Dual-function hydrotalcite-derived adsorbents with sulfur storage properties: Dyes and hydrotalcite fate in adsorption-regeneration cycles

Abstract

Thermal treatment of hydrotalcite at increasing temperatures resulted in formation of mixed oxides that exhibited different adsorption behavior toward anionic and cationic industrial dyes. The material annealed at 450 ○ C was characterized by the highest maximum adsorption capacity for both types of dyes. The adsorption was strongly pH dependent and for the anionic dye abatement low pH was favored whilst higher pH was more preferable for removal of the cationic dye. According to the equilibrium experiments, the maximum adsorption capacity increased from 179 ± 5 to 291 ± 8 mg g -1 in case of the anionic dye at pH 3.5 and from 6 ± 2 to 48 ± 2 mg g -1 in case of the cationic dye at pH 8.0, on starting and thermally treated material at 450 ○ C, respectively. Detailed characteristics of spent adsorbent and its reconstructed form revealed that after each cycle of adsorption and thermal regeneration the maximum adsorption capacity of the material decreased due to changes in the structure and accumulation of sulfur compounds. Evolution of specific surface area and porosity was correlated with annealing temperatures and behavior of dye's residues.

Facile preparation of porous organic copolymer based on triptycene and crown ether for efficient organic dye adsorption

“…For cationic dyes MEB and RhB, the equilibrium time was 100 min, which was faster than that of other materials. 32,33 However, for the anionic dye MO, the equilibrium time was 500 min because additional time was required for MO to enter the pores due to the weak relationship between MO and POP-TCE-15.…”

Fast adsorption of methylene blue, basic fuchsin, and malachite green by a novel sulfonic-grafted triptycene-based porous organic polymer

“…Aer a very rapid adsorption, the uptake rates slowly declined with time and reached equilibrium values at approximately 10 min for all the three dyes, which was faster than for some other materials. 38,39 The equilibrium adsorption rates constant(K 2 ) of the MEB, BF, and MG were 0.0026, 0.0149 and 0.0093 g mg À1 min À1 , respectively, those K 2 value were larger than those previously reported porous adsorbents for the three dyes are listed in Table S2. † The high initial uptake rate and the short adsorption equilibrium time demonstrated that the surfaces of the polymer TPP-SO 3 H had a high density of active sites for dyes adsorption.…”

Interaction between adsorbed molecules and tailor made large chelating ligands grafted on SBA-15 studied by means of thermoporometry

“…Furthermore, Rose Bengal dye can form H-type aggregates in water and polar, protic solvents [53]. Similar effect, with blue shift due to π-π interactions of phenyl groups in MO, was described in confined spaces of anionic clays [54]. On the contrary to MO anions, which were tightly organized perpendicular to the clay layers, AMB and CR anions were tilted or flat lying in the interlayers but still a hypsochromic shift of the absorption maximum was observed.…”