| Recently,organophosphorus pesticides have been widely used in the prevention and control of crop diseases and insect pests.Due to the unreasonable use of pesticides,the non-standard discharge of factory wastewater enters the water environment,resulting in severe pollution of natural water,so urgently need to remove organophosphorus insecticides in the environment.The effect is extremely harmful to the environment and humans,so there is an urgent need to remove organophosphorus pesticides in the environment.On the other hand,the plant-derived nanocellulose adsorbent prepared from waste biomass has attracted much attention in water treatment and environmental remediation.Therefore,based on the above two contexts,the typical pesticide-poisonous miutants is selected to remove the object,and a series of studies is carried out with nanoculic to the adsorbent.The first is the preparation of nanocellulose,and the optimal adsorption conditions were optimized by poisonous monopolysis test and response surface design tests.With analyzing the adsorption kinetics,adsorption isotherm models and characterization techniques,the adsorption characteristics of modified biomass-based adsorbents to remove pesticides in water are explored,in order to provide a theoretical basis for the removal of organophosphate pesticides and the recycling of agricultural waste.The main conclusion of this thesis is launched from the following four aspects:（1）Two adsorbents,namely,polyvinylamine-modified nanocellulose（PhaCNCs）and silane coupling agent-modified nano-cellulose（APTES-CNCs）were prepared by two different amino modification methods,and the removal effect of chlorpyrifos was compared to determine the chlorpyrifos Remove the best adsorbent.Under the same conditions,PhaCNCs showed higher adsorption capacity of chlorpyrifos than APTES-CNCs,and the removal rate of chlorpyrifos could reach more than 90%.Through single factor test,it is determined that the initial concentration of the poison is 10-40 mg·g-1,and the adsorbent investment is 0.2-1.0mg·g-1and the adsorption time is 2-10h,so as to prepare for optimizing the parameter range in the response surface test of chlorpyrifos adsorption by PhaCNCs.（2）Central composite design based on response surface methodology was used to evalute the influence of operational factors（chlorpyrifos concentration,PhaCNCs dose,and adsorption time）and optimize of three factors.The results showed that the influencing factors on the removal rate of chlorpyrifos in descending order were the initial concentration of chlorpyrifos>reaction time>the dosage of PhaCNCs,and there was the certain interaction between the variables.The results of adsorption experiments revealed that 0.57g·L-1PhaCNCs required 8.3h to adsorb 36.81mg·L-1 chlorpyrifos to yield an efficiency of 92.72%.（3）The adsorption kinetics fitting results show that the adsorption process of PhaCNCs on chlorpyrifos in water conforms to the the pseudo-first-order kinetic model（R2=0.977～0.983）,indicating that the adsorption of chlorpyrifos was mainly dominated by chemisorption.The fitting results of the adsorption isotherm model show that the Langmuir model described the adsorption process of PhaCNCs batter（R2>0.94）,indicating that the modified PhaCNCs have a strong binding capacity to chlorpyrifos,and the maximum adsorption capacity of chlorpyrifos is as high as 98.116mg·g-1.Compared with the original CNCs,the adsorption capacity of PhaCNCs is about 7.96 times that of the original CNCs.（4）PhaCNCs clearly observed the introduction of N elements in the infrared spectrum and XPS full spectrum,indicating that the amino-modified adsorbent was successfully prepared.PhaCNCs have a wider pore size distribution range and an increased specific surface area,up to 32.1705m2·g-1.Compared with the original CNCs,the crystal structure of PhaCNCs has not changed,and there are differences in morphology.PhaCNCs are composed of 50-150nm microsphere particles.The mechanism of this adsorption process mainly includes the following aspects:the surface of amino-modified nanocellulose is rich in amino and hydroxyl functional groups,and attracts more chlorpyrifos molecules through hydrogen bonding,electrostatic attraction and amino active sites. |
