Enhancing gaseous n-hexane removal using a novel nonaqueous phase in an airlift two phase partitioning reactor:...

The two-phase partitioning reactor (TPPB) efficiently achieved gaseous volatile organic compounds (VOCs) emission through employing a nonaqueous phase (NAP) with affinity to hydrophobic VOCs. However, the reuse of conventional NAPs is limited and leading to an increasing cost. In this study, a novel magnetic silicone oil (MSO580) was invented with a reusability of 98.6 %, which is superior to the typical conventional NAP silicone oil (62.3 %). The biodegradability of n-hexane was promoted by 23.8 % with the introduction of MSO580, accompanied by a 10 % increase in the partition coefficient in the oil-water system comparing to silicone oil. On this basis, two airlift TPPB treating n-hexane contaminated gaseous emissions were built with 10 %(v/v) addition of MSO580 (T(SO)) and silicone oil (T(MSO)) respectively. The enhanced removal performance along with improved stability was observed in T(SO). Facilitated extracellular polymers secretion led to the formation of oil-water interfacial biofilms and the acquisition of the pollutants by cells, which was probably related to the enrichment of the functional genera like Sphingomonas. The Fe from the MSO580 was probably beneficial to the metabolic activity through enriching the genes related to Fe-S and NADH-ubiquinone oxidoreductase. A mass transfer-biodegradation kinetic model was developed based on mass conservation and the Michaelis-Menten model, and it exhibited an accuracy exceeding 95 % fitting with the experimental data. The concentration of 200 mg m^-3 was observed to be the critical value where the reaction limitation shifted from mass-transfer to biodegradation, and the biodegrading capacity will reached its peak value at the concentration of 800 mg m^-3. The cell yield with declined removal performance were also predicted by the model. This study provided a novel MSO580 with economic feasibility for TPPB treating gaseous emissions contaminated by hydrophobic VOCs, and it would provide technical supports for efficient air purification.