Photocatalytic Reactor System Research Articles

Photocatalytic and antimicrobial efficacy of PVDF/TiO2 membranes fabricated by solution blow spinning

AbstractWith its ability to purify water and treat wastewater, photocatalytic membranes have become a promising solution. The membrane's unique properties allow for the separation of solid compounds and the degradation of organic materials through photocatalytic and antibacterial means. Poly(vinylidene fluoride)/titanium oxide (PVDF/TiO2) composite remain the materials of choice for making these membranes due to their economy, effectiveness, safety, and durability. In this work a photocatalytic membrane reactor (PMR) system was developed using PVDF/TiO2 membranes fabricated by the solution blow spinning (SBS) process. Obtaining photocatalytic membranes using this method is an efficient and ecological route that overcomes the disadvantage of separating the photocatalyst after the treatment is complete. The results of PMR system showed that the PVDF/TiO2 membrane could effectively remove total coliforms and E. coli from polluted water. After 10 min of contaminated water circulation through the PMR system, the presence of pathogens was not detected, indicating the efficiency of the obtained membranes.

Simultaneous removal of ciprofloxacin and disinfection from wastewater by combined photocatalytic reactor (PCR) and membrane bioreactor (MBR) system

Integrated photocatalytic-biological wastewater treatments are being explored as an effective alternative for removing emerging contaminants and pathogens. This study investigates ciprofloxacin (CPX) antibiotic removal and inactivation of Escherichia coli in simulated wastewater by using two systems (i) photocatalytic reactor (PCR) with 0.5 g/L of Ag-doped TiO2 nanoparticles (Ag:Ti in 1:1.7 molar ratio) with 180 min of blue LED light exposure and continuous mixing, and (ii) submerged membrane bioreactor (MBR) operated in continuous mode at 2.75 days hydraulic retention time (HRT) and 30 days of solid retention time (SRT) with 0.68 bar transmembrane pressure (TMP). TEM, XRD, and UV-Vis DRS characterization suggested that Ag doping in the lattice of 25 nm-sized nanoparticles lowered the bandgap from 3.10 to 2.41 eV, improving its photocatalytic performance. Studies on individual PCR, MBR, and combined systems were performed for optimum CPX removal and disinfection. MBR followed by PCR (MBR-PCR) was observed to be the best treatment among all four strategies achieving 99% removal of chemical oxygen demand (COD) and nitrogen from the system, and ensuring ∼99% CPX removal with complete disinfection of 106 CFU/mL E. coli. The study also suggested CPX biodegradation with marginal adsorption on bio-sludge in MBR, and predominant role of h+ over •OH radicals in CPX photocatalysis and bacterial cell disruption. The absence of E. coli zone of inhibition indicated the elimination of CPX toxicity in the treated effluent. Thus, integrated MBR-PCR may find application in the removal of such pharmaceutical compounds and disinfection from wastewater.

RETRACTED: Implementing machine learning and statistical optimization analysis for oily wastewater treatment in a photocatalytic membrane reactor

Photocatalytic membrane reactor systems usually face process problems, including photocatalyst deactivation, fouling formation on the membrane surface, and unwanted reactions. Optimizing effective parameters in this process is very important. In this study, the influence of operating parameters such as Trans Membrane Pressure, flow rate, and reaction time were investigated on the permeate flux in oily wastewater treatment purified by ultrafiltration process with γ-Al2O3 ceramic membrane and TiO2 photocatalyst in PMR. To find the optimized parameters, response surface methodology was used. In addition, experimental data were modeled with an artificial neural network. The correlation matrix analysis was used to determine the importance of selecting input parameters for the ANN model. To calculate the photo-reaction kinetics on the membrane surface, the Langmuir–Hinshelwood correlation was used. By doing this optimization, the efficiency reduction barriers such as sediment formation, photocatalyst deactivation, and unwanted reactions were reduced to some extent. Results of RSM showed that the interaction of TMP and flow rate had the most significant impact on the output of PMR. The ANN model predicted the experimental data with an AARD % of 1.276 %, MSE of 0.006237, and R2 = 0.999614. The value of 0.005 for the overall degradation rate constant was obtained based on the experimental data. Based on the experimental and modeling results, to control and optimize the operating parameters, this system can be used on an industrial scaleup to increase the efficiency of the purification process.

