Synthesis and Characterisation of Activated Carbon Obtained from Marula (Sclerocarya birrea) Nutshell

Abstract

Globally, a ninth of people use polluted water sources because an estimated 300–400 Mt of waste and 90% of sewage are discharged into water bodies from industries and developing countries, respectively. The utilisation of indigenous fruit pits in producing novel adsorbents will greatly benefit in wastewater treatment. In most underdeveloped countries, activated carbon (AC) is imported at a high cost. The study was aimed at synthesising and characterisation of AC obtained from Marula nutshell. Carbonization of organic matter from Marula nutshell was carried out at 200°C, 400°C, 500°C, and 600°C. Sulphuric (H2SO4) and phosphoric (H3PO4) acids were used as activating agents at concentrations of 20–60% ( v / v ). Physicochemical characteristics of the AC, such as bulk density, moisture, ash, pH, and iodine number, were analyzed using standard methods. Functional groups and total carbon content were determined using the FTIR spectroscopy and Nitrogen Carbon Sulphur (NCS) analyzer, respectively. The values of carbon yield and total carbon in activated samples with H2SO4 and H3PO4 were 32.2–93.2%, 26.9–95.8%, and 46–79%, 20.8–69.8%, respectively. The pH, ash, moisture, and bulk density of activated high carbon samples with H2SO4 ranged from 2.4–6.1, 0.65–3.49%, 1.3–8.4%, and 0.42–0.62 gcm−3, respectively. Activated high carbon samples with H3PO4 had 2.7–3.2, 11.3–29.8%, 4.7–14.6%, and 0.39–0.54 gcm−3 pH, ash, moisture, and bulk density, respectively. The synthesised AC samples with 40% H3PO4 at 500°C had the highest iodine value of 1075.7 mg/g. FTIR results showed the presence of aliphatic carboxylic acid salt, inorganic nitrate (NO3−), and phosphate groups in the synthesised AC and were not significantly different ( p < 0.05 ) from commercial AC. The untreated Marula nutshell had some aliphatic hydrocarbon (alkanes), inorganic phosphate ( PO 4 3 − ), aliphatic ester (–COO), and aliphatic carboxylic acid salt (–C(=O)O–) groups. A novel adsorbent, AC was produced from Marula nutshell with the potential to be used in water treatment.

Synthesis and Characterization of Activated Carbons Prepared from Agro-Wastes by Chemical Activation

“…The precursors used to prepare commercial activated carbons are highly costly and nonrenewable such as petroleum residues, lignite, wood, coal, and peat [1]. On the other hand, low-cost activated carbon is reported to have been successfully prepared from agricultural byproducts, for instance, Marula nutshell [10], grains, corn cobs, almond shells [11], and bamboo [10,11].…”

The Application of the Activated Carbon from Cordia africana Leaves for Adsorption of Chromium (III) from an Aqueous Solution

“…1483 cm −1 , 1417 cm −1 , and 1405 cm −1 wavelengths correspond to C=C ring stretching. In 1046 cm −1 , 1022 cm −1 , and 1040 cm −1 wavelengths, there is C-O stretch vibration [36]. Te peaks observed at 855 cm −1 , 879 cm −1 , and 873 cm −1 correspond to C-H bending vibration [37].…”

Synthesis of Sulfonated Polystyrene-Based Porous Activated Carbon for Organic Dyes Removal from Aqueous Solutions

“…The dried product was grinded well for fine powder using an agate mortar. The carbonization process was conducted at high temperature for 4 h under N2 atmosphere adopting phosphoric acid as an activated agent as reported previously [40]. Typically, 10 g of dried powder was impregnated into 100 mL of 18.9% phosphoric acid solution .The suspension is then stirred at 100 rpm for 2 h and it left to soak for a week at ambient conditions.…”