Removal of an anionic dye by adsorption/precipitation processes using alkaline white mud

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Industrial wastewater often contains persistent anionic dyes like acid blue 80.
• Effective and low-cost dye removal methods are crucial for environmental protection.
• Alkaline white mud (AWM) is an abundant industrial byproduct with potential adsorbent properties.

Purpose of the Study:

• To investigate the efficacy of alkaline white mud (AWM) for removing acid blue 80 dye.
• To evaluate the influence of various parameters on dye removal efficiency.
• To compare AWM's performance with conventional adsorption methods.

Main Methods:

• Batch experiments were conducted to assess AWM's dye removal capacity.
• Parameters studied included contact time, initial pH, AWM dosage, and interfering anions (sulfate, phosphate).
• Dye concentration effects and sludge production were analyzed.

Main Results:

• AWM demonstrated high removal efficiency (up to 95%) for acid blue 80, particularly at concentrations above 300 mgL(-1).
• At low dye concentrations, adsorption dominates; at high concentrations, chemical precipitation with Ca(2+) and Mg(2+) becomes significant, reducing sludge.
• AWM's high alkalinity and buffer capacity minimize pH's impact on removal.

Conclusions:

• Alkaline white mud is a cost-effective and efficient material for acid blue 80 removal.
• AWM offers advantages over conventional methods, especially in sludge reduction.
• Phosphate significantly inhibits dye removal, while sulfate has a lesser effect at higher concentrations.