Special Issue "Photocatalytic Membrane Reactors"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Photocatalysis".

Deadline for manuscript submissions: 31 August 2019

Special Issue Editors

Guest Editor
Prof. Dr. Raffaele Molinari

Department of Environmental and Chemical Engineering, Università della Calabria, 87036 Rende (CS), Italy
E-Mail
Interests: membrane processes; catalytic and photocatalytic membrane reactors; complexation reactions coupled with membranes (supported liquid membranes; ultrafiltration assisted by polymers); saving, recovery and recycle of matter and energy by membrane processes
Guest Editor
Prof. Dr. Sylwia Mozia

West Pomeranian University of Technology, Szczecin, Faculty of Chemical Technology and Engineering, Institute of Inorganic Chemical Technology and Environment Engineering, ul. Pułaskiego 10, 70-322, Szczecin, Poland
E-Mail
Interests: inorganic chemical technology; water/wastewater treatment; membrane processes, especially pressure driven membrane techniques and membrane distillation; hybrid membrane processes; advanced oxidation processes; photocatalysis

Special Issue Information

Dear Colleagues,

Since Honda and Fujishima described their research on photocatalytic splitting of water on TiO2 electrodes (Nature, 1972), the interest of scientific world in various applications of photocatalysis has been systematically increased. It is commonly accepted that photocatalysis fits to the Green Chemistry principles allowing both removal of toxic compounds or synthesis of useful substances. The most commonly investigated applications of this process are air and water/wastewater purification in terms of degradation of organic contaminants to innocuous products, such as water, carbon dioxide or inorganic salts, as well as removal of toxic metals. The most recent attempt is utilization of photocatalysis in organic synthesis.

The advantages of photocatalysis can be significantly enhanced by coupling this process with membrane technology. Photocatalytic membrane reactors (PMRs) are hybrid systems of various configurations which combine photocatalysis with membrane separation taking advantages of both processes. PMRs have been found a promising tool for water/wastewater treatment and organic synthesis. Application of a membrane gives a possibility to realize a continuous operation with a simultaneous recovery of a photocatalyst (immobilized or in suspension), coupled with the photoreaction and separation of the substrates or (by)products from the reaction environment. Improvement of process efficiency compared to conventional photoreactors, modularity and easy scale up are some other potential advantages of PMRs. All of these resulted in a significant growth of interest in this area observed in the recent years. Nonetheless, the full-scale applications of PMRs still need detailed investigations to improve the processes performance. This Special Issue aims to cover all aspects of hybrid photocatalysis–membrane systems, including both photocatalytic membranes and reactors with suspended photocatalyst. Experimental and theoretical contributions being within the scope of this Special Issue, including original research papers, short communications and review articles are invited for submission.

Prof. Dr. Raffaele Molinari
Prof. Dr. Sylwia Mozia
Guest Editors

Manuscript Submission Information

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Keywords

  • Photocatalysis
  • Membrane separation
  • Photocatalytic membrane reactor
  • Photocatalytic membrane
  • Immobilized photocatalyst
  • Water treatment
  • Wastewater treatment
  • Organic photosynthesis
  • Photodegradation
  • Photodecomposition

Published Papers (3 papers)

