Removal of Bisphenol A using bio-membranes based on modified cellulose, lignin, and tannic acid

Bisphenol A (BPA), classified as a type of endocrine-disrupting chemical (EDC), is widely used in the production of epoxy resins, plasticizers, polycarbonates, and other chemical products. Since BPA at low concentrations can cause adverse health effects on humans, wastewater containing BPA has to be treated adequately before being discharged into the environment. The development of efficient bio-membranes for the removal of BPA was, therefore, the objective of this study. The optimized methods for the production of a fully bio-renewable membranes were based on reactivity between amino groups of cellulose fibers (Cell), modified in the first step with 3-(carbomethoxy)propionyl chloride (CPC) and diethylenetriamine in the second step (Cell-DETA), with epoxy groups of Cell fibres modified with 3-glycidoxypropyltrimethoxy-silane (Cell-Glymo) and epichlorohydrin (EL) modified lignin. Tannic acid was used as an additional crosslinker. The obtained membranes marked as Cell-El and Cell-El-Ta were used for BPA removal from an aqueous solution. The membranes were characterized by Fourier-Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Influences of operational parameters: pH, contact time, initial concentration, adsorbent dose, and temperature on adsorption and kinetics were studied by conducting batch adsorption tests. The equilibrium adsorption data fitted well with Langmuir isotherm indicated with high obtained correlation coefficient values (R2). The calculated correlation coefficients of 0.995 and 0.996, and adsorption capacities of 204.6 and 197.5 mg g-1 for Bisphenol A (BPA) using Cell-El and Cell-El-Ta, respectively, were obtained from Langmuir model fitting at 25°C. Thermodynamic parameters indicated spontaneous and low endothermic processes. The kinetics of adsorption followed a pseudo-second order rate equation. The low cost and high adsorption capacity provide Cell-El and Cell-El-Ta great potential to be used as excellent adsorbents for BPA removal from wastewaters.