การดูดซับโลหะหนักบางชนิดจากน้ำเสียด้วยดินเบา / ชฎาภรณ์ บุญแท้ = Adsorption of some heavy metals from waste water by diatomaceous earth / Chadaporn Boontae
The adsorption ability of cadmium (II), chromium (III) and arsenic (V) from synthetic wastewater by diatomaceous earth was studied in a batch experiment. The results indicated that concentration of heavy metal, amount of diatomaceous earth, pH and contact time affected the heavy metal removal efficiency. The appropriate conditions for this study were as follow : for cadmium, 40 ppm. of Cd at pH 5, 2.0 grams of diatomaceous earth, 100 rpm. of shaking rate and contact time for 10 hours., and for chromium, 40 ppm. of Cr at pH 4, 1.0 gram of diatomaceous earth, 100 rpm. of shaking rate and contact time for 10 hours. As the results, the removal efficiency was 99.92% and 99.82%, respectively. For arsenic, the calcined diatomaceous earth was used, and the condition was as follow : 40 ppm. of As at pH 4, 1.0 gram of calcined diatomaceous earth, 100 rpm. of shaking rate and contact time for 6 hours. The result showed that the removal efficiency was 99.96% The adsorption isotherm of cadmium can be described by the Freundlich isotherm. For chromium, the equilibrium was not followed the adsorption isotherm because the removal of chromium is based on the precipitation, and for arsenic, the adsorption isotherm could be described by the Langmuir isotherm. The results from leaching test showed that concentration of cadmium and chromium in the solution were less than those value of the Ministry of Industry's standard but concentration of arsenic in the solution was higher than the standard. In the case of battery factory's wastewater containing chromium, arsenic and lead at 0.23, 0.42 and 5.89 ppm., respectively, more than 99% of all heavy metals could be removed by diatomaceous earth.
