Visible and solar light photocatalytic disinfection of bacteria by N-doped TiO2

2014 ◽  
Vol 14 (5) ◽  
pp. 924-930 ◽  
Author(s):  
V. Arya ◽  
Ligy Philip
Keyword(s):  
Batch Reactor ◽  
Reaction Rates ◽  
Water Disinfection ◽  
Continuous Reactor ◽  
Pseudo First Order Reaction ◽  
Doped Tio2 ◽  
Complete Inactivation ◽  
Bicarbonate Ions ◽  
Solar Water Disinfection ◽  
Inactivation Of Bacteria

A water treatment system was developed based on a photocatalytic process, employing immobilized N-doped TiO2, which worked under solar radiation. Batch reactor studies were conducted using an immobilized and suspended form of N-doped TiO2. Activities of Degussa P-25 and N-doped TiO2 were compared. Optimization of catalyst concentration was also carried out. Reaction rates under different working conditions were compared. The bacterial kill followed a pseudo first-order reaction. Continuous reactor studies were carried out using N-doped TiO2 coated glass plates. Three-log inactivation of bacteria was obtained after a contact time of 40 min. The effects of turbidity, bicarbonate ions and organic matter were studied. It was found that the efficiency of the system decreased due to these components. Comparison of the performance of solar water-disinfection (SODIS) and solar photocatalytic treatment for disinfection of water was also carried out. The results showed that the suspended catalyst achieved complete inactivation in 1 h compared to SODIS which took 6 h. Bacterial regrowth was observed in the case of SODIS treatment whereas no bacterial growth was observed after solar photocatalytic treatment.

Photocatalytic degradation of azo dye in TiO2 suspended solution

2001 ◽  
Vol 43 (2) ◽  
pp. 313-320 ◽  
Author(s):  
C.-H. Hung ◽  
P.-C. Chiang ◽  
C. Yuan ◽  
C.-Y. Chou
Keyword(s):  
Reaction Time ◽  
Light Intensity ◽  
Photocatalytic Degradation ◽  
Azo Dye ◽  
Batch Reactor ◽  
Reaction Rates ◽  
Pseudo First Order Reaction ◽  
Degradation Rates ◽  
Orange G ◽  
Degradation Of Azo Dye

The photocatalysis of azo dye, Orange G, by P-25 anatase TiO2 was investigated in this research. The experiments were conducted in a batch reactor with TiO2 powder suspension. Four near-UV lamps were used as the light source. The experimental variables included solution pH level, amount of TiO2, illumination light intensity, and reaction time. A pseudo-first order reaction kinetic was proposed to simulate the photocatalytic degradation of Orange G in the batch reactor. More than 80% of 10 mg/L Orange G decomposition in 60-minute reaction time was observed in this study and fast decomposition of Orange G only occurred in the presence of both TiO2 and suitable light energy. Faster degradation of Orange G was achieved under acid conditions. The degradation rates of Orange G at pH = 3.0 were about two times faster than those at pH = 7.0. Faster degradation of azo dye was observed for greater irradiated light intensity and more TiO present during the reaction. The reaction rates were proportional to TiO2concentration and light intensity with the power order of 0.726 and 0.734, respectively.

Reactions and Reactors Basic Concepts

2001 ◽  
Author(s):  
L. K. Doraiswamy
Keyword(s):  
Reaction Time ◽  
Reaction Rate ◽  
Batch Reactor ◽  
Reaction Rates ◽  
Heterogeneous Reactions ◽  
Rate Equations ◽  
Continuous Reactor ◽  
Rigorous Treatment ◽  
Reactor Types ◽  
Definition Of

