Comparison of the Efficiency of Raw and Calcined Powder Marble Waste for the Removal of Acid Orang 7 Dye from Aqueous Solution

Finding a low-cost adsorbent as well as discovering a simple modification technique to increase the efficiency of adsorbent for the removal of environmental pollutants is always important. Therefore, this study aimed to evaluate the effectiveness of the calcination to increase the efficiency of raw marble powder in the removal of Acid Orange 7 dye from aqueous solution.
In this laboratory study, the effects of different parameters including contact time, pH, initial dye concentration, and adsorbent dose on efficiency of dye removal were investigated. SEM, XRD, and FT-IR were used to characterize the Raw Powder Marble Waste (RPMW) and Calcined Powder Marble Waste (CPMW). The experimental data were analyzed using Langmuir and Freundlich isotherm models and kinetic studies. Liner regression and R2 were used to analyze the data.
The highest dye removal efficiency was achieved in pH= 12 for RPMW and pH= 7 for CPMW. With increasing contact time from 5 to 180 minutes, the efficiency of dye removal increased for two adsorbents. The highest amounts of dye removal for RPMW and CPMW within the initial dye concentrations of 5 and 300 mg/L were 53.54% and 94.45%, respectively. By increasing the absorbents dosage, dye removal efficiency increased. The results showed that the dye adsorption using two adsorbents followed the Freundlich isotherm model (R2= 0.99%) and the adsorption kinetics of the dye followed pseudo-second-order model (R2= 0.99%).
Calcination process increased 40-fold in dye adsorption capacity and hence, CPMW could be used as a relatively efficient and low-cost adsorbent in dye removal from aqueous solution.