Adsorption Capacity Of Heavy Metals By Spunlaced Nonwoven Material Made Of Collagen Fibers

China is a big country of manufacturing leather products, however, the waste leather resultsin serious waste of resources. How to make rational use of the waste leather and turn waste intotreasure has become an important factor in the sustainable development of our economy. Inorder to expand the application of the waste leather, we treat the waste collagen fiber as researchobjection to study how the wet-heat condition affects the structure and elongation properties. Weproduce the waste collagen fiber into collagen spun-lace nonwoven material through theprocedure of air-laid and water jet process. Then spun-lace material is immobilized by tanninthrough the cross-link of glutaraldehyde which can absorb the heavy metal waste water. Westudy the adsorption and desorption properties of the material to provide new ideas for the wastecollagen fiber application.We analyze the fiber’s resistance property to wet-heat and find the sensitive temperature is105.83℃through the TG, DSC, FTIR and XRD. Therefore in the following process, thetemperature can’t be higher than105.83℃. Otherwise the protein molecules three-ply helixchain structure of the collagen will be damaged resulting in bad strength and elongationperformance.We obtain the optimal processing parameters through orthogonal design: the spun-lacematerial is immersed in60g/L tannin(aq) solution under40℃for8h, then the material istransferred into4%glutaraldehyde solution and treated10h under40℃, at last the material isdried for10h under30℃. The surface density of the fabric is increased by40%, and there is noobvious difference in the thickness. The MD and CD strength are increased by65.5%,22.5%respectively, and the MD and CD elongation are decreased by57.7%,46.9%respectively. The material has a better acid-resistance property than alkali-resistance property because of thematerial hydrolyzing into Gel polypeptide chain.in the high alkali solution.The material immobilized by tannins has a better heavy metal absorption capacity propertythan untreated. The initial Cu2+、Pb2+concentration, temperature and pH value of the solutionwhich influence on the absorption capacity are studied. It shows that with the increase of thesethree parameters, the adsorption capacity of Cu2+、Pb2+increases. We conduct the adsorptionkinetics analysis and find that the second order kinetics equation can match well with theabsorption result otherwise the first order kinetics equation can’t. Form the adsorption isothermanalysis, we can see that Freundlich equation and Langmuir equation can both match well withthe heavy metal absorption isotherm. We use the HCl solution for desorption treatment and findthat part of the material combined with the heavy metal to form stable complex compound,someother to form unstable complex compound. After a few repeated adsorption-desorption cycles,the adsorption and desorption volume of the heavy metal constantly decay. So the reuseperformance is unsatisfactory after two cycles.