MEDIATED ELECTROCHEMICAL OXIDATION USING CE4+/CE3+ SYSTEM AND AG+ ION AS CATALYST FOR METHYLENE BLUE DEGRADATION

• Main Author: Rokhima, Ummu
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/52150
• Institution: Institut Teknologi Bandung

Methylene blue is a basic dye commonly used in the textile industry. Textile industrial waste has a negative impact on the environmental ecosystem, namely changes in the physical and chemical properties of river water. The main pollution from textile industry activities comes from the dye waste resulting from the dyeing process. The presence of dye in the river due to the textile industry requires serious handling. One of the textile dye waste degradation methods is mediated electrochemical oxidation. Mediated electrochemical oxidation is an oxidation – reduction reaction using a support medium, which is called a mediator. The mediator acts as an oxidizer that oxidizes textile dye waste into simpler compounds. There are many kinds of mediators in electrochemical reactions, one of which is a metal ion. Electrochemical oxidation mediated in this study was an electrolysis cell system using Pt wire with the addition of metal ion mediator Ce4+/Ce3+ in H2SO4. The addition Ag+ ion catalyst is used to increase the efficiency of the waste degradation process. The degradation of methylene blue is indicated by a decrease in the peak current of methylene blue oxidation. The peak methylene blue oxidation current was measured using square wave voltammetry technique. The degradation percentage of methylene blue was calculated by comparing the peak current oxidation of methylene blue before and after degradation. Previously, the oxidation potential value of methylene blue and ion mediator was measured using the cyclic voltammetry technique. The results showed that the oxidation potential of methylene blue was 0.2880 V, while the oxidation and reduction potential of Ce4+/Ce3+ were 1.2640 V and 1.0860 V, this potential values is relative to Ag/AgCl reference electrode and the electrode carbon paste as a working electrode. This measured value indicates that the oxidation potential of methylene blue is not disturbed by the potential of mediator. Degradation of methylene blue using the mediator Ce4+/ Ce3+ with and without the addition of an Ag+ ion catalyst can increase the percent degradation value of methylene blue. The effect of potential difference, degradation time, mediator ion concentration, and catalyst ion concentration were optimized in this study. The optimum concentration of Ag+ ion catalyst added to the degradation system is 1.5 mM. The optimum conditions for electodegradation were obtained at 0.8 mM methylene blue with addition of 15 mM Ce3+ ion and 1.5 mM Ag+ ion with potential 6 V for 30 minutes. The degradation percentage obtained was 93.12%. The electrochemical degradation kinetics of methylene blue obtained pseudo-first-order for methylene blue. The equation for the rate of degradation of methylene blue can be written as r = k'[MB] with the value of the reaction rate constant (k’) was 0.06887 minutes?1. The degradation of methylene blue by this electrochemical mediated oxidation method was influenced by the initial concentration of methylene blue. The higher the initial concentration of methylene blue, the longer it will take to degrade. This could be due to the reduced activity of the Ce4+ ion to oxidize methylene blue due to the higher concentration of methylene blue. This indicates that the degradation of methylene blue at higher concentrations is not affected by mass transport. In addition to measurements using the voltammetry method, measurements the results of methylene blue degradation were also carried out using the UV-VIS spectrophotometric. The maximum wavelength of methylene blue is 664 nm. The t- test of these two measurement methods yields texp <ttable (2.17 <2.68), which means that there is no significant difference between the measurement results of the two methods.