Abstract
The aim of this study was to investigate the adsorption characteristics of malachite green (MG) dye onto the raw (RLAPW) and activated (ALAPW) surface of Lupinus albus seed peel waste prepared via physicochemical activation under alkaline condition as a dye adsorbent. Proximate analysis, surface area (Sears’ method), point of zero charge (pHzpc), and FTIR analysis were used to characterize the adsorbents. The effects of operational parameters such as pH (4) for ALAPW and pH (6) for RLAPW, adsorbent dose (0.2 g), initial dye concentration (30 mg/L), contact time (60 min), and temperature (298 K) were optimized. The experimental data well fitted with the Freundlich adsorption isotherm with the adsorption capacity of 7.3 mg/g for activated Lupinus albus seed peel waste (ALAPW) and Sips isotherm for raw Lupinus albus seed peel waste (RLAPW) with the adsorption capacity of 6.6 mg/g. The kinetics data well fitted to pseudo-second-order kinetic model for both adsorbents. Thermodynamic study revealed that the bioadsorption process using bioadsorbents was spontaneous and exothermic in nature. Desorption experiment was conducted and showed desorption efficiency at an acidic pH of 2. The results showed that the prepared adsorbents exhibited good adsorption capacity and can be used as an alternative adsorbent for the adsorptive removal of malachite green dyes.
Highlights
Academic Editor: Ester Chiessi e aim of this study was to investigate the adsorption characteristics of malachite green (MG) dye onto the raw (RLAPW) and activated (ALAPW) surface of Lupinus albus seed peel waste prepared via physicochemical activation under alkaline condition as a dye adsorbent
E experimental data well fitted with the Freundlich adsorption isotherm with the adsorption capacity of 7.3 mg/g for activated Lupinus albus seed peel waste (ALAPW) and Sips isotherm for raw Lupinus albus seed peel waste (RLAPW) with the adsorption capacity of 6.6 mg/g. e kinetics data well fitted to pseudo-second-order kinetic model for both adsorbents
Desorption of MG dye was investigated on the adsorbents with preadsorbed dye at optimum conditions (pH 4 (ALAPW) and pH 6 (RLAPW), adsorbent dose 0.2 g, MG dye concentration 30 mgL−1/50 mL, contact time 60 min, and temperature 298 K), and the mixture was shaken with a magnetic stirrer on digital hot plate at 200 rpm. e preadsorbed MG dye and adsorbent was isolated from the mixture by centrifugation at 4000 rpm for 5 min and placed into 25 mL Me-OH (99%), NaOH (0.1 M), and HCl (0.1 M), at pH 2
Summary
All adsorption experiments were carried out in batch mode by optimizing different variable parameters: pH (2–12), adsorbent dosage (0.0–0.4 g), initial dye concentration (10–50 mg/L), contact time (10–70 min), and temperature (298 K–323 K). E initial pH of all the solutions was adjusted with 1M NaOH or 1M HCl. e solid-liquid separation was performed by centrifugation (4000 rpm for 10 min) followed by filtration. Desorption of MG dye was investigated on the adsorbents with preadsorbed dye at optimum conditions (pH 4 (ALAPW) and pH 6 (RLAPW), adsorbent dose 0.2 g, MG dye concentration 30 mgL−1/50 mL, contact time 60 min, and temperature 298 K), and the mixture was shaken with a magnetic stirrer on digital hot plate at 200 rpm. Where C is MG dye concentration in the desorption solution (mg/L), V is the volume of the desorption solution (L), q is the amount of MG dye adsorbed on the adsorbents before desorption experiment (mg/g), and m is the amount of the adsorbent used in the desorption experiment (g)
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