Sorption of As(V) from aqueous solution using acid modified carbon black

Area of Science:

• Environmental Chemistry
• Materials Science

Background:

• Arsenic contamination poses a significant environmental and health risk.
• Developing efficient and cost-effective sorbent materials for arsenic removal is crucial.

Purpose of the Study:

• To investigate the arsenic sorption performance of acid-modified carbon black.
• To characterize the modified material and optimize removal conditions.

Main Methods:

• Commercial carbon black was modified using a mixture of nitric and sulfuric acids.
• Batch equilibrium experiments were conducted to evaluate arsenic removal.
• Sorption kinetics and isotherm models (pseudo-second-order, Langmuir, Freundlich) were applied.
• Desorption studies were performed using various acidic and basic solutions.

Main Results:

• Acid modification significantly altered carbon black properties, creating an acidic material (pH(pzc) < 7).
• The modified carbon black demonstrated excellent arsenic sorption, removing ~93% from a 50 mg/L solution.
• Optimal sorption occurred in the acidic pH range (3-6), with maximum efficiency at pH 5.0.
• Sorption followed pseudo-second-order kinetics, with intra-particle diffusion as a rate-limiting step.
• Langmuir isotherm provided a better fit than Freundlich for equilibrium data.
• Sorption is spontaneous, endothermic, and favored by increased temperature.
• Potassium hydroxide (KOH) achieved ~85% desorption.

Conclusions:

• Acid-modified carbon black is a highly effective sorbent for arsenic removal from aqueous solutions.
• The material's performance is strongly dependent on solution pH and temperature.
• The study provides insights into the sorption mechanism and potential for regeneration.