Kinetic modelling of TOC removal by H2O2/UV, photo-Fenton and heterogeneous photocatalysis processes to treat dye-containing wastewater

Abstract

Wastewater from textile manufacturing introduces recalcitrant organic compounds, such as dyes and toxic by-products into the environment, where advanced oxidation processes are used to treat toxic and non-biodegradable organic pollutants which cannot be removed by traditional methods. H 2 O 2 /UV, photo-Fenton and heterogeneous photocatalysis (TiO 2 /H 2 O 2 /UV) processes were used, and the effect of the hydraulic retention time on total organic carbon (TOC) removal was evaluated by fitting the analytical data for the three processes to different kinetic models. The high correlation between empirical and modelled data was accomplished with a pseudo-first-order model for the three processes (R 2 = 0.9823 ± 0.017). Mineralisation, decolourisation and disinfection of textile wastewater were investigated with laboratory-scale experiments for each process. Data showed that when 5 g/L H 2 O 2 was used, heterogeneous photocatalysis was the most effective method for the removal of TOC (94.55 %). With respect to colour, all three processes achieved nearly 100 % removal (99.6, 99.3 and 99.9 % at 120 min for the H 2 O 2 /UV, photo-Fenton and TiO 2 /H 2 O 2 /UV processes, respectively).

Photocatalytic degradation of rhodamine B based on membrane catalyst of H3O40PW12/quaternized chitosan

“…The aforementioned hydroxyl radicals were strong oxidants, which was available to oxidize different organic dye components at low concentrations (Lopez‐Lopez et al . ).…”

“…Among these technologies, photolysis (chemical method), which is used as a potential technology for dye disposal, has demonstrated excellent degradation results for most types of dye waste water due to the generation of hydroxyl radical (•OH). The aforementioned hydroxyl radicals were strong oxidants, which was available to oxidize different organic dye components at low concentrations (Lopez-Lopez et al 2015).…”

Degradation and mineralization of 4-tert-butylphenol in water using Fe-doped TiO2 catalysts

“…In the irradiated solution, there is competition between the parent pollutant and the formed intermediate compounds for oxidizing agents 55 . The base TiO 2 catalyst seems to have favoured the conversion of 4-t-BP, while the 4% Fe/TiO 2 catalyst clearly promoted the carbon oxidation to CO 2 .…”

“…Some studies reported that this combination increased the efficiency of the process, since UV light was combined with both the oxidant and the photocatalyst 59 , while others claimed that the efficiency of the process was reduced due to the competition for ultraviolet irradiation between the oxidant and the photocatalyst 60 or due to H 2 O 2 adsorption on the surface of catalytic particles, which reduced the activity of the catalyst 61 . In addition, it could be suggested that hydrogen peroxide was consumed at the beginning of the process, and the rest of the organic matter was removed by the catalyst 55 .…”

Combined photocatalytic and biological process for textile wastewater treatments

“…An alternative for the treatment of textile wastewater is the advanced oxidation processes (AOP) based on the generation of hydroxyl radicals, a powerful oxidizing agent, allowing the transformation of the pollutants into CO 2 , water, and inorganic ions or otherwise less complex compounds (Lopez‐Lopez et al, ). Since AOPs may have high costs to achieve high pollutant removal efficiencies, these treatments may be applied to enhance wastewater biodegradability, allowing the biological process to be used (Oller, Malato, & Sánchez‐Pérez, ; Soares et al, ).…”