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.

Automated summary

In this study, a porous foam-like composite Cu-BTC@agarose (Cu-BTC@AG) was prepared by compounding high crystallinity Cu-BTC with agarose to solve the problem of difficult recovery when Cu-BTC is used in water treatment. The adsorption behavior of Cu-BTC@AG towards methylene blue (MB) in wastewater was systematically studied, and the adsorption mechanism was explored using isothermal adsorption and adsorption kinetics models. The results showed that the adsorption capacity of Cu-BTC@AG for MB increased with increasing MB initial concentration and reached equilibrium within 120 minutes.