Separation and recovery of dual dye system via bio-polymer based complexation ultrafiltration: optimization using response surface methodology

Abstract Globally, water has become a valuable commodity, and huge volume of wastewater has been generated due to the increasing demand driven by rapid growth in the population and industrialization. Among all the pollutants in wastewater, synthetic dye effluents are more toxic and complex since they are highly resistant to degradation even at lower concentrations. In recent years, membrane separation processes, specifically the complexation ultrafiltration (C-UF) process, have emerged as a promising technology for dye effluent treatment. The biopolymer-based water-soluble complexing species, such as chitosan derivatives, have gained attention due to their abundance and biodegradability. This paper aims to separate the cationic dye malachite green (MG) and the anionic dye methyl orange (MO) using C-UF with carboxymethyl chitosan (CMC) as a complexing medium, which is compatible with both cationic and anionic dyes. The influence of process variables such as initial solution pH, CMC-dye ratio (w/w), and initial concentration of dye has been investigated to assess their impact on the dye separation efficiency. The process optimization was performed using Response Surface methodology, and predicted values of percentage retention of dye were compared with the actual values. The C-UF with CMC has been demonstrated as a sustainable approach for the treatment of MG and MO.