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Research

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Open AccessArticle Synthesis of High Crystalline TiO2 Nanoparticles on a Polymer Membrane to Degrade Pollutants from Water
Catalysts 2018, 8(9), 376; https://doi.org/10.3390/catal8090376
Received: 27 July 2018 / Revised: 22 August 2018 / Accepted: 3 September 2018 / Published: 5 September 2018
Cited by 2 | PDF Full-text (5204 KB) | HTML Full-text | XML Full-text
Abstract
Titanium dioxide (TiO2) is described as an established material to remove pollutants from water. However, TiO2 is still not applied on a large scale due to issues concerning, for example, the form of use or low photocatalytic activity. We present [...] Read more.
Titanium dioxide (TiO2) is described as an established material to remove pollutants from water. However, TiO2 is still not applied on a large scale due to issues concerning, for example, the form of use or low photocatalytic activity. We present an easily upscalable method to synthesize high active TiO2 nanoparticles on a polyethersulfone microfiltration membrane to remove pollutants in a continuous way. For this purpose, titanium(IV) isopropoxide was mixed with water and hydrochloric acid and treated up to 210 °C. After cooling, the membrane was simply dip-coated into the TiO2 nanoparticle dispersion. Standard characterization was undertaken (i.e., X-ray powder diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, water permeance, contact angle). Degradation of carbamazepine and methylene blue was executed. By increasing synthesis temperature crystallinity and photocatalytic activity elevates. Both ultrasound modification of nanoparticles and membrane pre-modification with carboxyl groups led to fine distribution of nanoparticles. The ultrasound-treated nanoparticles gave the highest photocatalytic activity in degrading carbamazepine and showed no decrease in degradation after nine times of repetition. The TiO2 nanoparticles were strongly bound to the membrane. Photocatalytic TiO2 nanoparticles with high activity were synthesized. The innovative method enables a fast and easy nanoparticle production, which could enable the use in large-scale water cleaning. Full article
(This article belongs to the Special Issue Photocatalytic Membrane Reactors)
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Open AccessArticle Photocatalytic Membrane Reactor (PMR) for Virus Removal in Drinking Water: Effect of Humic Acid
Catalysts 2018, 8(7), 284; https://doi.org/10.3390/catal8070284
Received: 13 June 2018 / Revised: 2 July 2018 / Accepted: 10 July 2018 / Published: 16 July 2018
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Abstract
In the actual water environment, the health risk of waterborne viruses is evaluated to be 101–104 times higher at a similar level of exposure compared with bacteria and has aroused strong concern in many countries in the world. Photocatalytic membrane [...] Read more.
In the actual water environment, the health risk of waterborne viruses is evaluated to be 101–104 times higher at a similar level of exposure compared with bacteria and has aroused strong concern in many countries in the world. Photocatalytic membrane reactor (PMR), a new process for virus inactivation in water, has gradually become one of the main tools to inactivate pathogenic organisms in water. However, there is relatively little attention to the effect of natural organic matters (NOMs) on the PMR system, which actually exists in the water environment. In this paper, the TiO2-P25, a common type in sales and marketing, was selected as the photocatalyst, and humic acid was regarded as the representative substance of NOMs for investigating thoroughly the influence of humic acid on virus removal by the PMR system. It was found that competitive adsorption between the virus and humic acid occurred, which markedly reduced the amount of virus adsorbed on the surface of the photocatalyst. Moreover, with humic acid, the direct contact behavior between the virus and the photocatalyst was blocked to some extent, and the disinfection of phage f2 by the active free radicals produced by photocatalysis was furthermore badly affected. Meanwhile, the special structure of humic acid, which made humic acid be able to absorb light of 270–500 nm, led to the reduction of photocatalytic efficiency. Further experiments showed that when there was a certain concentration of humic acid in water, intermittent operation mode or higher membrane flux (>40 L/(m2·h)) was selected to partly alleviate the adverse effects of humic acid. Full article
(This article belongs to the Special Issue Photocatalytic Membrane Reactors)
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Review

Jump to: Research

Open AccessReview Overview of Photocatalytic Membrane Reactors in Organic Synthesis, Energy Storage and Environmental Applications
Catalysts 2019, 9(3), 239; https://doi.org/10.3390/catal9030239
Received: 8 February 2019 / Revised: 23 February 2019 / Accepted: 24 February 2019 / Published: 4 March 2019
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Abstract
This paper presents an overview of recent reports on photocatalytic membrane reactors (PMRs) in organic synthesis as well as water and wastewater treatment. A brief introduction to slurry PMRs and the systems equipped with photocatalytic membranes (PMs) is given. The methods of PM [...] Read more.
This paper presents an overview of recent reports on photocatalytic membrane reactors (PMRs) in organic synthesis as well as water and wastewater treatment. A brief introduction to slurry PMRs and the systems equipped with photocatalytic membranes (PMs) is given. The methods of PM production are also presented. Moreover, the process parameters affecting the performance of PMRs are characterized. The applications of PMRs in organic synthesis are discussed, including photocatalytic conversion of CO2, synthesis of KA oil by photocatalytic oxidation, conversion of acetophenone to phenylethanol, synthesis of vanillin and phenol, as well as hydrogen production. Furthermore, the configurations and applications of PMRs for removal of organic contaminants from model solutions, natural water and municipal or industrial wastewater are described. It was concluded that PMRs represent a promising green technology; however, before the application in industry, additional studies are still required. These should be aimed at improvement of process efficiency, mainly by development and application of visible light active photocatalysts and novel membranes resistant to the harsh conditions prevailing in these systems. Full article
(This article belongs to the Special Issue Photocatalytic Membrane Reactors)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Hybrid photocatalysis–membrane processes over the PVDF/ZnO nanocomposite membrane
Authors: Nurafiqah Rosmana,b, Wan Norharyati Wan Salleha,b, Ahmad Fauzi Ismaila,b
Affiliations: a Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia. 
b Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia.
Corresponding author: W.N.W. Salleh ([email protected]
Abstract: The ZnO nanoparticles was successfully incorporated with mixed phase Ag2CO3/Ag2O via phase transformation route and found to be a visible light driven heterojunction photocatalyst. The photocatalytic efficiency of PVDF/ZnO/Ag2CO3/Ag2O was evaluated by the degradation of AZO dye, Reactive Red 12 (RR12) under UV and visible light irradiation at room temperature. The prepared PVDF/ZnO nanocomposite membrane were characterized by means of thermogravimetric (TGA), x-ray diffraction (XRD), transmission emission microscope (TEM) analysis, UV-Vis-NIR spectroscopy, photoluminescence (PL) and XPS Spectroscopy. The incorporation of mixed phase Ag2CO3/Ag2O with ZnO as heterojunction was observed to give a great influence on the photocatalytic membrane performance. The results indicated that the PVDF/ZnO/Ag2CO3/Ag2O nanocomposite membrane had displayed much higher photocatalytic performances as compared to pristine PVDF/ZnO nanocomposite membrane. The improvement in the photocatalytic activity under visible light could be attribute to the formation of new energy level due to mixed phase of Ag2CO3/Ag2O, narrower the band gap energy and improve electron-holes separation. Moreover, the resultants PVDF/ZnO/Ag2CO3/Ag2O nanocomposite membrane exhibited significant efficiency for the degradation of Reactive Red 12 (RR12) under 100W LED lamp.
Keywords: Hybrid photocatalysis–membrane; ZnO; Ag2CO3/Ag2O; nanocomposite; visible light

