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.
Highlights
Activated carbon is a term that refers to a family of carbonaceous solid material resulting from biomass, coal, and polymer scrap through thermal or thermochemical processes [1]
E presence of hydrogen bonding and crystallinity in natural cellulose has been reported to contribute to the lower adsorption capacity; its capacity can be improved by modifying its structure using chemicals [28]
E activated carbon (AC) synthesised at 200°C and activated using H2SO4 had a decreased yield as the concentration of the reducing agent was increased. e yield of AC is affected by the temperature at which the carbonation process occurs
Summary
Activated carbon is a term that refers to a family of carbonaceous solid material resulting from biomass, coal, and polymer scrap through thermal or thermochemical processes [1]. E functional groups determine the important characteristics of the activated carbon, such as acidity, hydrophobicity, polarisation intensity, and adsorption properties [6]. Marula is a deciduous tree with a height of 7–18 m and grows well in semi and dry areas in sub-Saharan Africa [10, 11]. E fruits and seed have been used in producing cooking oils, jam, jelly and other tree parts have medicinal properties for treatment of diseases [15]. E extensive use of Marula fruit and seed has resulted in the nutshells (seed husk) often discarded as an agricultural waste material which causes pollution of the environment [15] Marula is a deciduous tree with a height of 7–18 m and grows well in semi and dry areas in sub-Saharan Africa [10, 11]. e tree is most abundant in eastern Africa (Kenya, Tanzania), southern Africa (Angola, Botswana, Namibia, Malawi, Mozambique, South Africa, and Swaziland) [12, 13]. e tree produces about approximately 500 kg of ripe fruits per year which have a gelatinous thick, gluey substance with a sweetly acid taste [14]. e fruits and seed have been used in producing cooking oils, jam, jelly and other tree parts have medicinal properties for treatment of diseases [15]. e extensive use of Marula fruit and seed has resulted in the nutshells (seed husk) often discarded as an agricultural waste material which causes pollution of the environment [15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
