Chekli, L, Kim, JE, El Saliby, I, Kim, Y, Phuntsho, S, Li, S, Ghaffour, N, Leiknes, TO & Kyong Shon, H 2017, 'Fertilizer drawn forward osmosis process for sustainable water reuse to grow hydroponic lettuce using commercial nutrient solution', Separation and Purification Technology, vol. 181, pp. 18-28.View/Download from: Publisher's site
© 2017 Elsevier B.V. This study investigated the sustainable reuse of wastewater using fertilizer drawn forward osmosis (FDFO) process through osmotic dilution of commercial nutrient solution for hydroponics, a widely used technique for growing plants without soil. Results from the bench-scale experiments showed that the commercial hydroponic nutrient solution (i.e. solution containing water and essential nutrients) exhibited similar performance (i.e., water flux and reverse salt flux) to other inorganic draw solutions when treating synthetic wastewater. The use of hydroponic solution is highly advantageous since it provides all the required macro- (i.e., N, P and K) and micronutrients (i.e., Ca, Mg, S, Mn, B, Zn and Mo) in a single balanced solution and can therefore be used directly after dilution without the need to add any elements. After long-term operation (i.e. up to 75% water recovery), different physical cleaning methods were tested and results showed that hydraulic flushing can effectively restore up to 75% of the initial water flux while osmotic backwashing was able to restore the initial water flux by more than 95%; illustrating the low-fouling potential of the FDFO process. Pilot-scale studies demonstrated that the FDFO process is able to produce the required nutrient concentration and final water quality (i.e., pH and conductivity) suitable for hydroponic applications. Coupling FDFO with pressure assisted osmosis (PAO) in the later stages could help in saving operational costs (i.e., energy and membrane replacement costs). Finally, the test application of nutrient solution produced by the pilot FDFO process to hydroponic lettuce showed similar growth pattern as the control without any signs of nutrient deficiency.
Lee, KY, Park, SM, Kim, JB, El Saliby, I, Shahid, M, Kim, G-J, Shon, HK & Kim, J-H 2016, 'Synthesis and Characterisation of Porous Titania-Silica Composite Aerogel for NOx and Acetaldehyde Removal', JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, vol. 16, no. 5, pp. 4505-4511.View/Download from: Publisher's site
Shahid, M, El Saliby, I, McDonagh, A, Chekli, L, Tijing, L, Kim, JH & Shon, H 2016, 'Adsorption and Photocatalytic Degradation of Methylene Blue Using Potassium Polytitanate and Solar Simulator', Journal of Nanoscience and Nanotechnology, vol. 16, pp. 4342-4349.View/Download from: Publisher's site
Solar photocatalytic degradation of organic water pollutants can be used to degrade toxic organic
pollutants in water. In this study, potassium titanate nanofibres were synthesized by an aqueous
peroxide route at high pH and examined as photocatalysts for photodegradation of methylene
blue (MB) using a solar simulator. Initially, MB was adsorbed on the surface of potassium polytitanates
to achieve adsorption equilibrium before the photocatalysts were illuminated using solar
simulator. The results showed that potassium polytitanate nanofibres were effective adsorbents of
MB and also facilitated its photocatalytic degradation. Sulphate ion evolution during photocatalysis
confirmed that some mineralisation occurred and hence photo-oxidative degradation of MB took
place. The optimum operational conditions for the photocatalytic degradation of MB were found
at 0.05 g/L of photocatalyst load, 10 mg/L MB and pH 7. The stability and regeneration of the
photocatalyst specimen was also studied for 3 degradation cycles using adsorption/photocatalysis
model. Morphological structure analysis of potassium titanate showed nanocrystallines structure of
longitudinally-oriented isolated fibre with a length up to several micrometres with diameters ranging
from 10 to 20 nanometres.
Shahid, M, Tijing, LD, El Saliby, I, McDonagh, A, Kim, J-B, Kim, J-H & Shon, HK 2016, 'Adsorption Behavior of Pb(II) Onto Potassium Polytitanate Nanofibres', JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, vol. 16, no. 2, pp. 1916-1919.View/Download from: Publisher's site
Kunhikrishnan, A, Shon, H, Bolan, NS, El Saliby, I & Vigneswaran, S 2015, 'Sources, distribution, environmental fate and ecological effects of nanomaterials in wastewater streams', Critical Reviews in Environmental Science and Technology, vol. 45, no. 4, pp. 277-318.View/Download from: Publisher's site
Engineered nanomaterials (ENM) are manufactured, as opposed to being an incidental by-product of combustion or a natural process, and they often have unique or novel properties that emerge from their small size. These materials are being used in an expanding array of consumer products and, like all technological developments, have both benefits and risks. As the use of ENM in consumer products becomes more common, the amount of these nanomaterials entering wastewater stream increases. Estimates of nanomaterials production are in the range of 500 and 50,000 tons per year for silver and titanium dioxide (TiO2) alone, respectively. Nanomaterials enter the wastewater stream during the production, usage, and disposal of nanomaterial-containing products. The predicted values of nanomaterials range from 0.003 (fullerenes) to 21 ng L−1 (nano-TiO2) for surface waters, and from 4 ng L−1 (fullerenes) to 4 μg L−1 (nano-TiO2) for sewage treatment effluents. Therefore, investigating the fate of nanomaterials in wastewater streams is critical for risk assessment and pollution control. The authors aim first to identify the sources of nanomaterials reaching wastewater streams, then determine their occurrence and distribution, and finally discuss their fate in relation to human and ecological health, and environmental impact.