Title: Analysis of Performance Characteristics of an Oscillatory Membrane Photocatalytic Reactor
Authors: H. G. Gomaa and R. Sabouni(a)
Affiliation: Chemical and Biochemical Engineering Department, Western University London, ON, Canada, N6A 5B9
(a) Present address: Department of Chemical Engineering, American University of Sharjah, Sharjah, UAE.
Abstract: Experimental and theoretical analysis of the hydrodynamics and performance characteristics of an oscillatory membrane photocatalytic reactor are conducted using suspended ZnO and TiO2 photocatalysts. The investigation involved degradation of dyes and pharmaceuticals by-products micropollutants. The effect of hydrodynamics and design parameters on the system performance and its relation to the membrane-catalyst retention characteristics is evaluated using flat surface membranes as well as ones equipped transverse turbulence promoters (TP). The theoretical analysis was supported by the experimental results which showed that application of oscillatory motion resulted in enhancing the reactor photocatalytic performance by minimizing catalyst particles deposition on the membrane which increased its concentration in suspension. Such effect was further augmented by the increase in membrane permeate flux due to the lower hydraulic resistance caused by catalyst deposition on the membrane surface. Furthermore, application of oscillatory motion provided effective mixing in the reaction channel that minimized particles sedimentation and agglomeration, which further enhanced the catalyst suspension and increased its effective reaction area. Assessment of the specific energy consumption (kWh/m3) compared favourably to membrane cross flow filtration system, which when added to the smaller footprints of the oscillatory design configuration, could make the latter an attractive option for confined space applications for water and wastewater treatment applications. Such advantages however must be assessed in light of the design and maintenance requirements of the oscillatory mechanism in comparison to a conventional cross flow filtration membrane system.
Keywords: Photocatalysis, membranes, oscillatory motion

Title: A dialysis photocatalytic reactor for the green production of vanillin
Authors:
G. Camera Rodaa, F. Parrinob, V. Loddob, L. Palmisanob
Affiliation:
aDepartment of Civil, Chemical, Environmental, and Materials Engineering, University of Bologna, via Terracini 28, 40131 Bologna, Italy
bDipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici (DEIM), University of Palermo, viale delle Scienze Ed. 6, 90128 Palermo, Italy.
Abstract:
In the present work, dialysis has been used to recover vanillin while it is phocatalytically produced by partial oxidation of ferulic acid in an aqueous solution at ambient temperature. The relatively high value of the permeate flux through a dense polyether-block amide membrane allows to continuously extract vanillin from the reacting solution thus avoiding its successive oxidation. The rate of reaction remains almost constant, because the ferulic acid, which is consumed by the reaction, is restored into the reactor by permeation through the membrane. The results obtained with a mathematical model, which accounts for the kinetics of the reaction and the transport of vanillin and ferulic acid into the upstream and downstream liquid phase and through the membrane, agree with the experimentally observed behavior. The model shows that concentration polarization might limit the process if the tangential velocity is not sufficiently high. The increase of the yield of production of vanillin is most important outcome obtained with this membrane reactor.

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