Solvent and catalyst free preparation of sulfonic acid functionalized magnetic covalent organic polymer as efficient adsorbent for malachite green removal

A series of –SO 3 H functionalized magnetic covalent organic polymer (M-TpBD-SO 3 H) was synthesized in a few minutes under solvent-free and catalyst-free condition, and their adsorption properties toward organic contaminant were studied by using malachite green (MG) as model. The compositions and microstructures of M-TpBD-SO 3 H are characterized by TEM, XRD, FT-IR and VSM. M-TpBD-SO 3 H with a different content of the –SO 3 H group could be synthesized by adjusting the ratio of benzidine (BD) and 2,2-bissulfonic acid benzidine (BDSA) in the precursor. The results show that with the increase of the BDSA proportion, the adsorption performance of the resulting materials for MG increased. Remarkably, the maximum adsorption capacity for MG was 333.4 mg g ‐ −1 when all the employed building block was BDSA. In addition, the material can selectively adsorb the MG from the mixed solution of MG and MO. Furthermore, the synthesized M-TpBD-SO 3 H (100%) also has good magnetic separation ability and excellent reusability, suggesting that the resulting materials can be used as fantastic candidates for environmental water remediation. • M-TpBD-SO 3 H was synthesized using a solvent and catalyst-free strategy in a few minutes. • The density of –SO 3 H functional groups on the as-prepared M-TpBD-SO 3 H could be easily tuned. • Malachite green in the water can be removed effectively by resulting materials. • The composites possessed great stability and can be recycled more than 5 times.