Shahid, M, Saliby, IE, Tijing, LD, McDonagh, A, Park, SM, Lee, KY, Shon, HK & Kim, J 2015, 'Synthesis and Characterisation of Silica-Modified Titania for Photocatalytic Decolouration of Crystal Violet', Journal of Nanoscience and Nanotechnology, vol. 15, no. 7, pp. 5326-5329.View/Download from: Publisher's site
In the past few years, silica-modified titania has drawn increasing attention due to their special properties making them ideal candidates for a wide range of applications. In this study, we report a novel method for the synthesis of silica-modified titania by a sol–gel method using sodium silicate solution (1 M). The hydrolysis and condensation reactions of titanium dioxide (TiO2, Degussa Aeroxide® P25) in sodium silicate solution proceeded with citric acid (3 M) as a catalyst. The orbital shaking method was followed for the removal of sodium salt formed during the sol–gel process. Solvent exchange was carried out using methanol and hexane. Finally, chemical modification of the gel was conducted using trimethylchlorosilane followed by ambient pressure drying. The obtained silica-modified titania was characterised for nanostructural analysis using scanning electron microscopy and transmission electron microscopy. The nitrogen adsorption–desorption measurements were employed to investigate the BET surface area, pore structure and pore volume of specimens. Thermal gravimetric analysis showed exothermic peaks at temperature range of 90–190 °C representing the oxidation of organic groups from –Si–R network. The silica-modified titania showed high photocatalytic activity and an easy recovery using crystal violet as model water pollutant.
El Saliby, I, Erdeib, L, McDonagh, A, Kim, JB, Kim, JH & Shon, HK 2014, 'Co-doped mesoporous titania photocatalysts prepared from a peroxo-titanium complex solution', Materials Research Bulletin, vol. 49, pp. 7-13.View/Download from: Publisher's site
In this study, nitrogen doped and nitrogen/silver co-doped TiO2 photocatalsysts were fabricated using a sol–gel method at room temperature. The obtained gels were neutralized, washed with pure water, and calcined at 400 °C for 4 h. The photocatalysts were characterized by scanning and transmission electron microscopy, X-ray diffraction, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, and BET specific surface area. The results showed that spherical particles with anatase structure were produced after annealing at 400 °C. N 1s (400 eV) and Ag 3d (367.3 eV) states indicated that nitrogen doping and silver co-doping were in the form of NO bonds and AgO, respectively. The photocatalytic activity of photocatalysts was investigated using a batch reactor system exposed to artificial solar irradiation. Both nitrogen and silver/nitrogen co-doped materials were effective in the photocatalytic degradation of hexamethyl pararosaniline chloride.
Shahid, M, El Saliby, I, McDonagh, A, Tijing, LD, Kim, J & Shon, HK 2014, 'Synthesis and characterisation of potassium polytitanate for photocatalytic degradation of crystal violet', Journal of Environmental Sciences, vol. 26, no. 11, pp. 2348-2354.View/Download from: Publisher's site
Potassium titanate nanostructures were synthesised by hydrothermal treatment of TiO2 (P25) in KOH and H2O2. As-produced powders were characterised by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and nitrogen adsorption-desorption methods. Longitudinally-oriented-wire-like structures with a length up to several micrometres and diameters ranging from 10 to 30 nm were obtained. Larger size fibrous nanowires resulting from the hydrothermal treatment showed high affinity in adsorbing crystal violet (CV), which was mainly due to their high surface area. The photocatalytic bleaching of CV solution revealed that the wires are photoactive under ultraviolet light irradiation. Macroporous nanowires are considered as effective adsorbents of CV, capable of photocatalytic degradation, and they can be easily separated from the solution by settling.
Shahid, M, El Saliby, I, McDonagh, AM, Kim, JH & Shon, H 2014, 'Photodesorption of specific organic compounds from titanium dioxide particles in aqueous media', Desalination and Water Treatment, vol. 52, no. 4-6, pp. 867-872.View/Download from: Publisher's site
This study investigates the photodesorption of organic compounds (beef extract, peptone, humic acid, tannic acid, sodium lignin sulphonate, sodium lauryl sulphate, arabic gum powder and arabic acid) from TiO2 (1 g/L in water, pH 7). After a period to reach adsorption equilibrium, photodesorption experiments were conducted in a recirculated reactor at a constant flow rate of 150 mL/min with a UV light intensity of 24 W. Photodesorption was observed only for sodium lauryl sulphate (50%), sodium lignin sulphonate (43.47%), beef extract (20.35%) and tannic acid (10.5%) indicating that photodesorption is specific to some organic compounds but not to all. Using liquid chromatography-organic carbon detection, untreated beef extract and sodium lignin sulphonate were found to contain significant amounts of humic substances (∼1,000 g/mol), which decreased in concentration after dark phase adsorption, while a significant increase in low molecular weight (<350 g/mol) concentrations was observed after photodesorption. UV-treated sodium lauryl sulphate photodesorbed to give both higher molecular weight (HMW) and lower molecular weight (LMW) organics. Thus, the HMW fractions of organic compounds decomposed into smaller compounds after UV irradiation, which subsequently desorbed from TiO2 surface. However, untreated tannic acid contained a larger proportion of LMW acids, which shows a high adsorption affinity to TiO2 during adsorption and poorly desorbs upon irradiation.
