Arabian Journal for Science and Engineering https://doi.org/10.1007/s13369-018-3682-4 RESEARCH ARTICLE - CHEMISTRY Silver Nanoparticle-Loaded Activated Carbon as an Adsorbent for the Removal of Mercury from Arabian Gas-Condensate Salawu Omobayo Adio 1 · Azeem Rana 1 · Basheer Chanabsha 1 · Abdulmalik Adil Khalid BoAli 1 · Mohammad Essa 2 · Abdulaziz Alsaadi 1 Received: 2 August 2018 / Accepted: 10 December 2018 © King Fahd University of Petroleum & Minerals 2018 Abstract For the first time, an efficient method for the removal of mercury from Arabian gas-condensate samples was reported. Silver nanoparticles (AgNPs) functionalized with activated carbon (AC) prepared from local date-pits were used as an adsorbent. The physical and chemical properties of AgNP-AC were characterized using surface characterization techniques, and the adsorbent was evaluated under different experimental conditions. These factors considered include AgNP concentrations, contact time, the adsorbent dosage of AgNP-AC and initial mercury concentration. Langmuir adsorption isotherm, pseudo-second-order kinetics and Weber intraparticle diffusion models were used to evaluate the adsorption properties of the AgNP-AC. The results obtained revealed that at a low contact time, 25 mM AgNPs functionalized on AC provided the highest adsorption efficiency (98%) in the removal of mercury from Arabian gas-condensate. Also, it was observed that the increase in AgNP-AC dosage and initial mercury concentration plays a significant role in the mercury removal process. With a correlation coefficient of 0.9987, the adsorption process fits the Langmuir isotherm, suggesting that the adsorption is homogenous and monolayer. Keywords Activated carbon · Date-pits · Silver nanoparticles · Arabian gas-condensate · Mercury removal 1 Introduction Mercury is widely distributed in air, water bodies and land and can be found in different forms either as elemental, inorganic or organic mercury [1]. Irrespective of its form, mercury is a hazardous element that is listed as a priority pol- lutant by the United States Environmental Protection Agency (US-EPA). Unlike many other heavy metals, mercury is naturally present in crude gas-condensate at variable concen- trations [2,3]. The presence of mercury in crude oil during petroleum refining processes often results in the degradation of gas-condensate processing plants and catalyst poisoning and may pose health and safety risks to plant workers [4]. The quantity of mercury in petroleum is mainly dependent on the geologic location of its source. The concentration of mercury in petroleum fuel varies between 0.01 μg/L and 10 B Azeem Rana azeemakbar@kfupm.edu.sa 1 Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia 2 Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia mg/L [4]. When hydrocarbons are burnt to produce energy for industrial activities or in vehicles, the exhaust gases pro- duce mercury compounds that enter the environment [5,6]. According to the United States Environmental Protection Agency, the burning of fossil fuel is the primary human- made source of mercury pollution in the environment [7]. To decrease health hazards and industrial problems, more efficient methods are needed to remove mercury at low con- centrations. More detailed studies on mercury contamination and removal from aqueous matrices have been reported in the literature [8–11]. However, research on the removal of mer- cury from petroleum products is scarce. Activated carbon (AC) has been extensively applied as an adsorbent for removal of contaminants from water samples because of high porosity and large surface area [12,13]. It is produced from carbon source materials with carbon contents ranging from 45 to 55% [14]. In recent years, different lit- erature has been published explaining the production of AC using inexpensive organic matrices [15]. Some of the mate- rials that have been used include coconut shells, grape stalk, almond shells, birch, olive stones, pecan shells, rice husk and cassava peel [14,16]. The physical and chemical char- acteristics of the raw material and the activation procedure 123