Preparation Of Polymer Membrane Modified By MXene And Its Performance In Wastewater Treatment

Population explosion and social development have brought significant water environment problems,such as oil leakage,dye discharge,domestic sewage,industrial wastewater and so on,eroding the few fresh-water resources on the earth.Meanwhile,human demand for water resources is increasing,resulting in a severe water shortage.Therefore,to cope with the water shortage caused by the rapid development of the world today,the research and development of water treatment technology have received great attention.Among them,membrane separation technology is considered the most practical water treatment technology in the 21st century.Compared with the traditional treatment process,it possesses a small footprint,high water quality,simple operation,low-cost characteristics,and has strong competitiveness in the current field of water treatment.However,due to the existence of membrane fouling,the further expansion and application of membrane separation technology are blocked,which is the bottleneck problem of membrane technology development.For this reason,the rising field of membrane modification has become a beacon in the application process of membrane separation,which can effectively control the problem of membrane pollution and can also cater to different situations and develop membranes with different properties,which is one of the hotspots of current research.Herein,this research selected MXene which is currently attracting more attention in the field of two-dimensional materials prepared various hybrids through a series of modifications and combined them with polymer membranes to prepare new modified membranes.The separation efficiency of the membrane was improved,the anti-fouling performance of the membrane was improved,and the photocatalytic self-cleaning benefit of the membrane was given.The extended Derjaguin–Landau–Verwey–Overbeek（XDLVO）theory also explained the anti-fouling mechanism of the modified membrane.And due to the preparation method of MXene nanoribbons（MNRs）,it is stipulated that such modified membranes should be used under non-alkaline conditions.The main findings are as follows:（1）The magnetic Ni@MXene nanoparticles were firstly developed and then elevated to the upper layer of polyether sulfone（PES）membrane by an external magnetic field during the wet phase inversion process to prepare a PES-Ni@MXene membrane.The membrane possessed ultra-high flux and also showed significant anti-fouling ability,evidenced by the flux recovery rates（FRR）of 64.6%and 99.8%for bovine serum albumin（BSA）and humic acid（HA）solutions,respectively.Meanwhile,the optimal PES-Ni@MXene membrane possessed an efficient decoloration ability for Congo red（CR）solution and obvious oil-water separation ability.In order to analyze the anti-fouling mechanism,the XDLVO theory calculated the interaction energy between the membrane surface and the pollutants（BSA and HA）.This research provided new impetus for the development of efficient MXene-based membranes.（2）PES-Ti O₂@MXene composite membrane was prepared using a simple hydrothermal method,and two-dimensional Ti O₂@MXene nanomaterial was introduced.The composite membrane displayed superior separation and antifouling performance.When filtrating BSA solution,the flux of the optimal membrane（BSA rejection rate 95%）reached to 756.8 L·m^-2·h^-1·bar^-1.Moreover,PES-Ti O₂@MXene composite membrane possessed excellent self-cleaning function under UV irradiation.According to the XDLVO approach,the PES-Ti O₂@MXene composite membrane showed an optimal interface condition,significantly reducing attractive interactions with foulants.The facile fabrication method,together with the efficient membrane performance,indicated good application prospects of the PES-Ti O₂@MXene composite membrane proposed in this study.（3）The new fibrous MXene nanoribbons（MNRs）material was prepared by alkalizing MXene with KOH.The material was vacuum filtered on the surface of the mixed cellulose membrane（MCE）to design a new type of MCE-MNRs two-dimensional composite membrane.The membrane had super hydrophilicity and superhydrophobicity underwater,and meanwhile it exhibited outstanding resistance to oil droplets.At the same time,the flux of the modified membrane reached 1.59×10⁴ L·m^-2·h^-1·bar^-1,and the rejection rate for four different oil-water mixtures of diesel,gasoline,edible oil and n-hexane were all>99%.In addition,due to the oxidation of the material,the modified membrane was given the photocatalytic self-cleaning ability.The contaminated membrane recovered up to 76%flux recovery rate after being irradiated by ultraviolet light,and it illustrated that its self-cleaning ability was good.Based on the simple preparation method and excellent separation performance of MCE-MNRs cater to the current industrial production needs and have promising application prospects.