruthenium(II) dichloride or Rose bengal (RB) subject to simulated sunlight have been compared. Although TiO2 is the prototypical material for heterogeneous photocatalysis, the other two dyes are known to generate significant amounts of O21 by photosensitization but have different chemical structures. The concentration of dye, illumination time, photostability, presence of scavengers, and post-treatment regrowth of bacteria have been investigated. Results. After 1hr of solar illumination the Ru(II) complex produced a strong loss of E. coli culturability monitored with solid selective agars. Both the collection- and wild-type bacteria are sensitive to the treatment with 2-10mgL−1 of dye. This photosensitizer showed a better inactivation effect than TiO2 and the anionic organic dye RB due to a combination of visible light absorption, photostability, and production of O21 and other ROS when bound to the bacterial membrane. A complete loss of culturability was observed when the initial concentration was 103CFUmL−1, with no bacteria regrowth detected after 24hr of the water treatment. At higher initial microorganism levels, culturability still remains and regrowth is observed. Scavengers show that the HO• radical is not involved in bacteria inactivation by photosensitization. Conclusions. A higher quantum yield of ROS generation by the sensitizing dyes compared to the semiconductor photocatalyst determines the faster sunlight-activated water disinfection of photodynamic processes. The homogeneous nature of the latter determines a more efficient interaction of the toxic intermediates with the target microorganisms. Solid supporting of the Ru(II) dye is expected to eliminate the potentials problems associated to the water-soluble dye.

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Synthesis, Characterization and Bactericide Properties of Al2O3 Nanoparticles and Al2O3-PAN Membranes for Alternative Water Disinfection Methods

MRS Advances ◽

10.1557/adv.2017.6 ◽

2017 ◽

Vol 2 (30) ◽

pp. 1605-1610 ◽

Cited By ~ 1

Author(s):

Abdiel Oquendo-Cruz ◽

Ana Vega-Avila ◽

Oscar Perales-Pérez

Keyword(s):

Water Treatment ◽

Water Disinfection ◽

Diffusion Method ◽

Al2o3 Nanoparticles ◽

E Coli ◽

Disinfection Methods ◽

Removal Capacity ◽

Bacterial Removal ◽

Electrospun Membranes ◽

Ft Ir

ABSTRACTAs the global populations grow, water demand and pollution of water resources will increase. As a consequence, water borne disease outbreaks are on the rise and current disinfection methods have been shown to be ineffective in inactivating all pathogens during water treatment. Aluminum oxide nanoparticles (Al2O3 NPs) have been shown to poses antimicrobial properties. Also, Al2O3 has high thermal and chemical stability, which makes these NPs an excellent candidate for water treatment applications. Thus, the objective of this work is to assess the bactericidal properties of Al2O3 NPs synthesized using a polyol-based process in presence of polyvinylpyrrolidone (PVP). For practical applications nanoparticles must be immobilized in a medium to ensure that particles are not dispersed into the treated water. For this reason, synthesized nanoparticles were dispersed in electrospun polyacrylonitrile (PAN) membranes to also evaluate the bacterial removal capacity. X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) analysis suggests that synthesized nanoparticles are γ-Al2O3 after annealing at 800°C for 6 hours. Scanning Electron Microscopy (SEM) characterization was used to determine the morphology and size of synthesized nanoparticles. Composite electrospun membranes were also characterized by XRD, FT-IR, and SEM. The bactericide activity of the synthesized γ-Al2O3 NPs and commercially available Al2O3 particles was evaluated by the disc diffusion method against E. coli bacteria. Also, Al2O3-PAN composite electrospun membranes bacterial filtration capacity was tested. Both synthesized and industrially produced particles exhibited antibacterial activity against E. coli, but polyol-based synthesized nanoparticles demonstrated better bactericide properties. The bacterial removal capacity of PAN and PAN/Al2O3 fibers was comparable to that of paper filters.

