Efficient removal of basic yellow 51 dye via carbonized paper mill sludge using sulfuric acid

Abstract

In present study, paper mill sludge (PMS) in cellulosic structure carbonized with sulfuric acid was utilized for adsorption of cationic basic yellow 51 (BY 51) dye from synthetic solution. The parameters affecting on removal of BY 51 dye following; initial pH (2-11), amount of carbonized paper mill sludge (CPMS) (0.25-1.5 g/l), initial concentration (0.5-2 mM), time (0-360 min.) and temperature (25-55oC) were studied in the batch adsorption experiments. The physical and chemical properties of prepared CPMS were determined using elemental analyzes, scanning electron microscopy (SEM) and BET techniques. Optimum initial pH was measured to be 7 for the removal of BY 51 dye. The obtained equilibrium data in various initial concentrations of BY 51 dye solution varied from 0.5 to 2.5 mM for three temperatures (25oC, 40oC and 55oC) were applied to Langmuir and Freundlich isotherms. The calculated maximum adsorption capacity (qmax) from Langmuir equation was achieved 1089.45 mg/g depending on increasing temperature from 25oC to 55oC. The experimental results for all temperatures were applied to pseudo-first order kinetic model, pseudo-second order kinetic model and intra-particle diffusion model. Consequently, it was good agreement with the secondorder kinetic model and the activation energy (Ea) is calculated as 11.642 kJ/mol. Thermodynamic parameters such as enthalpy (∆Ho, +19.32 kJ/mol), free energy (∆Go, -23.02 kJ/mol) and entropy (∆So, 0.142 kJ/molK) were also calculated. The results showed that the adsorption phenomena of cationic BY 51 dye is of endothermic and spontaneous nature. The findings presented that CPMS could be utilized as adsorbent in the treatment of industrial wastewater.