Narong Chaisongkroh, Juntima Chungsiriporn, and Charun Bunyakan

pp. 423 - 432

Abstract

Emission of ammonia (NH₃
) contaminated waste air to the atmosphere without treatment has affected humans and
environment. Eliminating NH₃
 in waste air emitted from industries is considered an environmental requisite. In this study,
optimization of NH₃
 adsorption time using acidic rubber wood biochar (RWBs) impregnated with sulfuric acid (H₂SO₄) was
investigated. The central composite design (CCD) in response surface methodology (RSM) by the Design Expert software
was used for designing the experiments as well as the full response surface estimation. The RSM was used to evaluate the
effect of adsorption parameters in continuous mode of fixed bed column including waste air flow rate, inlet NH₃
 concentration in waste air stream, and H₂
SO₄
 concentration for adsorbent surface modification. Based on statistical analysis, the NH₃
symmetric adsorption time (at 50% NH₃
 removal efficiency) model proved to be very highly significant (p<0.0001). The optimum conditions obtained were 300 ppmv inlet NH₃
 concentration, 72% H₂
SO₄, and 2.1 l/min waste air flow rate. This resulted
in 219 minutes of NH₃
 adsorption time as obtained from the predicted model, which fitted well with the laboratory verification result. This was supported by the high value of coefficient of determination (R²
=0.9137). (NH₄)₂SO₄
, a nitrogen fertilizer
for planting, was the by-product from chemical adsorption between NH₃
 and H₂
SO₄.