Adsorption Potential of Contaminants with Activated Carbon Monoliths from Dried Fruit Epicarp of Lecythis minor

Abstract

Lecythis minor is a tree commonly known as Monkey pot tree. Its fruits are composed of urn-shaped epicarps, which are bulky ligneous capsules of slow degradation. Activated carbon monoliths were prepared from this fruit epicarp (bioresidue, the source of lignocellulosic matter) by chemical activation with H3PO4. The activation conditions were optimized using a central composite design, considering parameters of temperature, time, and chemical ratio as variables, and iodine and methylene blue number (IN and MBN), along with yield (Y), as responses. The best conditions for activation were 532°C (T), 1.5 h (t), and 1.5-g H3PO4/1-g raw matter (chemical ratio, CR), with response values of 996 mg I/1-g activated carbon (AC) (IN), 361-mg MB/1-g AC (MBN), and 42% (Y). Likewise, the physicochemical/surface characterization of the activated carbon Lecythis minor (ACLM) allowed establishing that it developed micro- and mesopores (Vmicro=0.72 cm3/g; Vmeso=0.87 cm3/g), as well as ultra-microporosity, a BET surface area of 2,164 m2/g, and a total pore volume of 1.7 cm3/g; also, the removal percentages of the emerging contaminants diclofenac and cephalexin in water were above 96%. It is concluded that fruit epicarp of L. minor is a natural-origin resource to produce AC monoliths, with satisfactory yield, desirable surface development, and high thermal stability, capable of adsorption and removal of pharmaceutical products, and other emergent contaminants from water bodies.