Experimental Study On Synchronous Treatment Of High Fluoride High Iron And Manganese Groundwater By Calcined Serpentine Loaded Hydroxyapatite

High-fluorine,high-iron-manganese groundwater pollution seriously affects the health of residents and the quality of life of residents.By calcining and modifying serpentine,the author prepared a new adsorbent material of calcined serpentine loaded hydroxyapatite with good performance.The author research on the static and dynamic adsorption properties of the new adsorbent materials for F^-?Fe²⁺and Mn²⁺,and established isothermal adsorption and reaction kinetic models.Microscopic characterization was carried out by surface characterization methods such as SEM,EDS,XRD,BET and FTIR.The main findings are as follows:?1?The author carried out metal salt immersion modification,acid-base activation modification and fire modification on serpentine.The results showed that the modified serpentine was best after calcination at 500?for 120 min.450 mg of calcined serpentine was treated at pH7,temperature 35?,reaction for 150 min,150 ml containing F^-,Fe²⁺,When groundwater with Mn²⁺concentration of 5 mg/L,20 mg/L,and 5 mg/L?hereinafter referred to as test water sample?,the removal rates of F^-,Fe²⁺,and Mn²⁺were 97.1%,99.0%,and 99.2%.?2?Synthesis of hydroxyapatite by sol-gel method.The authors analyzed the adsorption properties of hydroxyapatite on F^-,Fe²⁺and Mn²⁺under different conditions of N/P,pH,aging time,calcination temperature and calcination time,and determined the optimal preparation conditions of hydroxyapatite.Combined with calcined serpentine,the OH^-alkalinity can be released into water.The optimum conditions for preparing a new adsorbent material for calcined serpentine-supported hydroxyapatite are as follows:mixing the calcined serpentine and nitric acid at a solid-liquid ratio of 20%.Calcium solution,aged for 20 h,adjusted pH to 11,can save 2/3 of ammonia water,aged 24 h,dried at 90?for 72 h,then calcined at 300?for 60 min,added 2%,80?gelatinization The etherified starch was prepared into 3-5 mm pellets and calcined at 180?for 90 min.?3?The optimum reaction conditions for the treatment of 150ml test water sample by calcined serpentine loaded hydroxyapatite are:dosage of 450 mg,pH of 6,temperature of 35?,rotation speed of 150 rad/min,reaction The time was 150 min.At this time,the removal rates of F^-,Fe²⁺,and Mn²⁺were 98.6%,99.9%,and 99.8%,respectively.The adsorption process of F^-,Fe²⁺and Mn²⁺accords with the Freundlich isotherm adsorption model,and the kinetic model conforms to the quasi-secondary dynamic model and the internal diffusion model.?4?After the calcined serpentine loaded hydroxyapatite treatment test water sample,the surface has filamentous crystals,and the reaction product is silicate and phosphate phase containing F^-,Fe²⁺,Mn²⁺,after reaction The Si-O-Si symmetric stretching vibration peak and the OH vibration peak area at the wavelengths of 794.67 cm^-1,1058.9 cm^-1,and 3444.8 cm^-1 are reduced,and the P=O vibration peak at a wavelength of 1384.8 cm^-1 After disappearing,the calcined serpentine-loaded hydroxyapatite particles had a BET specific surface area of 42.10m²/g.?5?The height of the adsorption mass transfer zone of F^-,Fe²⁺and Mn²⁺in the dynamic column is positively correlated with the filling quality of the adsorbent and the influent flow rate.When the adsorbent filling mass is 250 g and the influent flow rate is 4 ml/min,the dynamics The dynamic adsorption capacities of the columns for F^-,Fe²⁺,and Mn²⁺are:1.474 mg/g,5.614 mg/g,and 1.209 mg/g,respectively.When the initial concentration of F^-in the test water is 10 mg/L,the dynamic column can be obtained.The dynamic adsorption capacity of F^-,Fe²⁺,and Mn²⁺is maximized.The Yoon-Nelson equation has the best fit to the F^-?Fe²⁺and Mn²⁺breakthrough curves.This thesis contains 100 pictures,31 tables,and 69 references.