Carbon adsorbents derived from biomass (agricultural and household residues) have been widely used in the sequestration of hazardous substances from the environment due to their distinctive qualities of large internal surface area, mechanical integrity, and regeneration. The need for carbon adsorbents for sequestration of dyes, heavy metals, and crude oil components has increased because of environmental concerns. This has led to studies of carbon adsorbents derived from agricultural and household biomass residues. These adsorbents have been used to remove pollutants. Although numerous reviews have been published before, analogy of results obtained using different adsorbents is hard due to dissimilarities in research data. Against this backdrop, the purpose of the research survey was to review the contemporary publications regarding the production of activated carbon from biomass sources highlighting specifically its utilization in removing toxic wastes from water solution such as oil spill, dyes, and sundry hazardous substances. Also the work focuses on the methods for the restoration of the spent adsorbents and their end use.

The concentrations of heavy metals in rice grains and soils from Ada cultivated fields were investigated. Rice and soil samples were digested and the heavy metal concentrations determined using atomic absorption spectrophotometer. The results showed the following concentrations of metals (mg/kg): soil—Pb (4.64 ± 2.18), Cd (0.83 ± 0.83), Zn (20.26 ± 18.60), Mn (68.90 ± 19.91), Ni (3.46 ± 2.42), and Cr (21.41 ± 14.6); rice—Pb (3.99 ± 1.43), Cd (1.10 ± 0.53), Zn (65.37 ± 58.09), Mn (37.81 ± 5.82), Ni (3.12 ± 1.49), and Cr (10.87 ± 6.47). The Canadian, Nigerian and Chinese maximum allowable concentration for cadmium in soil were exceeded by 15%, 30%, and 85% of the soil samples, respectively. Heavy metals in all the rice samples evaluated were found to be above the World Health Organization (WHO) maximum permissible limit for lead, cadmium, and chromium. Strong positive and significant correlations were observed between some metal pairs in soil and rice indicating the similarity in origin. The estimated daily intakes of Pb and Cd from rice grown on the fields were higher than the safety levels established by WHO and the Joint FAO/WHO Expert Committee Food Additive, respectively. Hazard quotients and total hazard index for Pb and Cd were greater than 1. This indicates that consumption of rice from these fields will likely induce adverse health effects arising largely from Pb and Cd exposure.

This work evaluated the use of Dialium guineense seed waste (DGS) and its sodium hydroxide modified form (NH-DGS) as biosorbent for ciprofloxacin (CPF) from synthetic solution as well as the desorption potentials. Central composite design (CCD) was applied for optimization of the alkaline treated biosorbent by response surface methodology using design expert. Both biosorbents were characterized by FTIR, SEM, EDX, and BET analysis. The CCD showed NaOH concentration of 0.46 M and temperature of 96 °C to be effective for optimized modification of NH-DGS. Optimum removal of CPF was obtained at pH 6.0, contact time 120 min, temperature 300 K, and dosage of 0.1 g. The Freundlich model gave the best fit compared to the other isotherms tested with R² values >0.97951. NH-DGS exhibited a maximum uptake capacity of 120.34 mg/g higher than some reported adsorbents for CPF. The pseudo-second-order model was suitable in the fitting of the kinetic data. A non-spontaneous process was obtained for CPF biosorption on DGS which became spontaneous after alkaline treatment. Over 84% desorption of CPF was achieved on both biosorbents using 0.3 M HCl which envisaged the use of NH-DGS as an efficient material for treatment of waters contaminated with CPF.

Heteroleptic divalent metal complexes [M(L) (bipy)(Y)]• n H ₂ O (where M = Mn, Co, Ni, and Zn; L = Schiff base; bipy = 2,2’-bipyridine; Y = OAc and n = 0, 1) have been synthesized from pyrimidine Schiff base ligand 3-{( E )-[(4,6-dimethylpyrimidin-2-yl)imino]methyl} naphthalen-2-ol, 2,2’-bipyridine and metal(II) acetate salts. The Schiff base and its complexes were characterized by analytical (CHN elemental analyses, solubility, melting point, conductivity) measurements, spectral (IR, UV-vis, ¹ H and ¹³ C-NMR and MS) and magnetometry. The elemental analyses, Uv-vis spectra and room temperature magnetic moment data provide evidence of six coordinated octahedral geometry for the complexes. The metal complexes’ low molar conductivity values in dimethylsulphoxide suggested that they were non-ionic in nature. The compounds displayed moderate to good antimicrobial and antifungal activities against S . aureus , P . aeruginosa , E . coli , B . cereus , P . mirabilis , K . oxytoca , A . niger , A . flevus and R . Stolonifer . The compounds also exhibited good antioxidant potentials with ferrous ion chelation and, 1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging assays. Molecular docking studies showed a good interaction with drug targets used. The structural and electronic properties of complexes were further confirmed by density functional theory calculations.