Efficient removal of sulfonamide and tetracycline antibiotics using triazine-based porous organic polymers

Abstract

• Triazine porous organic polymer shows high removal efficiencies for three sulfonamides and tetracycline. • A sequential batch adsorption methodology can improve the removal of tetracycline. • T-POP can be reused for antibiotic adsorption after five cycles without loss of properties. • Hydrophobic interactions play a relevant role on the adsorption mechanism between T-POP and antibiotics. This study reports the application of a triazine-based porous organic polymer containing amine groups (T-POP) as an efficient adsorbent for the removal of sulfonamides (e.g., sulfamethazine (SMT)) and tetracycline (TC) from aqueous solutions. These antibiotics are emerging, persistent, and potentially toxic pollutants, contributing to the worrying increase in antimicrobial resistance. The impact of different parameters on the adsorptive performance was evaluated. T-POP, having a high surface area (239.6 m 2 g −1 ), mesopores (14.2 nm) and high physicochemical stability, exhibited high adsorption capacities and efficiencies. T-POP performance was better for SMT than for TC (maximum adsorption capacities of 0.40 mmol g −1 and 0.153 mmol g −1 , and removal efficiencies up to 88% and 76%, respectively). Additionally, the polymer proved to have good reusability over 5 cycles. Molecular dynamics simulations provided crucial insights on the molecular details that govern the systems’ behaviour and allowed to rationalise the main experimental results. In this sense, surfactants with different alkyl chain lengths and charges were used to assess the role of the hydrophobic effect on the adsorbent–adsorbate interactions. It was demonstrated that the interactions between the carbon chain of surfactants and T-POP were more significant for the longest surfactant studied (hexadecyltrimethylammonium bromide). Interestingly, advanced models were used to analyse the adsorption data at molecular scale. Overall, this paper provides a new vision of the adsorption mechanism via different advanced approaches.