Reactive orange 5 removal from aqueous solution using hydroxyl ammonium ionic liquids/layered double hydroxides intercalation composites

A series of hydroxyl ammonium ionic liquids/layered double hydroxides intercalation composites (ILs/LDHs) were synthesized and adopted to study the adsorption process of anionic dye reactive orange 5 from aqueous solutions. The ILs/LDHs and LDHs were characterized by infrared spectroscopy (IR), X-ray diffractometry (XRD), thermogravimetric analysis (TG), total organic carbon (TOC) analyzer and BET surface area measurement. The successful intercalation of the anion of ILs (2-hydroxyethylammonium acetate) into the interlayer space of LDHs was confirmed. The effects of contact time, temperature, adsorbent dosage and solution pH on the adsorption experiments were investigated. The experimental results showed that the maximum adsorption capability of ILs/LDHs reached up to 300.9 mg/g, which was obviously higher than that of LDHs. The adsorption isotherms were well described by Freundlich model in the presence of the LDHs and ILs/LDHs. The adsorption kinetics followed the pseudo-second order kinetic model. The negative value of ΔG0 and the positive value of ΔH0 indicated spontaneous and endothermic nature of reactive orange 5 adsorption. For ILs/LDHs(b), desorption percentages were 57.91%, 46.67%, and 37.34% in each cycle, respectively. This innovative approach, using ILs/LDHs, was more efficient and could be envisaged as a promising process for reducing the pollution of the textiles manufacturing.