چكيده به لاتين
The importance of the absorption process and the growing demand for efficient and low-cost cost mineral adsorbents treatment methods have increased. In this study, batch operation was applied for the removal of malachite green dye by raw, calcined and sodium dodecyl sulfate modified magnesite from aqueous solution. In first step, the raw magnesite was used for removal of the cationic malachite green dye. Then, in order to increase the adsorption capacity of adsorbent, magnesite modified with the sodium dodecyl sulfate surfactant was investigated. The characteristics of natural, calcined and modified magnesite has been accomplished by XRF, BET, FTIR, FESEM, and EDX analysis. The effects of sorption parameters such as contact time, solution pH, adsorbent dosage, initial dye concentration, and temperature were evaluated in a batch system and the best removal percentage for magnesite was 180 minutes, 60 minutes for calcined magnesite and 120 minutes for magnesite modified with surfactant. The results of the experimental data were fitted by three isothermal models (Langmuir, Freundlich and Temkin) and according to the obtained results, Langmuir adsorption isothermal for the removal of malachite green by magnesite and calcined magnesite and Freundlich isothermal for modified magnesite are in better agreement with the results. The measured maximum adsorption capacities calculated according to the Langmuir isotherm were 23/78, 19/97 and 11/36 mg/g at 25 °C, and for Freundlich 11 mg/g at 25 °C, respectively. In each of the cases, the adsorption kinetic data for adsorbents were better described by the pseudo-second order kinetic model. The calculated absorption capacity parameter of absorption kinetics for three adsorbents, magnesite, calcined magnesite and modified magnesite with SDS surfactant are 4.749, 4.917 and 4.981, respectively. Eventually, in batch studies, the results indicate that natural magnesite with a removal percentage of 73.29%, calcined magnesite of 95.54% and modified magnesite with a removal percentage of 95.34% could be employed as mineral alternatives for removal of dye from wastewater streams.
