Construction And Properties Of Light-convert Functional Materials Fabricated By Phenolic Acid In Coffee Bean Shell

Coffee,one of three major drinks in the world,which was popular with people.Coffee bean shell is the main waste in the preparation process of coffee,which is large in quantity but low in price.However,it causes the waste of resources and pollution of environment,due to the low utilization rate.The phenolic acid compound in coffee shell have a wide range of physiological activities,and its excellent antioxidant capacity and properties of chelate with metal ions make it have a wide value of research and application prospects.The main phenolic acid compounds in coffee bean shell were extracted by two kinds of methods.The components and structures were analyzed and characterized Chlorogenic acid,protocatechualdehyde and catechin were the main components.Chlorogenic acid was used as raw material to carry out.The catechol group in chlorogenic acid is structurally similar to the dopamine in mussel byssus protein.Hence,mussel-inspired plant dopamine doped polyacrylamide hydrogel was prepared.The formation mechanism of hydrogels was verified by ultraviolet visible spectroscopy(UV-vis)and electron spin resonance spectroscopy(ESR).Free radical released by chlorogenic acid can accelerate the speed of polymerizaion under UV light.The hydroxyl and carboxyl acid groups of chlorogenic acid had non-covalent interactions with amino groups of acrylamide,forming a more dense network structure than before.The structure and morphology of hydrogels were characterized by fourier transform infrared spectroscopy(FTIR),X ray photoelectron spectroscopy(XPS)and scanning electron microscope(SEM).The mechanical and adhesion properties of hydrogels were tested by an electronic universal testing machine.The results showed that the mechanical properties of hydrogel with chlorogenic acid were successfully improved,and the as-prepare hydrogel has excellent adhesion ability,which could be adhered to the surface of materials with different substrate.Inspired by the characteristic of chelation between phenolic acid and metal ions,a chlorogenic acid-iron chelate was formed,which can block the radiative of excited state to ground state.The luminous energy is transformed to thermal energy,which means solar-to-thermal.The porous three-dimensional aerogels doped with chelates were solar-to-thermal materials.The structure and morphology of solar-to-thermal materials were characterized by various conventional characterization methods.The thermal stability was verified by simultaneous thermal analyzer.The dry sample can be heated to 76.9?,while the wet one can be heated to 40.2? under one sun.The material produced an evaporation rate is 1.804 kg m-2 h-1,and had an efficiency of 89.9%,which means the as-prepared solar-to-thermal materials has good photothermal conversion effect and a high water evaporation rate of water.The four ions concentrations of seawater before and after desalination were measured by inductively coupled plasma spectrometer(ICP),which confirmed the success of solar-to-thermal materials in saline water desalination application.Due to the conjugated ? structure of chlorogenic acid,it self-assembled in the solvent,which led to the aggregation of molecules,and thus the supramolecular aggregation of chlorogenic acid was explored.The nano scale fluorescent carbon dots were prepared by homogeneous aggregation of chlorogenic acid.The spherical carbon dots with a diameter of 1.4-3.4 nm were showed by transmission electron microscopy(TEM)images,and the crystal texture was clearly visible.The optical properties were investigated by UV-vis and photo luminescence(PL)spectra.Then,a transparent composite membrane material was prepared by doping carbon dots into polyvinyl alcohol membrane.The structure and morphology of the composite film was characterized by SEM and atomic force microscope(AFM).The mechanical properties,water vapor permeability and CO2 of the composite membrane permeability were compared with blank film.The results showed that the addition of carbon dots would not affect the mechanical and physical properties of composite film.In addition,the as-prepared film was found to be unique fluorescence sensitivity to pH and Al3+,excellent good resistance to photobleaching,and antioxidant ability.The as-prepared film can be used to detect Al3+and basic substances,including amines produced during spoilage,and also be used for food storage,which can extend the shelf life of food.The composite film has broad application prospects in food packaging film materials.The alkali-solution and acid-isolation extract of coffee bean shell would self-assemble to form a J-type aggregation,which triggers the homogeneous aggregation of supramolecules to form fluorescent carbon dot.Basic structural properties were characterized by FTIR,XPS and Raman spectra.The diameter of carbon dots with clear crystal structure were in the range of 1-5 nm,which was observed by TEM images.The as-prepared carbon dots have good optical properties and can resist to photobleaching even in phosphate buffered saline(PBS).The viability of L929 cells cultured with carbon dots was more than 95%,which means that carbon dots had low toxicity and good biocompatibility.The cellular uptake and distribution of carbon dots on HeLa cells verified the feasibility of carbon dots as agents for nuclear staining.Except cellular imaging,vivo bioimaging was conducted to tumor enrichment.Based on the results,the as-prepared carbon dots could be used in the field of bioimaging.In addition,the free radical scavenging ability of carbon dots is more than 85%,which is superior to commercial food antioxidants.It can be used for banana storage and prolonging the shelf life.This bifunctional carbon dots can be applied in many fields with widely prospects.