Synthesis and Characterization of Activated Carbon from Dabai (Canarium odontophyllum) Nutshell for Removal of Water Pollutants

AHMAD ADZHAR, MOHD KHAIRULZAIM (2024) Synthesis and Characterization of Activated Carbon from Dabai (Canarium odontophyllum) Nutshell for Removal of Water Pollutants. Masters thesis, Faculty of Engineering, UNIMAS.

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Abstract

This research is conducted to explore the potential of utilizing dabai nutshell as the precursor for the purpose of synthesizing biochar and activated carbon (AC) for the purpose of removing water pollutants. Dabai nutshell is commonly thrown away as waste instead of being utilized for industrial purpose. Previous studies on chemical activation of the biomass do not meet the required properties of the AC, and do not include the optimization of carbonization temperature. The potential of the AC from dabai nutshell for removal of heavy metal ions are not explored in prior studies. Inert gases and complex equipment set up to provide oxygen-less atmosphere for the synthesis of AC are not available in rural areas, thus further studies are required to determine the alternatives for the inert gas. This research aimed to synthesise the AC from Dabai nutshell using chemical activation and carbonization (both processes are without inert gas flow) and characterize it using several analytical techniques. This work also studies on the effect of different chemical activating agents with different concentration on the synthesis of AC, to optimize the carbonization temperature and to apply the AC on removal of selected water pollutants. The dabai nutshell underwent physical treatment to clean, dry and reduce its size down to 1 mm. The biomass then carbonized under different atmosphere, and at different temperature, in order to perform optimization study for the process’s temperature. The resulting biochar is then activated using sodium hydroxide (NaOH), potassium chloride (KCl) or hydrochloric acid (HCl). The synthesized AC were then characterize using several analytical methods and applied on removal of dye methylene blue and heavy metal ions (zinc, chromium, and lead). The results showed that the biochar is dominated by carbon and oxygen, and the percentage yield and ash content of the biochar are more than 26% and less than 4.00%, respectively. The nitrogen adsorption isotherm of the biochar is similar to Type I of IUPAC classification, and biochar is observed to have the surface area more than 370 m2/g. The optimization of the carbonization temperature on synthesizing biochar that met the set criteria concluded that 721.469 °C is the optimum temperature. The biochar derived without inert gas flow during carbonization have comparable properties with the biochar derived under nitrogen and argon gas flow. AC derived through chemical activation using NaOH have comparable BET surface properties with commercial AC, with micropores properties, BET surface area of more than 328 m2/g, and total pore volume of more than 0.194 m3/g. The nitrogen adsorption isotherms are similar to Type II isotherm of the IUPAC categorization across all replicates. AC replicates derived through HCl and KCl activation are dominated with carbon and oxygen and have ash content less than 3%. All AC replicates however are having low MB adsorption uptake, lower than the standard (60-120 mg/g), and the kinetic study of MB adsorption reveals that the most suited model to describe the MB adsorption on the AC replicates are pseudo-second-order model and Elovich kinetic model. All AC replicates have more than 35% removal of heavy metal ions with initial concentration of 30 ppm. These findings conclude that dabai nutshell are suitable to be utilized as precursor for AC, with carbonization and chemical activation are performed on the precursor without the use of inert gas flow. The resulting AC also performed excellent adsorption to reduce the concentration of heavy metal ions.

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