Adsorption and photocatalytic degradation of 2-chlorophenol in water: Evaluating the performance of TiO2/activated carbon vs. using a mixture of TiO2 and activated carbon

Abstract

The work reported here compared between two photocatalytic degradation strategies of 2-chlorophenol (2-CP). The first strategy utilized titanium dioxide (TiO2) immobilized on activated carbons (AC) to produce TiO2/AC photocatalysts of various TiO2 loadings. Various immobilization techniques were used: chemical vapour deposition (CVD), direct air hydrolysis (DAH), high-temperature impregnation (HTI). In the first strategy, characterization, adsorption and photocatalytic degradation of 2-CP using TiO2/AC revealed that: 1) deposition of anatase TiO2 occurred in the micro pores of AC; 2) adsorption capacity decreased with increasing anatase TiO2 loading on TiO2/AC; 3) adsorption kinetics followed pseudo first order kinetics where 40 % of 2-CP was adsorbed; 4) photocatalytic degradation caused removal of all 2-CP and 80 % of total organic carbon (TOC), while no chloride ion (Cl−) was produced. In the second strategy, naked TiO2 (anatase) and mixtures of (anatase and AC) were involved to investigate the effect of presence of AC on degradation ability of anatase TiO2 towards 2-CP. The results showed that: 1) naked TiO2 (anatase) caused better degradation of 2-CP than TiO2/AC (Cl− was liberated; complete degradation of 2-CP occurred; some TOC remained in the suspension); 2) presence of AC with anatase TiO2 in the reaction mixture negatively affected Cl− production, but positively affected 2-CP and TOC disappearance; 3) when all 2-CP was adsorbed on AC, production of Cl− was inhibited but continued at a reduced rate. This might indicat that both dissolved and adsorbed 2-CP contributed to the degradation process.