Nik Athirah Yusoff

Evaluation on the molecular structure of azo dye in photocatalytic mineralization under solar light irradiation

AbstractThe aim of this study was to investigate the effects of number of sulphonic groups on solar photocatalytic degradation of Acid Orange 7 (AO7), Orange G (OG), New Coccine (NC), Reactive Black 5 (RB5) and Reactive Green 19 (RG19) in aqueous solution. The data obtained for photocatalytic degradation of AO7, OG, NC, RB5 and RG19 were well fitted with the Langmuir–Hinshelwood kinetic model. The pseudo-first-order rate constant of RG19 with six sulphonic groups was the highest among the dyes in this study. Results showed that photocatalytic degradation rate of the azo dyes increased following the increase of the number of sulphonic groups of the dyes in the sequence of: AO7 < OG < NC < RB5 < RG19.

Comparison on solar photocatalytic degradation of orange g and new coccine using zinc oxide as catalyst

The mineralization of azo dyes could be realized through solar photocatalytic degradation that is a green method where non-harmful end products are produced. The aim of this study was to investigate the mineralization of Orange G (OG) and New Coccine (NC) using ZnO as catalyst. The degradation of the azo dyes was conducted at different experimental conditions, and parameters such as effect of sunlight to the degradation rate, initial azo dye concentration, amounts of catalyst dosage, pH and effect of aeration to the decolorization of azo dye were investigated. Photocatalytic mineralization of the azo dyes was evaluated through the analysis of UV-Vis spectra, chemical oxygen demand (COD) and ion chromatography (IC) for residual ionic species analysis. The results showed that solar photocatalytic degradation using ZnO was effective for colour removal and the photodegradation rate followed Langmuir-Hinshelwood kinetic model. It was observed that the degradation rate of NC was higher than OG which may be due to the different number of sulphonate ions that are attached on to the azo dye molecule.

Exploring the relationship between molecular structure of dyes and light sources for photodegradation and electricity generation in photocatalytic fuel cell

Reactive green 19, acid orange 7 and methylene blue are employed as the organic pollutants in this work. A photocatalytic fuel cell is constructed based on the idea of immobilizing zinc oxide onto zinc photoanode and platinum loaded carbon cathode, both evaluated under sunlight and ultraviolet irradiation, respectively. Influence of light and dye structures on the performance of photocatalytic fuel cell are examined. With reactive green 19, 93% and 86% of color removal are achieved after 8 h of photocatalytic fuel cell treatment under sunlight and ultraviolet irradiation, respectively. The decolorization rate of diazo reactive green 19 is higher than acid orange 7 (monoazo dye) when both dyes are treated by photocatalytic fuel cell under sunlight and ultraviolet irradiation, as the electron releasing groups (-NH-triazine) allow reactive green 19 easier to be oxidized. Comparatively, acid orange 7 is less favorable to be oxidized. The degradation of methylene blue is enhanced under sunlight irradiation due to the occurrence of self-sensitized photodegradation. When methylene blue is employed in the photocatalytic fuel cell under sunlight irradiation, the short circuit current (0.0129 mA cm-2) and maximum power density (0.0032 mW cm-2) of photocatalytic fuel cell greatly improved.

Integrated photocatalytic and sequencing batch reactor (SBR) treatment system for degradation of phenol

This study will examine the efficiency of the simultaneous photocatalytic and biodegradation process in the same treatment reactor. The sequencing batch reactor or also known as SBR is an effective wastewater treatment method that has been applied widely. SBR system has become an alternative method for industrial wastewater treatment with high concentration of chemical oxygen demand (COD), and phenolic compound. In order for the photocatalytic process to occur, ZnO nanoparticles immobilized onto sponge were introduced to the reactor. It was observed that the COD value were decreased, indicated that the simultaneous biodegradation and photodegradation process in functional. The effect of ZnO nanoparticles on the production and composition of extracellular polymeric substances (EPS) and the physiochemical stability of activated sludge in hybrid growth type SBR were monitored. The percentages of removal are varied with different concentration of ZnO nanoparticles. The highest COD removal recorded is 31.5% wi...

Comparison the performance of carbon plate and Pt-loaded carbon in photocatalytic fuel cell (PFC) process

The objective of this study is to compare the performance of cathode electrode in photocatalytic fuel cell (PFC) system under UV light irradiation. The initial concentration 10 mg/L of Reactive Black 5 (RB5) with carbon plate (CP) and Pt-loaded carbon (Pt/C) as cathode reduced to 2.052 and 0.549 mg/L, respectively, after 24 h irradiated by UV light. The value for open circuit voltage, Voc, short-circuit current density, Jsc and maximum power density, Pmax for CP was 0.825 V, 0.00035 mA/cm2 and 0.000063 mW/cm2, respectively, meanwhile Voc, Jsc and Pmax for Pt/C was 1.15 V, 0.0015 mA/cm2 and 0.000286 mW/cm2, respectively, by varying external resistor value from 300 kΩ to 10 Ω. The degradation of RB5 and generation of electricity with Pt/C as cathode showed greater performance than CP.

Comparative Study of Basic, Acid and Reactive Dyes Adsorption onto Rubber Seed-Coated Activated Carbon

In this present study, rubber seed-coated activated carbon (RSCAC) was used as a natural adsorbent to remove basic (MB), acid (MR) and reactive (RBV) dyes using batch process. Each dye in the adsorption process was tested at different initial concentration from 50-500 mg/l. Different dyes showed different percentage removals. The highest removal was recorded by MB which was up to 99.9 %. The experimental data was analyzed with Langmuir and Freundlich adsorption models. The data fitted well with Langmuir. The adsorption capacity were 332.99, 210.33 and 155.37 mg/g for MB, MR and RBV, respectively.