Facile synthesis of ZIF-8-lignosulfonate microspheres with ultra-high adsorption capacity for Congo red and tetracycline removal from water

Zeolitic imidazolate frameworks (ZIFs) can be used as adsorbent to efficiently adsorb organic pollutants. However, the hydrophobicity of the ZIFs may be easily to form ZIFs nanoparticles aggregates, hampering the effective and practical application in adsorption. In this study, novel spherical composites of ZIF-8 incorporated with lignosulfonate (LS) were synthesized by in-situ growth method. The effects of different mass ratios of LS and Zn in ZIF-8-LS composites were evaluated with respect to structural characteristics and adsorption properties. As an adsorbent for adsorptive removing Congo Red (CR) and tetracycline (TC) from water, the prepared ZIF-8-LS4 shows the best adsorption capacity of 31.5 mg g−1 and 48 mg g−1, respectively. The spherical structure facilitates the contact between the ZIF-8 and the adsorbed substance, in addition to the H-bonding, electrostatic and π–π stacking interactions also contribute to the improvement of the adsorption performance of the ZIF-8-LS4 composite. The outstanding adsorption capacity and good reusability of the ZIF-8-LS4 composite provide a good prospect for the effective removal of other contaminants from water.