This study examined the levels of some heavy metals in soils of Oke-Ere mining area in Yagba West, Kogi State, Nigeria, aim at ascertaining the degree of pollution, and risk pose to the environment, and human health to the residents in the area. A total of 48 soil samples were analysed by using Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The mean concentrations (mg/kg) were As(1.92), Cd(< 0.004), Co(29.8), Cr(117), Mo(4.00), Ni(51.4), Pb(24.1), Sc(17.8), Sn(21.9), and Zn(85.8). Principal component analysis revealed significant anthropogenic contributions of Sc, Cr, Ni, and As in soils. Geochemical assessment evaluated based on models of geochemical load index (Igeo), enrichment factor (EF), contamination factor (C_f) and pollution load index (PLI), revealed that the soils were highly polluted by Sc, moderately polluted by Sn and non-polluted to slightly polluted by other metals. Enrichment factor shows significant enrichment by Sc, while Cr, Pb, Co, Mo and Sn were moderately enriched. The contamination factor indicated low contamination for most of the studied metals except Cu and Co which recorded considerable contamination. The values of pollution load index PLI > 1, signifies that the mining activities deteriorated soil quality. The total hazard index (HI) of the metals for adult and children, indicates HI < 1 which connotes a non-carcinogenic health risk effect. The cancer risk (CR) value for ingestion and dermal exposure pathways was higher than the permissible limits (1 x 10⁻⁶ to 1 × 10⁻⁴), which indicated adverse health risk to the local resident. This study suggested adequate attention be directed to detailed risk assessment of heavy metals in the study area.

Nanoparticles (NPs) have found numerous applications in various areas of science, technology, engineering, and mathematics (STEM), including drug delivery, quality control, environmental assessment, and diagnostics. This is primarily because of its environmentally friendly nature and cost-effectiveness. In recent times, NPs have been explored for metal remediation over traditional methods. ZnONPs were produced successfully from Ocimum gratissimum (OG) leaf extract (ZnONP-OG) and characterized using SEM-EDX, XRD, BET, and FTIR. The potency and optimal clean-up conditions for aqueous-bound Cd were investigated using the batch-type adsorption process. The optimal cleanup conditions were observed at a contact time of 15 min, temperature of 303 K, adsorbent dose of 0.5 g, initial concentration of 25 mg/L, and pH of 11. Optimum removal percentage of >93% was observed, and the experimental data best fitted the Langmuir isotherm model (R²:0.999) and the pseudo-second order kinetic model (R²:0.99). Thermodynamic studies revealed a spontaneous and exothermic sorption process for the uptake of Cd from aqueous solutions onto the ZnONP-OG. Overall, the results demonstrated that the ZnONPs synthesized from OG were effective in decontaminating Cd from aqueous solutions and could serve as a potent and cheap substitute compared to conventional adsorbents.

Recently, composite of metal oxide has continually elicited tremendous attention from research scientist globally as a viable adsorbent for the removal of phenol and its derivative from aqueous media owing to their improved physicochemical structures which enhanced adsorption capacity. In this study, a composite of alumina-zirconia (Al2O3–ZrO2) was synthesised by calcination techniques and characterised using scanning electron microscopy–energy dispersive X-ray Spectroscopy (SEM-EDX), and X-ray diffraction (XRD). Results from characterisation revealed the formation of this composite with amorphous structure. The composite was employed to evaluate the performance removal of phenol and 2,4-dichlorophenol from solutions using the batch adsorption technique by considering the influence of varying solution pH, initial concentration, adsorbent dosage, contact time and temperature. The optimal conditions predicted from the study are pH of 7 and 8 at a contact time of 90 minutes for phenol and 120 minutes for 2,4-dichlorophenol, respectively, at a temperature of 301 K. The isothermic empirical models of Langmuir, Freundlich and and Dubinin-Radushkevich were employed. The Freundlich model best described the adsorption process with R2 correlation values (0.945–0.998). The pseudo-second-order kinetics model adequately depicted the rate of adsorption with higher correlation values (≥0.99) for both compounds as compared to the pseudo-first order. The thermodynamic parameters computed suggest non-spontaneous, exothermic reaction and decreased randomness. The study portends the composite Al2O3–ZrO2 composite to be viable for removal of phenolic compounds from wastewater.