Organic synthesis is replete with countless classes of reactions, including several that are named after their discoverers (the name reactions), but fortunately they can all be conducted in less than a half-dozen broad types of reactors. Choosing a reactor for a given reaction is based on several considerations and combines reaction analysis with reactor analysis. Thus in this chapter we consider the following aspects of reactions and reactors, much of which should serve as an introduction to chemists and a refresher to chemical engineers: reaction rates, stoichiometry, and rate equations; the basic reactor types, as a prelude to a more rigorous treatment of these in Parts III and IV; transport of mass (represented by reactant and product molecules) and heat across phase boundaries for heterogeneous reactions; and types of laboratory reactors used by chemists and chemical engineers for their specific objectives. The first step in any consideration of reaction rates is the definition of reaction time. This depends on the mode of reactor operation, batch or continuous. For the batch reactor, the reaction time is the elapsed time; whereas for the continuous reactor, it is given by the time the reactant spends in the reactor, called the residence time, that is measured by the ratio of reactor volume to flow rate (volume/volume per unit time with units of time). An equally important consideration is the concept of reaction space (which can have units of volume, surface, or weight), leading to different definitions of the reaction rate. We begin this section by considering different ways of defining the reaction rate based on different definitions of reaction time and space. The basis of all reactor design is an equation for the reaction rate.

An Electrohydraulic Direct Current Discharge for Inactivation of Escherichia coli in High-Bacterial Density Wastewaters

2021 ◽  
Vol 55 ◽  
pp. 190-206
Author(s):  
Emmanuel Gwanzura ◽  
Oluyemi O. Awolusi ◽  
Sheena Kumari ◽  
Deresh Ramjugernath ◽  
Samuel A. Iwarere
Keyword(s):  
Escherichia Coli ◽  
Direct Current ◽  
Copper Ions ◽  
Batch Reactor ◽  
Water Source ◽  
Plasma Discharge ◽  
Water Disinfection ◽  
High Voltage Direct Current ◽  
Complete Inactivation ◽  
Reactor Operating

The United Nations, through its Sustainable Development Goals, have identified access to clean water as one of the challenges facing society. With reported global deaths exceeding 1 million annually linked to untreated water consumption, which is usually contaminated by pathogenic micro-organisms, further research continues in water disinfection. The direct generation of non-thermal plasma in water is a promising method for the inactivation of disease-causing bacteria present in the wastewater. This study explored the efficacy of plasma in the inactivation of different bacterial densities (4.0×104, 1.5×105, and 2.5×107 CFU/mL) using a 500 mL plasma batch reactor operating at atmospheric pressure. The plasma discharge was generated in water by a Technix-SR-10R-5000 high voltage direct current power supply in negative polarity with a set current of 0.45 A and a maximum pre-set ignition voltage of 9 kV. The electrodes used in the discharge was a copper material. A bacterial culture of Escherichia coli ATCC® 25922TM (E.coli) was used as a model for the direct plasma discharge. The study further investigated the contribution of copper ions (0.4 and 0.7 mg/L) released into the water during treatment by having two control reactors that were not exposed to plasma. The results show a complete inactivation at 180 seconds for the bacterial densities from 4.0×104 to 2.5×107 CFU/mL. The results from this study indicated the potential of a direct electric discharge in handling water source with high-bacteria densities.

scholarly journals SODIS potential: A novel parameter to assess the suitability of solar water disinfection worldwide

2021 ◽  
Vol 419 ◽  
pp. 129889
Author(s):  
José Moreno-SanSegundo ◽  
Stefanos Giannakis ◽  
Sofia Samoili ◽  
Giulio Farinelli ◽  
Kevin G. McGuigan ◽  
...  
Keyword(s):  
Water Disinfection ◽  
Solar Water ◽  
Solar Water Disinfection

scholarly journals Solar water disinfection in high-volume containers: Are naturally occurring substances attenuating factors of radiation?

