Adsorption behavior of methylene blue on regenerable composite Cu-BTC@AG

The application of metal-organic frameworks (MOFs) Cu-BTC with good adsorption performance in wastewater treatment is limited due to its powder form. The high crystallinity Cu-BTC was compounded with agarose (AG) to obtain a porous foam-like composite Cu-BTC@agarose (Cu-BTC@AG). The Cu-BTC@AG is easy to recycle, the problem of difficult recovery when Cu-BTC is used in water treatment is well solved. In this paper, the influence of contact time, methylene blue (MB) initial concentration, adsorbent dosage, Na + concentration, pH and temperature on the adsorption of MB by Cu-BTC@AG were studied systematically. Results showed that the adsorption amount of MB by Cu-BTC@AG increased with increasing of MB initial concentration, and the adsorption equilibrium was reached in 120 ​min. The solution pH ​= ​7 is favorable for Cu-BTC@AG to adsorb MB. In addition, the adsorption mechanism of MB on Cu-BTC@AG was further explored by isothermal adsorption model and adsorption kinetics model. The adsorption of MB on Cu-BTC@AG was well fitted with Langmuir isotherm and pseudo-second-order model. Maximum adsorption capacities of MB was 282.466 ​mg/g. The adsorption of MB was carried out through formation of a monolayer adsorption onto the homogeneous surface of Cu-BTC@AG. The adsorption behavior of MB on Cu-BTC@AG was analyzed by adsorption thermodynamics. The composite Cu-BTC@AG has a good quality and excellent removal efficiency for the dye methylene blue. The adsorption process is dominated by chemical adsorption. • The composite Cu-BTC@AG is a promising adsorbent for removing of organic dye methylene blue from wastewater. • Porous foam-like composite Cu-BTC@AG is easy to separate from water. • The adsorption process was exothermic.