Groundnut shell, an agricultural waste was used as a precursor for the preparation of activated charcoal using zinc chloride as a chemical activating agent. The results of the optimization studies showed that the activated charcoal had best iodine adsorption capacity at 1.0 mol dm-3 activator’s concentration, 2:1 impregnation ratio, 70 ℃ impregnation temperature, 12 hr impregnation time, 500 ℃ activation temperature, and 2hr activationtime. The surface chemistry of the adsorbent was studied by Fourier transform infra-red spectroscopy and scanning electron microscopy–energy dispersive X-ray spectroscopy. The activated charcoal was found to contain porous structures with adsorption capacities significantly correlated with iodine value, porosity, and surface area. The surface morphology of the activated charcoal was altered as compared with the un-activated product, signifying that the adsorbent had been chemically modified. The disappearance of some functional groups and shift in some absorption bands were further indication that surface structural modification took place during activation and carbonization.This research has revealed that groundnut shell could be employed for the production of an alternative adsorbent which can be utilize for filtration and detoxification of impure water, treatment of effluent and wastewater, adsorption of pesticides, heavy metals and dyes from aqueous media.

Hamburger seed coat is a readily available agricultural waste product generated in large quantities annually. In this study, activated charcoal was produced using hamburger seed coat activated with zinc chloride and its physicochemical properties such as fixed carbon, specific surface area, volatile matter, ash and moisture content were investigated. Scanning electron microscopy and Fourier transform infrared spectrometry techniques were used to study the surface morphology and variations in the absorption bands of functional groups, respectively. The adsorbent biosorption of pollutants abilities from contaminated water was investigated using standard methods with a view to ascertaining the adsorbent purification potential. The results showed that the adsorbent was of high porous structure with adsorption capacity significantly correlated with iodine value. The physicochemical properties of the contaminated water treated with the adsorbent were comparable with commercial activated charcoal (control)-treated water but indicated a significant decrease ( p < 0.05) in the pH, temperature, total dissolved solids, total suspended solids, conductivity, turbidity, alkalinity, hardness, biochemical oxygen demand, chemical oxygen demand, anions and heavy metal ions when compared to the untreated water. With the exception of alkalinity, other parameters investigated in the water treated with the test adsorbent fell within the standards set for potable water. Results of this study therefore revealed possibility of converting large quantities of hamburger seed coat wastes that could constitute environmental pollution to a profitable product that could be employed for treatment of wastewater. Supplementary Information The online version contains supplementary material available at 10.1007/s13762-021-03577-8.

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This research studied decontamination of laboratory wastewater with an activated carbon derived from maize cob, an agricultural waste to ascertaining its adsorption effectiveness for water treatment. The preparation conditions such as the concentration of the activating agent, impregnation ratio, impregnation temperature, impregnation time, activation temperature and activation time were optimized. The adsorbent’s porous properties revealed its adsorption potency was correlated with the iodine value. The test adsorbent showed significant contaminants adsorption in the laboratory wastewater; the results obtained were within the standards for drinking water set by the regulatory agencies. This agricultural waste could be considered for the preparation of activated carbon which would ultimately serve as an alternative method of decontaminating laboratory wastewater.