El Saliby, I, Erdei, L, Kim, J & Shon, H 2013, 'Adsorption and photocatalytic degradation of methylene blue over hydro-genetitanate nanofibres produced by a peroxide method', Water Research, vol. 47, no. 12, pp. 4115-4125.View/Download from: Publisher's site
In this study, Degussa P25 TiO2 was partially dissolved in a mixture of hydrogen peroxide and sodium hydroxide at high pH. The fabrication of nanofibres proceeded by the hydrothermal treatment of the solution at 80 C. This was followed by acid wash in HCl at pH 2 for 60 min, which resulted in the formation of hydrogenetitanate nanofibres. The nanofibres were annealed at 550 C for 6 h to produce crystalline anatase nanofibres. The nanofibres were characterised for physico-chemical modifications and tested for the adsorption and photocatalytic degradation of methylene blue as a model water pollutant. An average specific surface area of 31.54 m2/g, average pore volume of 0.10 cm3/g and average pore size of 50 A were recorded. The nanofibres were effective adsorbents of the model pollutant and adsorbents and good photocatalysts under simulated solar light illumination. No reduction in photocatalytic activity was observed over three complete treatment cycles, and the effective separation of nanofibres was achieved by gravity settling resulting in low residual solution turbidity.
Kim, JB, Lee, KW, park, S, Shon, H, Shahid, M, El, SI, Lee, WE, kim, G & kim, J 2013, 'Preparation of Iron-Doped Titania from Flocculated Sludge with Iron-Titanium Composite Coagulant', Journal of Nanoscience & Nanotechnology, vol. 13, no. 6, pp. 4106-4109.View/Download from: Publisher's site
The main drawback of flocculation process with dye wastewater is the large amount of unrecyclable sludge which needs disposal. A novel process using Ti-salt flocculation to purify wastewater was developed to produced sludge that can be calcined to produce titania. In this study, irondoped TiO2 nanomaterial was successfully produced from sludge obtained by the flocculation of dye wastewater with a composite floculant including TiCl4 and FeSO4. The titania was characterised using scanning electron microscopy (SEM/EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and the photodecomposition of acetaldehyde. The XDR results showed that the anatase and rutile structures were found after sludge calcination at 550 C and 640 C respectively. The elemental analyses were carried out using EDX. The rutile titania sample consisted of Ti (35.7 wt.%), Fe (14.7 wt.%), O (42.3 wt.%), P (2.6 wt.%) and Ca (4.7 wt.%). The photocatalytic activity was monitored for the photodecomposition of gas acetaldehyde. Iron-doped titania seems to play an important role in increasing the photocatalytic activity under UV light irradiation.
El Saliby, I, Okour, Y, Shon, H, Kandasamy, JK, Lee, WE & Kim, J 2012, 'TiO2 nanoparticles and nanofibres from TiCl4 flocculated sludge: Characterisation and photocatalytic activity', Journal of Industrial and Engineering Chemistry, vol. 18, no. 3, pp. 1033-1038.View/Download from: Publisher's site
In this study, dye and secondary effluent wastewaters were used to generate a non-hazardous sludge. Anatase TiO2 nanoparticles have been successfully synthesised from the calcination of the TiCl4 flocculated sludge. A conventional hydrothermal method was adopted to produce anatase nanofibres (calcined at 600 8C) from TiO2 nanoparticles. X-ray diffraction, scanning electron microscopy and transmission electron microscopy investigations showed the highly crystalline nanoparticles and nanofibres after calcination. The size of nanofibres was related to the size of their nanoparticles precursors. Nanoparticles had larger surface area than nanofibres, lower pore volume and bigger pore diameter. Energy dispersive X-ray analysis revealed that impurities can be successfully removed by a subsequent hydrothermal/acid wash of nanoparticles. Nanoparticles had better overall photocatalytic activity for the degradation of organics in synthetic wastewater compared to nanofibres. On the other hand, nanofibres had a better adsorption capacity.
