The Preparation Of MXene-metal Organic Framework Nanolaminate Film And Its Application In Agricultural Chemical Hazards Enrichment And Detection

Agricultural products safety is critical to ensuring national food security,social stability,and national health.Agricultural chemicals can help solve the shortage of agricultural resources problems and have been widely used in agricultural production,storage,and consumption.However,excessive use of agricultural chemicals may cause agricultural and veterinary drug residues to contaminate the food chain,thus threatening human health and the economy.Therefore,it is essential to develop separation,enrichment,and detection technologies for hazards related to agricultural products.Membrane materials have good selective permeability and are often used to separate and enrich target molecules in agricultural samples.However,common membrane materials are challenging to balance the permeability and selectivity during filtration.It is hard to meet the needs for rapid enrichment of agricultural substances and efficient separation of sample pretreatment.In addition,the existing membrane materials have a relatively single function and are mainly used as a pre-technique in the detection field.It is challenging to combine the separation and enrichment with the identification and signal output steps of detection,which further limits the application of membrane materials in the separation,enrichment,and detection of harmful agricultural substances.This study developed a novel nanoconfined MXene-metal organic frameworks(MOFs)laminate film to rapidly and efficiently separate and concentrate hazardous molecules in agricultural products.The separation mechanism of the laminate film was elucidated.By combining the nanoconfined MXene-MOFs composite membrane with a fiber-based electrode(Nylon-Au),a novel Nylon-AuMXene-MOFs electrochemical detection platform was constructed to separate,enrich and detect harmful molecules in agricultural samples.The specific research content includes the following three aspects:(1)Preparation of nanoconfined MXene-MOFs nanolaminate film.Firstly,a novel MXene-MOFs nanolaminate film was prepared from the internal structure of the separation membrane.The film consists of intercalated MOFs nanoparticles and MXene nanosheets.The MOFs particles enable the interlayer spacing to adjust and form a nanoscale confined space with MXenes nanosheets.By changing the ratio of MXene to MOFs,nanolaminate films with different microscopic morphologies can be obtained,which lays the foundation for the rapid and efficient separation and enrichment of harmful molecules in agricultural samples in subsequent research.(2)Nanoconfined MXene-MOFs nanolaminate films for antibiotics separation and enrichment.The liquid phase separation performance of MXene-MOFs nanolaminate films constructed in(1)was evaluated.The water flux and filtration performance of the nanolaminate membrane were investigated.The water flux of MXene-MOFs nanolaminate films with different proportions was tested,and the effect of intercalation particles on the adjustment of the two-dimensional nanosheet spacing was verified.The maximum water flux could reach 308.2 L m-2 h-1 bar-1,which was three times the control group.In addition,the one-time removal efficiency of the composite membrane for a variety of targets was investigated.For the selected three types of dye molecules,the removal rate was higher than 99%,for the chosen antibiotics,the removal rate was higher than 90%,for the green quantum dots,the filtration efficiency reached 99.7%,and the removal rate was similar to or better than the control two-dimensional membrane and MOF-polymer fiber membrane.The double separation mechanism of the composite membrane based on size exclusion and adsorption was also explored.Based on the dual separation mechanism,a new paradigm of hierarchical filtration of multiple harmful substances from a complex matrix is constructed,which can realize the mode of "one divided into three" of a single sample.The new separation model is preliminarily applied to the separation of actual agricultural complex samples,which is expected to support the detection of agricultural products.(3)Nanoconfined MXene-MOFs nanolaminate film combined with fiber membrane-based electrode for agricultural hazards detection.Based on the MXeneMOFs nanolaminate film prepared and explored in(1)and(2),a new Nylon-AuMXene-MOFs electrochemical detection platform was constructed by combining the composite film with the fiber membrane-based electrode.The platform contains the function of membranes and electrodes,which can realize separation,concentration,and detection.For the selected target methylene blue(MB),the detection range is 0.01-10 mg L-1,LOD is 1 μg L-1,and the detection range of tetracycline(TC)is 0.001-5 mg L-1,LOD is 1 μg L-1.In addition,depending on the separation and enrichment function of the composite membrane,the confinement effect can effectively increase the detection current,which is expected to realize the sensitive detection of the target.