Hydroxyl-Terminated Dendrimer Acting as a High Exhaustion Agent for Chrome Tanning

摘要

Severe restrictions for chromium discharge and scarcity of chromium resources have forced the tanners to seek for lowwaste and high exhaust chrome tanning technology. Based on the structural traits of dendrimers, in this paper, a series of hydroxyl terminated dendrimers (HTD) with different molecules weight (Mw) was synthesized and applied in the chrome tanning of pigskin. The effect of HTD was investigated on chromium discharge in effluent, and on the shrinkage temperature (Ts), denaturation temperature (Td), mechanical properties, and microstructure of the leather. The experimental results indicated that the chromium discharge in effluent by applying HTD (A1) was reduced to 236.0 mg/L, almost one-sixth of the conventional chrome tanning. HTD that, possesses high hydroxyl density, has endowed the obtained leather with higher chrome uptake, Ts, and mechanical properties. Specially, HTD could slow down the basification process by the forming of hydrogen bonds with collagen residues. In addition, HTD could combine more chromium and form net crosslink, notably improve the chrome uptake and hydrothermal stability. Therefore, it is conceivable that the HTD could act as a high exhaustion agent in chrome tanning process.