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The removal of phenol compounds (such as phenol (Ph), 4-chlorophenol (4-CPh), and 4-phenolsulfonic acid (4-APS)) was studied using catalytic ozonation and cerium oxide (CeO2) as the catalyst. Conventional ozonation removes 40% and 30% of total organic carbon (TOC) for 4-CPh and 4-APS, respectively. The presence of the catalyst doubled the TOC removal in comparison with ozone alone. Chloride and sulfate ions, detached from the target compounds, did not affect the mineralization degree. The effect of ions was studied by adding NaCl and Na2SO4 during the ozonation of Ph with CeO2 as a catalyst. The O3-CeO2 process was responsible for 89% TOC removal, while the presence of NaCl and Na2SO4 decreased TOC removal by nearly 50%. Ozonation alone only removed 20% of TOC at 120 min with or without inorganic salts. The presence of salts in the Ph ozonation provoked in detrimental effect in comparison when inorganic ions were produced along with the decomposition of 4-CPh and 4-APS. [ABSTRACT FROM AUTHOR]

The current study presents the treatment of water contaminated with the dye Direct Red 28 in the presence of Na2SO4 at three different concentrations (10, 40 and 80 g/L) by simple ozonation. This wastewater treatment was considered in a wastewater recycling process. At the end of each ozonation cycle, ozonation dynamics, ozone consumption, pH, electrical conductivity and UV/Vis spectra variation were analyzed and correlated with the stoichiometric analysis balance. The efficiency of the wastewater treatment in each reuse cycle was evaluated by a novel image processing method. The image results show that the presence of sulfate improves more than 45% the dye fixation on a cotton sample. However, at high additive concentrations, the color quality decreases 25%, compared with the system with low additive concentration, due to the presence of peroxysulfate ions and the compounds accumulated through the ozonation process. [ABSTRACT FROM AUTHOR]

This study presents the treatment of wastewater contaminated with Reactive Black 5 (RB5) by simple ozonation in the presence of Na2SO4, Na2CO3 (inorganic additives), and their mixture. This oxidative treatment was a single step into a wastewater recycling process. At the end of each recycle, pH variation and UV/Vis spectroscopy of the ozonated samples were analyzed. The absorbency variations were correlated with the dynamics of ozone consumption after each recycle. The quality of the treated wastewater was evaluated by the dye fixation on cotton textile samples after each cycle. The quality of dyeing process was evaluated by a novel image processing method. The image analysis results demonstrated that the mixture of salts improved the fixation of dye after each of the eight recycling procedures. The presence of Na2SO4 favored the fixation of color and Na2CO3 catalyzed the reaction between dye and fiber. Moreover, the effect of Na2CO3 dominated the additives effect over the recycling ozonation of the RB5 dye. [ABSTRACT FROM AUTHOR]

The removal of phenol compounds (such as phenol (Ph), 4-chlorophenol (4-CPh), and 4-phenolsulfonic acid (4-APS)) was studied using catalytic ozonation and cerium oxide (CeO2) as the catalyst. Conventional ozonation removes 40% and 30% of total organic carbon (TOC) for 4-CPh and 4-APS, respectively. The presence of the catalyst doubled the TOC removal in comparison with ozone alone. Chloride and sulfate ions, detached from the target compounds, did not affect the mineralization degree. The effect of ions was studied by adding NaCl and Na2SO4 during the ozonation of Ph with CeO2 as a catalyst. The O3-CeO2 process was responsible for 89% TOC removal, while the presence of NaCl and Na2SO4 decreased TOC removal by nearly 50%. Ozonation alone only removed 20% of TOC at 120 min with or without inorganic salts. The presence of salts in the Ph ozonation provoked in detrimental effect in comparison when inorganic ions were produced along with the decomposition of 4-CPh and 4-APS. [ABSTRACT FROM AUTHOR]