Herein, sodalite zeolite nanoparticle (SZN) was synthesized and modified by different amounts of (3-aminopropyl) triethoxy silane and denoted as SZN(0.5), SZN(1) and SZN(1.5). They were characterized by FTIR, XRD, SEM and zeta potential. The surface modified zeolite nanoparticles were used for adsorbing Direct Red 23 (DR23) and Direct Red 80 (DR80) from wastewater. Effect of main parameters on adsorption capacity of adsorbents was studied. The maximum uptake of DR23 and DR80 was carried out by SZN(0.5) at pH 2.1. The data followed to the Langmuir isotherm and pseudo-second order kinetic. Adsorption capacity of SZN(0.5) was 2415 and 4842 mg/g for DR80 and DR23, respectively. The removal of DR23 and DR80 was a physical adsorption process, exothermic and spontaneous reaction. The Gibes free energy 298, 313, 323 and 333 K were −12.53, −14.68, −16.12, and −17.55 kJ/mol for DR23 and −9.27, −11.73, −13.37, and −15.01 kJ/mol for DR80, respectively.
In this paper, enzymatic decolorization of dyes using laccase from single and binary systems was studied. Direct red 31 (DR31) and Acid blue 92 (AB92) were used as model dyes. The effect of several parameters, such as enzyme concentration, pH, dye concentration, and salt (sodium chloride, sodium carbonate, sodium bicarbonate and sodium sulfate) on decolorization of dyes was evaluated. The optimized enzyme concentration, reaction time, and pH for decolorization of DR31 and AB92 were 500 mg/L, 10 min, and 5, respectively. The presence of salt in solution does not have significant effect on decolorization of dyes. However, addition of sodium chloride salt has significant effect on decreasing decolorization of dyes because of its inhibitory effect on enzymatic processes. Dye decolorization kinetics followed Michaelis–Menten Model. The results showed that the enzymatic process using laccase was an effective method to decolorize dyes from single and binary systems.