2020 ◽  
Vol 399 ◽  
pp. 125852 ◽  
Author(s):  
Ángela García-Gil ◽  
Rafael Valverde ◽  
Rafael A. García-Muñoz ◽  
Kevin G. McGuigan ◽  
Javier Marugán
Keyword(s):  
High Volume ◽  
Water Disinfection ◽  
Solar Water ◽  
Naturally Occurring ◽  
Solar Water Disinfection

Excystation ofCryptosporidium parvumat temperatures that are reached during solar water disinfection

Parasitology ◽  
2009 ◽  
Vol 136 (4) ◽  
pp. 393-399 ◽  
Author(s):  
H. GÓMEZ-COUSO ◽  
M. FONTÁN-SAINZ ◽  
J. FERNÁNDEZ-ALONSO ◽  
E. ARES-MAZÁS
Keyword(s):  
Solar Radiation ◽  
Cryptosporidium Parvum ◽  
Gradual Increase ◽  
Water Disinfection ◽  
Waterborne Diseases ◽  
Pathogenic Microorganisms ◽  
Simple Method ◽  
Solar Water ◽  
Solar Water Disinfection ◽  
Notable Increase

SUMMARYSpecies belonging to the generaCryptosporidiumare recognized as waterborne pathogens. Solar water disinfection (SODIS) is a simple method that involves the use of solar radiation to destroy pathogenic microorganisms that cause waterborne diseases. A notable increase in water temperature and the existence of a large number of empty or partially excysted (i.e. unviable) oocysts have been observed in previous SODIS studies with water experimentally contaminated withCryptosporidium parvumoocysts under field conditions. The aim of the present study was to evaluate the effect of the temperatures that can be reached during exposure of water samples to natural sunlight (37–50°C), on the excystation ofC. parvumin the absence of other stimuli. In samples exposed to 40–48°C, a gradual increase in the percentage of excystation was observed as the time of exposure increased and a maximum of 53·81% of excystation was obtained on exposure of the water to a temperature of 46°C for 12 h (versus8·80% initial isolate). Under such conditions, the oocyst infectivity evaluated in a neonatal murine model decreased statistically with respect to the initial isolate (19·38%versus100%). The results demonstrate the important effect of the temperature on the excystation ofC. parvumand therefore on its viability and infectivity.

The effect of the textile industry dye bath additive EDTMPA on colour removal characteristics by ozone oxidation

2007 ◽  
Vol 55 (10) ◽  
pp. 145-153 ◽  
Author(s):  
T. Ölmez ◽  
I. Kabdaşlı ◽  
O. Tünay
Keyword(s):  
Organic Matter ◽  
Textile Industry ◽  
Reaction Rates ◽  
Textile Dye ◽  
Pseudo First Order Reaction ◽  
Ozone Oxidation ◽  
Reactive Dyeing ◽  
First Order ◽  
Organic Matter Oxidation ◽  
Pseudo First Order

In this study, the effects of the phosphonic acid based sequestering agent EDTMPA used in the textile dye baths on colour and organic matter removal by ozone oxidation was experimentally investigated. Procion Navy HEXL dyestuff that has been commonly used for the reactive dyeing of cellulose fibers was selected as the model component. The organic matter oxidation by ozone was determined to obey the pseudo-first order kinetics as they are treated singly or in combination. COD removal rates obtained from pseudo-first order reaction kinetics showed that oxidation of Navy HEXL alone (0.0947 L/min) was faster than that of EDTMPA (0.0171 L/min) and EDTMPA with dye (0.0155 L/min) at pH 3.0. It was also found that reaction rates of single EDTMPA removal and EDTMPA and dye mixture removal increased as the reaction pH was increased from 3.0 to 10.5.

scholarly journals C-,N- and S-Doped TiO2 Photocatalysts: A Review

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 144
Author(s):  
Aleksandra Piątkowska ◽  
Magdalena Janus ◽  
Kacper Szymański ◽  
Sylwia Mozia
Keyword(s):  
Carbon Dioxide Reduction ◽  
Air Purification ◽  
Lithium Storage ◽  
Tio2 Photocatalysts ◽  
Doped Tio2 ◽  
Preparation Conditions ◽  
Production Of Hydrogen ◽  
Methods Of Synthesis ◽  
Metal Doped ◽  
Inactivation Of Bacteria

This article presents an overview of the reports on the doping of TiO2 with carbon, nitrogen, and sulfur, including single, co-, and tri-doping. A comparison of the properties of the photocatalysts synthesized from various precursors of TiO2 and C, N, or S dopants is summarized. Selected methods of synthesis of the non-metal doped TiO2 are also described. Furthermore, the influence of the preparation conditions on the doping mode (interstitial or substitutional) with reference to various types of the modified TiO2 is summarized. The mechanisms of photocatalysis for the different modes of the non-metal doping are also discussed. Moreover, selected applications of the non-metal doped TiO2 photocatalysts are shown, including the removal of organic compounds from water/wastewater, air purification, production of hydrogen, lithium storage, inactivation of bacteria, or carbon dioxide reduction.

