Preparation Of Water-treatment Absorbent From Activated Bamboo Fibers

Cellulose,as the most abundant biomass material on the earth,is a kind of renewable resource that is environmentally friendly,biodegradable and can replace traditional fossil fuels.In recent years,with the increasingly serious water pollution problem,the adsorption of cellulose based composite materials for water pollutants has attracted much attention.In order to expand the application of pulp fiber outside papermaking,the study of preparation of high added-value products of pulp fiber by using pulp fiber as raw material directly in this paper.Therefore,the pretreatment of raw materials was needed firstly to improve the reagent and solubility of the fiber.The fiber was dissolved in alkali/urea aqueous solution at low temperature,and cellulose microspheres(CB)were regenerated from coagulation bath,then,magnetic nanoparticles(Fe3O4)were synthesized in the pore on the surface of CB by in situ polymerization to prepare the adsorption materials of functional magnetic cellulose microspheres(MCB).The absorption efficiency of MCB on the methyl orange(MO)in simulated dyeing waste water was detected.The reaction performance,water retention value(WRV),specific surface area,solubility(S)were used as the evaluation indexes to discusses the processes effects of PFI mechanical refining combined alkali swelling and ultrasonic assisted alkali swelling pretreatments on the properties of fiber respectively.Testing technologies,such as FQA,XRD,SEM,FT-IR and so on,were employed to analyze the changes of the characterizations of pulp fibers before and after processing.The results showed that the fiber fibrillation was increased,and the oxidation rate of the hydroxyl groups increased by 25% in the oxidation reaction after PFI beating.Besides,the fiber specific surface area could be increased ten times and the WRV was increased up to 422.75% after treated by PFI mechanical refining combing with alkali swelling,the crystallinity decreased from 71.30% to 61.17%,and the solubility increased to 96.98%.The effect of ultrasonic wave on the fiber crystal area is obvious,the crystallinity of fiber was decreased to 59.22%,and the fiber specific surface area increased with the solubility of 90.66% at the same time after treated by ultrasonic assisted alkali swelling process;In addition,the crystal form of fiber transferred from celluloseⅠto celluloseⅡ with the alkali pretreatment.Cellulose solution was dripped into coagulation bath to prepare regenerated cellulose microspheres(CB),and the optimum conditions were gotten with fiber solution concentration was 2.0%,dripping height is 5 mm,coagulation time was 30 min.The material of CB with uniform size and good spherical structure could be obtained,and the average particle dimeter is about 1.86 mm.Magnetic cellulose microspheres(MCB),average diameter increased to 2.01 mm,prepared by in situ polymerization,showing excellent magnetic responsiveness and could be separated rapidly under magnetic field.The SEM images showed that Fe3O4 nanoparticles were distributed evenly in the pores of CB surface,and the vibration peak of –NH2 can be observed in FT-IR spectrogram,proved that the amino functional groups were grafted on the surface of MCB successfully.The results of adsorption experiment showed that MCB adsorption materials have excellent adsorption capacity for methyl orange(MO).The optimum adsorption conditions were obtained by single factor experimental analysis,which can be seen as the PH value is in the range of 3-7,the initial concentration is 120 mg·L-1,adsorbent additive quantity is 1.8 g·L-1 and adsorption time is 80 min.Maximum adsorption quantity was 61.77 mg·g-1 and MO removal rate could be reach to 92.65%;In addition,the studies of isothermal adsorption process and adsorption kinetics showed that the adsorption process is more consistent with the Langmuir isothermal adsorption model and the pseudo-first-order kinetic equation,which proved that a chemical adsorption with single molecule layer dominated the adsorption process.Finally,a good recycling ability of MCB was showed,the adsorption rate over 90% can be maintained after recycling within five times.