El Saliby, I, Shahid, M, McDonagh, AM, Shon, H & Kim, J 2012, 'Photodesorption of organic matter from titanium dioxide particles in aqueous media', Journal of Industrial and Engineering Chemistry, vol. 18, pp. 1774-1780.View/Download from: Publisher's site
Photo-induced desorption of organic compounds from TiO2 particles in aqueous media during photocatalysis has promising applications in water treatment. Photodesorption is a relatively fast phenomenon that facilitates the regeneration of photocatalysts with low energy consumption while concentrating the waste products in an energy and water efficient process. We propose that this transport phenomenon involves a significantly reduced affinity between the photocatalyst and pollutants upon UV illumination, and leads to the rapid detachment/decomposition of adsorbed pollutants. In this study, we report the effect of experimental conditions (pH, photocatalyst loading, organic loading, UV light irradiation and flow rate) on this phenomenon in a recirculating photocatalysis continuous reactor. Initially, organic compounds were allowed to adsorb on the surface of the photocatalyst (Degussa P25) until adsorption equilibrium was achieved. The photodesorption phenomenon was observed shortly after UVlight illumination of TiO2 but before the bulk photocatalytic oxidation takes place. The pH of the solution was found to affect both the adsorption and the desorption percentages revealing the role of particle charge on this phenomenon. Additionally, a 1 g/L loading of photocatalyst showed an optimum photodesorption rate using a single strength synthetic wastewater at pH 7.
Phuntsho, S, Shon, H, Majeed, T, El Saliby, I, Vigneswaran, S, Kandasamy, JK, Hong, S & Lee, S 2012, 'Blended Fertilizers as Draw Solutions for Fertilizer-Drawn Forward Osmosis Desalination', Environmental Science & Technology, vol. 46, pp. 4567-4575.View/Download from: Publisher's site
In fertilizer-drawn forward osmosis (FDFO) desalination, the final nutrient concentration (nitrogen, phosphorus, potassium (NPK)) in the product water is essential for direct fertigation and to avoid over fertilization. Our study with 11 selected fertilizers indicate that blending of two or more single fertilizers as draw solution (DS) can achieve significantly lower nutrient concentration in the FDFO product water rather than using single fertilizer alone. For example, blending KCl and NH4H2PO4 as DS can result in 0.61/1.35/1.70 g/L of N/P/K, which is comparatively lower than using them individually as DS. The nutrient composition and concentration in the final FDFO product water can also be adjusted by selecting low nutrient fertilizers containing complementary nutrients and in different ratios to produce prescription mixtures. However, blending fertilizers generally resulted in slightly reduced bulk osmotic pressure and water flux in comparison to the sum of the osmotic pressures and water fluxes of the two individual DSs as used alone. The performance ratio or PR (ratio of actual water flux to theoretical water flux) of blended fertilizer DS was observed to be between the PR of the two fertilizer solutions tested individually. In some cases, such as urea, blending also resulted in significant reduction in N nutrient loss by reverse diffusion in presence of other fertilizer species.
Atallah, S, El Saliby, I, Baalbaki, R & Talhouk, S 2011, 'Effects Of Different Irrigation, Drying And Production Scenarios On The Productivity, Postharvest Quality And Economic Feasibility Of Origanum Syriacum, A Species Typically Over-collected From The Wild In Lebanon', Journal of the Science of Food and Agriculture, vol. 91, no. 2, pp. 337-343.View/Download from: Publisher's site
Background: The potential of Origanum syriacum L. to become a cultivated crop in Lebanon rather than being harvested from the wild was investigated at the production, postharvest and economic levels. Three irrigation schemes were tested on growth paramet
El Saliby, I, Erdei, L, Shon, H & Kim, J 2011, 'Development of visible light sensitive titania photocatalysts by combined nitrogen and silver doping', Journal of Industrial and Engineering Chemistry, vol. 17, no. 2, pp. 358-363.View/Download from: Publisher's site
In this study we present the effects of non-metal (nitrogen) and metal/non-metal (silver/nitrogen) dopants on titanium dioxide (TiO2) in synthesising visible-light reactive photocatalysts. Nanopowders of TiO2-N and TiO2-NâAg were synthesised using a simple procedure at room temperature. For nitrogen doping, a dispersion of Degussa P-25 was treated with ammonium hydroxide. The obtained modified catalyst was further treated with silver nitrate powder to facilitate silver-nitrogen co-doping. The produced catalysts were characterised using X-ray diffraction, X-ray photoelectron spectroscopy, and specific surface area measurements. Scanning electron microscopy/energy dispersive X-ray and transmission electron microscopy were adapted to detect changes in the morphology and in the chemical composition of synthesised catalysts. The results show that both the morphology and appearance of catalysts were modified to yield nanopowders of yellowish color and relatively high specific surface area. Methylene blue (MB) dye was used as a model aquatic contaminant in 23 mg/L concentration to study the performance of these novel photocatalysts in an aerobic mixed batch reactor system under white light irradiation. Both nitrogen and nitrogen-silver co-doping lead to visible light sensitivity and the new catalysts showed remarkable activities in the decolorisation of MB.
El Saliby, I, Erdei, L, Shon, H, Kim, JB & Kim, J 2011, 'Preparation and characterisation of mesoporous photoactive Na-titanate microspheres', Catalysis Today, vol. 164, no. 1, pp. 370-376.View/Download from: Publisher's site
Mesoporous Na-titanate microspheres were fabricated by a simple low temperature hydrothermal synthesis. Microsphereswereobtained after treating TiO2 (Degussa P-25) with a mixture of sodium hydroxide (NaOH) and hydrogen peroxide (H2O2) at 25â¦C and 80 â¦C. The as-prepared powders were characterised by X-ray diffraction, N2 adsorptionâdesorption measurements and scanning electron microscope/energy dispersive X-ray spectroscopy. The as-prepared microspheres were calcined at 550 â¦C to investigate the effect of calcination on morphology and characteristics. Microspheres were tested for the adsorption and photodecomposition of methylene blue (MB) under ultraviolet light. The results revealed that microspheres with average diameter of 700nmwere formed by self-assembly of tiny TiO2 nanoparticles during the reaction at 25 â¦C, whereas spherical aggregation of nanofibres was detected in powders produced at 80 â¦C. Calcination of samples had low impact on morphology, adsorption and photocatalytic degradation of MB. These novel materials are effective adsorbents of MB, and also capable of its photodecolorisation.
