The sludge-based adsorbent from oily sludge and sawdust: preparation and optimization

Area of Science:

• Materials Science
• Environmental Engineering
• Chemical Engineering

Background:

• Oily sludge presents a significant waste management challenge.
• Valorizing oily sludge into functional materials like adsorbents offers environmental and economic benefits.
• Developing efficient adsorbents for petroleum removal is crucial for environmental remediation.

Purpose of the Study:

• To prepare and optimize a sludge-based adsorbent (S-AB) from oily sludge and sawdust for raw petroleum adsorption.
• To identify the optimal chemical activator and preparation conditions for maximizing adsorbent performance.
• To characterize the adsorbent and evaluate its adsorption capacity and kinetics.

Main Methods:

• Chemical activation of oily sludge and sawdust using zinc chloride (ZnCl2).
• Parallel comparative experiments to determine the optimal chemical activator.
• Orthogonal experiments to optimize preparation parameters (temperature, time, ratios, heating rate).
• N2-adsorption characterization and petroleum adsorption experiments.
• Langmuir adsorption isothermal modeling and kinetic analysis.

Main Results:

• Zinc chloride (ZnCl2) was identified as the most effective chemical activator.
• Optimized preparation conditions (550°C, 3.5h, 1:1.5 solid-liquid ratio, 1:0.5 sludge-sawdust ratio, 15°C/min heating rate) significantly enhanced adsorption.
• The optimized sludge-based adsorbent (S-AB-ZnCl2) achieved a maximum adsorption capacity (Q0) of 434.78 mg/g.
• Higher mesopore surface area and volume correlated with improved adsorption performance.
• Adsorption kinetics followed a second-order model.

Conclusions:

• Chemically activated sludge-based adsorbents are effective for raw petroleum removal.
• Optimization of preparation conditions is critical for maximizing adsorbent capacity.
• The developed S-AB-ZnCl2 adsorbent demonstrates high potential for petroleum spill cleanup and wastewater treatment.