Effect of Enhancers and Inhibitors on Photocatalytic Sunlight Treatment of Methylene Blue

Abstract

In view of the fatal illnesses which Methylene Blue (MB) leads to upon ingestion, the present study focused on the use of natural sunlight in heterogeneous photocatalysis to decolourize MB. Most past studies utilized UV, visible or simulated sunlight in photocatalysis of MB. The present study also investigated the effects of enhancers (hydrogen peroxide and persulphate ion) and inhibitors (chloride and carbonate ions) on photodecolourization of MB. Pseudo-firstorder rate constants for each studied effect were determined through Langmuir-Hinshelwood model. The recommended conditions to photodecolourize 60 ppm of MB under natural sunlight were 1.0 g/L titanium dioxide nanopowder at initial pH 10.5 in order to achieve 85.3% decolourization (rate constant of 10.8 ×10-3 min-1). The addition of 4080 ppm hydrogen peroxide and persulphate ion significantly enhanced the decolourization efficiency up to 96.6 and 99.3%, respectively (rate constants of 66.2 and 91.0×10-3 min-1 , respectively). However, the addition of 2000 ppm chloride and carbonate ions reduced the decolourization efficiency of MB to 74.7 and 70.2%, respectively (rate constants of 7.8 and 7.3×10-3 min-1 , respectively). The present study implied that it was possible to use natural sunlight as a light source for photocatalytic treatment of dye in tropical countries like Malaysia.

Photocatalytic degradation of tetracycline using nanosized titanium dioxide in aqueous solution

“…Several recent researches have reported that kinetics of the photocatalytic degradation of aqueous pollutants by TiO 2 follows the Langmuir-Hinshelwood (L-H) kinetic model (Lazar et al 2012;Daghrir and Drogui 2013;Subramonian and Wu 2014). The kinetic model data were evaluated by regression analysis method using Excel software.…”

Decolorization of synthetic brilliant green carpet industry dye through fungal co-culture technology

“…Synthetic dyes are generally very stable to light, temperature, and microbial attack, making them recalcitrant (Pagga and Brown, 1986;Subramonian and Wu, 2014). Furthermore, dye wastewater has a large amount of suspended solids, a broadly fluctuating pH, and is highly colored (Subramonian and Wu, 2014;Wu et al, 2013). However, during last decades researchers focussed on for an effective treatment technology of dyes waste water, but no satisfactory solution has been searched for broad spectrum of dyes degradation.…”

Application of a novel bimetallic hydrogel based on iron and cobalt for the synergistic catalytic degradation of Congo Red dye

“…Fourier-transform infrared (FTIR) Spectrometry of No metals@PAM and FeCo@PAM was investigated. In Figure 1, the spectra of both (a) No metals@PAM and (b) FeCo@PAM exhibited many common bands, as both contained typical PAM bands, [26,27] see Figure 1. A broad band in the region 3,000-3,700 cm −1 appears in both the IR spectra, due to the OH stretching vibrations of absorbed water, the hydroxyl group being H-bound as the peak is very broad.…”