Environment and Ecology Research 11(2): 340-361, 2023 http://www.hrpub.org DOI: 10.13189/eer.2023.110209 Removal of Lead Ions from Aqueous Media Using Rice Husk Modified with Manganese Oxide Ta Thi Huong * , Tran Y Doan Trang Haui Institute of Technology, Hanoi University of Industry, Vietnam Received November 26, 2022; Revised March 8, 2023; Accepted April 7, 2023 Cite This Paper in the Following Citation Styles (a): [1] Ta Thi Huong, Tran Y Doan Trang , "Removal of Lead Ions from Aqueous Media Using Rice Husk Modified with Manganese Oxide," Environment and Ecology Research, Vol. 11, No. 2, pp. 340 - 361, 2023. DOI: 10.13189/eer.2023.110209. (b): Ta Thi Huong, Tran Y Doan Trang (2023). Removal of Lead Ions from Aqueous Media Using Rice Husk Modified with Manganese Oxide. Environment and Ecology Research, 11(2), 340 - 361. DOI: 10.13189/eer.2023.110209. Copyright©2023 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract The creation of effective adsorbents from agricultural waste to remove heavy metals such as toxic lead ions has been widely used. The goal of this research is to remove lead from water using rice husk-manganese oxide (RH-Mn). The raw rice husk was processed in three stages: (1) treatment with hydrochloric acid (HCl) 1M and sodium hydroxide (NaOH) 1M; (2) keep treating the material at the first stage in an ultrasonic water bath with a solution of 50 mL distilled water and 5 mL ethanol (90°C) plus 1,5g potassium permanganate (KMnO 4 ); (3) Continuously adding few drops of 10% hydro peroxide (H 2 O 2 ) to the solution and stirring until the precipitation solid turns brown or black. The material was filtered and dried for 6 hours at 80 0 C. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) were used to determine MnO 2 and observe the differences between the raw rice husk and modified rice husk. Besides, batch adsorption tests were carried out to investigate the influence of time, pH, and adsorbent dose on the adsorption removal process. Particularly, several outstanding performances in the research are: (1) Based on the statistically experimental design and response surface method (RSM) were applied to improve the adsorption system; (2) Pseudo-second-order kinetics and Freundlich isotherm models were shown to be effective in explaining lead adsorption on RH-Mn; (3) The modified adsorbent took four hours to reach the adsorption equilibrium. Over 99% of lead ions were eliminated from water under ideal conditions if the pH of the water was 4, the initial concentration was 15 mg/L, the contact period was 3 hours, and the RH-Mn dose was 1.5 g/L. This research can aid in the development of novel bioengineered low-cost adsorbents. Keywords Lead Ions, Rice Husk, Manganese Oxide, Adsorption, Response Surface Methodology 1. Introduction Due to its exceptional qualities, including superior softness, ductility, insulation, and corrosion resistance, lead ion (Pb(II)) is widely utilized in various sectors, including paint, electrical equipment, welding, batteries, electrical insulating materials, vehicles, automobiles, fuel, cosmetics, ceramics, etc. [1, 2]. However, this metal is also widely recognized for being extremely poisonous, and both natural and human activities may cause it to enter the air, water, and soil directly or indirectly [3, 4]. As per human health effects, many Pb(II) exposure symptoms were widely recognized such as anemia, renal failure, cardiovascular damage, hematological, nervous system damage, and even death can result from lead poisoning [5-7]. Since, it is important to get rid of lead contamination, especially marine lead pollution. Current methods for removing Pb(II) include physical-chemical, chemical precipitation, coagulation and flocculation, ion exchange, reserve osmosis, electrochemical treatments, membrane filtration, evaporation, flotation, oxidation, and bio-sorption procedures [8–11]. However, most of these methods have some disadvantages in that they may be