No abstract

No abstract

No abstract

A high nitrate concentration in scrubber water is a major factor that restricts ship applications of NO x wet absorption technology. In this paper, an absorption system (Na 2 SO 3 /NaHSO 3 ) that can effectively improve NO 2 absorption and reduce the concentrations of nitrate and nitrite was studied. Several factors that affect the NO x absorption efficiency and the concentrations of nitrate and nitrite were investigated in a bubble reactor by using Na 2 SO 3 and Na 2 SO 3 /NaHSO 3 . In addition, the reaction mechanism for the process of NO 2 absorption was deduced. The results illustrate that increases in S(IV) concentration and initial NO 2 concentration could enhance the NO x absorption efficiency while increases in the NO/NO 2 ratio and SO 2 concentration decreased the NO x absorption efficiency. Moreover, the maximum NO x absorption efficiency was 97.8% at 0.15 mol/L S(IV) and 1400 ppm of NO 2 when using the Na 2 SO 3 /NaHSO 3 absorption system. The S(IV) concentration was the main factor affecting the NO x absorption efficiency and the concentrations of nitrate and nitrite. Increasing the SO 2 concentration slightly affected the NO x absorption efficiency but was beneficial for decreasing the concentrations of nitrate and nitrite. The performance of the Na 2 SO 3 / NaHSO 3 absorption system was better than that of Na 2 SO 3 in the presence of oxygen. Furthermore, the minimum concentrations of nitrate and nitrite were 13.5 and 0 mg/L, respectively, in the Na 2 SO 3 /NaHSO 3 absorption system for 1100 ppm of NO 2 and 0.3 mol/L S(IV) and were much lower than current regulations for scrubber water. Finally, compared with other experimental results, the Na 2 SO 3 /NaHSO 3 absorption system exhibits great potential for ship NO x wet absorption, and the addition of NaHSO 3 plays a key role in decreasing the concentrations of nitrate and nitrite.

No abstract