Photocatalytic Removal of Water Emerging Pollutants in an Optimized Packed Bed Photoreactor Using Solar Light

Photocatalysis is an advanced oxidation process that is an environmentally friendly option and one of the most critical technologies in green chemistry today. This work studied the upscaling of photocatalysis as a suitable process for wastewater treatment to remove emerging pollutants. For this purpose, unsupported and supported TiO2 photocatalysts were tested in the photodegradation of ciprofloxacin as a model molecule of an emerging wastewater component, using visible, UV radiation, and solar light. The suitability of TiO2 as a photocatalyst to decompose ciprofloxacin was confirmed in batch photoreactor under Visible and UV radiation, with degradation rates up to 90% after 30 min of irradiation and low adsorption values. TiO2 as a photocatalyst coated in glass support material at the packed bed photoreactor showed good photoactivity for emergent contaminants degradation (95%) under solar radiation. It has been possible to verify that the photocatalytic reactor system constitutes a viable process for eliminating emerging contaminants through environmentally sustainable treatments. Our results corroborate the possibility of degrading emerging contaminants by solar radiation using a packed bed photoreactor, providing a more effective option from a practical and economical point of view for wastewater effluent treatments.

Ag@BiOBr/PVDF photocatalytic membrane for remarkable BSA anti-fouling performance and insight of mechanism

Membrane technologies offer great potential in desalination and wastewater treatment. However, the serious issue of membrane fouling results in the unsatisfactory sustainability and reusability for treating wastewater containing high level of organic foulants. In this work, a photocatalytic membrane reactor system combining Ag@BiOBr photocatalyst and polyvinylidene fluoride (PVDF) ultrafiltration with remarkable anti-fouling property was constructed. The integrated Ag@BiOBr/PVDF photocatalytic ultrafiltration membranes were prepared by blending Ag@BiOBr nanoparticles (NPs) into PVDF membrane via phase inversion method. The membrane separation performance and fouling resistance were studied in a cross-flow ultrafiltration system using bovine serum albumin (BSA) as the model foulants. Compared with the pristine PVDF membrane, the hydrophilicity and surface smoothness of composite membranes were promoted by photocatalyst-incorporation, the Ag@BiOBr/PVDF membrane with the optimal Ag@BiOBr blending content of 2.0 wt% achieved both enhanced water flux and higher BSA rejection efficiency. More importantly, the mechanism of anti-fouling and self-cleaning performances were further studied, the photocatalysis process based on Ag@BiOBr/PVDF membrane effectively decomposed the BSA foulant into broken protein with induced change of carbonyl, ionic bond and hydrogen bond contents in BSA foulants via the active radicals, weakened the intermolecular force of BSA foulants to prevent membrane pore blockage. Meanwhile, the broken protein peptide chains with more negative charges could result in the strength of electrostatic repulsive forces between BSA molecules and membrane. As a result, the BSA foulant could be stably removed in the Ag@BiOBr/PVDF photocatalytic ultrafiltration system under visible light irradiation, achieving the excellent anti-fouling performance by preventing the membrane pore blockage and foulant adhesion. We believe the Ag@BiOBr/PVDF photocatalytic membrane presented in this study will be one example among many photocatalyst-membrane combinations that can be further pursued for organic pollutants removal. In particular, we expect the theoretical support can present a great opportunity to design novel photocatalytic membranes with sustainable anti-fouling performance.

Treatment of pharmaceutical wastewater using photocatalytic reactor and hybrid system integrated with biofilm based process: Mechanistic insights and degradation pathways

