Application of NaOH modified rice husk as a potential sorbent for removal of Congo red from an aqueous solution
Muhammad Imran Khan, Abdallah Shanableh, Noureddine Elboughdiri, Suryyia Manzoor, Sidra Mubeen, Aziz ur Rehman
Abstract
ABSTRACT Due to the prevailing treacherous impacts of dyes on aquatic as well as terrestrial ecosystems, the designing of cost effective and facile removal methods are utmost need of time. The current research encompasses the study of modified rice husk (MRH) as an efficient adsorbent for the abatement of Congo red (CR), an anionic dye from an aqueous solution. Fourier transform infrared (FTIR) confirmed adsorption of CR onto MRH. Morphology of rice husk before and after modification was investigated by using scanning electron microscopy (SEM). Moreover, a prominent increase in surface area and porosity occurred through chemical treatment of rice husk. The effect of various factors including contact time, mass of MRH (dosage), initial concentration of CR in an aqueous solution, temperature and pH on CR adsorption was explored. Adsorption of CR was studied by using several isotherm models including Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R). Results showed that CR adsorption onto MRH fitted well to Freundlich isotherm. Adsorption kinetics for CR adsorption was revealed by applying many models such as pseudo-first-order, pseudo- second-order, Elovich model, modified Freundlich equation, and Bangham equation. Obtained results showed that CR adsorption from an aqueous solution onto MRH obeyed pseudo-second- order model. Adsorption thermodynamics result showed that CR adsorption onto MRH was exothermic process (ΔH° = –4.75 kJ/mol). The maximum adsorption capacity of 10.13 mg/g was found.