El Saliby, I, Shon, H, Kandasamy, JK & Kim, J 2011, 'Synthesis, characterisation and separation of photoreactive Hydrogen-titanate nanofibrous channel', Separation and Purification Technology, vol. 77, no. 2, pp. 202-207.View/Download from: Publisher's site
Australia is the world's largest wool producing country, accounting for about 25â30% of world production. As a biotemplate, we explored the possibility of using wool to produce micro-channel of Hydrogentitanate nanofibres through morphology transcription of wool microfibres. Hydrothermal method was adopted to synthesise titanate nanofibres. A facile method of impregnation followed by incineration at 600 â¦C was utilised to prepare the nanofibrous channel. Anatase undoped nanofibrous (average nanofibre diameter = 44 nm) channel of around 50min length and an average diameter of 9.5mwere obtained. The photocatalytic activity of nanofibrous channel was monitored under UV irradiation for the decomposition of humic acid in aqueous solution using an aerobic batch reactor system. The photodegradation results showed that UV254 absorbing moeities and DOC were respectively reduced by 82% and 66% after 3 h of photoreaction at 1 g/L catalyst load. The novel nanofibrous channel could be easily separated from the aqueous suspension by sedimentation after the end of the photocatalytic reaction.
Shon, H, Okour, Y, El Saliby, I, Kim, JB & Kim, J 2011, 'Effect of Phosphorous on the Properties of Titania Produced from Ti-Salt Flocculated Sludge in Water Treatment', Journal of Nanoscience & Nanotechnology, vol. 11, no. 8, pp. 7456-7458.View/Download from: Publisher's site
In this study, the removal of phosphorous (P) using Ti-salt flocculation of biologically treated sewage effluent (BTSE) was investigated for a year. The pH, alkalinity and concentration of P, before and after Ti-salt flocculation, were measured and compared. The sludge of Ti-salt flocculation was incinerated at 600 C to produce titania nanoparticles which found to be doped with P. Titania nanoparticles were characterised and their photocatalytic activity under UV light irradiation were also tested. Results indicated that the removal of P, which exceeded 97% in average, was not affected by the pH and the alkalinity of BTSE. The concentration of P in titania had no effect on the characteristics of titania nanoparticles in different seasons. Titania nanoparticles exhibited superior properties in terms of BET surface area and photocatalytic activity.
El Saliby, I, Shon, H, Okour, Y, Vigneswaran, S, Senthilnanthanan, M & Kandasamy, JK 2010, 'Production of Titanium Dioxide Nanoparticles and Nanostructures from Dye Wastewater Sludge - Characterisation and Evaluation of Photocatalytic activity', Journal of Advanced Oxidation Technologies, vol. 13, no. 1, pp. 15-20.
Producing a useful catalyst (TiO2) from sludge is possible after the incineration of sludge produced from the flocculation of wastewater by Ti-salts. In this study, TiO2 was successfully produced from dye wastewater sludge. Titanate nanotubes and nanoaggregates were produced through alkaline-hydrothermal and hydrogen peroxide treatments, respectively. Catalysts were characterised using scanning electron microscope and BET surface measurement. The photocatalytic activity was monitored for the photodegradation of organics in synthetic wastewater (SWW) and the photodecomposition of gas acetaldehyde. Nanotubes with a high surface area of 155.83 m2/g were obtained by alkaline-hydrothermal treatment, while lower surface area (65.22 m2/g) nanoaggregates were synthesized after hydrogen peroxide treatment. In general, nanoparticles, nanotubes and nanoaggregates showed mild photocatalytic activity. All catalysts showed similar photocatalytic activity for the photodecomposition of organics in SWW and the photodecomposition of acetaldehyde.
