Deterioration in soil–water environment severely contributed by heavy metal bioavailability and mobility on soil surface and sub-surface due to irrational increase in wastewater discharge and agrochemical activities. Therefore, the feasibility of adsorption characteristics of the soil is paramount in curbing the problem of micropollutant contamination in the farming vicinity. Soil from a farming site in a populated area in Enugu, Nigeria was collected and tested to measure the lead and cadmium contents using atomic absorption spectrophotometer (AAS). The adsorption potency of the ultisol soil was estimated for identifiable physicochemical properties by standard technique. The mean activity concentration of Pb²⁺and Cd²⁺was 15.68 mg/kg and 3.01 mg/kg. The pH, temperature, metal concentration and contact time adsorptive effect on the Pb²⁺and Cd²⁺uptake was evaluated by batch adsorption technique. The Langmuir, Freundlich and Temkin models were fitted into equilibrium adsorption data and the calculated results depict a better and satisfactory correlation for Langmuir with higher linear regression coefficients (Pb²⁺, 0.935 and Cd²⁺, 0.971). On the basis of sorption capacity mechanism of the soil, pseudo-second-order model best described the kinetics of both metal ions retention process. The results of the present study indicated that the soil being a low cost-effective adsorbent can be utilized to minimize the environmental risk impact of these metal ions.

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) are predominant pollutants linked with anthropogenic activities across a host of environmental mediums. The level of pollution, ecological and health risk were assessed in surface water from Ekulu in Enugu metropolis, Nigeria for 17 PAHs and selected HMs (As, Cd, Cr, Cu, Pb, Ni, Zn) components. PAHs and HMs were determined using a gas chromatography-flame ionization detector (GC-FID) and atomic adsorption spectrophotometer (AAS). The total PAHs in station A (3.17mg/l), B (1.51mg/l), and C (1.83mg/l) were due to high molecular weight (HMW) PAHs than low molecular weight (HMW) PAHs. HMs contents were within USEPA and WHO minimum contamination levels (MCL) except Cr and Pb. The molecular diagnostics of PAHs showed that incomplete combustion of carbonaceous compounds was dominant, while petrogenic was insignificant across all samples. The ecological indices of PAHs and HMs varied from medium to high pollution due to anthropogenic activities that pose a threat to the ecosystem. The non-carcinogenic models showed that hazard index (HI) ranged from PAHs (0.027 – 0.083) and HMs (0.0067 – 0.087) which is less than unity implying no adverse health issues. The lifetime cancer risk (LCR) for PAHs (4.21×10–4 – 9.61×10–4) and HMs (1.72×10–5 – 3.98×10–5) suggested significant cancer risk is possible over some time for a population of 1 in 10,000 and 100,000 for both PAHs and HMs exposure for 70 years. Therefore, there is an urgent need for proper pollution control and mitigation plan to preserve both age groups from being continuously exposed to anthropogenic activities in the Ekulu River and further study should be carried out to monitor the available toxicants.

Ciprofloxacin (CIP) is one of the most reported antibiotic pollutants in hospital and industrial wastewater systems. The inclusion of nanosized transition metal oxides in adsorbent materials is able to improve the affinity and aqueous phase uptake of CIP from water. In this study, we report for the first time composites of corn silk with impregnated nanoparticles of NiO (NiONPs-CS) and CuO (CuONPs-CS) for the removal of CIP from water. The adsorbent was characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), energy-dispersive X-ray spectroscopy (EDX), an adsorption/desorption analyzer, and X-ray diffractometer (XRD) to study the morphology, surface functionality, elemental composition, textural properties, and crystal phases. The monolayer adsorption capacities of NiONPs-CS and CuONPs-CS were 108.3 and 120.2 mg/g, which were over 2 times higher than the capacity for unloaded corn silk. The kinetics of the adsorptive uptake followed the pseudo-second-order kinetics, revealing that both adsorption site density and CIP aqueous concentration control the removal rate. NiONPs-CS and CuONPs-CS were reusable for five cycles, with the uptake efficiency being 63.1 and 66.9%, respectively. This dropped to 47.8% for the unloaded corn silk. The mechanism of uptake was mainly by electrostatic attraction, pi-pi interaction, hydrogen bonding, and hydrophobic interaction. Based on our findings, the adsorbents have proven to be an efficient, cheap, and reusable material for CIP uptake.

Pollution monitoring of potentially toxic elements (PTEs) in a typical peri-urban area in Ora-Eri, Nigeria has been unchecked. Thus, unified evaluation process was developed to assess the pollution load index and potential health risk to inhabitants in mapped regions. The environmental risk was evaluated using contamination factor, geo-accumulation index and Nemerow integrated index. The source of heavy metal pollution was identified by Pearson correlation statistics. Public health risk caused by intake of leafy vegetables and soil exposure were estimated in regard to location of the farmland. The soil was non-contaminated by lead (Pb), arsenic (As), selenium (Se) and chromium (Cr) but gongronema latifolium was contaminated with As exceeding WHO/FAO limit. The bioaccumulation of PTEs in the vegetable follows this order: Se > Pb > As > Cr. The retention of selenium in leaf is high because is an essential metalloid. The pollution status of the studied locations ranged from low to moderate. Arsenic is the main contributor to the ecological contamination. The potential hazard health risk ranged from 5.37E-03 to 2.75E-02 for adults and 5.40E-02 to 2.60E-01 for children. The cancer risk for adults (2.43E-06 to 1.24E-05) and children (8.75E-05 to 1.15E-04) exceeded the acceptable standard (1 × 10⁻⁶) signifying gradual cancer effects. Therefore, the estimated hazard index and total cancer risk revealed that children are more prone to potential health risk than adults. Nevertheless, further continuous works should be carried out to monitor health risk in humans especially children and the control management policy of the peri-urban area should be adopted.

Nickel- and copper oxide-loaded Bryophyllum pinnatum (BP) nanocomposites (NiONPs-BP and CuONPs-BP) were prepared by a thermo-chemical precipitation process for sequestration of malachite green dye from a synthetically prepared aqueous solution.