Adsorption of Methylene Blue from Aqueous Solutions by Silk Cocoon ‎

This study concerns the performance of cocoons spun by silk worms as a natural ‎adsorbent for removal of Methylene Blue (MB) from aqueous solutions. To study the adsorption ‎process, the effect of various parameters such as contact time, adsorbent dosage, dye initial ‎concentration, and pH of the solution were investigated. According to the experiments, the kinetic ‎data were best described by pseudo second order model and the equilibrium data were properly ‎fitted to Langmuir model. The maximum adsorbent capacity at ambient temperature was calculated ‎to be 86.2 mg/g. Thermodynamic analysis showed that the process was spontaneous, endothermic ‎with increased randomness at the solid-liquid interface. It was also observed that by manipulating ‎the pH of the solution in acidic range, the adsorbed dye would desorb into the solution suggesting ‎the reusability of the adsorbent. Macroscopic size of the adsorbent offered an additional advantage ‎of advantage of ease of its separation from ease of separation from the solution.