Fixed-bed adsorption of methylene blue by rice husk ash and rice husk/CoFe2O4 nanocomposite

AbstractRice husk ash (RHA) is a promising low-cost adsorbent. Meanwhile, the magnetic and catalytic capabilities of ferrite nanoparticles make it efficient for water purification. In this study, we prepared RHA and rice husk/CoFe2O4 composite (RHC) and studied their methylene blue (MB) adsorption capacities in fixed-bed columns. The column regeneration was also investigated. Both RHA and RHC are amorphous materials with Brunauer, Emmet and Teller (BET) surface area of >180 m2 g−1 and mesopore volume of >0.1 cm3 g−1. The CoFe2O4 nanoparticles are mainly located on the inner surface of RHC, which significantly increased the mesopore volume and average pore size but decreased the BET surface area and micropore volume. The adsorption ability of RHC was investigated in a fixed-bed column, with RHA as control. The effects of column parameters including bed height, flow rate, and inlet MB concentration on breakthrough curves were studied. The mathematical models, such as bed-depth service time (BDST), Thomas, a...