Experimental and modeling studies for the simultaneous removal anionic dyes in single and binary systems using...

Area of Science:

• Environmental Chemistry
• Materials Science
• Adsorption Science

Background:

• Dye and pigment treatment poses a global environmental challenge.
• Industrial wastewater often contains persistent anionic dyes like Bemacid Blue (BB) and Congo Red (CR).

Purpose of the Study:

• To investigate the adsorption efficiency of hydrochloric acid-activated bentonite clay (B-8 N) for BB and CR.
• To characterize the adsorbent and analyze adsorption, desorption, and regeneration processes in single and binary systems.

Main Methods:

• Characterization of activated bentonite using TGA, DTA, SEM, and EDS.
• Adsorption experiments in single and binary dye systems at 55°C.
• Kinetic modeling (pseudo-second-order) and isotherm analysis (Extended Sips, Extended Langmuir).

Main Results:

• In binary systems, Congo Red (CR) exhibited higher adsorption capacity (247.72 mg g⁻¹) than Bemacid Blue (BB) (152 mg g⁻¹).
• The pseudo-second-order kinetic model and Extended Sips/Langmuir isotherms best described adsorption.
• Desorption achieved 83.82% CR and 55.23% BB release using NaOH, with high performance maintained over three regeneration cycles.

Conclusions:

• Activated bentonite clay is a sustainable and efficient adsorbent for removing anionic dyes.
• Adsorption is spontaneous, driven by electrostatic attraction and hydrogen bonding.
• The material shows promise for treating industrial wastewater contaminated with dyes.