Putthiporn CharoenphunKrisanat ChuamsaamarkkeePongtanawat KhemthongMahidol UniversitySasiprapha Pochun2026-02-262026-02-26202320262023Thesis (M.Sc. (Medical Physics))--Mahidol University, 2023https://repository.li.mahidol.ac.th/handle/123456789/115371Iodine-(131) is commonly used to treat thyroid cancer in nuclear medicine. Approximately 50-90% of the administered activity is excreted through urine in the first 24 hours, and it could cause unwanted exposure to the people nearby and environmental contamination. This study aimed to investigate (131)I removal efficiency using activated carbon (AC) and modified activated carbon with ammonia (NH3-AC) from synthetic urine and the factors affecting (131)I removal. Batch experiments with AC and NH3-AC were performed with (131)I synthetic urine concentrations of 0.5, 1, 2, and 3 μCi/mL at various contact times ranging from 3 minutes to 7 hours. The effect of adsorbent dosage was also investigated by varying the sample weights of 0.25, 0.50, 0.75, and 1.00 gram of AC and NH3-AC to obtain the adsorption capacity and isotherm. Column experiments were conducted with (131)I synthetic urine concentrations of 0.06, 0.03, and 0.015 mCi/mL under 25°C and 37°C to determine the removal efficiency of AC and NH3-AC. Column reusability was investigated by repeatedly adding 3.5 mL (131)I synthetic urine concentration of 0.06 mCi/mL for 20 times. The results from batch experiment revealed that AC and NH3-AC removed (131)I from synthetic urine with a removal efficiency of about 34% and 48%, respectively, over all concentrations. The removal efficiency increased with contact times and was rapidly increased before reaching the equilibrium time at 1 hour for AC and NH3-AC. In addition, removal efficiency increased with AC and NH3-AC weights up to 43% and 45% of 1 gram of both adsorbents. Adsorption isotherms demonstrated that AC presumably fitted with Langmuir model with the maximum adsorption capacity (qm​) of 222.22 μCi/g while NH3-AC tended to fit with Freundlich isotherm with Kf of 2,472.78 μCi/g. For the column experiment, AC and NH3-AC removed (131)I varying from 59% to 68%, respectively, over all concentrations. Removal efficiencies of AC and NH3-AC ranged from 57% to 59% at temperatures between 25°C and 37°C. Column reusability test indicated that the AC and NH3-AC columns removed (131)I from synthetic urine up to 20 times of loading by decreasing with the number of loads. In conclusion, AC and NH3-AC could be promising materials to remove (131)I from the urine of patients treated with radioiodine. Implication of thesis: The efficiency of iodine-(131) removal from synthetic urine was investigated and compared between activated carbon (AC) and ammonia-doped activated carbon (NH3-AC). The batch experiment was conducted to obtain the adsorption capacity data and study the factors affecting the (131)I removal efficiency. Furthermore, the column experiment evaluated the possibility of (131)I removal from the urine in the dynamic system under different concentrations of (131)I synthetic urine and temperatures. In this study, the concentrations of (131)I were further diluted based on the probably lowest concentrations of (131)I excreted in the patient urine. Temperatures were set based on the room temperature and body temperature. This study demonstrated the feasibility of using AC and NH3-AC to remove (131)I from the urine of patients treated with radioiodine. Additionally, results from this work provided information for further investigation and for designing of the adsorption system for (131)I from urine. Nevertheless, the observation of this study could represent regarding the experimental conditions.ix, 82 leaves : ill.application/pdfengผลงานนี้เป็นลิขสิทธิ์ของมหาวิทยาลัยมหิดล ขอสงวนไว้สำหรับเพื่อการศึกษาเท่านั้น ต้องอ้างอิงแหล่งที่มา ห้ามดัดแปลงเนื้อหา และห้ามนำไปใช้เพื่อการค้าRadioactive waste disposal -- Purification.Iodine -- Isotopes.Carbon, Activated -- Research.Adsorption -- IsothermsM.Sc. (2023)Medical Physics (Mahidol University 2023)Master ThesisMahidol University.