Sichuan University

Research Institute of Leather and Footwear Industry of Wenzhou

Bi Shi

Jianfei Zhou

Yanan Wang

Yue Yu

Wenhua Zhang

Yunhang Zeng

Xin Huang

Shuangyang Li

Weixing Xu

Yawen Huang

Xueru Guo

Mingrong Cao

Liming Zhao

Yuling Tang

A method for chromium removal from post-tanning wastewater includes the following steps: (a) mixing pretreated post-tanning wastewater with an induction reagent to allow an induction reaction; and (b) adjusting a pH of a mixture obtained after the induction reaction to higher than 7.0 for precipitation; where the induction reagent includes a soluble metal salt. In the treatment method of the present disclosure, pretreated post-tanning wastewater is mixed with an induction reagent, a small amount of neutral chromium complexes remaining in the wastewater are converted into cationic chromium complexes under the action of the induction reagent (that is, a charge property of the chromium complex is changed), and then a pH is adjusted for precipitation to remove chromium, which greatly improves the removal efficiency of chromium in wastewater.

Method for chromium removal from post-tanning wastewater

A chrome-free tanning process of an ecological leather is characterized by a TWS+sodium lignosulfonate+TWLZ ternary tanning process system. The sodium lignosulfonate added can not only have a fixation effect on a TWS tanning agent to make the TWS tanning not undergo detanning at a low pH, but also significantly improve the uniformity of distribution of a TWLZ tanning agent in a hide/skin and promote the formation of a stable cross-linked network structure by the TWLZ tanning agent in a collagen fiber, which effectively overcomes the defects of tanning performance of the existing tanning systems to obtain a leather with uniform and sufficient tanning, a high isoelectric point, a strong electropositivity, excellent absorption for post-tanning chemicals, and a prominent softness, and gives a leather a wide use range and a high quality.

Chrome-free tanning process of ecological leather

A light-colored polycarboxylated polysaccharide tanning agent, and a preparation method and use thereof are provided. The light-colored polycarboxylated polysaccharide tanning agent includes the following raw materials: a polysaccharide, an organic solvent, a catalyst, and hydrogen peroxide. Based on a weight of the polysaccharide, a weight of the organic solvent accounts for 1 wt % to 15 wt %, a weight of the catalyst accounts for 0.05 wt % to 2 wt %, and a weight of the hydrogen peroxide accounts for 30 wt % to 80 wt %. The preparation method provided by the present disclosure adopts a two-phase solution system. Compared with the existing preparation technologies, the preparation method of the present disclosure can efficiently extract and remove colored substances produced during an oxidation process, and can timely block a polymerization reaction of the colored substances with an oxidized polysaccharide, such as to significantly reduce a chromaticity of an oxidized product.

Light-colored polycarboxylated polysaccharide tanning agent, and preparation method and use thereof

A tanning agent-free leather making method is provided. A raw hide is subjected to controllable dehydration with a molecular sieve-polar organic solvent composite dehydration media to achieve a dehydrated hide, and then a tanning agent-free leather is prepared by increasing the surface roughness of the dehydrated hide and reducing the surface energy of the dehydrated hide. The present disclosure does not use any metal or non-metal tanning agent, which is eco-friendly. The present disclosure breaks the balance of water distribution between the raw hide and the polar organic solvent, which realizes a multi-medium self-driven directional controllable dehydration of the raw hide, effectively solving the problems during dehydration of the raw hide only using polar organic solvent. The molecular sieve-polar organic solvent dehydration system is easy to recover and can be recycled for the controllable dehydration of the raw hide multiple times. Therefore, a brand-new clean leather making technology is provided.

Tanning agent-free leather making method

A modified collagen fiber preparation method and application are provided. The modified collagen fiber is prepared by modifying a collagen fiber with a plant tannin; and a method of the preparation includes: mixing the plant tannin with the collagen fiber in a liquid environment with a pH of 5 to 8 to allow a reaction, and washing and drying a product. In the present disclosure, a plant tannin rich in phenolic hydroxyl can be combined with a collagen fiber in various ways such as multi-point hydrogen bonding and hydrophobic bonding, such that the plant tannin structure is introduced into a natural multi-layer micro/nano-structure of the collagen fiber; and due to a large number of phenolic hydroxyl structures in the plant tannin, the collagen fiber introduced with the plant tannin structure shows improved compatibility with a waterborne resin, and can produce strong hydrogen bonding with polar groups in the waterborne resin.

Modified collagen fiber, and preparation method and application

Growing community of inventors

Chengdu, China

Bi Shi