Surface Modification Of Waste Yeast And Its Application

Yeast is a low-cost microorganism that is mainly derived from alcohol production and bread baking;It is an ellipsoidal single cell fungal microorganism with a strong cell wall.Even in an extremely harsh external environment,the firm cell wall of yeast can maintain the environmental stability of the entire cell.Yeast has the characteristics of low price,wide source,and environmentally friendly.However,a large number of waste yeasts have not been effectively used,leading to serious waste of resources.In order to make effective utilization of waste yeast,this paper strives to solve the problem of poor effect of traditional adsorbent for treating antibiotic wastewater and obtain an adsorbent with excellent performance using yeast as a substrate and urea as a modifying monomer;In addition,a pharmaceutical carrier was prepared by adipic dihydrazide modified yeast.The prepared ammoniated yeast adsorbent and ADH@yeast carrier were applied in the field of antibiotic wastewater treatment,drug release and other fields.Finally the adsorption and recycling performance of the adsorbent was examined.The specific research contents are as follows:(1)Using yeast as raw material and urea as modified monomer,ammoniated yeast composites were prepared by semi-dry method.Characterization of ammoniated yeast composites by field emission scanning electron microscopy(FE-SEM),energy dispersive spectroscopy(EDS)and Fourier transform infrared spectroscopy(FT-IR).FE-SEM scans showed that the ammoniated yeast composites have an ellipsoidal structure with uniform particle size and good dispersion.EDS test results indicate that the amino group has been successfully bound to the yeast surface.FT-IR confirmed that the surface of the ammoniated yeast composite had a rich functional group.(2)The tetracycline hydrochloride was used as a simulated antibiotic wastewater to study the adsorption and regeneration performance of ammoniated yeast composites.The experimental results showed that the removal rate of tetracycline hydrochloride in the adsorption process was affected by various factors such as temperature,solution pH,and the amount of adsorbent added.Adsorption process of tetracycline hydrochloride adsorbed on the quasi-second-order kinetic model,and the adsorption process was carried out in two steps.The Langmuir and Freundlich isotherm models were used to fit the adsorption data.The results showed that the adsorption of tetracycline hydrochloride by ammoniated yeast adsorbent was in accordance with the Langmuir model and was monolayer adsorption.The calculation of the thermodynamic equation showed that the adsorption process was a spontaneous and endothermic process.By recycling the adsorbent under strong acid conditions,efficient recycling was achieved.(3)ADH@yeast vector was prepared by semi-dry method using yeast as raw material and adipic dihydrazide as monomer(ADH).The ADH@yeast vector was characterized byFE-SEM,EDS and FT-IR.The swelling performance in deionized water and 1.0% NaCl solution was studied.The effect of pH and temperature on the swelling performance of ADH@yeast was also investigated.The results showed that the swelling ratio of ADH@yeast increased with the increase of pH value and swelling performance of ADH@yeast was better at lower ambient temperatures.Ciprofloxacin hydrochloride(CIP)was used as the target drug to study the ADH@yeast load release performance of CIP.The experimental results showed that the ADH@yeast vector had a good loading rate for CIP,and the loading rate could reach 65.3% after 12 hours of input;the carrier loaded with CIP exhibited different release efficiency under different pH conditions.The release effect is better in the simulated solution with pH=7.8,in which the release rate could reach 64.1%.The above experimental results prove that ADH@yeast has a certain pH sensitivity,good load and release properties for drugs,which has a certain research prospect in the medicine industry.