PREPARATION OF CALCIUM ALGINATE HYDROGEL AS ADSORBENT FOR METHYLENE BLUE DYE

• Main Author: Sandy Pangestu, Christian
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/65375
• Institution: Institut Teknologi Bandung

Methylene blue is a synthetic dye derived from cationic phenothiazines. Disposal of toxic methylene blue in high concentrations into the aquatic environment can cause a decrease in water quality and cause disease in living things. Adsorption is a method of removing methylene blue dye which has several advantages, such as cost effectiveness, simplicity of design, ease of use, reusability, and good adsorptive properties. Alginate is an alternative biosorbent to remove dyes in wastewater because it is simple to manufacture, environmentally friendly and easily biodegradable in the environment. The purpose of this research was to determine the variation of alginate composition to CaCl2 solution to make calcium alginate hydrogel, as well as to study its characteristics and stability as an adsorbent of methylene blue. The hydrogel beads that have been made are immersed in a solution of acid, base and aqua dm for a certain period of time, and their diameter is measured using a digital microscope. Calcium alginate hydrogels have been successfully prepared by cross-linking alginate with Ca2+ ions. The size of the resulting hydrogel grain diameter is in the range of 3.4 to 3.8 mm. The hydrogel beads made from the 2% (w/v) variation of alginate were larger than the hydrogel beads made from the 1% (w/v) alginate variation. The Ca2+ 4% (w/v) crosslinker solution gave smaller grain size results than the 2% (w/v) Ca2+ crosslinker solution. Calcium alginate hydrogel showed the phenomenon of size shrinkage in acidic solution, size swelling in alkaline solution, as well as in aqua dm calcium alginate hydrogel did not show a significant change in grain size. The results of the adsorption performance of methylene blue using calcium alginate hydrogel showed that the optimum conditions for adsorption of methylene blue using 1.0 gram of 4% (w/v) calcium – 2% (w/v) alginate hydrogel were reached at pH 4 and a contact time of 240 minutes. The adsorption of methylene blue with the resulting adsorbent followed the pseudo-second-order kinetics model and the Freundlich adsorption isotherm model.