Study On The Adsorption Properties Of Zirconium Phosphate And Its Application In Uric Acid Bioelectrochemical Senso

The lamellarα-zirconium phosphate（α-ZrP）materials have the advantages of simple preparation,high chemical stability,high crystallinity,large specific surface area,stable and easily adjustable laminate structure,which have received great attention and have a wide range of application prospects in adsorption,catalysis,solid loading,and ion exchange,et.al.However,the adsorption effects ofα-ZrP materials on heavy metal ions Pb²⁺and urea molecules are still not well studied,andα-ZrP as an emerging material is still in the preliminary exploration stage for the application of uric acid bio-electrochemical sensors.Based on this,in this thesis,α-ZrP powder with stable lamellar structure and adsorption of Pb²⁺and urea molecules was synthesized by direct precipitation method,and the intercalation composite（α-ZrP/UAO_x）was obtained by loading uric acid enzyme（UAO_x）betweenα-ZrP lamellae to study the application of bio-electrochemical sensor which based onα-ZrP/UAO_x in uric acid detection;Meanwhile,in order to compensate for the own deficiencies of uric acid bio-enzyme,the MOF material（MIL-101（Cr））has been produced to replace uric acid enzyme and also applied to the uric acid bio-electrochemical sensor.In this way,static adsorption experiments were carried out to investigate the influence of different influencing factors on the adsorption performance ofα-ZrP and to analyze the feasibility of the two bio-electrochemical sensors based on different catalysts for the detection of uric acid concentration.The main results of the study are as follows:Theα-ZrP powder,the compositeα-ZrP/UAO_x,and MIL-101（Cr）produced were characterized.Theα-ZrP obtained in the experiment has high crystallinity and presents a regular hexagonal lamellar structure,the specific surface area S_BET was 4.3497 m2/g;the average pore size was 13.6 nm;theα-ZrP lamellar structure is stable,and the interlayer spacing increases after the successful insertion of UAO_x,but the lamellar structure has not changed significantly;the MIL-101（Cr）crystals show a regular ortho-octahedron with abundant pore structure and uniform distribution,and the particle size is in the range of 200～300 nm.The best adsorption conditions for Pb²⁺byα-ZrP powder are:above 25℃,solution p H around 4,and adsorption for more than 3h,the removal rate of Pb²⁺in the solution is up to 90%and the maximum adsorption capacity was 37.42 mg/g;For the adsorption of urea molecules,when the initial concentration was 200 mg/L,the amount of adsorbent was 0.5 g,about 30°C,and the solution was alkaline,the optimal adsorption can be achieved after 12h;The equilibrium adsorption capacity was 17.44 mg/g when the adsorption reaches the equilibrium state,which was closer to the theoretical value of quasi-secondary kinetic simulation（17.76 mg/g）.The adsorption ofα-ZrP on both is more consistent with the Langmuir adsorption isotherm model,indicating that both adsorptions are monolayer adsorption.The adsorption of Pb²⁺byα-ZrP includes physical and chemical adsorption,while the adsorption of urea molecules includes surface adsorption and internal particle diffusion processes.The bio-electrochemical sensor of uric acid based on composite material（α-ZrP/UAO_x）,the electrochemical reaction on the electrode surface is a surface-controlled process,and the electron transfer rate（k_s）was 3.83s^-1 at a scan rate of 10m V·s^-1.The linear detection range is 50μmol/L～500μmol/L with high linearity fit,the high sensitivity:226.31μA·（mmol/L）^-1·cm^-2,the detection limit was 3.56μmol/L（S/N=3）,and the lower limit of detection for the linear range of uric acid concentration was 10.68μmol/L.Moreover,the sensor has excellent reproducibility and good stability.Compared with UV spectrophotometry to detect the same concentration of uric acid,the relative error is smaller and the accuracy is higher.The modified electrode MIL-101（Cr）/GCE was produced by replacing uricase with metal organic framework（MOF）material（MIL-101（Cr））,and the electrochemical sensor based on this electrode has a linear detection range of uric acid concentration from 25μmol/L to 1 mmol/L.The range of uric acid concentration detection is wider than that the bio-electrochemical sensors based onα-ZrP/UAO_x.The sensor also can be used for the detection of trace uric acid with the detection limit of 5.53μmol/L,and the stability of the sensor is much better.The results show that MIL-101（Cr）has high electrocatalytic activity,which can replace uricase and make up for its limitations,thus broadening the application of electrochemical methods for the detection of uric acid concentration.