Basic red 2 and methyl violet adsorption by date pits: adsorbent characterization, optimization by RSM and CCD,...

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Agricultural waste, such as date pits, presents an opportunity for developing low-cost, sustainable adsorbents.
• Industrial wastewater often contains cationic dyes that require efficient removal methods.
• Date pits are abundant, natural materials with potential adsorbent properties.

Purpose of the Study:

• To investigate the efficacy of raw date pits for adsorbing cationic dyes from aqueous solutions.
• To optimize the adsorption process for Basic Red 2 (BR2) and Methyl Violet (MV) using response surface methodology (RSM).
• To characterize the adsorption kinetics and equilibrium of dye removal by date pits.

Main Methods:

• Date pits were characterized using FTIR, SEM, BET, and XRD analyses.
• Response surface methodology with a central composite design (CCD) was employed to optimize adsorption parameters (contact time, temperature, initial concentration, pH).
• Adsorption kinetics were modeled using pseudo-first-order and pseudo-second-order models, while equilibrium data were fitted to various isotherm models (Langmuir, Temkin, Freundlich, etc.).

Main Results:

• The second-order polynomial model effectively described the experimental data for BR2 and MV adsorption.
• The pseudo-second-order kinetic model provided the best fit for the adsorption process.
• Maximum adsorption capacities were determined to be 92 mg g⁻¹ for BR2 and 136 mg g⁻¹ for MV.
• Isotherm modeling indicated Dubinin-Radushkevich and Langmuir models for BR2, and Freundlich, Temkin, and Halsey models for MV.

Conclusions:

• Raw date pits are a promising, cost-effective adsorbent for removing cationic dyes from wastewater.
• Response surface methodology successfully optimized the adsorption process, demonstrating the potential of date pits in environmental remediation.
• The adsorption mechanism involves multiple steps, with pseudo-second-order kinetics and various isotherm models describing the equilibrium, suggesting complex interactions.