Fabrication of weakly basic-functionalized poly(styrene-co-maleic anhydride) hyper-cross-linked resins for the efficient adsorption of organic acid

Herein, four hyper-cross-linked amide resins (DMDs) were synthesized by suspension polymerization and amination reaction. In the process of suspension polymerization, different feed ratios of divinylbenzene (DVB) and maleic anhydride (MAH) generated macroporous interpenetrating network resins (DMH) with different pore structures. After chemical modification of DMH with N,N'-dimethyl-1,3-propanediamine (DMAPA), the weak base exchange ability of the resulting resins was significantly improved, with values of 1.01 mmol/g (DMD1), 1.15 mmol/g (DMD2), 1.22 mmol/g (DMD3), and 1.34 mmol/g (DMD4), respectively. Salicylic acid (SA), benzoic acid (BA), gallic acid (GA), and phenol (PHE) were selected as adsorbents to investigate the adsorption performance of the resins. At 288 K, the maximum capacity (qmax) of SA, BA, and GA on the DMD4 were 193.7 mg/g, 143.8 mg/g, and 145.2 mg/g, respectively. The adsorption of BA and GA reached equilibrium within 100 min, and the kinetic data could be described using the pseudo second order (PSO) rate model. DMD4 resin had high adaptability for adsorbing salicylic acid in both aqueous and isopropanol solutions. This universal suspension polymerization synthesis method was of great significance for synthesizing other functionalized hyper-cross-linked polymers, and this weak alkaline functionalization strategy was universal for the amination modification of other resins.