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Photocatalytic Inactivation of Enterobacter cloacae and Escherichia coli Using Titanium Dioxide Supported on Two Substrates

Processes ◽

10.3390/pr6090137 ◽

2018 ◽

Vol 6 (9) ◽

pp. 137

Author(s):

Yelitza Aguas ◽

Margarita Hincapié ◽

Camilo Sánchez ◽

Liliana Botero ◽

Pilar Fernández-Ibañez

Keyword(s):

Escherichia Coli ◽

Borosilicate Glass ◽

Enterobacter Cloacae ◽

Water Disinfection ◽

Inactivation Rate ◽

E Coli ◽

Bacteria Inactivation ◽

Glass Tubes ◽

Bacterial Concentrations ◽

Total Bacteria

The antibacterial photocatalytic activity of TiO2 supported over two types of substrates, borosilicate glass tubes (TiO2/SiO2-borosilicate glass tubes (BGT)) and low-density polyethylene pellets (TiO2-LDPE pellets), which were placed in a compound parabolic collectors (CPC) reactor, was evaluated against Enterobacter cloacae and Escherichia coli under sunlight. Three solar photocatalytic systems were assessed, suspended TiO2, TiO2/SiO2-BGT and TiO2-LDPE pellets, at three initial bacterial concentrations, 1 × 105; 1 × 103; 1 × 101 CFU/mL of E. coli and total bacteria (E. cloacae and E. coli). The solar photo-inactivation of E. coli was achieved after two hours with 7.2 kJ/L of UV-A, while total bacteria required four hours and 16.5 kJ/L of UV-A. Inactivation order of E. coli was determined, as follows, suspended TiO2/sunlight (50 mg/L) > TiO2-LDPE pellets/sunlight (52 mg/L) > TiO2/SiO2-BGT/sunlight (59 mg/L), the best E. coli. inactivation rate was obtained with TiO2-LDPE pellets/sunlight, within 4.5 kJ/L and 90 min. The highest total bacteria inactivation rate was found for TiO2/sunlight (50 mg/L) and TiO2-LDPE pellets/sunlight (52 mg/L), within 11.2 kJ/L and 180 min. TiO2 deposited over LDPE pellets was the most effective material, which can be successfully used for water disinfection applications. Bacterial regrowth was assessed 24 h after all photocatalytic treatments, none of those microorganisms showed any recovery above the detection limit (2 CFU/mL).

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Highly Efficient Photocatalytic Disinfection of Escherichia coli by Rose Bengal-Functionalized Graphene Oxide Nanosheets

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2020.18615 ◽

2020 ◽

Vol 20 (12) ◽

pp. 7558-7568

Author(s):

Fenping Chi ◽

Pengpeng Chen ◽

Changjie Mao

Keyword(s):

Electron Microscopy ◽

Graphene Oxide ◽

Rose Bengal ◽

Photoelectron Spectroscopy ◽

Infrared Spectrometry ◽

Ros Generation ◽

Functionalized Graphene Oxide ◽

E Coli ◽

Transmission Electron ◽

Sterilization Effect

Rose Bengal (RB) was used as a functional pigment and poly dimethyl diallyl ammonium chloride was used as a coupling agent to modify Graphene Oxide (GO) in order to enhance the light absorption and ROS generation of GO. GO, RB and the obtained RB-PDDA-GO were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry, thermogravimetric analysis, Raman spectroscopy, UV-visible spectrophotometry, and X-ray photoelectron spectroscopy. The oxidation of hydroquinone to p-benzoquinone was used to evaluate the oxidation ability. Three kinds of reactive oxygen species (O2·-, 1O2 and ·OH) produced by the materials under light irradiation were detected by the ESR method using TEMP (2,2,6,6-tetramethyl-4-piperidine) and DMPO (5,5-dimethyl-1-pyrroline-N-oxide) as capture agents. The results showed that RB-PDDA-GO produced more ROS under light than GO. Antibacterial experiments were carried out with E. coli as the target strain to detect the actual utility of ROS produced by the materials. The results showed that RB-PDDA-GO had a significant sterilization effect.

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Antibacterial properties of Ag and Ag/AgCl nanoparticles from radish and tea extracts for water treatment applications

Water Science & Technology Water Supply ◽

10.2166/ws.2015.124 ◽

2015 ◽

Vol 16 (1) ◽

pp. 171-179

Author(s):

Yuphada Boonto ◽

Jirapat Ananpattarachai ◽

Puangrat Kajitvichyanukul

Keyword(s):

