Production and Characterization of Graphene Oxide for Adsorption Analysis of the Emerging Pollutant Butylparaben

Emerging pollutants such as butylparaben (BP) are often difficult to remove via conventional wastewater treatment. Therefore, this study aimed to produce and characterize graphene oxide (GO) and evaluate the adsorption of BP on this adsorbent. The GO was made using the Hummers method and characterized by TGA/DTA, XRD, XRF, BET, point of zero charge (pHpzc), SEM, and the Boehman method. Adsorption experiments were performed in a batch system. The removal efficiency from a Box–Behnken experimental design was 84.3% at a BP concentration 600 µg∙L−1, adsorbent five g∙L−1, and pH 7 in solution. The first-order (PFO) kinetics obtained the best fit to the experimental data compared to the other models tested in this study: pseudo-second-order (PSO), Elovich (ELC), and intra-particle diffusion (IPD). The Langmuir isotherm provided the best fit compared to the Freundlich isotherm. The temperature effect showed that the system has a spontaneous adsorption process, with a Gibbs energy lower than zero, and that increasing the temperature increases the adsorption capacity. The ionic effect showed that increasing the salt concentration of 1 M increased the repulsive forces but did not decrease the adsorption capacity. The regeneration cycle showed a rate of 85% up to the second cycle. The toxicity analysis confirmed the efficiency of the adsorption process using GO before and after BP adsorption on GO.