Diclofenac and tetracycline, the pharmaceutically active compounds, are ubiquitously found in water bodies. The inability of conventional processes has mandated the use of advanced treatment techniques. This study has demonstrated the use of sulfur-doped g-C3N4/ZnO (SCZ) catalyst for removing diclofenac and tetracycline and achieved ∼94 % and ∼97 % degradation efficiencies, respectively, in 240 min using UV light (wavelength: 320–400 nm). The SCZ catalyst exhibited enhanced mineralization efficiency (∼95 %) in 600 min and reusability (11 cycles) for targeted contaminants. The physicochemical characterization of the used catalyst depicted the presence of crystalline structures, defects, and roughness, similar to that of the pristine catalyst. The degradation pathways of diclofenac and tetracycline delineated the possible reaction mechanisms for the transformed product formations. The SCZ catalyst was used in the continuous photocatalytic reactor to treat synthetic and real wastewater spiked with pharmaceuticals. Additionally, moving and stationary bed bioreactor-sedimentation tank was coupled with the continuous photocatalytic reactor removing suspended and biodegradable impurities, which enhanced the organic removal efficiency from ∼70–94 %. The SCZ catalyst showed ∼85 % degradation efficiency for the targeted pharmaceutical compounds from the solution mixture. The results of this study suggest that SCZ catalyst and the hybrid photocatalytic system can be a promising solution for the treatment of pharmaceuticals from real wastewater.

A Review on the Design and Performance of Enzyme-Aided Catalysis of Carbon Dioxide in Membrane, Electrochemical Cell and Photocatalytic Reactors.

Multi-enzyme cascade catalysis involved three types of dehydrogenase enzymes, namely, formate dehydrogenase (FDH), formaldehyde dehydrogenase (FaldDH), alcohol dehydrogenase (ADH), and an equimolar electron donor, nicotinamide adenine dinucleotide (NADH), assisting the reaction is an interesting pathway to reduce thermodynamically stable molecules of CO2 from the atmosphere. The biocatalytic sequence is interesting because it operates under mild reaction conditions (low temperature and pressure) and all the enzymes are highly selective, which allows the reaction to produce three basic chemicals (formic acid, formaldehyde, and methanol) in just one pot. There are various challenges, however, in applying the enzymatic conversion of CO2, namely, to obtain high productivity, increase reusability of the enzymes and cofactors, and to design a simple, facile, and efficient reactor setup that will sustain the multi-enzymatic cascade catalysis. This review reports on enzyme-aided reactor systems that support the reduction of CO2 to methanol. Such systems include enzyme membrane reactors, electrochemical cells, and photocatalytic reactor systems. Existing reactor setups are described, product yields and biocatalytic productivities are evaluated, and effective enzyme immobilization methods are discussed.

An automated coating process to produce TiO2-coated optical fibre for photocatalytic reactor systems

A recent development in photocatalytic reactor systems is the introduction of catalyst coated optical fibre for improved illumination efficiency. A high catalyst loading per unit reactor volume would require a large amount of coated fibre. Hence, an automated optical fibre catalyst coating process (AOFCCP) was developed. Here, we report on the effect of process variables in the deposition of TiO2 (P25 and anatase) on the coating thickness and surface morphology. The thickness of the photocatalytic layer increases with an increase in the withdrawal speed, which is attributed to a reduced flow back of the slurry prior to the drying process. This is further substantiated by the observed increase the catalyst layer thickness upon increasing the drying/calcination temperature (200 – 500 °C) upon coating P25 on to the optical fibre. The surface of the layer created by dip-coating through a P25-slurry was often corrugated, whereas the anatase surface obtained by gel-coating was smooth.

Photocatalytic quorum quenching: A new antifouling and in-situ membrane cleaning strategy for an external membrane bioreactor coupled to UASB

Microbial quorum sensing (QS) induces biofilm formation on the membrane surfaces leading to severe biofouling, which remains a major bottleneck for membrane-based systems. Here, we report an effective UV photocatalytic quorum quenching (QQ) strategy in an integrated upflow anaerobic sludge blanket – photocatalytic membrane reactor (UASB-PMR) system, where TiO2 nanoparticles immobilized in porous polymeric beads were kept in suspension as the photocatalysts. The UASB unit reached a methane yield of 0.30 ± 0.05 L CH4/g COD removal while treating the synthetic wastewater, slightly higher than a typical internal anaerobic membrane bioreactor (AnMBR). This novel system showed 7-fold higher efficacy in membrane fouling control than the UV photolytic QQ system (19.1 ± 2.4 d vs. 2.7 ± 1.0 d) under intermittent UV irradiation (17% of total operation time). Continuous UV irradiation, both in photolytic and photocatalytic QQ, significantly alleviated membrane biofouling, while long-term UV exposure exerted some changes in the surface properties of the membranes, which were not observed under intermittent UV irradiation. The reactive oxygen species (ROS) generated by the UV-excited TiO2 not only oxidized the foulants on the membrane surface, but also quenched acyl-homoserine lactones (AHLs), the QS signal molecules, thus retarding membrane fouling to the maximum extent. Additionally, in-situ membrane cleaning, enhanced COD removal, and almost complete disinfection of the effluent were realized in the photocatalytic QQ system. Equipped with these advantages, this innovative photocatalytic QQ can be a readily implementable strategy to prevent fouling in external membrane bioreactors (MBRs) for the pilot- and/or full-scale applications.

