Evaluation of the physical properties and photodegradation ability of titania nanocrystalline impregnated onto modified kaolin

In this study, a microporous layer photocatalyst of titania nanocrystallites heterocoagulated with structurally modified kaolin (TiO2-K) was synthesised via a modified sol-gel method. Physical properties (particle size, morphology, stability and settleability) and photodegradation capacity of the TiO2-K catalyst subject to its synthesis, regeneration and use for water treatment were studied. The modified kaolin, as a support for the titania nanocrystallites had a delaminated sandwich silica structure that minimises chemical intercalation within the nanocomposite structure. Microscopic examination revealed that the TiO2 nanocrystallites were uniformly deposited on the kaolin external surface, resulting in a high degree of photon activation. Compared to the commercial TiO2 P25, the TiO2-K demonstrated a superior photocatalytic degradation capacity to remove an anionic Congo red dye. Its removal efficiency and photo-reaction performance were improved when the TiO2-K was regenerated by a thermal treatment. The TiO2-K particles can be easily separated from the water system for further reuse. This unique nanocomposite photocatalyst shows promising technical advantages for a continuous industrial process of water treatment. © 2010 Elsevier Inc.Vipasiri Vimonses, Meng Nan Chong and Bo Ji

Insight into removal kinetic and mechanisms of anionic dye by calcined clay materials and lime

Our recent work reported that a mixed adsorbent with natural clay materials and lime demonstrated an enhanced capacity and efficiency to remove anionic Congo Red dye from wastewater. This study aims to investigate the removal kinetic and mechanisms of the mixed materials involved in the decolourisation of the dye to maximise their prospective applications for industrial wastewater treatment. The experimental results showed that dye removal was governed by combined physiochemical reactions of adsorption, ion-exchange, and precipitation. Ca-dye precipitation contributed over 70% total dye removal, followed by adsorption and ion-exchange. The dye removal kinetic followed the pseudo-second-order expression and was well described by the Freundlich isotherm model. This study indicated pH was a key parameter to govern the removal mechanisms, i.e. adsorption/coagulation at acidic pH and precipitation at basic condition. Yet, the overall removal efficiency was found to be independent to the operation conditions, resulting in more than 94% dye removal. This work revealed that the mixed clays and lime can be applied as alternative low-cost adsorbents for industrial wastewater treatment.Vipasiri Vimonses, Bo Jin and Christopher W.K. Chowhttp://www.elsevier.com/wps/find/journaldescription.cws_home/502691/description#descriptio

A novel titania impregnated kaolinite photocatalyst: from catalyst engineering to reactor development and modelling

The semiconductor photocatalysis technology has been known as a "green" approach and/or "zero" waste solution for the elimination of organic and microbial pollutants in water. Nanoscale TiO2 has received great attention in R&D as a promising photocatalyst. Application of the photocatalysis technology for an industrial water treatment process is still being impeded by a number of technical challenges. This chapter provides an overview on the development of a novel titania impregnated kaolinite (TiO2/K) photocatalyst and an annular slurry photoreactor (ASP) system. We will introduce the overall results from our recent engineering science research, including synthesis and characterisation of the TiO2/K photocatalyst, hydrodynamic analysis of the ASP system, evaluation of photo-degradation kinetics, and application of statistical and modelling method for the optimization of the ASP-TiO2/K water treatment process. © 2012 Nova Science Publishers, Inc. All rights reserved.Bo Jin, Meng Nan Chong, Chris Saint, Vipasiri Vimonse

Development of a pilot fluidised bed reactor system with a formulated clay-lime mixture for continuous removal of chemical pollutants from wastewater

This study was to determine the prospective application of a newly developed fluidised bed reactor (FBR) system using a formulated clay-lime mixture for a large-scale wastewater treatment implementation. A lab-made FBR was designed to assess the application of this formulated clay-lime mixture for the removal of several potential pollutants present in wastewater streams. The operating conditions of the FBR system was first optimised in batch mode by individual experiments prior to progressing into the continuous scheme. The results revealed that the dye elimination was enhanced significantly, by which 99% removal of 30 mg L-1 dye can be achieved with 0.8 g L-1 loading and aeration rate of 1 L min-1. This process was found effective in removal of anionic dye and phosphate while less favourable towards nitrate. This can be attributed to the different dominant removal mechanisms i.e. precipitation and adsorption. The potential reaction time of the formulated clay-lime mixture was found to be pH dependent where the removal performance was superior in strong alkaline conditions. Several municipal primary effluent samples were also treated using the developed FBR system in continuous operation mode. This system contributed an average 10-15% and 20-40% reduction of the nitrate and COD, respectively, while 100% removal of phosphate was obtained over the experimental period. This study demonstrated that the developed FBR system with the formulated clay-lime mixture can be a cost-effective alternative treatment process for a large-scale application for the treatment of industrial wastewater. © 2010 Elsevier B.V.Vipasiri Vimonses, Bo Jin, Christopher W.K. Chow and Chris Sainthttp://www.elsevier.com/wps/find/journaldescription.cws_home/601273/description#descriptio

