Adsorption of cationic dye onto Raphanus seeds: optimization, adsorption kinetics, thermodynamic studies

Area of Science:

• Environmental Chemistry
• Materials Science
• Water Treatment

Background:

• Industrial wastewater often contains persistent dye contaminants.
• Adsorption is a preferred method for dye removal due to its efficiency and cost-effectiveness.
• Developing novel, low-cost adsorbents is crucial for sustainable water treatment.

Purpose of the Study:

• To investigate the efficacy of activated carbon derived from Raphanus seeds solid residual (ACRS) for removing Methylene Blue (MB) dye.
• To characterize ACRS using BET, SEM, FT-IR, and XRD.
• To optimize the adsorption process using Response Surface Methodology (RSM).

Main Methods:

• Adsorption experiments were conducted varying dye concentration, pH, contact time, and adsorbent dosage.
• Surface area, porosity, and structural properties were analyzed using BET, SEM, FT-IR, and XRD.
• Adsorption kinetics, thermodynamics, and process optimization were performed using pseudo-second-order models and Box-Behnken Design (BBD) within RSM.

Main Results:

• ACRS demonstrated high MB removal efficiency, reaching 99.4% under optimized conditions.
• Effective MB adsorption (>99%) was observed across a wide pH range (2-8) with optimal performance at pH 7.
• Adsorption followed pseudo-second-order kinetics, and the process was found to be exothermic.
• RSM optimization identified optimal conditions: pH 7, 120 min contact time, 10 ppm initial concentration, 1 g/L ACRS dosage, and 45°C.

Conclusions:

• Activated carbon from Raphanus seeds is a highly efficient, economical, and environmentally friendly adsorbent for cationic dyes.
• ACRS offers a sustainable alternative for treating industrial dye-contaminated wastewater.
• RSM proved effective in optimizing the adsorption process, reducing experimental costs and time.