Performance of tight ultrafiltration membrane in textile wastewater treatment via MPR system: effect of pressure on membrane fouling

Industrial textile wastewater can be considered as main water polluting source in which constitutes a threat to human health and ecosystems; due to high water consumption and generated a large volume of color liquid waste. In the present study, the effect of various applied pressure in membrane photocatalytic reactor (MPR) system using ZnO-PEG nanoparticles and polypiperazine amide tight ultrafiltration (UF-PPA) for textile wastewater treatment was systematically investigated mainly through membrane fouling phenomenon. Results showed that the final permeate flux after 180 min was found to increase with the increase of applied pressure which obtained 0.4133 at 6 bar. Under 6 bar of pressure, the dye rejection of permeate was successfully reduced by approximately 100%. The Field Scanning Electron Microscopy (FESEM) analysis was also revealed that 6 bar of applied pressure did not affect or changed the structure of membrane cross-sectional pattern of UF-PPA membrane. In summary, the integrated usage of ZnO-PEG nanoparticles in photocatalysis combined with UF-PPA process improved the membrane fouling phenomenon and able to completely remove the colour from the feed of industrial dye wastewater.

Engineering approach in stimulating photocatalytic H2 production in a slurry and monolithic photoreactor systems using Ag-bridged Z-scheme pCN/TiO2 nanocomposite

Ag-bridged pCN/TiO2 Z-scheme heterojunction composite with faster charges separation for stimulating H2 evolution under UV and visible light in different photo-catalytic reactor systems has been investigated. The photo-catalytic activity was tested using slurry, fixed bed and monolith photo-reactor systems for continuous H2 production from glycerol-water mixture. Using slurry system, Ag-pCN/TiO2 photo-catalyst produced 470 µmol h−1 of H2 which is 8.41 and 9.66 times higher than pCN/TiO2 and pristine TiO2, respectively. The efficiency was improved due to development of heterojunction with faster charges separation, whereas, Ag provides hot photo-generated electrons by surface plasmon resonance (SPR) and active sites for H2 production. The parameters study reveals that highest H2 was obtained at pH 7, glycerol concentration of 5 wt% and 0.15 g of catalyst loading. Furthermore, by applying engineering approach Ag-pCN/TiO2 showed H2 production rate of 10150 μmol h−1 using monolith reactor, a 13.36 and 21.6 times higher than fixed-bed and slurry photoreactors. The monolith honeycomb reactor exhibited higher AQY and space yield of 49.15% and 67.67 µmol h−1 cm−3 than slurry reactor (15.77%, 3.615 µmol h-1cm−3) and fixed-bed reactor (1.63%, 3.233 µmol h-1cm−3). The superior performance of a monolith reactor was due to higher photon flux utilization, large illuminated surface area and processing volume. The schematic of conversional and Z-scheme mechanism of Ag-pCN/TiO2 were proposed based on the results. Thus, excellent performance of catalyst using monolith reactor compared to slurry and fixed-bed reactor for H2 production would offer a new opportunity of engineering approach for renewable fuels applications.

Enhanced photocatalytic degradation of cyanide employing Fe-porphyrin sensitizer with hydroxyapatite palladium doped TiO2nano-composite system

