# Study of the Ciprofloxacinacin Adsorption of Activated Carbon Prepared from Mangosteen Peel
## 1 Introduction  
Ciprofloxacin (CIP) is a fluoroquinolone antibiotic which has been widely employed in the treatment of infections in humans and animals in recent decades. Chemically, CIP is a 1-cyclopropyl 6-fluoro-4-oxo-7-piperazine-1-yl-quinolone-3-carboxylic acid, which has an extended aromatic region and functional groups suitable for hydrogen binding. CIP can possibly enter an aqueous environment via either the incomplete metabolism of the body or wastewater from drug manufacturers [1]. The concentrations of CIP can be detected in wastewater and surface water at concentrations of one-hundred ng/L to ug/L [2]. The presence of CIP in wastewater and surface waters, even at trace concentrations, can still have negative effects on environmental ecology and human health [3].  
Thus, various chemical reagents and physical and chemical methods have been developed to remove CIP from wastewater, such as adsorption [4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16], photocatalysis [17; 18; 19; 20; 21], internal electrolysis [22], ozonation, oxidation [2], flocculation [23], and microbial treatment [24]. Among these methods, adsorption has been proven to be an effective approach because of its ease of operation, low cost, and high efficiency.  
Activated carbon is an adsorbent commonly used in practical applications due to its well-developed pore size, the reactivity of its surface functional groups, and its large surface area, which provides more binding sites for adsorption [25]. Currently, the researchdirection for manufacturing activated carbon from agricultural by-products is of great interest to many scientists because of the available, abundant, and cost-effective raw materials. Mangosteen, scientifically known as _Garcinia mangostana_ L., is a plant belongs to the _Clusiacae_ family. Mangosteen is primarily grown in Southeast Asia, Sri Lanka, and India. In addition, this fruit also appears in some tropical South American countries, for example, Colombia and Puerto Rico. Vietnam is also has probable land for cultivating mangosteen. However, mangosteen only grows well in the South Central, Southeast, and Southwest regions of Asia. Particularly, the Southwest region (the Mekong River Delta) has the largest growing area of mangosteen, approximately 4.9 thousand hectares, with an output of approximately 4.5 thousand tons. Mangosteen peel is the discarded part of mangosteen fruit, containing lignin and hemicellulose compounds, which are primary materials for fabricating activated carbon. Therefore, activated carbon derived from mangosteen peel (ACMP) has been synthesized and applied as a material to treat aqueous environments contaminated with metal ions and dyes by many scientists [26, 27, 28, 29, 30, 31, 32, 33, 34, 35]; nonetheless, no studies in the literature have ever reported CIP adsorption via mangosteen peel derived activated carbon.  
When making activated carbon from mangosteen peel, the authors used chemical agents such as K\({}_{2}\)CO\({}_{3}\)[30], KOH [31], H\({}_{3}\)PO\({}_{4}\) and KOH [34], and H\({}_{3}\)PO\({}_{4}\)[35] combined with physical agents such as temperature (500-900 \({}^{\circ}\)C [30, 31, 34, 35]) and CO\({}_{2}\)[29].  
Up to now, no author has studied CIP adsorption on activated carbon materials derived from mangosteen peel. According to previous research papers, the adsorption of CIP on biological activated carbon materials is usually physical adsorption, and the adsorption process is endothermic [7]. No author has studied the [PERSON] isotherm adsorption model and calculated the activation energy of CIP adsorption on biological activated carbon [7].  
Therefore, in this work, we introduce a method to make activated carbon from mangosteen peel through thermal activation at 500 \({}^{\circ}\)C for 2 h, followed by chemicall activated by ZnCl\({}_{2}\). We studied the adsorption isotherm models of [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON], as well as the kinetics, chemical thermodynamics, and activation energy of CIP adsorption processes using the as-fabricated activated carbon.