A Comparative Study of Removal Efficiency for Methylene Blue Aqueous Solution Using Coral Limestone Granule and LECA Granule from of Synthetic Wastewater

Dyes are one of the main pollutants in textile wastewater and due to their molecular structures, they are usually toxic, carcinogen and persistent in the environment. Therefore, the aim of present work was to compare the efficiency of LECA and coral limestone to remove Methylene Blue aqueous solution from synthetic wastewater.
This work is a basic-applied study in which, LECA and coral limestone were used as efficient adsorbents for removal of Methylene Blue aqueous solution. The parameters studied included absorbent weight, contact time, dye concentration and solution pH. As well, data acquired from equilibrium constant were evaluated using various isotherm and kinetic models.
The results of the experiments showed that absorption of Dye by both absorptions was increased by increasing the pH, contact time and adsorbent dosage. By increasing the concentration of dye from 50 mg/l to 100 and 150 mg/l, the removal efficiency of organic matter and color has been reduced. The results showed that constant equilibrium data obeyed both isotherm models, With the difference that Langmuir isotherm model showed a higher correlation coefficient in the use of calcareous coral absorber (R2= 1) and higher LECA absorption coefficient (R2= 0.999) in using Frendlich model. Also checking the data showed that kinetics of methylene blue removal is followed by both kinetic models that in this case, the second-order kinetic equation showed a higher correlation coefficient (R2.870).
According to the results, it was determined that coral limestone has higher efficiency than LECA in removal of Methylene Blue aqueous solution. The use of these adsorbents due to rapid sedimentation and lack of effective residual in the wastewater can be easier to use than other adsorbents.