Tannin as a renewable resource with the potential to play an increased role in the tanning of leather by the virtue of its low pollution and biodegradability. In this work, a valuable tannin resource was obtained from the Coriaria nepalensis bark (CNB), the extraction of tannin from CNB with sodium hydroxide was optimized by the Box-Behnken design response surface. The effects of extraction time, extraction temperature, liquid-solid ratio and sodium hydroxide concentration on the yield of CNB tannin were examined. Extracting the bark at 82 °C over 63 min with 0.22 % sodium hydroxide at a 23 mL g⁻¹ liquid-solid ratio, the CNB tannin extraction yield was 16.02 ± 0.08 %. Nuclear magnetic resonance spectroscopy revealed that CNB tannin is a hydrolysable tannin that contains carbonyl, phenolic hydroxyl and glycosyl, with relative molecular weights between 424 Da and 1464 Da, as determined by gel permeation chromatography. CNB tannins were used to tan sheep skin, and the shrinkage temperature of the tanned leather was found to be 76.4 °C. Other physical properties, including elongation at break (75.8 %), tear strength (38.2 N mm^-1) and tensile strength (6.1 MPa), were comparable to those achieved using commercial valonia tannin reagents. Scanning electron microscope and atomic force microscope revealed that CNB tannin penetrates into the collagen fibers of leather to provide stable cross-linking, resulting in firm and delicately grained surfaces.

单宁作为一种可再生资源，由于其低污染和可生物降解性，在皮革鞣制中潜力更大。在这项工作中，从Cariaaria nepalensis树皮（CNB）获得了宝贵的单宁资源，并通过Box-Behnken设计响应面优化了用氢氧化钠从CNB中提取单宁的工艺。研究了提取时间，提取温度，液固比和氢氧化钠浓度对CNB单宁得率的影响。用0.22％的氢氧化钠在23 mL g ^-1下于82°C萃取63分钟液固比下，CNB单宁的提取率为16.02±0.08％。核磁共振波谱表明，CNB单宁是一种可水解的单宁，其中含有羰基，酚羟基和糖基，相对分子量在424 Da和1464 Da之间，通过凝胶渗透色谱法测定。使用CNB单宁鞣制绵羊皮，发现鞣制皮革的收缩温度为76.4°C。其他物理性能，包括断裂伸长率（75.8％），撕裂强度（38.2 N mm ^-1））和抗拉强度（6.1 MPa），与使用市售的瓦隆单宁试剂可比。扫描电子显微镜和原子力显微镜显示，CNB单宁能渗透到皮革的胶原纤维中以提供稳定的交联，从而形成牢固而细腻的表面。