Material Safety and Integrity of Water-Filled Low-Density Polyethylene Bags in an Accelerated Weathering Investigation for Applications in Solar Water Disinfection (SODIS)

2015 ◽  
Vol 659 ◽  
pp. 269-273
Author(s):  
Weerawat Terdthaichairat ◽  
Ratchatee Techapiesancharoenkij ◽  
Apirat Laobuthee ◽  
Supamas Danwittayakul ◽  
Sittha Sukkasi
Keyword(s):  
Significant Degree ◽  
Water Disinfection ◽  
Uv Exposure ◽  
Mechanical Degradation ◽  
Accelerated Weathering ◽  
Solar Water Disinfection ◽  
Alternative Material ◽  
Ft Ir ◽  
Polyethylene Bags ◽  
Uv Transmittance

In this work, the potential use of LDPE bags as containers in the SODIS application by simulated in an accelerated weathering tester (QUV), with respect to material safety and durability, was investigated. For the material integrity, a decrease in the elongation at break from 818% (at the beginning) to 21% (after 6 weeks of UV exposure) corresponded to the long UV exposure. A significant degree of mechanical degradation was evident during 2 to 4 weeks of UV exposure. The UV-Vis results showed that the UV transmittance of the bags, mostly in the UV-B region, decreased with longer duration of UV exposure. The FT-IR results showed a slight increase in carbonyl group, particularly observable in the bags exposed under UV for 3 weeks or longer. For the material safety, the amount of plastic additives that were leached into water was negligibily small and much lower than the limit of the safety standard. The results and analyses from this work provide insights into the feasibility of LDPE as an alternative material for SODIS containers and potentially be useful for future designs of SODIS containers to improve the disinfection and durability performances.

scholarly journals In vitro toxicity studies of novel solar water disinfection reactors using the E-screen bioassay and the Ames test

2021 ◽  
Author(s):  
Paloma Ozores Diez ◽  
M. Inmaculada Polo-López ◽  
Azahara Martínez-García ◽  
Monique Waso ◽  
Brandon Reyneke ◽  
...  
Keyword(s):  
Ames Test ◽  
Daily Intake ◽  
Cost Effective ◽  
Water Disinfection ◽  
In Vitro Toxicity ◽  
Toxic Substances ◽  
Solar Water ◽  
Point Of Use ◽  
Solar Water Disinfection

Abstract Solar water disinfection (SODIS) is a cost-effective point of use method for disinfecting water, usually in a 2 L polyethylene terephthalate (PET) plastic bottle. To increase the volume of water disinfected, three novel transparent reactors were developed using PET in 25 L transparent jerrycans, polymethyl methacrylate (PMMA) in tubular solar reactors capable of delivering >20 L of water and polypropylene (PP) in 20 L buckets. In vitro bioassays were used to investigate any toxic substances leached from the plastic reactors into disinfected water as a result of exposure to sunshine for up to 9 months. The Ames test was used to test for mutagenicity and the E-screen bioassay to test for estrogenicity. No mutagenicity was detected in any sample and no estrogenicity was found in the SODIS treated water produced by the PMMA reactors or the PP buckets. While water disinfected using the PET reactors showed no estrogenicity following exposure to the sun for 3 and 6 months, estrogenicity was detected following 9 months' exposure to sunlight; however levels detected were within the acceptable daily intake for 17β-estradiol (E2) of up to 50 ng/kg body weight/day.

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