Abstract

To study the release of formaldehyde from tetrakis (hydroxymethyl) phosphonium (THP) salts, the contents of free formaldehyde in THPC solutions and in the leathers tanned with THPC and tetrakis hydroxymethyl phosphonium sulfate (THPS) were determined by the spectrophotometric method. Zeta potential of THPC at different pHs was tested. To decrease the content of free formaldehyde in the leather H2O2 was used at the end of the tanning process. The results indicated that the HCHO contents varied with pH both in THP salt solutions and in the tanned leathers. The free formaldehyde in the leathers can be oxidized by H2O2 and thus leads to the decrease of the content of free formaldehyde.