A new combined green method for 2-Chlorophenol removal using cross-linked Brassica rapa peroxidase in silicone oil

• A new technique for 2-CP removal coupling absorption to biodegradation was used.
• The partition coefficient air-silicone oil of 2-CP was determined.
• Silicone oil (47V20) allowed the reduction of 2-CP concentration in gas phase five times lower.
• 70% of 2-CP degradation in silicone oil was achieved using cross-linked enzyme aggregates of BRP peroxidase (BRP-CLEAs).

This study proposes a new technique to treat waste air containing 2-Chlorophenol (2-CP), namely an integrated process coupling absorption of the compound in an organic liquid phase and its enzymatic degradation. Silicone oil (47V20) was used as an organic absorbent to allow the volatile organic compound (VOC) transfer from the gas phase to the liquid phase followed by its degradation by means of Cross-linked Brassica rapa peroxidase (BRP) contained in the organic phase. An evaluation of silicone oil (47V20) absorption capacity towards 2-CP was first accomplished by determining its partition coefficient (H) in this solvent. The air-oil partition coefficient of 2-CP was found equal to 0.136 Pa m3 mol−1, which is five times lower than the air–water value (0.619 Pam3 mol−1). The absorbed 2-CP was then subject to enzymatic degradation by cross-linked BRP aggregates (BRP-CLEAs). The degradation step was affected by four parameters (contact time; 2-CP, hydrogen peroxide and enzyme concentrations), which were optimized in order to obtain the highest conversion yield. A maximal conversion yield of 69% and a rate of 1.58 mg L−1 min−1were obtained for 100 min duration time when 2-CP and hydrogen peroxide concentrations were respectively 80 mg L−1 and 6 mM in the presence of 2.66 UI mL−1 BRP-CLEAs. The reusability of BRP-CLEAs in silicone oil was assessed, showing promising results since 59% of their initial efficiency remained after three batches.