Decolourization of an azo dye in aqueous solution by ozonation in a semi-batch bubble column reactor

ABSTRACT: The oxidative degradation of the azo dye Reactive Red 120 by ozonation was investigated. The decolourization was carried out by bubbling ozone at the bottom of a bubble column reactor containing the dye solution. The colour, chemical oxygen demand, and total organic carbon removal were evaluated, and the contaminants were characterized based on the changes in UV-Vis and FT-IR spectra. It was observed that changes of UV-Vis spectra represent the disappearance of both azo and aromatic groups, which causes the colour removal. FT-IR analysis indicated that ozonation shifts the functional groups in the azo dye which results in decolourization, a decrease in aromaticity, and an increase in acidity. The results indicate that the chromophore is destroyed and partially mineralized to small fragments during ozonation. The alkaline pH was favourable to decomposition by ozonation, initiated by the formation of the hydroxyl radicals. The oxidation followed first-order kinetics and the completed decolourization confirmed the capability of ozonation to cleave the azo bond from the dye

Oxidation of p-Cresol by ozonation

Oxidation of p-Cresol was investigated by using ozonation process. The aim of this research is to assess the effectiveness of ozonation on oxidation of micropollutant such as p-Cresol. Ozonation performance was evaluated based on p-Cresol concentration reduction and chemical oxidation demand (COD) reduction. It was found ozonation at pH11 achieved the highest p-Cresol degradation, with 95.8% of p-Cresol reduced and 96.0% of COD reduced, for an initial 50 mgL-1 of p-Cresol. The degradation of p-Cresol could be expressed by second-order of kinetic model. The second-order rate constant k increases as the initial pH increased, but decreases with the increasing of initial p-Cresol concentrations. Besides, the absorption spectra of p-Cresol over ozonation time were analyzed by spectrophotometry. The evolution of absorption spectra of p-Cresol degradation suggests that the oxidation of p-Cresol follows three stages mechanisms with cycloaddition as the first step to produce aromatic intermediates followed by ring-opening reactions, degradation of the intermediates, and subsequently achieved mineralization

Study of O

This research was carried out to study the efficiency of O3/S2O82- system in removal of Reactive Red 120 (RR120) dye sample. Different operating parameter such as pH, initial dye concentration and persulfate dosage were studied to evaluate the performance on removing colour and COD. The removal of colour and COD achieved higher efficiency at pH 7, 100 mg/L of initial dye concentration and persulfate dosage of 5 g S2O82-/1 g RR120. O3/S2O82- with the most effective conditions experienced effective decolourization and degradation of organic pollutants than O3 only. Furthermore, it achieved faster breakdown of azo bond and aromatic groups than O3 after treatment as observed with UV-Vis absorption spectra. The FT-IR analysis obtained new absorption peak that represents alkenes after 20 min of O3 treatment whereas mostly of the absorption bands of O3/S2O82- flattened

Lignin recovery and it effects quality of anaerobic treated palm oil mill effluent (AT-POME)

Lignin is one of the main structural polymers present in plant tissue. It can also be found as an isolated product of the pulp and paper industry. Palm oil mill effluent (POME) has been known as high strength industrial wastewater that is difficult to treat due to its large variety of inorganic and organic contents. The main purpose of this study is to recover soluble lignin from anaerobically treated palm oil mill effluent (AT-POME) and indirectly improves the quality of AT-POME. AT-POME was adjusted to different pH using different type of acids. Response Surface Methodology (RSM) was utilized to obtain the optimum operating parameters as well as to analyse the interaction between them. Model shows that 74.67 % of lignin can be recovered from AT-POME after 5 minutes reaction time using sulfuric acid (H2S04) at pH 5. Hence from the experiment, it was proved that simple pH adjustment could precipitate the soluble lignin from AT-POME

Lignin recovery and it effects quality of anaerobic treated palm oil mill effluent (AT-POME)

Lignin is one of the main structural polymers present in plant tissue. It can also be found as an isolated product of the pulp and paper industry. Palm oil mill effluent (POME) has been known as high strength industrial wastewater that is difficult to treat due to its large variety of inorganic and organic contents. The main purpose of this study is to recover soluble lignin from anaerobically treated palm oil mill effluent (AT-POME) and indirectly improves the quality of AT-POME. AT-POME was adjusted to different pH using different type of acids. Response Surface Methodology (RSM) was utilized to obtain the optimum operating parameters as well as to analyse the interaction between them. Model shows that 74.67 % of lignin can be recovered from AT-POME after 5 minutes reaction time using sulfuric acid (H2S04) at pH 5. Hence from the experiment, it was proved that simple pH adjustment could precipitate the soluble lignin from AT-POME

Preliminary screening oxidative degradation methyl orange using ozone/ persulfate

The present study focusing on the performances of advanced oxidation process by using ozonation method towards Methyl Orange based on the efficiency of colour removal and Chemical Oxygen Demand (COD) removal. Factorial design with response surface methodology (RSM) was used to evaluate the interaction between operational conditions, such as pH, initial concentration, contact time and persulfate dosage to obtain the optimum range conditions using a semi-batch reactor. The range of independent variables investigated were pH (3-11), initial concentration (100-500mg/L), contact time (10-50min) and persulfate dosage (20-100mM) while the response variables were colour removal and COD removal of Methyl Orange. The experimental results and statistical analysis showed all the parameters were significant. Thus, from this findings, optimization of operational conditions that had been suggested from the ozone/persulfate RSM analysis were (pH 3, 100 mg/L, 50min, 60mM) that would be produced 99% Colour Removal and 80% COD Removal and help in promoting an efficient ozonation process. The effect list data that showed the most contributed effects to increase the percentages of colour removal were pH and persulfate dosage whereas the contact time and initial concentration had the highest positive effects on the COD removal. Other than that, the interaction between pH, contact time and persulfate dosage were found to be the most influencing interaction. Therefore the least influencing interaction was interaction between persulfate dosage and pH. In this study, the correlation coefficient value R2 for colour removal and COD removal of Methyl Orange were R2= 0.9976 and R2= 0.9924 which suggested a good fit of the first-order regression model with the experimental data

Preliminary screening oxidative degradation methyl orange using ozone/ persulfate

The present study focusing on the performances of advanced oxidation process by using ozonation method towards Methyl Orange based on the efficiency of colour removal and Chemical Oxygen Demand (COD) removal. Factorial design with response surface methodology (RSM) was used to evaluate the interaction between operational conditions, such as pH, initial concentration, contact time and persulfate dosage to obtain the optimum range conditions using a semi-batch reactor. The range of independent variables investigated were pH (3-11), initial concentration (100-500mg/L), contact time (10-50min) and persulfate dosage (20-100mM) while the response variables were colour removal and COD removal of Methyl Orange. The experimental results and statistical analysis showed all the parameters were significant. Thus, from this findings, optimization of operational conditions that had been suggested from the ozone/persulfate RSM analysis were (pH 3, 100 mg/L, 50min, 60mM) that would be produced 99% Colour Removal and 80% COD Removal and help in promoting an efficient ozonation process. The effect list data that showed the most contributed effects to increase the percentages of colour removal were pH and persulfate dosage whereas the contact time and initial concentration had the highest positive effects on the COD removal. Other than that, the interaction between pH, contact time and persulfate dosage were found to be the most influencing interaction. Therefore the least influencing interaction was interaction between persulfate dosage and pH. In this study, the correlation coefficient value R2 for colour removal and COD removal of Methyl Orange were R2= 0.9976 and R2= 0.9924 which suggested a good fit of the first-order regression model with the experimental data