Low-cost activated carbon preparation from Corn stigmata fibers chemically activated using H3PO4, ZnCl2 and KOH: Study of methylene blue adsorption, stochastic isotherm and fractal kinetic

The aim of this study was to produce a low-cost activated carbon (AC) from an inexpensive precursor material, corn stigmata (CS), by chemical activation at low temperatures using H3PO4, ZnCl2 and KOH. The results were showed that activation with phosphoric acid provides an adsorbent with a larger specific surface area (S-BET) and high pore size. Textural and physicochemical properties of ACs activated with H3PO4 were then studied in different activation temperature. The increase of activation temperature from 200 degrees to 500 degrees C allows the development of many surface functions and the development of a mixture of meso and microporosity, so the S-BET increase from 0.25 to 820 m(2)/g. The physicochemical and textural properties of ACs were analyzed by N-2 adsorption-desorption, FTIR, Boehm's titration, point of zero charge (pH(PZC)), SEM and EDX. The kinetics and isotherm of methylene blue (MB) adsorption were well described by BSf and GBS models indicating the stochastic and fractal adsorption process and a highly heterogeneous AC surface. The maximum adsorption capacity toward MB, 330.5 mg/g, was high compared to many other results found in literature.

Automated summary

This study aimed to produce low-cost activated carbon (AC) from corn stigmata (CS) through chemical activation at low temperatures using H3PO4, ZnCl2, and KOH. The results showed that activation with phosphoric acid resulted in an adsorbent with a larger specific surface area and high pore size. Increasing the activation temperature from 200 to 500 degrees C led to the development of surface functions, a mixture of meso and microporosity, and a significant increase in specific surface area. The physicochemical and textural properties of ACs were analyzed using various techniques, and the adsorption process of methylene blue (MB) was well described by mathematical models. The maximum adsorption capacity for MB was found to be high compared to previous literature.