Kim, JK, Seol, D, Shon, H, Kim, G & Kim, JK 2010, 'Preparation and characterization of titania nanoparticles from titanium tetrachloride and titanium sulfate flocculation of dye wastewater', Journal of the Japan Petroleum Institute, vol. 53, no. 3, pp. 167-172.View/Download from: Publisher's site
Titanium dioxide (TiO2) is the most widely used metal oxide for environmental applications, cosmetics, paints, electronic paper and solar cells, so demand is increasing rapidly. TiO2 can be produced from Ti-flocculated sludge, which is superior to the co
Na, SH, Shon, H, Kim, JB, Park, HJ, Cho, DL, El Saliby, I & Kim, JH 2010, 'Recycling of excess sludge using titanium tetrachloride (TiCl4) as a flocculant aid with alkaline-thermal hydrolysis', Journal of Industrial and Engineering Chemistry, vol. 16, no. 1, pp. 96-100.View/Download from: Publisher's site
The highly strengthened treatment and disposal of excess sludge based on economic and environmental regulation factors is one of the important issues to be dealt with in the activated sludge process. In this study, the reduction and recycling technology of excess sludge were investigated for the aim of achieving a zero emission of excess sludge produced from the activated sludge process using titanium tetrachloride (TiCl4) as a flocculant aid with alkaline-thermal hydrolysis. Alkaline-thermal hydrolysis of excess sludge was obtained 73% and 40% reduction rate at pH 13 (60 8 Â°C) and pH 11 (60 8 Â°C), respectively. Flocculation was carried out using a Ti-salt flocculant and the collected sludge was dewatered and incinerated at 600 Â°C to produce TiO2 nanoparticles. The amount of total suspended solids and volatile suspended solids was significantly decreased with pH increase. The optimal dose of Ti-salt flocculation aid to improve dewatering ability of sludge breakage was 23.95 Ti-mg lâ1. Also, in the batch culture, the supernatant after flocculation and the organic matter released from the lysed sludge were found to be useful as a source of energy for the growth of microorganisms during the aerobic operations period. TiO2 produced from Ti-salt flocculation of excess sludge (TES) was characterized by X-ray diffraction, scanning electron microscopy/energy dispersive X-ray and photocatalytic activity.
Okour, Y, Shon, H, El Saliby, I, Naidu, R, Kim, JB & Kim, JH 2010, 'Preparation and characterisation of titanium dioxide (TiO2) and thiourea-doped titanate nanotubes prepared from wastewater flocculated sludge', Bioresource Technology, vol. 101, no. 5, pp. 1453-1458.View/Download from: Publisher's site
In this study, titanium (Ti), ferric (Fe) and aluminum (Al) salt flocculants were compared for their efficiency in treating wastewater collected from Sydney Olympic Park wastewater treatment plant by following the jar test procedure. Produced sludge from Ti-salt flocculation was dried and titanium dioxide (TiO2) nanoparticles were generated after the incineration of sludge produced from the Ti-salt flocculation of wastewater. Later on, titanate nanotubes were synthesized after TiO2 nanoparticles were hydrothermally treated with 10 N NaOH solution at 130 Â°C for 24 h. Titanate nanotubes were either acid or deionised water-washed, while thiourea-doping was employed to produce visible light-responsive nanotubes. Wastewater flocculation using Ti-salt was found to be as efficient as Fe and Al flocculation in terms of turbidity and DOC removal. XRD results showed that the anatase structure was predominant for TiO2 nanoparticles, while thiourea-doped titanate nanotubes only indicated anatase structure with an increased crystallinity after being crystallized at 600 Â°C. The photocatalytic activity of all photocatalysts was evaluated using the photooxidation of acetaldehyde. Thiourea-doped nanotubes showed a greater photocatalytic activity than as-prepared TiO2 nanoparticles, deionised water-washed, acid-washed titanate nanotubes and P25 under UV and visible light irradiation.
Shon, H, Vigneswaran, S, El Saliby, I, Okour, Y, Kim, IS, Cho, J, Park, HJ, Kim, JB & Kim, JH 2010, 'Hydrogen production affected by Pt concentration on TiO2 produced from the incineration of dye wastewater flocculated sludge using titanium tetrachloride', Desalination and Water Treatment, vol. 15, no. 1-3, pp. 214-221.View/Download from: Publisher's site
TiO2 from the incineration of dye wastewater flocculated sludge using TiCl4 coagulant was produced. Optimal catalyst amount and Pt-loading on TiO2 were studied for the production of H2 by photocatalytic reforming of methanol (6% vol.). On the other hand, BTSE (biologically treated sewage effluent) was flocculated using TiCl4 and produced sludge was incinerated to generate TiO2. TiO2 was loaded with optimum Pt and added to the supernatant in a photocatalytic reactor to test the efficiency of using remaining organics as a âsacrificial reagentâ for photocatalytic hydrogen production. Dissolved organic carbon (DOC) and molecular weight distribution (MWD) were measured for nanofiltration (NF) and TiCl4 flocculation followed by photocatalysis. TiO2 (from the incineration of BTSE flocculated sludge using TiCl4) was produced and loaded with 0.5% Pt. Results showed that the optimum concentration of TiO2 (from dye wastewater) for H2 production was 0.3 g/L, while the optimum amount of Pt was 0.5%. DOC and MWD removal was similar for the flocculation of BTSE followed by photocatalytic reaction and the NF process. Remaining organic compounds after flocculation could not be used as sacrificial reagent to induce H2 production. Further investigations on studying the UV intensity and/or identifying organic/inorganic scavengers to inhibit H2 production are underway.
