Ka-lok Chiu

Bio: Ka-lok Chiu is an academic researcher from Hong Kong Polytechnic University. The author has contributed to research in topics: Thermogravimetric analysis & Solar simulator. The author has an hindex of 5, co-authored 8 publications receiving 64 citations.

Removal of reactive dyes in textile effluents by catalytic ozonation pursuing on-site effluent recycling

Abstract: The textile wash-off process consumes substantial amounts of water, which generates large volumes of wastewater that pose potential pollution issues for the environment. In the present study, catalytic ozonation was applied to degrade residual dyes present in rinsing effluents from wash-off processes towards the aim of recycling the waste effluents. A magnetic catalyst was prepared for promoting dye degradation by catalytic ozonation. Via a hydrothermal reaction, highly magnetic manganese ferrite (MnFe2O4) particles were successfully loaded on carbon aerogel (CA) materials (MnFe2O4@CA). The results showed that the developed catalyst strikingly promoted the degradation of dye contaminants by catalytic ozonation, in terms of color removal and reduction of chemical oxidation demand (COD) in rinsing effluents. COD removal efficiency in catalytic ozonation was enhanced by 25% when compared with that achieved by ozonation alone under the same treatment conditions. Moreover, we confirmed that after catalytic ozonation, the rinsing effluents could be recycled to replace fresh water without any evident compromise in the color quality of fabrics. The color difference (ΔEcmc(2:1)) between fabrics treated with recycled effluents and water was not more than 1.0, suggesting that the fabrics treated with recycled effluents displayed acceptable color reproducibility. Although colorfastness and color evenness of fabrics treated with recycled effluents were slightly poorer than those of fabrics treated with water, they were still within the acceptable tolerance. Therefore, the present study validated that catalytic ozonation was a promising technology for saving water and wastewater elimination in textile dyeing. It provides a feasibility assessment of catalytic ozonation for recycling waste effluents to reduce water dependence in textile production. Furthermore, we show a new perspective in on-site recycling waste effluents by catalytic ozonation and enrich the knowledge on feasible approaches for water management in textile production.

Treatment of industrial dye wastewater and pharmaceutical residue wastewater by advanced oxidation processes and its combination with nanocatalysts: A review

Abstract: With the rapid development of industrialization and globalization in recent years, an increasing amount of textile dye wastewater and pharmaceutical wastewater has been discharged into the environment. Current wastewater treatment technology has difficulty meeting all the practical requirements of harmless wastewater discharge, and therefore, the exploration and development of new technologies to treat various types of wastewater is urgently needed. Advanced oxidation processes (AOPs) have the advantages of strong oxidation ability, complete decomposition of organic pollutants, and no secondary pollution, and scientists have found that the introduction of nanocatalysts with good performance into AOPs can achieve excellent treatment effects. Numerous studies have shown that the introduction of catalysts to AOPs can greatly improve the treatment effect. These results demonstrate that AOPs may be an efficient approach for the large-scale treatment of wastewater, however, there are very few systematic reviews that address the treatment of textile dye wastewater and pharmaceutical residue wastewater by AOPs. This study provides a unique focus on the advantages and disadvantages of single AOPs, AOPs combined with nanocatalsyts, and other technologies for the treatment of textile dye wastewater and pharmaceutical residual wastewater, and several critical mechanisms of the degradation of pollutants have been summarized and analyzed. Finally, the challenges and prospects of AOPs in wastewater treatment are summarized. This study provides a useful theoretical foundation and practical guidance for scientists in the fields of environmental science, environmental engineering, and environmental health.