Solar energy is energy derived from the sun’s radiation. The sun’s energy can be exploited using a variety of technologies, including (a) photovoltaic (PV)/concentrator photovoltaics (CPV) systems that convert photons to electricity; and (b) solar thermal technologies that capture thermal energy from the sun’s radiation using solar collectors or concentrated solar power systems (CSP). Due to the quest for power supply from renewable, cheap, and non-gaseous emission sources coupled with the attempts to combat the shortage of potable water in rural areas, much research on the interface of solar energy power systems with water treatment plants has been reported. However, the greater part of the existing reports are based on theoretical modelling, with only minimal experimental, cost analysis, pilot projects and strategic studies. Also, even though solar-powered water treatment technologies are still in the early stages of research, and very rare studies based on real plants have been conducted, existing publications are mostly focused on single principles, making it impossible to assess and compare several technologies. Globally, this review has particularly highlighted the recent advances in the application of solar energy technologies in desalination and wastewater treatments. It likewise highlighted the key research findings and the critical gaps in the existing achievements. It further highlighted the attempts made on hybrid techniques with other renewable energy sources such as wind and geothermal energies which are paramount for scaling up and commercialization uses. However, the findings revealed that most of these studies were restricted to particular parts of the globe without candid evidence from the African perspective, especially Sub-Saharan Africa. Thus, due to the paucity of information concerning this topic within the region, there is a need for further studies on the application of solar energy for water treatment, especially on a pilot scale level for sustainable development. PRZEGLĄD ZASTOSOWAŃ ENERGII SŁONECZNEJ DO OCZYSZCZANIA ŚCIEKÓW; PERSPEKTYWA GLOBALNA I AFRYKAŃSKA Energia pochodząca z promieniowania słońca może być eksploatowana przy użyciu różnorodnych technologii, w tym (a) fotowoltaiki (PV)/skoncentrowanej fotowoltaiki (CPV), systemów, które przekształcają fotony w energię elektryczną; i (b) słoneczne technologie cieplne, które wychwytują energię cieplną z promieniowania słonecznego przy pomocy kolektorów słonecznych lub skoncentrowanych systemów energii słonecznej (CSP). Z powodu poszukiwań dostaw energii ze źródeł odnawialnych, tanich i nie emitujących zanieczyszczeń gazowych, a także wysiłków na rzecz walki z niedoborem wody pitnej w obszarach wiejskich, opublikowano wiele badań na temat systemów pozyskiwania energii słonecznej dla obsługi oczyszczalni ścieków. Jednakże większość istniejących opracowań oparta jest o modelowanie teoretyczne, jedynie z minimalną częścią eksperymentalną, analizą kosztów, projektami pilotażowymi i studiami strategicznymi. Co więcej, technologie oczyszczania wody zasilane energią słoneczną wciąż są na wczesnym etapie, a prace dotyczące badań w prawdziwych oczyszczalniach są rzadkie, publikacje w większości skupiają się na pojedynczych przypadkach, uniemożliwiając porównywanie kilku technologii wykorzystujących energię słoneczną do odsalania wody i oczyszczania ścieków. Wskazuje również kluczowe wyniki badań oraz istotne braki w istniejącym stanie zaawansowania. Ponadto przedstawia próby z technikami hybrydowymi, wykorzystującymi inne odnawialne źródła energii, takie jak wiatr i energia geotermalna, które są kluczowe w zwiększaniu skali produkcji i komercjalizacji. Jednakże wyniki badań wskazują, że większość prac ograniczona jest do innych kontynentów; brak jest jasnej afrykańskiej perspektywy, szczególnie dotyczącej Afryki subsaharyjskiej. Tak więc, z powodu skąpych informacji na ten temat, które dotyczą tego regionu, istnieje potrzeba dalszych badań nad zastosowaniem energii słonecznej do oczyszczania ścieków, szczególnie w skali pilotażowej, które przyczynią się do zrównoważonego rozwoju.