Unlocking the Potential of N,N,N′,N′-Tetraphenylbenzidine Based on Conjugated Microporous Polymers for Rhodamine B Adsorption: A Synergistic Experimental and Density Functional Theory Perspective

This study presents the synthesis and construction of two innovative conjugated microporous polymers (CMPs), TPBZ-PyT CMP and TPBZ-TPET CMP, which incorporate pyrene (Py) and tetraphenylethene (TPE) subunits, respectively. These subunits are selected for their complementary properties, with the TPE moiety offering enhanced flexibility compared to the more rigid Py structure. The flexibility of TPE is hypothesized to improve the adsorption performance of the CMPs for removing rhodamine B (RhB) dye from aqueous solutions. The TPBZ CMPs were characterized using a suite of techniques, including Brunauer–Emmett–Teller (BET) surface area analysis, SEM, and FTIR. Batch adsorption experiments demonstrated that TPBZ-TPET CMP achieved a remarkable RhB removal efficiency of 49.49% within the first 30 min, reaching 98.72% after 60 min. In comparison, TPBZ-PyT CMP attained a maximum removal efficiency of 53.49% at the 60 min mark. Kinetic studies revealed distinct adsorption mechanisms for the two TPBZ CMPs. The adsorption process for TPBZ-TPET CMP was analyzed using a pseudo-second-order model, showing that chemisorption is the dominant mechanism. Meanwhile, TPBZ-PyT CMP exhibited pseudo-first-order kinetics, suggesting a different rate-limiting step. These findings highlight the critical role of subunit flexibility in designing CMPs for enhanced adsorption performance. The superior efficiency of TPBZ-TPET CMP underscores the potential of flexibility-engineered CMPs in advancing water purification technologies and addressing dye contamination in aquatic environments.