Preparation Of Modified Cellulose/Attapulgite And Adsorption Of Arsenic And Cadmium

Cellulose is a natural biodegradable polymer material and an environmentally friendly material without secondary pollution.In this Thesis work,aluminum oxide supported by cellulose was prepared from wood chip cellulose as green-based adsorbents for the removal of arsenic ions in water.Moreover,three types of metal oxides supported by cellulose,including aluminum oxide,cerium bimetallic oxide and cerium manganese bimetallic oxide,were prepared and used as stabilizers for controling the migration of arsenic ions in soil.The resulting adsorbents,the aluminum oxide supported by cellulose in particular,were characterized with SEM,SEM-EDX and FT-IR before and after the synthesis of modified materials,so as to prove the success of thepreparation.The cellulose-supported aluminum oxide（CASO）adsorbent was prepared by co-precipitation method using sawdust cellulose as the matrix material.The adsorption performance of arsenic ion（As）in water under adsorption conditions was investigated experimentally.The results showed that when the concentration of arsenic ions was lower than 50 mg/L,the adsorption efficiency could reach more than 90%.Under the conditions ofthe p H of the solution 4-8,the adsorbent dosage at 2 g/L,the adsorption temperature 25℃,and the initial concentration of As at 50 mg/L,the adsorption capacity of As on CSAO adsorbent was as high as 22.89 mg/g.By fitting the adsorption data,it was found that the adsorption isotherm of arsenic ions on CSAO by the supported aluminum oxide cellulose adsorbent was in accordance with the Langmuir adsorption model,indicating that the adsorption was mainly monolayer adsorption.The adsorption kinetics data showed that the whole adsorption process was better decribed by the quasi-secondary adsorption kinetics model,indicating that the chemical adsorption was dominantApart from CASO,the ferric cerium bimetallic oxide supported by cellulose and the cerium manganese bimetallic oxide supported by cellulose were also prepared and used along with Ca CO₃ to stablized the arsenic in the mimic contaminated soil.Afterwards,the effective arsenic in the soil was extracted with 0.1 mol/L HCl solution as the leaching solution.The stabilization effects of three stabilizers on effective arsenic in soil at 7 days and 14 days were analyzed and compared.Among three adsorbents,CASO has the maximum stabilizing efficiency of 42%to arsenic in the soil.Attapulgite（ATP）is a kind of polymeric clay mineral material rich in magnesium aluminum silicate.g-C₃N₄ and has a negative surface charge.A series of surface functional modification were performed on ATP to enhance the adsorption affinity towards Cd（II）.In this work,with ATP as the base material,urea as the C source and N source,g-C₃N₄/ATP was prepared using a dissolving and freeze-drying calcination method for adsorption of Cd（II）.The g-C₃N₄/ATP was characterized by XRD,transmission electron microscopy,Fourier transform infrared spectroscopy,high-resolution transmission electron microscopy,and XPS before and after modification of the material,so as to prove the success of modification and adsorption mechanism.Based on different ratios of compoments,various types of g-C₃N₄/ATP were prepared.The adsorption properties of Cd（II）in water under different adsorption conditions were investigated to identify the optimal adsorption conditions.The results were also fitted with different adsorption kinetics and isotherm models.It was found that the maximum adsorption capacity of g-C₃N₄/ATP（CA-0.50 in particular）towards Cd（II）was 61.1mg/g,which is higher than that of ATP（34.7 mg/g）.The findings from model fitting indicated that the adsorption behaviors of Cd（II）on five adsorbents were in accordance with the Langmuir model,suggesting that the adsorption was mainly monolayer.To further utilize the adsorbents after adsorption,Cd S/ATP/g-c3n4-x was obtained via the hydrothermal reaction between recovered adsorbent and thiourea at high temperature.The catalytic degradation of tetracycline by Cd S/ATP/g-C₃N₄-x was studied under xenon lamp of 300w.The photocatalytic materials had good degradation effect on tetracycline 15 min before illumination.Moroever,Cd S/ATP/g-C₃N₄-1.0 degraded tetracycline up to 75%when exposed to light for 15 min.Tetracycline was rapidly mineralized on Cd S/CA-0.50 samples,and the TOC removal rate reached 59.7%within15min.