An adsorption-photocatalysis hybrid process using multi-functional-nanoporous materials for wastewater reclamation

In this study, two of our recently developed laboratory scale wastewater treatment systems, fluidized-bed reactor (FBR) using formulated clay mixture absorbents (clay-FBR adsorption) and an annular slurry photoreactor (ASP) using TiO(2) impregnated kaolin catalysts (TiO(2)-K-ASP) were integrated as an adsorption-photocatalysis hybrid process to treat municipal wastewater as alternative secondary and tertiary treatment for wastewater reclamation. Primary effluent from sewage and secondary effluent from a membrane bioreactor treatment process were used to assess chemical removal capabilities of the FBR and ASP systems, and the hybrid process. The formulated clays-FBR system demonstrated the prevailing removal efficiency toward PO(4)(3-), NO(3)(-) and suspended solids. The TiO(2)-K-ASP showed superior degradation of dissolved organic content; while the presence of inorganic ions caused a detrimental effect on its performance. The integration of the adsorption and degradation system as a hybrid treatment process resulted in a synergetic enhancement for the chemical removal efficiency. Complete elimination of PO(4)(3-) content was obtained in the adsorption stage; while 30% and 65% NO(3)(-) removal were obtained from the hybrid treatment of the primary and secondary effluents, respectively. The corresponding COD reduction during the photodegradation was further investigated by the high-performance size exclusion chromatography technique, where it revealed the shift of apparent molecular weight of the dissolved organic contaminants toward the smaller region. This present study demonstrated that this adsorption-photocatalysis hybrid technology can be used as a feasible alternative treatment process for wastewater reclamation.Vipasiri Vimonses, Bo Jin, Christopher W.K. Chow, Christopher Sain

Enhancing removal efficiency of anionic dye by combination and calcination of clay materials and calcium hydroxide

We explored a feasible approach to enhance removal capacity of three natural clays for removing anionic dye from aqueous solution. Optimal mixing proportions of the clay materials and temperature range for the calcination were investigated. We found that the removal efficiency can be improved significantly when the clay materials were mixed at certain ratio with the addition of lime and the mixed clay materials were calcined 100-300 degrees C. Batch experiments were conducted to study the effects of initial concentration, material dosage, contact time and pH on dye elimination. Kinetic study showed that more than 80% dye removal took place in 5 min. A high removal capacity (>575 mg g(-1)) of the mixed clay materials can be achieved at a low adsorbent dose. The mixed clay materials can be easily recovered by thermal treatment. The recovered mixtures demonstrated an enhanced removal capability after a few cycles of removal and regeneration. The results revealed that use of these clay materials could develop a low-cost treatment process for industrial wastewater.Vipasiri Vimonses, Bo Jin, Christopher W.K. Chow and Chris Sain

Activating natural bentonite as a cost-effective adsorbent for removal of Congo-red in wastewater

Abstract not available.Manjot Toor, Bo Jin, Sheng Dai, Vipasiri Vimonse

Adsorption of congo red by three Australian kaolins

Crown copyright © 2009 Published by Elsevier B.V.This study investigated the potential use of kaolin as alternative adsorbents for removal of congo red from wastewater. The effect of adsorbent dosage, dye concentration, pH and temperature were experimentally studied to evaluate the adsorption capacity, kinetics and equilibrium. Experimental results revealed that optimal adsorption took place at acidic pH and high dye concentration. Ceram kaolin had the highest removal efficiency among studied kaolins, followed by K15GR and Q38. The dye uptake process obeyed the pseudo-second order kinetic expression and was best described by the Langmuir isotherm. Intra-particle diffusion studies showed that the adsorption mechanism was not exclusively controlled by the diffusion step and was more likely to be governed by external mass transfer. Thermodynamic studies showed congo red adsorption on all kaolins was exothermic and spontaneous in nature. Recovered Q38 and K15GR kaolin demonstrated an enhanced adsorption capability. The results indicate that these local kaolins could be employed as low-cost alternatives for removal of anionic dyes from industrial wastewater.Vipasiri Vimonse, Shaomin Lei, Bo Jin, Chris W.K. Chow and Chris Sain