Facile synthesis of water plant Salvinia adnata activated porous carbon for fast and highly efficient dye adsorption

The low-cost and high-efficiency porous activated carbon materials as adsorbents have attracted extensive attention to solving the increasing problems of water pollution. Aquatic plant Salvinia adnata (SA) derived porous carbon is a promising candidate as an adsorbent due to its wide distribution and low cost, and well-developed porous structure with abundant pores after activation. In this paper, a series of porous Salvinia adnata activated carbons (SAACs) were successfully synthesized via a facile two-step method with carbonization and KOH activation varying different activated temperatures and KOH addition ratios. The morphology and structure of the SAACs were characterized using various analytical and spectroscopic techniques. The prepared SAAC-1000–3 (activated temperature is 1000 °C, mass ratio of SA and KOH is 1:3) exhibits a well-developed hierarchical porous structure with a large specific surface area of 2583 m2 g−1 and pore volume of 2.17 cm3 g−1, which facilitates the diffusion and adsorption of dye molecular into SAAC. The batch adsorption experiments were applied to systematically evaluate the adsorption properties for organic dyes with different contact time, initial concentration, temperature, pH, and co-existing ion concentration. The adsorption performance results show that SAAC-1000–3 demonstrates a fast adsorption process for the complete adsorption of methylene blue (MB) and methyl orange (MO) within 3 min, moreover, it also displays a remarkable maximum adsorption capacity of 643.63 mg g−1 at higher MB concentration of 500 mg L−1. Furthermore, an ultrahigh removal efficiency of 99.9% for MB after nine adsorption-desorption cycles indicates the good reusability of SAAC. The Salvinia adnata activated carbon can be as an alternative adsorbent for the fast and high-efficiency treatment of dye-containing wastewater. This work also provides a new idea for waste utilization of water plants.