Showing papers by "Muhammad Kaleem Khosa published in 2019"

Azadirachta indica leaves extract assisted green synthesis of Ag-TiO2 for degradation of Methylene blue and Rhodamine B dyes in aqueous medium

Abstract: Abstract Aqueous pollution due to textile industry is an important issue. Photocatalysis is one of the methods used for eradication of dyes from textile industrial effluents. In this study, the synthesis, characterization and evaluation of photo catalytic activity of Ag-TiO2 is reported. TiO2 catalysts with 2, 4, 6 and 8% loading of Ag were prepared by green methods using Azadirachta indica leaves extract as reducing agent with titanium dioxide and silver nitrate as precursor materials. Prepared catalyst was characterized by advanced techniques and was used as catalyst for degradation of Methylene blue and Rhodamine B dyes. Deposition of Ag greatly enhanced the catalytic efficiency of TiO2 towards degradation of dyes. Irradiation of catalyst excites electrons from conduction band of catalyst to valence band yielding an electron-hole pair. This electron-hole pair undergoes secondary reactions and produce OH∙ radicals. These active radicals take part in degradation of dyes. More than 90% dyes were degraded in 120 min. Photo catalytic degradation of Methylene blue and Rhodamine B followed Eley-Rideal mechanism which states that dye react in fluid phase with adsorbed oxygen.

Radiation induced degradation of Congo red dye: a mechanistic study

Abstract: Abstract Synthetic dyes are persistent pollutants with poor biodegradability. The present study is about the degradation of direct Congo red dye in aqueous media using the Co-60 gamma radiation source. The experimental conditions such as gamma-ray absorbed doses, amount of oxidant (H2O2) and pH conditions were evaluated. The λmax of dye solution was noted as 498 nm, and then, decrease in absorbance and reduction in chemical oxygen demand (COD) were examined. The complete colour removal of dye was observed at 5 kGy, while a significant COD removal was observed at 15 kGy gamma-ray absorbed dose in conjunction with oxidant for 50 mg/L concentration. It was found that pH has no influence on degradation efficiency. A possible degradation pathway was proposed. The radiolytic end products were monitored by Fourier transform infrared (FTIR) and gas chromatography coupled with mass spectrometry (GC-MS) to explore the degradation mechanism. It was imperative to study the oxidative degradation pathway to provide directions for potential applicability of advanced oxidation process (AOP) in industrial wastewater treatment.

Ultrasonic Assisted Improvement in DyeingBehaviour of Polyester Fabric UsingDisperse Red 343

Abstract: Ultrasonic (US) energy has revolutionized the dyeing process by introducing the cost and energy effective tools for textile processing. The objective of this research was to use ultrasonic waves as eco-friendly technique to enhance the dyeing process of polyester fabric using disperse red. The fabrics and dye solutions were exposed to ultrasonic waves for 10-60 min. at 60oC. It was found that 40 min. is the optimal treatment time for fabric to get good colour strength using untreated Disperse Red 343. Whereas good colour strength was obtained by dyeing US treated fabric using non US treated dye solution for 30 min. keeping M:L of 1:60 at pH 10 of dyeing bath. At these conditions not only leveled dyeing was achieved but the good colour fastness characteristics were achieved. It is found that ultrasonic radiation has a great potential to improve the dyeing beahviour of polyester fabric using Disperse Red343 dye.