Abstract

A severe issue is the release of carcinogenic formaldehyde, especially in the wood industry where it is utilized in large quantities. Tannin additions have shown promise in lowering this dangerous emission. By optimizing tannin extraction using different maceration protocols, determining their reactivity towards formaldehyde using Stiasny numbers, and examining the condensed tannin contents of selected extracts, we evaluated the potential of Bauhinia purpurea pod husk and bark biomass as a workable source of reactive tannins in this study.

The samples were collected from more than 65 trees on the University of Bamenda campus, shade dried, and manually seed husk and pod separation. To increase yields, different maceration techniques were used to extract tannins after performing particle size analysis, moisture and ash contents determination in triplicates, and yield optimization.

By refluxing tannin extracts with formaldehyde, it was possible to realize the reactivity of the tannins (Stiasny numbers/Index). Before grinding, the pod husk and bark were both chopped into 3.0-5.0 cm pieces and oven dried at various times at 60.0–5oC.  81.2% of the pod husk and 18.8% of the seeds were seeds, respectively.

The moisture and ash contents for the particle size ranges (≥1.00mm, ≥0.5mm, ≥0.25mm and < 30.25mm) ranged between 10.0% to 12.8%, and 10.0% to 11.4% respectively for the pod-husk and 4.0% to 5.0%, and 7.3%, to 12.6% respectively for the bark. Extraction yields with respect to dry mass ranged from 6.56% to 73.65.

Averagely, best yields were observed for particle size < 0.25mm. This is thus considered the optimal particle size. FT-IR spectra indicate diagnostic peaks at H1 (942/cm), H2 (955/cm), H3(944/cm, B3(954/cm) and B2(947/cm) characteristic of condensed tannins.

In comparison to red mangrove, which had a Stiasny number of 77%–83.5% but a very low tannin concentration of 23.78%–26.76%, selected extracts had reactivity to formaldehyde that ranged between 64.5% and 85% and condensed tannin values between 36.24 and 42.56%. The pod husk’s comparatively large yield of reactive tannins suggests that Bauhinia purpurea may be a reliable source of tannins for the creation of environmentally friendly adhesives.

Check out: Chemistry Project Topics with Materials