การดูดซับโลหะหนักบางชนิดจากน้ำเสียด้วยดินเบาเคลือบแมงกานีสออกไซด์ / พรเพ็ญ มีทองมูล = Adsorption of some heavy metals from wastewater by manganese oxide-coated diatomite / Pornpen Meethongmool
The adsorption of arsenic, cadmium and lead in synthetic wastewater by using manganese oxide-coated diatomite was examined in a batch experiment at room temperature. The results indicated that type and concentration of heavy metal, pH of wastewater and contacting time affected the heavy metal adsorption efficiency. The finding of this study using 0.1 gram of manganese oxide-coated diatomite showed that the optimum pH of arsenic adsorption was 7 and the initial concentration was 40 mg/l. At contacting time for 12 hours, the adsorption efficiency was 35.19%. The optimun pH for cadmium adsorption was 5 and the initial concentration was 40 mg/l. At contacting time for 8 hours, the adsorption efficiency was 91.67%. The optimun pH for lead adsorption was 4 and the initial concentration was 50 mg/l. At contacting time for 45 minutes, the adsorption efficiency more than 99 % and the order of adsorption time was lead<cadmium<arsenic. The adsorption isotherm of three types of heavy metal was found that arsenic and lead were fitted in the Langmuir adsorption isotherm but cadmium was fitted in the Freundlich adsorption isotherm. The results from leaching test of three types of heavy metal was found that cadmium and lead was leached less than those of the Ministry of Industry's standard but arsenic was found higher than the standard. In the case of wastewater from a battery factory containing 0.42 mg/l of arsenic and 5.89 mg/l of lead, the manganese oxide-coated diatomite has very good adsorption efficiency for both heavy metals.
