Preparation And Application Of Cellulose-based Composite Adsorbent

With the development of social and industrial progress, million tons of domesticsewage and industrial wastewater are produced everyday. If it is not treated properlybefore discharging into the natural water, the toxic substances (such as organic dyes,metal ions, etc.) in wastewater will cause severe environment pollution and hazards tohuman health. Adsorption is one of most cost-effective methods to remove the dyesand metal ions in water. Recently, more and more attentions has been attached to theuse of synthetic or natural polymer for wastewater adsorption treatment. However,synthetic polymer adsorbent materials are expensive, difficult to regenerate. Thus,more and more researchers began to focus on the natural polymer adsorbent materialwhich is cheap and easy to be obtained. Unfortunately, the existing natural polymerhas some disadvantages, such as small adsorption capacity, poor mechanical strengthand inferior chemical resistance. Those defects limit its application in wastewatertreatment.In order to solve the above problems of natural polymer cellulose, two kinds ofcellulose/graphene oxide materials were prepared and the adsorption of methyleneblue in the water was studied. Furthermore, cellulose/chitosan composite microsphereand modified pomelo peel were prepared. The adsorption of Pb2+by the adsorptionmaterials was investigated.(1) The new type of magnetic cellulose/graphene oxide composite material wasprepared. Furthermore, the proportion of components in composite materials wasoptimized by using the response surface method (RSM) and the optimal condition wasselected for preparation of composite materials. The adsorption of methylene blue bythe magnetic cellulose/graphene oxide composite was investigated. The experimentalresults show that the adsorption equilibrium in line with the Langmuir isotherm model,the maximum adsorption capacity is70.03mg g-1. The composite material is easy tobe recycled in a magnetic field and has a very good reusing performance. So it has agood application prospect in wastewater treatment.(2) The cellulose/graphene oxide composite microsphere was prepared by usingsol-gel method, and then the welan gum was grafted onto microsphere. Theexperimental results show that the spherical adsorbent and welan gum can effectively improve the adsorption performance of composite material, the maximum adsorptioncapacity of MB on composite microsphere reached282.88mg g-1. Furthermore, themechanical strength of composite microspheres has been improved. The dyeadsorption process was described well by the Sips model, it may be because in thecase of low dye concentration, adsorption is a multiple molecular layer adsorptionprocess, when the dye concentration is high, the adsorption process becomemonolayer adsorption.(3) Cellulose/chitosan composite microsphere was prepared, and applied to separatethe metal ions from water by adsorption. The maximum adsorption capacity of Pb2+on composite microsphere reached385.13mg g-1.The composite microsphere hasgood chemical resistance; it can exist stably for a long time in acid medium which pHis about1. The experiment of recycling and reusing found that the effect of metal ionsdesorption is better in lower pH value. The desorption efficiency is highest when thepH value is1.(4) The natural waste biomass pomelo peel has been selected as raw materials toprepare the aminated pomelo peel adsorption material, and it was used in adsorptionprocess of metal ions in water. Modification of pomelo peel can effectively removethe Pb2+ions in the water, its adsorption capacity reached158.80mg g-1. So it hasgood application prospect as a cheap and efficient biomass absorbent material.