The current research paper deals with the study of palladium doped TiO2 based photocatalytic system to remove cyanide from coke oven wastewater. The photocatalytic activity was improved by employing hydroxyapatite nanoparticles, which serves to enhance the concentration of cyanide near the photoactive sites of TiO2 and also prevents its agglomeration. Further, to enhance the rate of photocatalytic degradation of cyanide under visible light irradiation an iron tetracarboxy phenyl porphyrin sensitizer (Fe-TCPP) was employed. The structural and morphological characterization of the synthesized catalysts were carried out by Fourier transformation infrared spectroscopy (FTIR), X-ray diffraction (XRD), photoluminescence (PL) emission spectra, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and ultraviolet diffuse reflectance spectroscopy (UV- DRS). The photocatalytic activity of the TiO2-Pd-HAP-Fe-TCPP- nanocomposite has been evaluated on degradation of cyanide under visible light irradiation using a photocatalytic reactor system. The results demonstrate the existence of synergistic effect between TiO2-Pd-HAP and Fe-TCPP sensitizer on removal of cyanide. Almost 90% of cyanide degradation was achieved at pH 11 within a short time span of 90 min, using the TiO2-Pd-HAP -Fe-TCPP nanocomposite. The photocatalytic degradation of cyanide by the nanocomposite follows pseudo-first order kinetics. The apparent rate constant (kapp) value of the TiO2-Pd-HAP-Fe-TCPP nanocomposite is estimated to be 11.6 and 4.3 time higher than that of bare TiO2 and TiO2-Pd-HAP respectively. Further, at this condition, >90% toxicity removal was achieved in the photocatalytic system even at a very high initial concentration of cyanide. Therefore, the Fe-TCPP-TiO2-Pd-HAP nanocomposite system can be considered as an alternative technique for removal of cyanide from coke oven wastewater.

Photocatalytic performance of TiO2/Clinoptilolite: Comparison study in suspension and hybrid photocatalytic membrane reactor

Comparison studies in suspension and hybrid photocatalytic membrane reactor (HPMR) system was investigated by using Reactive Black 5 (RB5) as target pollutant under UVA light irradiation. To achieve this aim, hybrid TiO2/clinoptilolite (TCP) photocatalyst powder was prepared by solid-state dispersion (SSD) methods and embedded at the outer layer of dual layer hollow fiber (DLHF) membranes fabricated via single step co-spinning process. TiO2 and CP photocatalyst were also used as control samples. The samples were characterized by Scanning Electron Microscopy (SEM), Energy Dispersion of X-ray (EDX), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) analyses. The result shows that TCP was actively functioned as photocatalyst in suspension system and 86% of RB5 photocatalytic degradation achieved within 60 min; however the additional step is required to separate the catalyst with treated water. In the HPMR system, even though the RB5 photocatalytic degradation exhibits lower efficiency however the rejection of RB5 was achieved up to 95% under UV irradiation due to the properties of photocatalytic membranes. The well dispersed of TCP at the outer layer of DLHF membrane have improved the surface affinity of DL-TCP membrane towards water, exhibit the highest pure water flux of 41.72 L/m2.h compared to DL-TiO2 membrane. In general, CP can help on improving photocatalytic activity of TiO2 in suspension, increased the RB5 removal and the permeability of DLHF membrane in HPMR system as well.

Degradation kinetics of pollutants present in a simulated wastewater matrix using UV/TiO2 photocatalysis and its microbiological toxicity assessment

Water pollution is one of the major concerns over long-term sustainability of the environment. Effective and efficient treatment of polluted wastewater is still a serious challenge for global researchers. In the last 2–3 decades, due to the incessant emergence of micropollutants in surface and ground water bodies, several endeavors have been made to resolve the water pollution issues either through chemical, physical and biological degradation processes or through removal/separation processes using different adsorbents and membranes. It has been found that most of the studies are mainly limited to single or binary pollutant analysis in a pure water matrix. Therefore, in this novel investigation, a mixture of five different pollutants has been studied for UV/TiO2-based photocatalytic degradation. In the present study, a commercially available TiO2, an antibiotic, i.e. Ciprofloxacin and four different synthetic dyes, i.e. Rhodamine B, Methylene Blue, Methyl Orange and Amaranth have been used as a photocatalyst, a pharmaceutical and various industrial dyes, respectively, in a batch photocatalytic reactor system with a stirrer. It is important to note that the commercial TiO2 photocatalyst has also been characterized with the help of several characterization techniques. The present study is mainly focused on the degradation of different micropollutants present in the simulated wastewater matrix and their individual degradation kinetics. It is interesting to observe that MB and RhB have shown the maximum degradation followed by CIP (96.21, 96.15 and 89.62%, respectively). In addition, a microbiological assay has also been performed to check the toxicity variation in the degraded products. It is quite interesting to observe that the simulated wastewater matrix has completely lost its microbial toxicity within 120 min of UV/TiO2-based photocatalytic treatment. Finally, total organic carbon evaluations of various treated samples have also been performed and the obtained results substantiate the theory of assimilable organic carbon.

