Adsorptive removal of toxic dye from aqueous solution and real industrial effluent by tris(2-aminoethyl)amine functionalized nanoporous silica



Ordered nanoporous silica SBA-15 was successfully synthesized and functionalized by tris(2-aminoethyl)amine (Tren), a multi-amine ligand, to develop efficient cationic dye adsorbent. The prepared materials were characterized by XRD, N2 adsorption–desorption, TGA, and FT-IR analysis. Tren-SBA-15 was used for the removal of malachite green (MG) from both aqueous solution and real textile effluent. The effects of various operational parameters including solution pH, adsorbent dosage, contact time, initial concentration and temperature on removal of MG using Tren-SBA-15 were investigated in batch adsorption mode. Within the optimum conditions, Tren-SBA-15 exhibited an excellent adsorptive capability of 2330 m g−1 (6.38 mmol g−1) with removal of 89.8%. Equilibrium data was best described by the Freundlich and Sips isotherm models indicated a favorable adsorption process (nF > 1) and heterogeneous system for dye adsorption (nS > 1). The adsorption kinetic behavior was influenced by intraparticle diffusion and pseudo-second-order kinetic model provided well-fitted to the experimental data. The kinetic rate constant increased with temperature. Qualitative estimates of the thermodynamic parameters showed that the overall adsorption process is spontaneous (ΔG < 0) and a bit endothermic (ΔH > 0), and adsorption mechanism was assumed to be a physisorption. Experiment with real textile wastewater showed 48.7% MG removal by the use of 0.01 g Tren-SBA-15. The reusability of the adsorbent in real wastewater was shown to be successful along with its regeneration possibility. Desorption experiments were performed by two deferent eluents to desorbs both cationic ions and dye molecules from Tren-SBA-15. The results showed that dye is removed completely from real effluent after two continues adsorption/desorption cycles. © 2014 American Institute of Chemical Engineers Environ Prog, 33: 1242–1250, 2014