Antibacterial Activity ◽

Water Treatment ◽

Microwave Irradiation ◽

Green Synthesis ◽

Plant Extracts ◽

Antibacterial Properties ◽

Water Disinfection ◽

E Coli ◽

High Antibacterial Activity ◽

Complete Inactivation

Silver nanoparticles (AgNPs) have antibacterial properties and are widely used for water disinfection. This technology is commercially applied in point-of-use water treatment as a post-treatment for filtrate water. However, the current process of synthesizing AgNPs has several disadvantages including the use of hazardous chemicals, consumption of a large amount of energy and the formation of hazardous byproducts. Here, we report an alternative and green synthesis using plant extracts. In this work, the plant extracts came from radish (R) and tea (T), and the AgNPs were derived from a microwave irradiation method. The AgNPs synthesized by chemical-based microwave irradiation (Ag-C) were also used as a control material. The novel method produced a smaller size of nanostructures with good dispersion ability and less agglomeration than those from chemical synthesis. The antibacterial properties of AgNPs on Gram-negative bacteria Escherichia coli (E. coli) and Gram-positive bacteria Staphylococcus aureus (S. aureus) were investigated. The results revealed that AgNPs from both green synthesis and chemical-based methods inactivated both types of bacteria. The green-synthesized AgNPs from radish juice provided a higher percentage of inhibition of E. coli than that of S. aureus. The inactivation rates of the AgNPs increased with increasing concentration of AgNPs. As the concentration of the Ag/AgCl-R and Ag-R increased from 150 μg/mL to 300 μg/mL, complete inactivation required a reduced time for the reaction from 300 minutes to only 30 minutes. Finally, the Ag/AgCl-R and Ag-R offered high antibacterial activity while the Ag-T provided the lowest antibacterial activity. This work provides an alternative method for the eco-synthesis of antibacterial nanomaterials for water treatment.

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Evaluation of an alternative household water treatment system based on slow filtration and solar disinfection

Journal of Water and Health ◽

10.2166/wh.2021.211 ◽

2021 ◽

Author(s):

Guilherme Otávio Rosa e Silva ◽

Helen Oliveira Loureiro ◽

Laura Guimarães Soares ◽

Laura Hamdan de Andrade ◽

Rana Gabriela Lacerda Santos

Keyword(s):

Water Treatment ◽

Water Disinfection ◽

Treatment System ◽

Household Water Treatment ◽

Water Treatment System ◽

Total Coliforms ◽

Solar Disinfection ◽

E Coli ◽

Solar Water Disinfection ◽

Slow Filtration

Abstract Drinking water consumption is essential to maintain a good quality of life, but it is not available for all communities. Therefore, this work aimed to develop an alternative and accessible process for water treatment, based on filtration and solar disinfection, and evaluate it in both bench and pilot scales. The construction cost of the system was estimated and compared with other available options so that its economic viability could be discussed. For this purpose, water from a stream was collected and analyzed. A filter made of PVC tubes, sand, and gravel was built, acting, respectively, as a column, filtering medium, and support layer. As for the disinfection process, the SODIS (Solar Water Disinfection) methodology was adopted. The water was exposed to the sun, and the best exposure time was determined based on the analysis of total coliforms and E. coli. Finally, a prototype was built for a flow rate of 37.5 L d−1, consisting of two filters operating at a filtration rate of 2.38 m3 m−2 d−1. About 97% turbidity removal was obtained, as well as 99.9% for total coliforms and 99.1% for E. coli. It is estimated that the cost of building a water treatment system for one person is approximately USD 29.00.

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Bacterial Disinfection by CuFe2O4 Nanoparticles Enhanced by NH2OH: A Mechanistic Study

Nanomaterials ◽

10.3390/nano10010018 ◽

2019 ◽

Vol 10 (1) ◽

pp. 18 ◽

Cited By ~ 1

Author(s):

Yu Gu ◽

Furen Xiao ◽

Liumin Luo ◽

Xiaoyu Zhou ◽

Xiaodong Zhou ◽

...

Keyword(s):

