| At present,plastic pollution and water pollution is one of the most serious pollutions in the world.One way to solve the problems of plastic threatens is to replace traditional petro-chemical plastics by biodegradable plastics.As so far,poly 3-hydroxybutyrate as an intracellular thermoplastic and biodegradable polyester synthesized by bacteria,which is considered a best suitable candidate material to be produced biodegradable plastic.However,large-scale production is likely impossible because of the high cost of poly 3-hydroxybutyrate.Thence,it is meaningful to decrease extraction cost of poly 3-hydroxybutyrate.In addition,regarding the problem of water pollution,one of the most effective metheods is to adsorb harmful components（heavy metal ions,organic dyes,etc.）by adsorbents in sewage.Compared with the adsorbents prepared by some mineral and metal compounds,biosorbents are biodegradable and simutaneously sufficiently for adsorbing those toxic matters.After utilization,the waste biosorbents can be degraded by microorganisms without causing secondary pollution.Bacterial cellulose,extracellular polymers synthesized by Gluconacetobacter Xylinus,and intracellular polymer poly 3-hydroxybutyrate synthesized by Cupriavidus necator H16,both as biodegradable materials,have good modifiability and can be used as raw materials for the preparation of biosorbents.The good adsorbents performance can be developed after a series of chemical or physical modification.Based on those problems,this paper mainly did the following research:（1）It was found that N’N-dimethylacetamide/lithium chloride could be applied for the extraction of poly 3-hydroxybutyrate from bacteria without any pretreatment of Cupriavidus necator H16.This solvent can directly extract poly 3-hydroxybutyrate from C.necator without any other pretreatment,the recovery of poly 3-hydroxybutyrate could reach 100%and the purity was over 99%.The results showed that N’N-dimethylacetamide/lithium chloride could be applied as an effective recovery solvent for high purity PHB.（2）A new biosorbent of bacterial cellulose/poly 3-hydroxybutyrate composites was prepared by a new cosolvent method and raw material was bacterial cellulose and poly 3-hydroxybutyrate.Scanning electron microscope and nitrogen adsorption/desorption experiments showed that bacterial cellulose/poly 3-hydroxybutyrate had a more porous structure than poly 3-hydroxybutyrate.Fourier transform infrared scanning spectroscopy showed that the composite possessed active functional groups-COOH and-OH,which were beneficial to the capture of Ni（Ⅱ）and Pb（Ⅱ）.A series of controlled experiments were conducted to investigate the adsorption capacityes of bacterial cellulose/poly 3-hydroxybutyrate.The experimental results showed that the adsorption capacity of bacterial cellulose/poly 3-hydroxybutyrate for Ni（Ⅱ）and Pb（Ⅱ）was 44.8 mg g-1 and 223.7 mg g-1 after fitting with the Langmuir model,respectively.In thermodynamic analysis experiments,the adsorption capacity of bacterial cellulose/poly 3-hydroxybutyrate continued to increase with the increase of temperature.Furthermore,the adsorbent could be regenerated by low concentration HCl.After four sorption-desorption cycles,the adsorption performance of the material nearly remained unchanged,indicating that the material has good adsorption-desorption cyclic stability.（3）In order further optimize the adsorption performance of bacterial cellulose/poly3-hydroxybutyrate,dopamine hydrochloride was added to Na OH/Urea to obtained BC/poly 3-hydroxybutyrate/polydopamine composites by taking advantage of the characteristic that dopamine could self-polymerize under alkaline conditions.Fourier transform infrared scanning spectra showed that polydopamine successfully combined with bacterial cellulose/poly 3-hydroxybutyrate.The adsorption capacity on Ni of the material was nearly twice that of bacterial cellulose/poly 3-hydroxybutyrate,indicating that polydopamine could further improve the adsorption capacity of bacterial cellulose/poly 3-hydroxybutyrate. |
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