This study dealt with preparation of the activated carbon derived from active sludge as an adsorbent for the adsorption of crystal violet (CV) from aqueous solution. The waste active sludge was activated chemically with KOH and carbonized to get activated carbon with a large surface area and a high porosity. The activated carbon was characterized by Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) instrument, and scanning electron microscopy (SEM). Adsorption of CV from aqueous solution onto the activated carbon was investigated under varying conditions, such as adsorbent dosage (1–6 g/L), solution pH (4–9), contact time period (0–150 min), initial dye concentration (20–100 mg/L), and temperature (25–55 °C). 4.0 g/L of adsorbent dosage was chosen as the optimum level due to having a high removal rate (96.2%) (initial CV concentration 60 mg/L; 150 rpm; pH 6; 25 °C). The adsorption kinetic and adsorption isotherms were well described by the pseudo second order kinetic and the Freundlich isotherm model, respectively. The thermodynamic parameters indicated that the adsorption is a spontaneous process and favored at higher temperatures. The results show that the activated carbon derived from active sludge could be employed as a low-cost material for the removal of CV dye.
Synthetic dyes are harmful to human beings, and the removal of colour from process or waste effluents is environmentally important. Crystal violet (CV) is a typical triphenylmethane dye, which is widely used in textile dyeing and paper printing industries. The present study shows that granulated and calcinated waste mussell shells (CWMS) can be used as a potential low-cost and locally available adsorbent for the removal of CV from aqueous solutions. The adsorption capacities of the CWMS for CV were investigated with respect to the effect of pH value, adsorbent dosage, contact time, initial dye concentration and temperature. Process variables were optimized, and a maximum dye adsorption of 482.0 mg/g was achieved at pH 6, 0.2 g/L adsorbent dosage, 220 min contact time and 25 °C for dye initial concentration of 100 mg/L. Adsorption kinetics and isotherms were followed by the pseudo-second order model and Freundlich isotherm models, respectively. Thermodynamic parameters demonstrated that adsorption of CV was spontaneous and endothermic in nature. The results indicated that the CWMS as a new adsorbent had the potential to serve in wastewater treatment applications, especially in the removal of CV from aqueous solutions.
Cross-linked chitosan(C)/marble powder (M) composites with different weight ratio percentage (C100M0, C70M30, C50M50, and C30M70) were prepared from marble powder and chitosan and cross-linked using glutaraldehyde. The morphology and the surface area of the chitosan/marble powder composites were also characterized with a scanning electron microscope (SEM) and Micromeritics (ASAP 2020) BET (Brunauer, Emmett and Teller) instrument, respectively. To evaluate the adsorption behaviour of the chitosan/marble powder composites, 0.1 g adsorbent was added into 50 mL Diamozol Blue BRF %150 (C.I. Reactive Blue 221) solution with fixed concentrations (60 mg/L). At equilibrium, the adsorption capacity of C100M0, C70M30 and C50M50 for Dimozol Blue was about 27 mg/g and significantly greater than that of C30M70. C50M50 composite was more economical than C100M0 and C70M30 due to the higher marble powder content, and hence was selected as an adsorbent for the removal of Dimozol Blue from aqueous solution. The adsorption kinetics and equilibrium isotherms of Dimozol Blue onto the chitosan/marble powder composites from aqueous solution were investigated. The studies revealed that Dimozol Blue dye adsorption was described well by the pseudo-second-order and Freundlich isotherm models. The results of this study indicated the applicability of the chitosan/marble powder composites for removing industrial dyes from aqueous solution.
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