Exploring alkali-treated corn cob for high-rate removal of NOX and SO2 from flue gas: Focus on carbon release capacity, removal performance, and comparison with conventional carbon sources.

Abstract

This investigation explored the potential of utilizing alkali-treated corn cob (CC) as a solid carbon source to improve NO_X and SO₂ removal from flue gas. Leaching experiments unveiled a hierarchy of chemical oxygen demand release capacity: 0.03 mol/L alkali-treated CC > 0.02 mol/L > 0.01 mol/L > 0.005 mol/L > control. In NO_X and SO₂ removal experiments, as the inlet NO_X concentration rose from 300 to 1000 mg/m³, the average NO_X removal efficiency increased from 58.56 % to 80.00 %. Conversely, SO₂ removal efficiency decreased from 99.96 % to 91.05 %, but swiftly rebounded to 98.56 % by day 18. The accumulation of N intermediates (NH₄⁺, NO₃^-, NO₂^-) increased with escalating inlet NO_X concentration, while the accumulation of S intermediates (SO₄^2-, SO₃^2-, S⁰) varied based on shifts in the population of functional bacteria. The elevation in inlet NO_X concentration stimulated the growth of denitrifying bacteria, enhancing NO_X removal efficiency. Concurrently, the population of nitrate-reducing sulfur-oxidizing bacteria and sulfate-reducing bacteria expanded, aiding in the accumulation of S⁰ and the removal of SO₂. The comparison experiments on carbon sources confirmed the comparable NO_X and SO₂ removal efficiencies of alkali-treated CC and glucose, yet underscored differences in intermediates accumulation due to distinct genus structures.