Preparation Of Graphene Oxide Based Composites And Their Adsorption Performance For Methylene Blue In Dye Wastewater

Methylene blue（MB）is a typical cationic azo dye with high chromaticity,widely used in industries such as textiles,leather,printing,coatings,cosmetics,etc.It poses serious environmental and human health hazards.In addition,the vast of dyes have complex chemical structures that are difficult to degrade,and the discharge of dye wastewater is large and the water quality is complex.Therefore,a green and efficient treatment of dye wastewater has become an urgent problem to be solved.At present,the commonly used technologies for removing pollutants such as dyes include adsorption,precipitation,membrane separation,and biological treatment.Compared to other treatment methods,adsorption method has been widely used due to its advantages of simple operation,low cost,easy operation,and no secondary pollution during the adsorption process.Graphite oxide（GO）is a derivative of graphene,which is a two-dimensional structure nano material formed by single-layer carbon atoms in the way of sp²hybridization.GO contains larges number of oxygen-containing functional groups,such as hydroxyl,epoxy,carbonyl,and carboxyl groups.These characteristics make GO hydrophilic and easy to modify.At the same time,it also serves as an adsorbent for GO,providing larges number of active sites on the surface of GO,which can generate multiple interactions with MB such asπ-π,electrostatic and hydrogen bonds,thus ensuring its high adsorption capacity.This article developed a stripping method for preparing GO with fewer layers,larger size,and higher oxygen content using electrochemical methods.Based on GO,composite adsorbent with good magnetic separation ability and cyclic stability was prepared.In addition,the feasibility and superiority of prepared GO and composite materials as adsorbents for MB adsorption treatment were studied.Furthermore,the effects of concentration,temperature,p H and other factors on the adsorption of MB by GO and composites.The specific content is as follows:（1）Preparation of GO by liquid phase intercalation electrochemical method and its adsorption performance for MB:firstly,prepare GIC by electrochemical intercalation method,and then use H₂SO₄ aqueous solution as electrolyte to electrochemically oxidize and peel the obtained GIC at the anode,peeling is completed after 30 minutes.Finally,after ultrasonic and cleaning treatment,GO with an oxygen content of 33.7 wt.%was obtained.By characterization,it was found that 53%of GO nanosheets have sizes between 5-10μm.19%of EGO nanosheets have a size greater than 10μm;The thickness of single and double accounts for up to 88%,which helps improve the adsorption performance of MB.（2）Electrochemical two-step method for preparing GO and its adsorption performance on MB:in order to improve controllability,simplify the preparation process,and further shorten the preparation time,an improvement was made,and a step-by-step method for preparing GO was developed.Firstly,prepare GIC by electrochemical intercalation method.And then,using（NH₄）₂S₂O₈ aqueous solution as the electrolyte,the obtained GIC is subjected to electrochemical oxidation and stripping on the anode.Due to the GIC obtained in the first stage of anode preparation still serving as the anode in the second stage,and the voltage remains unchanged in the two steps,the operation process is greatly simplified.This method can complete the preparation of GO within 20 minutes,further shortening the preparation time.By characterization,it was found that the nanosheet distribution was 55%,with a size ranging from 5 to 10μm.21%of dimensions greater than 10μm.The thickness of 1-2 layers accounts for78%,and the oxygen content is as high as 35.6 wt.%.In addition,the effects of different conditions on the adsorption of MB by GO were studied,as well as the differences in the adsorption performance of MB by other commonly used carbon materials.（3）Preparation of MGO/CMC and its adsorption performance on MB:CMC,Fe₃O₄and GO were compounded by hydrothermal method and ultrasonic method,and the materials were characterized.The results indicate that the MGO/CMC magnetic composite adsorbent has been successfully synthesized.And the obtained MGO/CMC magnetic composite adsorbent was subjected to subsequent MB adsorption experiments,and it was found that the prepared composite adsorbent has advantages such as high adsorption capacity,easy separation,and good cycling stability.After 7 consecutive adsorption desorption cycles,the removal rate of MGO/CMC is still above 50%,and the adsorption capacity remains high at 190.6 mg/g,indicating good reusability.In summary,this article constructs two new methods for preparing GO and applies GO to the preparation of new adsorbents.The results indicate that the adsorbent has a good removal effect on MB in wastewater.This not only provides new strategies for producing high-quality GO more quickly,economically,and efficiently,but also provides new ideas for better treatment of dye wastewater,with certain potential application value.