This study investigated a new area of improving the adsorption capacity of clay using corn cob as an alternative means of clay modification to the more expensive and complicated chemical treatment techniques. Kaolinite Clay (KC), Calcined corncob-kaolinite Combo (CCKC), and Corncob (CC) adsorbents were utilized. The adsorbents were characterized by Fourier Transform-Infrared (FT-IR) Spectroscopy, Scanning Electron Microscopy (SEM), X-ray fluorescence spectroscopy, and Brunauer-Emmett-Teller (BET) surface area analyzer. Batch adsorption methodology was used to investigate the effect of pH, initial metal concentration, adsorbent dose, and contact time on adsorption of Pb (II) and Cd (II). A slight increase in BET surface area of 29.31 m2/g for CCKC from 14.12 m2/g for raw KC was achieved. The trend of metal adsorption on the adsorbents was in the order CC>CCKC>KC. The Langmuir isotherm was found to present the best fit for the unmodified adsorbents while the Freundlich was applicable for CCKC indicating multilayer heterogeneous surface. The pseudo second order kinetic model was found to be suitable in the kinetic analysis. Thermodynamic studies revealed a spontaneous physical adsorption process of metal ions on CCKC. The combo adsorbent showed highest percentage desorption (>70%) of Cd and Pb ions in both acid and basic media compared to the other adsorbents. The results of the study established the efficiency of calcined corn cob kaolinite combo as suitable adsorbent for metal ions.

The toxic effects of anionic dyes such as tartrazine and sunset yellow on humans and the aquatic environment are of serious concern. The need for the removal of these dyes from wastewaters led to the use of adsorption techniques as a cheap and efficient treatment method. Thus, this research was based on the preparation of a low-cost activated carbon derived from cassava sievate designated as CS, which was utilized in the adsorption of sunset yellow and tartrazine from simulated wastewater. The sorption process was carried out under varying process factors in a batch mode. Adsorbent characterization displayed the presence of surface functional groups by the FT-IR and a porous structure as revealed by scanning electron microscopy. Optimum dye uptake was recorded at pH (1.0–2.0), temperature (30–40 °C), CS dosage (0.1 g), and dye concentration (150 mg/L). A maximum CS monolayer uptake of 20.83 and 0.091 mg/g was recorded for tartrazine and sunset yellow dyes, respectively. The pseudo-second-order (R2 > 0.99) and Freundlich (R2 > 0.92) models were most fitted to the kinetics and isotherm data of the uptake of the dyes on CS. The adsorption equilibrium attainment was reached was within 90 min of dye sequestration. The experimental results revealed that both sunset yellow and tartrazine dyes were considerably adsorbed onto the environmentally compatible and low-cost activated carbon derived from cassava sievate.

Gongronema latifolium was used as a low-cost green inhibitor for mild steel by applying the weight loss method at 303–323 K. There was a decrease in percentage inhibition with temperature increase and a rise in inhibition efficiency with an increase in the concentration of inhibitor. The obtained results showed that Gongronema latifolium extract of methanol had percentage inhibition efficiencies in the range of 59.06–81.69%. Corrosion inhibition of mild steel showed a good fit to the Langmuir model compared to the Freundlich and El-Awardy adsorption models. Thermodynamics parameters, such as $$ E_{\text{a}} $$ E a , $$ Q_{\text{ads}} $$ Q ads and $$ \Delta G_{\text{ads}} $$ Δ G ads were evaluated and showed that the mechanism of corrosion inhibition of mild steel by methanol extract of Gongronema latifolium was physisorption. The results of this work indicated efficient potentials of the methanol extract of Gongronema latifolium as a low-cost corrosion inhibitor in acidic media for mild steel, which could be applied to reduce corrosion of metals in industries.

This study was focused on the synthesis of cobalt nanoparticles using Mangifera indica leaf extract and the characterization of the particles via UV–Vis spectroscopy, XRD, FT-IR and SEM. The XRD results showed the formation of cobalt nanoparticles that was crystalline in nature, with an average size of 25—40 nm. The FT-IR analysis of the leaf extract reviewed some functional groups responsible for the reduction of cobalt ions to cobalt nanoparticles while the SEM indicates that the synthesised cobalt nanoparticles possess a cubic, pentagonal and irregular in shape with a smooth surface. Application of colloidal cobalt nanoparticles in detecting Mn2+ ions was discussed which indicated that the absorption of the Mn (II) ions decreased at increased concentration of Mn (II) ions indicating that Mn (II) ion can be detected even at a very low concentration. The minimum and maximum detection limit was found to be 5 and 25 mM of Mn (II) ions, respectively. The obtained results encourage the use of economical synthesis of cobalt nanoparticles in the development of nanosensors to detect the pollutants present in industrial effluents.

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In this work, the adsorption of ciprofloxacin onto yam peel biosorbent was studied by batch method. The equilibrium isotherm analysis of the adsorption process was evaluated to provide insight into the removal mechanism. A decrease in the percentage removal (75.0 – 60.8%) and an increase in adsorption capacity (6.0 – 24.3 mg/g) with an increase in ciprofloxacin concentration from 20 – 100 mg/L was obtained. The isotherm was analyzed by the Langmuir, Temkin, Freundlich, and Scatchard models, and the best fit was obtained for the Freundlich model with a R2 of 0.9918. The separation factor in the range of 0.238 – 0.609 and the Freundlich adsorption intensity of 1.492 indicated a favorable adsorption of ciprofloxacin on yam peel. A monolayer adsorption capacity of 42.81 mg/g was obtained for yam peel which was higher than other efficient adsorbents. The Scatchard model gave a linear fit to the uptake data with R2 of 0.9653 and sum square error of 0.008. The isotherm analysis revealed complex adsorption involving multi mechanisms in the overall process. The results of this investigation showed that yam peel could be utilized as an efficient agricultural waste for the adsorption of ciprofloxacin from wastewater.

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The utility of Nru clay for industrial application, which was taken from the Nsukka local government area in Enugu State, Nigeria, is assessed in this study for its physical and chemical properties. The clay was investigated chemically which showed SiO 2 51.2%, Al 2 O 3 18.3% as the predominant constituents while other metallic oxides such as Fe 2 O 3 5.3%, MgO 2.2%, Na 2 O 1.8%, CaO 1.4%, K 2 O 1.3% and MnO 0.7% were present in considerable proportion. The physical and mechanical analysis acknowledged a range in the linear shrinkage (4.17 - 6.25%), total shrinkage (7.8 - 10.2%), apparent porosity (36.92 – 26.58%), apparent density (2.59 - 2.37 g/cm3), bulk density (1.63 - 1.74 g/cm3), water absorption (22.64 – 15.33%) and modulus of rupture (6.70 – 9.15 kg/cm2) with an increase in firing temperature from 900°C to 1200°C. Nru clay can withstand heat without melting or deforming at temperature up to 1200 °C and exhibited reasonable plasticity with a modulus of plasticity of 1.42. We can infer from our investigation that Nru clay is a potential raw material for industries in the production of ceramics, high melting clays, fired bricks, and paints. Alternatively, the clays’ properties can be tailored to achieve superior physical and mechanical properties by enhancing them with additives. Therefore, it can be employed to cushion the exorbitant cost of importing clay minerals from other nations.