Elucidating structure of pectin in ramie fiber to customize enzyme cocktail for high-efficiency enzymatic degumming

Pectin is one of the main components of bast fiber including ramie fiber, and must be removed before use. Enzymatic degumming is the preferred process as it is an environment-friendly, simple and controllable process for ramie degumming. However, an important problem limiting wide application of this process is the high cost due to the low efficiency of enzymatic degumming. In this study, pectin samples were extracted from raw ramie fiber and degummed ramie fiber, respectively, and their structures were characterized and compared to allow tailoring of an enzyme cocktail for degrading the pectin. It was elucidated that pectin from ramie fiber is composed of low esterified homogalacturonan (HG) and low branched rhamnogalacturonan I (RG-I), and the ratio of HG/RG-I is 1.72:1. Based on the pectin structure, potential enzymes to be used for enzymatic degumming of ramie fiber were proposed and an enzyme cocktail was customized. Degumming experiments confirmed that the customized enzyme cocktail can effectively remove pectin from ramie fiber. To our knowledge, this is the first time the structural characteristics of pectin in ramie fiber have been clarified, and it also provides an example of tailoring a specific enzyme system to achieve high-efficiency degumming for biomass containing pectin.

A study on the antibacterial property and biocompatibility of ramie fiber

Ramie fiber (RF) has excellent tensile strength and breathability, making it a promising material for biomedical applications. However, few studies on the antibacterial properties and biocompatibility of RF have been reported. This study aimed to investigate the antibacterial property and biocompatibility of RF with bacteria and fibroblasts. The results showed that the antibacterial activity of RF was better than that of natural cotton fiber (NCF) and close to that of medical cotton fiber (MCF) for both Staphylococcus aureus (S.a) and Escherichia coli (E.coli), and RF was more antibacterial against S.a than E.coli. The RF, MCF and NCF promoted the proliferation and spread of mouse fibroblast (L929) cells. The results indicated that RF has excellent antibacterial properties and biocompatibility, making it a potential biomaterial for biomedical applications.

High-efficiency and recyclability of ramie degumming catalyzed by FeCl3 in organic solvent

Although traditional alkaline (TAL) process for ramie degumming is commonly used in the industry, it causes severe environmental concerns. In this work, an emerging organic solvent degumming process utilizing FeCl₃ catalyst (FeCl₃-OS) was developed in one step. The influences of FeCl₃-OS system on fiber properties (e.g. residual gum content, tenacity, degree of polymerization (DP), etc.) were evaluated, and the recyclability of degumming solution was also studied. The results indicated that ramie fiber could be isolated with FeCl₃-OS treatment (FeCl₃ 1.0 %, 200 ℃, 121 min), and the tenacity and residual gum content of refined fibers were 7.9 cN/dtex and 3.88 %, respectively. Fibers treated in FeCl₃-OS system were endowed better moisture sorption (9.2 %) and higher yield (75.2 %) compared with that in TAL system. Moreover, fibers with five cycles' treatment possessed outstanding performances, that was 4.44 cN/dtex of tenacity and 4.33 % of residual gum content, which fulfilled the requirements of the spinning process.

Preparation of activated carbon hollow fibers from ramie at low temperature for electric double-layer capacitor applications

Activated carbon hollow fibers (ACHFs) with high surface area were prepared from inexpensive, renewable ramie fibers (RFs) by a single-step activation method under lower temperature than that of other reports. The effects of activation conditions on the pore structure and turbostratic structure of ACHFs were investigated systematically. The results show that ACHFs surface area decreased but micropore volume and conductivity increased as the increase of activation temperature and activation time. The electrochemical measurements of supercapacitors fabricated from these ACHFs electrodes reveal that the electrochemical properties improved with the enhancing of activation degree. However, too high activation temperature can make the ion diffusion resistance increase. It suggests that pore structure and conductivity are as important as surface area to decide the electrochemical performances of ACHFs electrode materials. A maximum capacity of 287 F g(-1) at 50 mA g(-1) was obtained for the ACHFs electrode prepared under suitable conditions.