Shon, HK, Vigneswaran, S, El Saliby, I, Okour, Y, Kim, IS, Cho, J, Park, HJ, Kim, JB & Kim, J-H 2010, 'Hydrogen production affected by Pt concentration on TiO2 produced from the incineration of dye wastewater flocculated sludge using titanium tetrachloride', DESALINATION AND WATER TREATMENT, vol. 15, no. 1-3, pp. 214-221.View/Download from: Publisher's site
Australia is the driest continent on earth and despite this the installed desalination capacity is still around 1% of the total world's desalination capacity. This paper reviews the main seawater issues considered in every desalination projectâthe history, the present situation and the future of desalination in Australia, the suitability of applying reverse osmosis (RO) and the project details of two desalination plants (Sydney and Perth). Ocean currents, seawater temperature and salinity are signifi cant indicators in the assessment of the feasibility of desalination as they aff ect the production costs, the maintenance frequency and the quality of the product water. Seawater reverse osmosis (SWRO) is the only type of desalination technology currently used or proposed for future large-scale desalination plants in Australia. Every capital city except Darwin has considered building at least one desalination plant as a means of providing water security after several years of unprecedented drought that has signifi cantly reduced dam storage levels. Perth was the fi rst major city to use desalinated water for drinking water supply and by early 2009 Sydney will be the second city. Thirteen other large-scale SWRO plants are being planned or proposed at several locations for the purpose of supplying drinking water.
El Saliby, I, Okour, Y, Shon, H, Vigneswaran, S, Kandasamy, JK & Kim, JH 2009, 'Detailed Investigation on the Effect of Washing TiO2 Prepared from Ti-salts Flocculated Wastewater Sludge', Journal of Advanced Oxidation Technologies, vol. 12, no. 2, pp. 194-201.
In this study, the effect of washing TiO2 produced from flocculated sludge was investigated. Produced TiO2 was washed with HCl, NaOH and Milli-Q-water and the washed TiO2 was then characterized in terms of X-ray diffraction imaging, scanning electron microscope/energy dispersive using X-ray analysis and surface area. Washed TiO2 was tested for adsorption and photocatalytic oxidation of acetaldehyde, and the decomposition of organics from synthetic wastewater (SWW) in terms of total organic carbon (TOC) and absorbance at UV-254. Results revealed that the anatase structure was dominant and TiO2 was mainly doped with C atoms. The surface area of TiO2 generated form TiCl4 flocculation was found to be twice larger than the TiO2 generated from Ti(SO4)2 flocculation. Acid and base washings of TiO2 improved its photocatalytic ability in decomposing acetaldehyde under UV-irradiation. Similarly, acid, base and Milli-Q water washings of TiO2 were better in reducing TOC and humic acids from SWW.
Okour, Y, El Saliby, I, Shon, H, Vigneswaran, S, Kim, JH, Cho, J & Kim, IS 2009, 'Recovery of sludge produced from Ti-salt flocculation as pretreatment to seawater reverse osmosis', Desalination, vol. 247, no. 1-3, pp. 53-63.View/Download from: Publisher's site
In this study, titanium tetrachloride (TiCl4), titanium sulfate (Ti(SO4)2) and ferric chloride (FeCl3) flocculation as a pretreatment to seawater reverse osmosis (SWRO) were investigated. Their ability to remove turbidity, seawater organic matter (SWOM) and controlling the feed water quality of SWRO was evaluated. Flux decline of SWRO and membrane autopsy were studied. Titanium dioxide (TiO2) produced from sludge after Ti-salt fl occulation was characterized in terms of particle structure and photocatalytic activity. A hybrid system of fl occulation followed by granular activated carbon (GAC) filtration was employed to remove the suspended micro-flocs after diff erent fl occulations. The optimum dose of 10 mg/L TiCl4 and FeCl3 were used. The turbidity removal for the three coagulants was marginal at different doses at pH 6 and 8. Flocculation followed by GAC fi ltration signifi cantly reduced the turbidity values from 1.5 NTU to about 0.35 NTU using TiCl4 and 0.40 using FeCl3. Silt density index (SDI15) was also decreased from 5.0 to 4.2 and 4.7, respectively. Removal of dissolved organic carbon (DOC), colour and UV absorbance after TiCl4 and FeCl3 flocculation followed by GAC fi ltration was found to be eff ective and similar. TiO2 produced from sludge showed very high photocatalytic activity under UV-irradiation. Acetaldehyde was completely removed after 45 min photocatalytic reaction
Okour, Y, Shon, H & El Saliby, I 2009, 'Characterisation of titanium tetrachloride and titanium sulfate flocculation in wastewater treatment', Water Science and Technology, vol. 59, no. 12, pp. 2463-2473.View/Download from: Publisher's site
Flocculation with titanium tetrachloride (TiCl4) and titanium sulfate (Ti(SO4)2) was investigated in terms of different coagulant doses, pH, turbidity, dissolved organic carbon (DOC), UV-254, colour, zeta potential, particle size and molecular weight distribution. The two coagulants were compared with the commonly used coagulants such as ferric chloride (FeCl3) and aluminium sulfate (Al2(SO4)3). Titanium tetrachloride showed the highest turbidity removal, while titanium sulfate showed the highest reduction of UV-254 and colour at all pH values. The four coagulants were found to have similar organic removal up to 6067% and resulted in similar organic removal in terms of various MW ranges. The decantability of the settled flocs was very high for titanium tetrachloride, titanium sulfate and ferric chloride compared with aluminium sulfate. The dominating coagulation mechanisms for titanium tetrachloride and titanium sulfate are still to be studied, since different precipitation reactions might take place at different pH even without flocculant addition. Titanium tetrachloride and titanium sulfate were found as effective new coagulants in wastewater treatment not only in terms of organic matter removal, but also in sludge reduction through the production of titanium dioxide.
