Extractive removal of astacryl blue BG and astacryl golden yellow dyes from aqueous solutions by liquid–liquid extraction

Extractive removal of cationic dyes namely astacryl blue BG and astacryl golden yellow were carried out from aqueous solutions using salicylic acid dissolved in toluene. Extraction efficiency was studied under various experimental conditions, such as pH of feed solution, concentration of stripping agent, extractant concentration, extraction time, temperature, initial dye concentration, and reusability of solvent. Under the optimised experimental conditions 93–98% of dyes were extracted. The extracted dyes were quantitatively stripped with sulphuric acid solution. The organic phase obtained after the stripping of dyes was washed with dilute sodium hydroxide solution to neutralise any sulphuric acid trapped or adhered to the solvent and then with distilled water. This solvent was reused in succeeding extraction of dyes. The optimised conditions were: pH of the feed 10 ± 0.2, extractant concentration 2.89 × 10− 2 mol/L, concentration of stripping agent 1.5 N H2SO4, extraction time 4 min, initial dye concentration 50 mg L− 1, aqueous to organic (A/O) ratio 1:1. Finally real industrial textile wastewater was tested under optimised conditions, 92% of dye was extracted at 25 °C.

Research highlights
► It does not produce any sludge.
► Low cost effective study.
► Solvent can be reused as many as times.