Water Treatment ◽

Noble Metals ◽

Low Cost ◽

Water Disinfection ◽

Mechanistic Study ◽

Copper Ferrite ◽

Bacterial Inactivation ◽

E Coli ◽

Reactive Oxygen Species Content ◽

Current Water

Many disinfection technologies have emerged recently in water treatment industry, which are designed to inactivate water pathogens with extraordinary efficiency and minimum side effects and costs. Current disinfection processes, including chlorination, ozonation, UV irradiation, and so on, have their inherent drawbacks, and have been proven ineffective under certain scenarios. Bacterial inactivation by noble metals has been traditionally used, and copper is an ideal candidate as a bactericidal agent owing to its high abundance and low cost. Building on previous findings, we explored the bactericidal efficiency of Cu(I) and attempted to develop it into a novel water disinfection platform. Nanosized copper ferrite was synthesized, and it was reduced by hydroxylamine to form surface bound Cu(I) species. Our results showed that the generated Cu(I) on copper ferrite surface could inactivate E. coli at a much higher efficiency than Cu(II) species. Elevated reactive oxygen species’ content inside the cell primarily accounted for the strong bactericidal role of Cu(I), which may eventually lead to enhanced oxidative stress towards cell membrane, DNA, and functional proteins. The developed platform in this study is promising to be integrated into current water treatment industry.

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Antibacterial silver-diatomite nanocomposite ceramic with low silver release

Water Science & Technology Water Supply ◽

10.2166/ws.2019.195 ◽

2019 ◽

Vol 20 (2) ◽

pp. 633-643

Author(s):

Xiaopeng Qi ◽

Junwei Chen ◽

Qian Li ◽

Hui Yang ◽

Honghui Jiang ◽

...

Keyword(s):

Electron Microscopy ◽

Water Treatment ◽

Photoelectron Spectroscopy ◽

Bactericidal Effect ◽

Ceramic Filter ◽

Ceramic Filters ◽

X Ray ◽

E Coli ◽

Point Of Use ◽

Silver Release

Abstract There is an urgent need for an effective and long-lasting ceramic filter for point-of-use water treatment. In this study, silver-diatomite nanocomposite ceramic filters were developed by an easy and effective method. The ceramic filters have a three-dimensional interconnected pore structure and porosity of 50.85%. Characterizations of the silver-diatomite nanocomposite ceramic filters were performed using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Silver nanoparticles were confirmed to be formed in situ in the ceramic filter. The highest silver concentration in water was 0.24 μg/L and 2.1 μg/L in short- and long-term experiments, indicating very low silver-release properties of silver-diatomite nanocomposite ceramic filter. The nanocomposite ceramics show strong bactericidal activity. When contact time with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of 105 colony forming units (CFU)/mL exceeded 3 h, the bactericidal rates of the four different silver content ceramics against E. coli and S. aureus were all 100%. Strong bactericidal effect against E. coli with initial concentration of 109 CFU/mL were also observed in ceramic newly obtained and ceramic immersed in water for 270 days, demonstrating its high stability. The silver-diatomite nanocomposite ceramic filters could be a promising candidate for point-of-use water treatment.

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Design, Synthesis and Biological Evaluation of Novel Benzothiazole Based [1,2,4]Triazolo[4,3-c]quinazoline Derivatives

Asian Journal of Chemistry ◽

10.14233/ajchem.2020.22453 ◽

2020 ◽

Vol 32 (3) ◽

pp. 580-586

Author(s):

Ranjit V. Gadhave ◽

Bhanudas S. Kuchekar

Keyword(s):

Biological Evaluation ◽

Bacterial Strains ◽

Active Compounds ◽

Design Synthesis ◽

Structural Modifications ◽

E Coli ◽

Chemical Structures ◽

Ft Ir ◽

Antioxidant Agent

A new series of N-(benzo[d]thiazol-2-yl)-[1,2,4]triazolo[4,3-c]quinazoline-5-carboxamide derivatives were synthesized by condensation of [1,2,4]triazolo[4,3-c]quinazoline-5-carboxylate derivatives with substituted benzothiazoles. The chemical structures of the synthesized compounds were confirmed by FT-IR, MS and 1H NMR spectra. Designed triazoloquinazoline derivatives were docked with oxido-reductase enzyme (PDB Code 4h1j) and DNA gyrase enzyme (PDB Code 3g75). Based on high binding affinity score, the best compound were selected for synthesis and subjected to in vitro antioxidant and antibacterial activity. Compounds 7a and 7d were found to be most active compounds as antioxidant agent among this series when compared with ascorbic acid. Compounds 7a, 7d and 7f were found to be most active compounds as an antibacterial agents among this series when compared with ciprofloxacin against bacterial strains such as S. aureus (ATCC 25923), E. coli (ATCC 25922) and P. aeruginosa (ATCC 27853). Study revealed that the most active compounds after structural modifications can be exploited as lead molecules for other pharmacological activities such as anti-inflammatory, anticancer and antidepressant activities.

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