Treatment of secondary effluent by sequential combination of photocatalytic oxidation with ceramic membrane filtration

The aim of the present work was to experimentally evaluate an alternative advanced wastewater treatment system, which combines the action of photocatalytic oxidation with ceramic membrane filtration. Experiments were carried out using laboratory scale TiO2/UV photocatalytic reactor and tubular ceramic microfiltration (CMF) system to treat the secondary effluent (SE). A 100-nm pore size CMF membrane was investigated in cross flow mode under constant transmembrane pressure of 20kPa. The results show that specific flux decline of CMF membrane with and without TiO2/UV photocatalytic treatment was 30 and 50%, respectively, after 60min of filtration. Data evaluation revealed that the adsorption of organic compounds onto the TiO2 particles was dependent on the pH of the suspension and was considerably higher at low pH. The liquid chromatography-organic carbon detector (LC-OCD) technique was used to characterise the dissolved organic matter (DOM) present in the SE and was monitored following photocatalysis and CMF. The results showed that there was no removal of biopolymers and slight removal of humics, building blocks and the other oxidation by-products after TiO2/UV photocatalytic treatment. This result suggested that the various ions present in the SE act as scavengers, which considerably decrease the efficiency of the photocatalytic oxidation reactions. On the other hand, the CMF was effective for removing 50% of biopolymers with no further removal of other organic components after photocatalytic treatment. Thus, the quantity of biopolymers in SE has an apparent correlation with the filterability of water samples in CMF.

Solar photocatalysis at semi-pilot scale: wastewater decontamination in a packed-bed photocatalytic reactor system with a visible-solar-light-driven photocatalyst

Particles of natural volcanic ashes as photocatalyst configured in a packed-bed photocatalytic reactor were studied for the photodegradation of wastewater pollutants under solar light. The photocatalytic system was equipped with a cylindrical parabolic sunlight concentrator, and the photocatalytic treatment has been developed with a continuous flow of wastewater under sunlight irradiation. The influence of incident radiation, amount of photocatalyst, and several configurations in the photoreactor hydrodynamics were studied. Moreover, results obtained were compared with those obtained from the photolysis and adsorption studies. Good photocatalytic activities have been observed, and this allows concluding that heterogeneous photocatalytic system in a packed bed is an effective method for wastewater pollutants removal. In a sunny day, more than 90% of the contaminant can be removed after 5 h by the continuous-flow photocatalytic treatment of the wastewater in the packed-bed reactor under sunlight. The possibility of combining the renewable energy (solar energy) and the photocatalytic technology, by means of a sustainable photocatalytic material, offers a powerful alternative in the wastewater treatment sector.

TiO2 Solar Photocatalytic Reactor Systems: Selection of Reactor Design for Scale-up and Commercialization—Analytical Review

For the last four decades, viability of photocatalytic degradation of organic compounds in water streams has been demonstrated. Different configurations for solar TiO2 photocatalytic reactors have been used, however pilot and demonstration plants are still countable. Degradation efficiency reported as a function of treatment time does not answer the question: which of these reactor configurations is the most suitable for photocatalytic process and optimum for scale-up and commercialization? Degradation efficiency expressed as a function of the reactor throughput and ease of catalyst removal from treated effluent are used for comparing performance of different reactor configurations to select the optimum for scale-up. Comparison included parabolic trough, flat plate, double skin sheet, shallow ponds, shallow tanks, thin-film fixed-bed, thin film cascade, step, compound parabolic concentrators, fountain, slurry bubble column, pebble bed and packed bed reactors. Degradation efficiency as a function of system throughput is a powerful indicator for comparing the performance of photocatalytic reactors of different types and geometries, at different development scales. Shallow ponds, shallow tanks and fountain reactors have the potential of meeting all the process requirements and a relatively high throughput are suitable for developing into continuous industrial-scale treatment units given that an efficient immobilized or supported photocatalyst is used.