Shon, H, Okour, Y, El Saliby, I, Park, J, Cho, DL, Kim, JB, Park, HJ & Kim, JH 2009, 'Preparation and Characterisation of Titanium dioxide Produced from Ti-salt Flocculated Sludge in Water Treatment', Journal of the Korean Industrial and Engineering Chemistry, vol. 20, no. 3, pp. 241-250.View/Download from: Publisher's site
In this study, titanium (Ti), ferric (Fe) and aluminum (Al) salt flocculants were compared for their efficiency in treating wastewater collected from Sydney Olympic Park wastewater treatment plant by following the jar test procedure. Produced sludge from Ti-salt flocculation was dried and titanium dioxide (TiO2) nanoparticles were generated after the incineration of sludge produced from the Ti-salt flocculation of wastewater. Later on, titanate nanotubes were synthesized after TiO2 nanoparticles were hydrothermally treated with 10 N NaOH solution at 130 °C for 24 h. Titanate nanotubes were either acid or deionised water-washed, while thiourea-doping was employed to produce visible light-responsive nanotubes. Wastewater flocculation using Ti-salt was found to be as efficient as Fe and Al flocculation in terms of turbidity and DOC removal. XRD results showed that the anatase structure was predominant for TiO2 nanoparticles, while thiourea-doped titanate nanotubes only indicated anatase structure with an increased crystallinity after being crystallized at 600 °C. The photocatalytic activity of all photocatalysts was evaluated using the photooxidation of acetaldehyde. Thiourea-doped nanotubes showed a greater photocatalytic activity than as-prepared TiO2 nanoparticles, deionised water-washed, acid-washed titanate nanotubes and P25 under UV and visible light irradiation.
El Saliby, I, McDonagh, A, Erdei, L & Shon, HK 2016, 'Water reclamation by heterogeneous photocatalysis over titanium dioxide' in Green Technologies for Sustainable Water Management, pp. 679-704.View/Download from: Publisher's site
© 2016 American Society of Civil Engineers. This chapter presents the fundamentals and basic principles of water reclamation by heterogeneous photocatalysis (HP). The effects of important operational parameters on the overall treatment efficiency of photocatalytic system are addressed in the chapter in terms of photocatalyst loading, pollutant concentration, pH and temperature of water, dissolved oxygen, and light intensity. The most popular semiconductor used in HP is Titanium dioxide (TiO2) for being relatively inexpensive, chemically stable, and nontoxic. Most water remediation technologies generate a significant amount of wastewater that requires costly retreatment or discharge to evaporation ponds, rivers, and oceans. HP processes that decompose aqueous contaminants are highly dependent on the reaction conditions and the setup of photocatalytic reactors. Visible-light responsive photocatalysts promise a more effective utilization of solar energy. Doping and co-doping of titania is a practical approach toward obtaining improved visible-light active photocatalysts.
El Saliby, I, Shon, H & McDonagh, AM 2013, 'Visible-light active doped titania for water purification: nitrogen and silver doping' in Lens, PNL, Virkutyte, J, Jegatheesan, V, Kim, SH & Al-Abed, S (eds), Nanotechnology for Water and Wastewater Treatment, IWA Publishing, London, UK, pp. 189-208.
Photocatalysis over semiconductors, mainly Ti02, has been employed and extensively studied over the past few decades (Malato et aI., 2009). The so-called "first generation photocatalYSIS" are characterised by their photoexcitation limited to the UV region of the solar spectrum. Nevertheless, many photocatalysts showed outstanding performance in decomposing a large number of pollutants of water and air. A number of water pollutants belong to the family of biorecalcitrant pollutants (non-biodegradable) and these include pharmaceutical and personal care products, industrial wastes, and a large number of pesticides/herbicides. Many of the emerging pollutants are resistant to conventional water treatment processes, noxious to the environment and some are classified as endoctine disrupting agents. The removal of non-biodegradable pollutants from wastewater poses a serious challenge for the water industry. Generally, advanced oxidation processes (AOP) are employed to achieve this goal. Heterogeneous photocatalysis, as part of AOP, is sometimes adopted as a tool to eliminate these contaminants. However, the high cost associated with the use of photocatalysis to treat such compounds has always been a disadvantage for its large-scale adoption in treatment processes. The high cost is mainly associated with: (1) the energy consumed for the UV light irradiation of the photocatalyst, (2) the energy required for the separation of the photocatalyst particles from water. A total of 40% of the solar light reaching the lithosphere is visible light, whereas UV light accounts only for 5% of the total solar radiation. The development of new photocatalysts that can effectively harvest visible light is crucial for making this technology viable in the waler treatment industry. The use of "second-generation riOz photocatalysts" to harvest visible light from solar energy is gaining popularity (Anpo, 1997). Most of the research involving the use of second generation TiOz photocatalysts has...