Synthesis And Properties Of Lignin-based Phenolic Microspheres

As a natural polymer with a wide range of sources,lignin exists greatly in papermaking waste liquor.The derivatives and new materials of industrial lignin have been hot research topics for a long time.The Phenolic resin composite dispersions were prepared using phenol-based structure in sodium lignosulfonate as phenol source and water as the main medium.And then the lignin-based porous carbon materials(C)and composite microspheres(C/TiO2)were prepared by calcination at high temperature.The effects of copolymerization modification/crosslinking monomer,preparation method and calcination temperature on the product structure were studied,and the performance of adsorption and photocatalytic degradation of BPA pollutants in water were explored.The main research contents are as follows:1.The water-soluble lignin-based phenolic resin was prepared using polyvinyl alcohol(PVA)as dispersant and ammonia as catalyst through reaction of sodium lignosulfonate with formaldehyde.Coprecipitation method and hydrothermal method were used to separate it from water,of which the structure was characterized by FTIR.The precipitated products were carbonized at high temperature.The morphology and pore structure of carbon materials obtained by different precipitation methods were characterized by TEM and BET.The results showed that lignin-based carbon microspheres with particle size around 180nm were prepared by co-precipitation method using tetrabutyl titanate as precipitant and hydrothermal method.The hydrothermal carbon had a high specific surface area and porosity,and the product which used tetrabutyl titanate as the coprecipitator of the coprecipitation method had a regular shape and uniform sizes.The isothermal adsorption of BPA by these two materials was studied,and both of them showed good adsorption performance of BPA at normal temperature.Their adsorption kinetics showed typical quasi-second-order kinetic characteristics,and hydrothermal products had a larger adsorption capacity.2.Based on the above-mentioned co-precipitation method,multifunctional glycidyl ether was added as co-crosslinking agent,and the cross-linking reaction between the highly active epoxy group and the hydroxymethyl group was used to promote the phase separation of the lignin-based phenol resin from water.The effects of the types and addition amount of co-crosslinking agents on particle size control,specific surface area after carbonization and pore size distribution were systematically studied by TEM and BET.The addition amounts of sodium lignosulfonate,the pH of the dispersant and the calcination temperature were further optimized,and the lignin-based carbon microspheres loaded with anatase nano-TiO2 were prepared.The loading rate of TiO2 was about 40%with a regular shape and uniform sizes.After 30 hours of UV irradiation(11W,254nm),the BPA degradation rate of CL-TiO2 reached 84.2%.3.The composite microspheres(C/TiO2)were prepared by using phenol and sodium lignosulfonate as phenol sources,which could improve the stability of the structure at high temperature and increase the internal porosity.The structure of phenol modified sodium lignosulfonate was characterized by FTIR and XRD.The effects of the types and addition amounts of co-crosslinking agents on the morphology and specific surface area of the microspheres were further studied.The results showed that the composite microspheres(CLp-TiO2)which prepared with phenolate sodium lignosulfonate had a higher specific surface area and more regular microtopography.After 30 hours of UV irradiation(11W,254nm),the degradation rate of CLp-TiO2 reached 98.9%detected by degrading BPA.Compared with unmodified products,it is significantly improved,which had developed new ideas for the high functional application of lignin.