Propane-1,3-bis(hexadecyldimethylammonium bromide)-bentonite-based novel hybrid material for the elimination of textile dyes

Abstract

This work addresses intercalation of a gemini surfactant, propane-1,3-bis(hexadecyldimethylammonium bromide) (g-16–3-16), into bentonite (Bt) clay for developing a novel hybrid material which can eliminate dyes from the wastewater. The prepared g-16–3-16-Bt hybrid material was characterized through FTIR, XRD, SEM-EDX, and BET. The material exhibited an approximate removal efficiency of 95 % for congo red (CR) and eriochrome black T (EBT) under optimal conditions (pH = 3, concentration of dyes = 10 mg/L, adsorbent dose = 2 g/L, equilibrium time = 180 min., temperature = 25 °C). With increase in concentration of both the dyes (1 to 25 mg/L), the g-16–3-16-Bt demonstrates a notable increase in adsorption capacity towards CR (0.4 to 11.1 mg/g) and EBT (0.5 to 10.7 mg/g), respectively. The adsorption was examined with several co-existing ions and found that among the Mg2+, Ca2+, Ni2+, Cu2+, EDTA, sulphate, bicarbonate and glycine, only bicarbonate and Mg2+ slightly impacted the EBT removal (from 95 % to 83 % and 78 %, respectively), whereas all affected in the case of CR. With a rise in the NaCl concentration, the efficiency of g-16–3-16-Bt towards CR removal declined (from 88 % to 62 %) considerably, however, it did not affect much with EBT. The results of adsorption studies were found to follow pseudo-second-order kinetic model and match well with the Langmuir isotherm. The maximum adsorption capacity of g-16–3-16-Bt towards CR and EBT were found to be 30.95 and 19.15 mg/g respectively. The g-16–3-16-Bt hybrid material exhibited a good efficiency even after 4th adsorption–desorption cycle (∼79 % removal) and was found to be efficient for the elimination of CR and EBT from real wastewater.