Preparation of Adsorption-degradation Collagen/ZnO Composites Based on Chrome-tanned Leather Shavings
The utilization of hazardous waste chrome-tanned leather shavings is a difficult problem in the leather industry.Collagen,the main component of chrome-tanned leather shavings,can be used as adsorbent material;however,its application in the wastewater treatment field is limited due to the low stability and subsequent desorption challenges.In this paper,adsorption-degradation collagen/ZnO composites were prepared by in-situ loading of zinc oxide nanoparticles(ZnO)on collagen fibrils extracted from chrome-tanned leather shavings via acid methods.The infrared and X-ray diffraction spectra showed that ZnO with sheet hexagonal wurtzite structure was successfully loaded;meanwhile,its own photoresponse range was unaffected and the forbidden bandwidth was 3.20 eV.When the concentration of zinc precursor solution was 0.12 mol/L,the pH value of collagen fibril dispersion liquid was 8 and the mass of collagen sponge was 60 mg,the photocatalytic degradation of the composite was the best;namely,the degradation ratio of 10 mg/L methylene blue(MB)reached 95.2％within 160 min and still reached 87.5％after five cycles.The fitting results of the kinetic models showed that the adsorption of MB by the composites was according with the pseudo-second-order adsorption kinetic model,which was controlled by chemisorption;moreover,the photo-catalytic degradation of MB obeyed the first-order degradation kinetic model,and the highest degradation rate was 0.0172 min-1.Additionally,the introduction of ZnO enhanced the antimicrobial property and thermal stability of the collagen/ZnO composites.
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