Removal Of Typical Pigments From Remelt Syrup By Rosin-based Adsorption Resin

The colored substances in the remelt syrup will affect the quality of white sugar,and should be decolorized during the syrup processing.At present,remelt syrup is decolorizated with resin,which originated form petrochemical industry and hardly degraded.The micromolecule remained in resin hole will be released into syrup in processing,causing food safety problems.The development of renewable and biodegradable bio-based adsorption materials to replace petro-based resins is significance.In this paper,the reducing sugar alkaline degradation pigments(RADPs)and melanoidin(MD)in remelt syrup were decolorized by rosin-based adsorption resins,which were prepared by natural biomass rosin.The main research contents are as follows:(1)The methyl acrylate tertiary amine rosin-based adsorption resin(MTARAR)was prepared using divinylbenzene(DVB)as cross-linker,hydrogenated rosin(β-Acryloxyethyl)ester(HRAE)as rosin-based monomer,and 2-(dimethylamino)ethyl methacrylate(DEAEMA)as functional monomer.The results showed that MTARAR carried tertiary amine group,and base value of MTARAR was 3.005 mmol/g.Under acidic and neutral conditions,the MTARAR carried positively charged.MTARAR has a rich three-dimensional pore structure and good thermal stability.Under the suitable conditions that the dosage of MTARAR was0.021 g/m L,the adsorption time was 60 h,the temperature was 333 K,the p H of the solution was 7,and the initial concentration of RADPs was150 mg/L,the adsorption capacity of MTARAR for RADPs was 6.50mg/g,and the corresponding removal rate was 86.16%.After 20 regeneration cycles,the removal rate of RADPS by MTARAR was84.28%,indicating good regeneration of MTARAR.Kinetics,isotherms,and thermodynamics studies showed that the adsorption of RADPs by MTARAR was a spontaneous,endothermic,and entropy increasing multi-layer adsorption process.The adsorption rate was affected by both liquid film diffusion and intra-particle diffusion.Adsorption was mainly caused by the interaction between the protonated tertiary amine with positive charge of MTARAR and the carboxylate with negative charge carried of RADPs(electrostatic attraction).(2)The methylacrylamide tertiary amine rosin-based adsorption resin(MATARAR)was prepared using DVB as crosslinking agent,HRAE as rosin-based monomer,dimethylaminopropyl methylacrylamide(DMAPMA)as functional monomer.The results showed that MATARAR carried amide and tertiary amine groups,and base value of MATARAR was 0.1551 mmol/g,and MATARAR carried positively charged.The MATARAR has a rich pore structure and good thermal stability.Under the suitable condition that the MATARAR dosage was 0.41 mg/m L and the temperature was 333 K,the equilibrium adsorption capacity of MATARAR for MD was 337.02 mg/g,and the corresponding removal rate was 92.43%.After five regeneration cycles,the removal rate of MD by MATARAR was 89.14%.The adsorption performance of MATARAR for MD was better than that of four same type commercial adsorbents.According to the fitting experiment results of thermodynamics and isotherm model,the adsorption process of MD by MATARAR was a spontaneous,endothermic,and entropy increasing multilayer adsorption process.Kinetic studies showed that the adsorption rate of MD by MATARAR positively correlated with the number of active sites of MATARAR.According to the calculation of quantum chemistry theory,adsorption was mainly caused by the interaction between the protonated tertiary amine with positive charge of MATARAR and the carboxylate with negative charge of MD(electrostatic attraction).