Hydrothermal Cetyltrimethylammonium Bromide Modified Palm Oil Fuel Ash as a Mesostructured Silica-Based Adsorbent for Produced Water Treatment

Vollständiger Abstract

Worum geht es in dieser Arbeit?

This study evaluates the adsorption performance of hydrothermally modified palm oil fuel ash (POFA) for the removal of chemical oxygen demand (COD) and ammonia nitrogen (NH3–N) from produced water, while identifying the dominant equilibrium mechanisms governing pollutant uptake. The novelty of this work lies in the utilization of cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal modification to enhance the mesostructural characteristics, surface functionality and adsorption selectivity of industrial POFA waste for simultaneous organic and nitrogen removal. Modified POFA was synthesized through hydrothermal treatment to improve surface reactivity, pore accessibility, and active site distribution. Adsorption experiments were conducted under varying contact times and adsorbent dosages to determine optimum operational conditions, while adsorption equilibrium behavior was analyzed using isotherm models. The results showed that the optimum contact time was 180 min and the optimum adsorbent dosage was 0.3 g. Under these conditions, COD removal reached 50.16 ± 1.03%, while NH3–N removal achieved 49.66 ± 0.99%. At the optimum contact time, COD and NH3–N removal efficiencies were approximately 53.98% and 38.34%. Isotherm analysis revealed that COD adsorption was best represented by combined Langmuir and Freundlich models (R2 = 0.93), indicating adsorption on a partially heterogeneous surface involving both monolayer and multilayer interactions. In contrast, NH3–N adsorption predominantly followed the Langmuir model (R2 = 0.967). These findings demonstrate that mesostructured and surface-functionalized modified POFA exhibits distinct adsorption selectivity toward organic and nitrogenous pollutants, highlighting its potential as a sustainable adsorbent material for produced water treatment applications.