Recovery of ferulic acid from nixtamalization wastewater by adsorption on MIL-88D(Fe)-MOF.

Ferulic acid (FA) is a high-value phenolic compound present in nixtamalization wastewater (nejayote), whose recovery could contribute to the valorization of this agro-industrial effluent. In this work, a microwave-synthesized flexible iron-based metal-organic framework, MIL-88D(Fe), was evaluated for FA adsorption and recovery from model solutions and real nejayote. Nonlinear kinetic analysis showed that the Elovich model provided the best statistical description of FA uptake, closely followed by the pseudo-second-order model, while the Freundlich isotherm best described the adsorption data at 311 K. The highest experimentally measured adsorption capacity was 30.36 mg g-1 at 311 K, and FA removal reached 91.62% at pH 3.3 in model solutions. In real nejayote, MIL-88D(Fe) removed 90.34% of FA and enabled an overall FA recovery of 74.19% after alkaline desorption. Reusability tests showed removal efficiencies of 87.19-75.19% over five consecutive adsorption-desorption cycles, corresponding to retention of 86.24% of the first-cycle performance. XRD and SEM analyses after regeneration confirmed preservation of crystallinity and rod-like morphology. These results demonstrate that MIL-88D(Fe) combines effective FA capture, recoverability, and recyclability, supporting its potential as a reusable adsorbent for recovery-oriented treatment and valorization of nixtamalization wastewater.