Effect of Calcination Temperature on Performance of Photocatalytic Reactor System for Seawater Pretreatment

Conservative desalination technology including distillation requires high energy and cost to operate. Hence, pretreatment process can be done prior to desalination to overcome energy demand and cost reduction. Objective of this research is to study the effect of calcination temperature of hybrid catalyst in photocatalytic reactor system in the seawater desalination, i.e. salt removal in the seawater. The catalyst was synthesized via wet impregnation method with 1:1 weight ratio of TiO2 and activated oil palm fiber ash (Ti:Ash). The catalyst was calcined at different temperature, i.e. 500 oC and 800 oC. The study was carried out in a one liter Borosilicate photoreactor equipped with mercury light of 365 nanometers for two hours with 400 rpm mixing and catalyst to seawater sample weight ratio of 1:400. The Chemical Oxygen Demand (COD), pH, dissolved oxygen (DO), turbidity and conductivity of the seawater were analyzed prior and after the testing. The fresh and spent catalysts were characterized via X-Ray Diffractogram (XRD and Nitrogen physisorption analysis. The calcination temperature significantly influenced the adsorption behaviour and photocatalytic activity. However, Ti:Ash which calcined at 800 oC has less photocatalytic activity. It might be because the surface of fiber ash was sintered after calcined at high temperature. The Ti:Ash catalyst that calcined at 500 oC was found to be the most effective catalyst in the desalination of seawater by reducing the salt concentration of more than 9 % compared to Ti:Ash calcined at 800 oC. It can be concluded that catalyst calcination at 500 °C has better character, performance and economically feasible catalyst for seawater desalination.

Photodegradation and permeability of conventional photocatalytic reactor and two different submerged membrane photocatalytic reactors for the removal of humic acid in water

AbstractThe combination of photocatalytic reactor with membrane provided considerable advantages over the conventional photocatalytic reactor. In this study, photodegradation and permeability of photocatalytic reactor system with and without membrane were assessed for the removal of HA. TiO2 particles were completely rejected membranes with nominal pore size of <0.4 μm. Membranes used in submerged photocatalytic membrane reactor (SMPR) were hollow fiber MF membrane and anodizing TiO2 membrane. The results show that photocatalytic reactor with hollow fiber MF membrane was more efficient photodegradation than that without membrane due to the synergistic effect by integration of photocatalytic reaction and membrane filtration, whereas SMPR with anodizing TiO2 membrane showed lower treatment efficiency compared to that conventional photocatalytic reactor and SMPR with hollow fiber membrane owing to the reduction of photocatalytic activity sites. Moreover, it was revealed that permeation decrease rate of membr...

Photocatalytic reactor system for seawater pretreatment: effect of calcination temperature

Conservative desalination technology including distillation requires high energy and cost to operate. Hence, pretreatment process can be done prior to desalination to overcome energy demand and cost reduction. The objective of this investigation is to study the effect of calcination temperature of hybrid catalyst in photocatalytic reactor system in the seawater desalination i.e salt removal in the seawater. The catalyst was synthesized via wet impregnation method with 1:1 weight ratio of TiO 2 and activated oil palm fiber ash (Ti:Ash). The catalyst was calcined at different temperature, i.e. 500 o C and 800 o C. The study was carried out in a one litre Borosilicate photoreactor equipped with mercury light of 365 nanometers for two hours with 400 rpm mixing and catalyst to seawater sample weight ratio of 1:400. The Chemical Oxygen Demand (COD), pH, dissolved oxygen (DO), turbidity and conductivity of the seawater were analyzed prior and after the testing. The fresh and spent catalysts were characterized via X-Ray Diffractogram (XRD and Nitrogen physisorption analysis. The calcination temperature significantly influenced the adsorption behaviour and photocatalytic activity. However, Ti:Ash which calcined at 800 o C has less photocatalytic activity. It might be because the surface of fiber ash was sintered after calcined at high temperature. The Ti:Ash catalyst that calcined at 500 o C was found to be the most effective catalyst in the desalination of seawater by reducing the salt concentration of more than 9 % compared to Ti:Ash calcined at 800 o C. It can be concluded that catalyst calcination at 500 °C has better character, performance and economically feasible catalyst for seawater desalination.