PEI-grafted boron-selective adsorbent with synergistic adsorption effects

This work presents a novel strategy for the development of boron-selective adsorbent with synergistic adsorption effects, which is achieved by using tannic acid (TA) modified MoS 2 nanosheets to graft polyethyleneimine (PEI) onto the boron-selective resin (BSR), preparing the BSR-MoS 2 -TA/PEI composite material, and leveraging the unique interlayer structure of molybdenum disulfide (MoS 2 ) nanosheets to reduce the resistance of H 2 O transport, thereby effectively exerting the synergistic adsorption effects of BSR and PEI. The influencing factors of boron adsorption by BSR-MoS 2 -TA/PEI, such as the PEI grafting amount, adsorbent dosage, pH value, and competitive anions, were investigated. The results revealed a maximum adsorption capacity of 31.10 mg·g −1 at 35°C, which is significantly higher than that of the commercial BSR (5.9–7.2 mg·g −1 ). The fitting results of adsorption kinetics, isotherms, and thermodynamics demonstrated the characteristics of boron adsorption by BSR-MoS 2 -TA/PEI, and the adsorption process conformed to the pseudo-second-order kinetic model and the Langmuir model. Owing to the outstanding stability of the BSR substrate, BSR-MoS 2 -TA/PEI could undergo at least five cycles of adsorption. The mechanism of boron adsorption mainly encompassed complexation, electrostatic attraction, and hydrogen bond formation.