Activated Carbon from local Sudanese Agricultural waste: Preparation and Characterization

Abstract

Activated carbon was prepared from agricultural waste of three Sudanese plants, mesquite trees (ACM), corn maize seeds (ACC1) for chemical activation and (ACC) for physical activation and Doum fruit(ACD). Three samples were chemically activated and only one was physically activated. Proximate analysis of the activated carbon including determination of the concentration of inorganic elements through XRF technique, determination of functional groups on activated carbon samples by (FT-IR) technique, Crystalline structure of minerals on activated carbon prepared from a sample by (XRD)technique and adsorption kinetic were studied. I The result showed that the carbon percentage of mesquite tree and doum fruit were 40.65% and 35.13% respectively. The carbon content of corn maize prepared by physical and chemical activation was (44.26%) and (49.42%) respectively. Ash content of samples were 3.90, 4.20 and 4.90% for ACM, ACCI, and ACD respectively low ash content was reported for ACC sample (3.60%) ’ - Results showed that the total iodine number of ACM and ACD were (13.22 mg I2/g and 15.42 mg I2/g), whereas for ACC and ACC1were 16.06, 13.0 mg I2 / g respectively. The number and type of porous in activated carbon in all the samples was measured using methylene blue test. ACD sample had methylene blue value of (200 mg/gm) compared to 166.6 and 190.6 for ACM and ACCl samples respectively. On the other hand ACC had a methylene blue value of (150.9 mg/gm). Porosity of the samples were in range between 54-60%, ACC have a porosity percentage of 52.20%.

Fourier- Transform Infrared Spectroscopy was used to determine the functional groups of all samples. The result showed a strong and broad adsorption peak at 1577.66 cm'1, which corresponds to the lactone in ACD samples, Conjugate carbonyl was observed at 1595.20 cm'1 for the same sample. The main functional groups in ACC were quinone, carboxyl and aromatic C-H, phenol lactone, C-O and aliphatic CH2 were found in samples ACM and ACC1. Concentration of inorganic element/s presents in the material play an important role during the adsorption process. Therefore the measurement of elements is required. XRF results showed that the major elements in ACD sample are potassium (1.04%), calcium (1.25%) and zinc(5.26%) while for ACM sample have the concentration of potassium ,calcium and iron were (0.30l%),(0.3 57%) and (0.687%) respectively . Comparative analysis between physical and chemical activated form of corn maize sample showed significant difference between ACC and ACC1 samples. The concentration of calciurn, strontium were (4.34%) , (3.66%), (0.023%) and (0.0075%) respectively. XRD analysis showed the presence of a highly organized crystalline structure of raw activated carbon for ACD sample. Carbon with crystalline structure rhombohedral and carbon supplied with crystalline structure orthorhombic were detected. ACM yield highly organized crystalline structure such as orthorhombic, cubic and monoclinic, while ACC sample had more crystalline structure of rhombohedral , orthorhombic and cubic than that detected for ACC1 sample which had one crystalline structure of monoclinic for potassium carbonate (K2CO3).