Efficient Adsorption of Methylene Blue in Aqueous Solution by Acid‐modified Sodium Alginate

Abstract The acid‐modified sodium alginate (AMSA) was synthesized utilizing a simple acidification method and its synthesis was confirmed by acid‐base titration method, SEM, XRD, FTIR, TGA and BET. The sodium alginate after acidification, with a large number of carboxyl groups introduced, was favorable to the adsorption of methylene blue (MB) from water. The maximum adsorption capacity calculated by Langmuir model was up to 1593 mg/g, which was significantly higher than the adsorption capacity of other adsorbents reported. The adsorption rate of MB by AMSA was very fast. After the addition of adsorbent, the adsorption removal rate reached 79 % in 30 min, and the adsorption was balanced in 120 min (94 % of MB was removed). Furthermore, electrostatic interaction and hydrogen bonding, pore‐filling and chemisorption were considered as the main adsorption mechanisms. AMSA is expected to be an optimal candidate for efficient and rapid removal of MB due to its simple synthesis, abundant sources, easy separation and no secondary pollution.