An insight into artisanal leather making in Ghana

The production of leather from animal skins and hides through tanning processes began in the pre-historic ages.Despite the origination of new leather making techniques such as chrome tanning which is being employed extensively today,the traditional method of leather production primarily through vegetable tanning is still being practised mostly in artisanal tanneries in developing nations including Ghana.Artisanal leather making,thus,contributes beneficially to rural livelihood.Nevertheless,the growth of this sector has been stifled by the lack of innovative technologies to enhance productivity.This challenge could be partly linked to the knowledge gap on the scientific principles governing artisanal leather production processes.This study,therefore,elaborates on various process steps and materials employed in traditional leather making in Ghana and the scientific principles underlying each of the processes.It also makes a comparison between traditional and modern leather manufacturing processes and identifies knowledge and technological gaps which would inspire in-depth scientific research into artisanal leather making.

Application of amphoteric polymers in the process of leather post-tanning

With the characteristics of controllable charge and environmental friendliness,amphoteric polymers can be used in post-tanning process to solve the problems that arise during leather making and are caused by the low absorption rate of single-charge chemicals,incompatibility with new tanning methods,and complex operation process.In this review,the structure,performance,and preparation of amphoteric polymers are reported.Then,the charge change of collagen during different tanning and pH treatments is introduced.Finally,the application and development of amphoteric polymers during the post-tanning process of leather making are discussed.This review has certain guiding significance to the preparation and application of amphoteric polymers for tanning system.

Efficient and ecological leather processing: replacement of lime and sulphide with dispase assisted by 1-allyl-3-methylimidazolium chloride

Leather is a collagen-based biomass prepared from raw skins or hides by a series of unit operations, in which the unhairing and fiber opening are extremely important operations. However, the conventional Na2S/Ca(OH)2 system used in unhairing and fiber opening has given rise to the pollution to the environment. It is necessary to develop substitute technology for the Na2S/Ca(OH)2. In the present study, 1-allyl-3-methylimidazolium chloride ([AMIm]Cl) was used to cooperate with dispase for cycle unhairing and one-pot beamhouse to recycle waste bovine hides and com-pared with conventional processing. During those processes, the mechanism of [AMIm]Cl-dispase synergistic unhair-ing and collagen fibers opening were studied. Besides, plant hazard, organic matter and [AMIm]Cl of wastewater from [AMIm]Cl-dispase process were respectively investigated and separated to evaluate the environmental and economic benefits of the [AMIm]Cl-dispase process. As a result, enzyme activity after unhairing by [AMIm]Cl-diapase system for using 5 times is higher than that by KCl-dispase system, and needs lower unhairing time, which is because of rapid penetration of [AMIm]Cl-dispase solution in bovine hides. For this reason, the tensile strength and elastic modulus of tanned leather from [AMIm]Cl-dispase process are higher than those from the KCl-diapase and conventional pro-cesses, and its hydrothermal shrinkage temperature is comparable to that of the conventional one. Because of the 58.13% lower wastewater discharge (WD), 66.60% lower total solids (TS), 97.23% lower ammonia nitrogen (NH3-N), non-toxic wastewater and organic matter recovery in wastewater are reached from [AMIm]Cl-dispase process, which is expected to be an alternative to the conventional process to reduce environmental pollution and realize the sustainable development of technology for leather manufacturing.

Screening of additives to reduce grain damage risk on unhairing by proteinase K

Enzymatic unhairing is a cleaner strategy for leather-making.It is a potential alternative to the traditional hairburning process.However,several shortcomings,such as uncontrolled enzymatic reaction,and risk of grain looseness and damage have restricted the broad application of enzymatic unhairing.In this work,metal ions and organic additives were screened for lessening the hydrolytic activity of proteinase K to collagen fiber.Then,the selected additives were applied to the enzymatic unhairing process for bovine hide.The results showed that a suitable concentration of metal ions(Cu(Ⅱ),Fe(Ⅲ)and Al(Ⅲ))and organic additives(salicylate,laurate,adipate,gallate and epicatechin(ECG))could diminish approximately 35% of the hydrolytic activity of proteinase K to collagen fibers.Then,the additives were applied for the bovine hide enzymatic unhairing process.Hydroxyproline determination in the unhairing float shows that applying additives could reduce collagen hydrolysis.The morphology results showed that the grain damage could be significantly reduced with the addition of the screened additives in the proteinase K enzymatic unhairing system,whereas the addition of ECG and gallate significantly slowed down the unhairing speed.This outcome provides new potential to reduce the risk of grain damage in enzymatic unhairing process.