Functional biobased resin from a blend of tannin and crude black liquor and its application as an adsorbent for dexamethasone and indomethacin removal

A novel route is proposed to synthesize a functional biobased resin and its carbonized counterpart by sol-gel polymerization of a blend of tannin and crude Kraft black liquor. The potential of the synthesized biomaterial as adsorbents for dexamethasone and indomethacin removal from contaminated water was also evaluated. The characterization points out the great variety of surface functional groups, promoting different adsorbent-adsorbate interfacial interactions. As a result, the diversified functional groups favor the adsorption by electrostatic interactions, hydrogen bonds, and pi-pi interactions. Moreover, the thermal treatment decreased the functionality and oxygenated groups of the carbonized counterpart, increasing the hydrophobic interactions. It also increased the specific area of the material (2-98 m(2) g(-1)) and the average pore size diameter (1.6-4.2 nm). Consequently, the carbonized counterpart exhibits superior adsorption of the model pollutants. The adsorption of dexamethasone occurred in multilayers, whose maximum adsorption capacity obtained experimentally were 11.38 mg g(-1) and 22.22 mg g(-1) for resin and the carbonized resin. Furthermore, the study concerning the adsorption of indomethacin showed that the indomethacin concentration must be controlled to optimize the adsorption process and avoid precipitation. Finally, the equilibrium studies disclosed an atypical isothermal profile, which is hardly found in the literature. Therefore, the ability to remediate the pollutants demonstrates this novel material potential for future application in water remediation technologies.