The Preparation Of Functional Materials Based On Biomass Cotton Fiber And Their Application In Wastewater Treatment

Recently,water pollution has become an important factor threatening the survival of human beings and other creatures.Two major pollutants are difficult to be harnessed.One is the dye wastewater that mainly comes from industry and handicraft industry.Even if a small amount of dye exists in the water,it can cause serious harm to human and the ecological environment.Therefore,how to effectively deal with the dye wastewater is one of the main problems.Another organic pollutant is nitrophenol due to its high toxicity.It can exist in the water system for a long time but is difficult to be degraded,which is also a serious problem in water purification.In this study,the natural cotton fibers were treated with chemical or physical methods to obtain the different functional materials.The synthesized functional materials were characterized by X ray powder diffraction?XRD?,transmission electron microscopy?TEM?,Flourier transformation infrared spectroscopy?FT-IR?,scanning electron microscopy?SEM?,nitrogen adsorption desorption isotherms and X-ray photoelectron spectroscopy?XPS?.Their performance of degradation of organic dyes and catalytic reduction of 4-nitrophenol were investigated.The main results are as follows:?1?A flexible carbon fiber aerogel material was synthesized from abandoned cotton by using air-limited calcination method.The obtained materials were used for the adsorption of MB.Characterization results indicated that carbon fiber aerogels were fibrous with an average diameter of 10?m.The specific surface area of as-prepared materials can reach 457.73 m² g^-1.The effect of the conditions in the preparation and the adsorption temperature were investigated in detail.Higher calcining temperature?600 ^oC?and lower cotton loading amount(L_cotton=0.25 g)can lead to a higher adsorption capacity with 102.23 mg g^-1.The equilibrium data were best represented by Langmuir isotherm model and the kinetic data was found to follow closely the pseudo-second-order kinetic model.?2?Natural cotton,featuring abundant oxygen-containing functional groups,had been utilized as a reductant to synthesize Ag particles on its surface.Therefore,the fibrous Ag/cotton composite?FAC?was synthesized and used for the catalytic reduction 4-nitrophenol?4-NP?.A series of characterization of FAC showed that the silver particles had been successfully loaded on the surface of the cotton,and the size of the silver particles was about 20 nm-100 nm.Moreover,the catalytic activity of FAC was excellent;the 4-NP can be degraded within only 2 min.The effects of the Ag content,the amount of FAC and the initial concentration of 4-NP on the catalytic reaction were investigated.The as-synthesized material had the highest catalytic activity with the addition of AgNO₃ was 0.5 g in preparation process.And the degradation rate was the fastest when the amount of FAC was 30 mg and the initial concentration of 4-NP was 1 mM.?3?In this experiment,the natural cotton was used as the template to reduce the Ag ions on its surface.The cotton-like Ag fibers?AFs?were obtained after the removal of cotton fibers.Moreover,the as-prepared AFs were used not only as the catalyst for 4-nitrophenol but also as the substrate for the Surface Enhanced Raman Scattering?SERS?.The results indicated that the AFs perfectly maintained the morphology of the cotton fibers and had a porous structure.It also exhibited the favorable catalytic activity for 4-nitrophenol.Additionally,preliminary SERS experiments showed that the AFs can be served as the sensitive SERS substrate for the detection of dye molecules?MB?.Its resolution can reach up to 10^-88 M.?4?According to the previous work,a series of cotton-like Ag fibers were synthesized by using cotton fiber as the template.And the Ag fibers were soaked in FeCl₃ solutions with different concentration to form the Ag/AgCl composite.The as-synthesized materials were served as the photocatalyst for the degradation of Methyl orange?MO?.The experimental results indicated that the Ag/AgCl composite retained the fibrous structure and the material with highest photocatalytic activity could be obtained when the molar ratio of Ag to Fe Cl₃ was 1:1.5.It can completely degrade the MO within 40 min under sunlight.