Application of expanded graphite/attapulgite composite materials as electrode for treatment of textile wastewater

Acid activation of attapulgite with hydrochloric acid was carried out to obtain greater specific surface area. The activated attapulgite was homogenized completely within an expanded graphite (EG) matrix for preparation of expanded graphite/attapulgite composite materials, which have excellent adsorption capacity and conductivity. The composite materials were used as electrode in treatment of textile wastewater, which was obtained from a local printing and dyeing mill, and contained various types of dyes, such as reactive blue and reactive yellow. The effects of initial pH value, electrolyte concentration, current density and electrolysis time on the treatment efficiency were investigated. Under optimum experimental conditions, the decolorization rate was close to 100%, and chemical oxygen demand (COD) was reduced from 443 g/L to 250 g/L. According to the results, EG/attapulgite composite seemed to be an excellent material for the degradation of organic pollutants in textile wastewater through adsorption and electrochemical oxidation. Also in the present work, scanning electron microscopy (SEM), infrared spectroscopy (IR), UV–vis, surface area and porosimetry systems were used to explain the relationship between the structure of EG/attapulgite and the possible interaction mechanism.