Dye Sorption from Mixtures on Chitosan Sorbents

Area of Science:

• Environmental Chemistry
• Materials Science
• Water Treatment

Background:

• Anionic dyes like Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84) are common textile pollutants.
• Effective removal of these dyes from wastewater is crucial for environmental protection.
• Chitosan-based materials are promising adsorbents due to their functional groups and biodegradability.

Purpose of the Study:

• To investigate the sorption efficiency of chitin and chitosan derivatives for RB5 and RY84.
• To determine the optimal pH conditions for dye sorption.
• To evaluate the sorption capacity of chitosan sorbents for individual dyes and dye mixtures.

Main Methods:

• Sorption experiments using chitin, chitosan DD75%, and chitosan DD95% as sorbents.
• Testing sorption efficiency across a range of pH values.
• Analysis of sorption equilibrium and capacity using the double Langmuir equation.

Main Results:

• Optimal sorption pH was found to be 3 for chitin and chitosan DD75%, and 4 for chitosan DD95%.
• Chitosan DD95% exhibited the highest sorption capacity, reaching 742 mg/g DM for RB5 and 760 mg/g DM for RY84 in single dye solutions.
• Sorption capacities decreased when using dye mixtures, with chitosan DD95% achieving 528 mg/g DM for RB5 and 437 mg/g DM for RY84.

Conclusions:

• Chitosan DD95% is a highly effective sorbent for removing anionic dyes RB5 and RY84.
• The sorption process is pH-dependent, with acidic conditions favoring higher efficiency.
• The double Langmuir model accurately describes the sorption behavior of these dyes onto chitosan sorbents.