Photocatalytic Degradation of Dyes in Wastewater Using Solar Enhanced Nickel Oxide (NiO) Nanocatalysts Prepared by Chemical Methods.

This study examined the surface morphology and photocatalytic activity of nickel oxide (NiO) nanoparticles prepared through a chemical method. The synthesized nanoparticle was characterized by using spectroscopic and microscopic techniques. Photocatalytic degradation of hazardous Eriochrome Black T (EBT) was carried out using the synthesized nanoparticle and the efficiency of the NiO used was determined. Highest degradation efficiency of 70% at 25 mg loading was observed at 40 min exposure time. The study concluded that the synthesized nanoparticles could be used in industrial wastewater treatment containing organic dyes.

A Review on Graphene Quantum Dots for Electrochemical Detection of Emerging Pollutants.

Graphene quantum dots which are known as zero-dimensional materials are gaining increasing attention from researchers all over the world. This is predicated upon their relatively unique chemiluminescent, fluorescent, electrochemiluminescent, and electronic properties. The precise mechanism of electrochemiluminescence continues to be a subject of debate in the research world, and this is important in identifying synthetic pathways for graphene quantum dots. Heavy metals and other emerging pollutants are global health and environmental concerns. Several studies have reported the sensitivity and limit of detection of graphene quantum dots up to the nano-, pico-, and femto- levels when used as sensors. This review seeks to bridge information gaps on the reported electrochemiluminescence chemosensors for emerging pollutants using graphene quantum dots under the sub-headings, synthesis, characterization, electrochemiluminescence chemosensor detection, and comparison with other detection methods.

Comparative chemical analysis of Indigenous Nigerian soaps with conventional ones.

This study compared the chemical properties of the indigenous Nigerian soaps with the conventional soaps in order to determine whether or not they met acceptable standards. The locally made soaps were obtained from markets in Ile-Ife, Osun State and Okitipupa, Ondo State, Nigeria. The soap samples were acid digested and trace metals (Cd, Pb, Cu, Zn, and Hg) in the digested samples were profiled using Atomic Absorption Spectrometry. Documented techniques were adopted to analyze the soaps for pH, moisture content, free fatty acid, chloride content, free caustic alkali, matters insoluble in water and ethanol. The margin of safety (MoS) and hazard index (HI) associated with the use of the soaps were also evaluated. The locally made soaps had higher physicochemical properties than the conventional soaps. Mercury (Hg) had the highest concentration in the locally made soaps ranging from 106.50 ± 0.23-273.58 ± 0.49 µg/g and 46.35 ± 0.22-55.12 ± 0.65 µg/g in the conventional soaps, while Cd had the least concentration in the locally made soaps ranging from 2.95 ± 0.45-6.05 ± 0.60 µg/g and 2.88 ± 0.11-5.20 ± 0.60 µg/g in the conventional soaps. Although highly mercuric soaps are known to kill bacteria and fungi, the observed MoS (<100) and HI (>1) indicated that the soaps might be safe if only restricted to occasional use by adults and children. A careful preliminary investigation and selection of the raw materials used in the production of indigenous soaps should be considered a necessary step.

Development of Electrochemical Nanosensor for the Detection of Malaria Parasite in Clinical Samples.

In this study, electrochemical nanosensors were developed from the synthesized metal oxide (MO) nanoparticles by supporting it on a gold electrode (Au). The activity of the developed nanosensor toward the detection of malaria biomarker (ß-hematin) was determined and the optimum conditions at which the maximum detection and quantification occurred were established. ß-Hematin current response at the sensors was higher when compared with the bare Au electrode and followed the order Au-CuO (C) > Au-CuO (M) > Au-Fe2O3 (M) > Au-Fe2O3 (C) > Au-Al2O3 (M) > Au-Al2O3 (C) > bare Au. The developed sensors were stable with a relatively low current drop (10.61-17.35 %) in the analyte. Au-CuO sensor had the best performance toward the biomarker and quantitatively detected P. berghei in infected mice's serum samples at 3.60-4.8 mM and P. falciparum in human blood serum samples at 0.65-1.35 mM concentration.

Concentrations of Polybrominated Diphenyl Ethers (PBDEs) in Water from Asunle Stream, Ile-Ife, Nigeria.

This study assessed the concentrations of polybrominated diphenylethers (PBDEs) in stream water obtained from Asunle stream, an adjoining stream of the Obafemi Awolowo University dumpsite. Water samples were collected for a period of eight months from six different locations comprising of a spot upstream in an uphill area relative to the refuse dumpsite and five others downstream along the stream course. The sampled waters were extracted with dicholoromethane using liquid-liquid extraction method and cleanup was carried out with silica gel. The final extracts after concentration were analyzed using GC-MS/MS. The recovery experiments were adequate (105%-110%). The mean levels of Æ©6PBDEs compounds analyzed ranged from 0.03 to 0.45 ng/mL. Seasonal variability of PBDEs indicated that higher levels were found during the wet season. The levels of PBDEs recorded in this work were relatively lower compared to the values reported in the literature from other developed nations.

Assessment of polybrominated diphenyl ethers in sediment of Asunle stream of the Obafemi Awolowo University, Ile-Ife, Nigeria.

Assessment of levels of polybrominated diphenyl ethers (PBDEs) from the sediment of Asunle stream, an adjourning stream of the Obafemi Awolowo University dumpsite, has been carried out. Sediment samples were collected from the stream at six locations for a period of 8 months, composed of 4 months each of wet (May-Aug) and dry (Nov-Feb) seasons. Soxhlet extraction was employed for the isolation of all the target compounds from the sediment samples. Extracts were further subjected to multi-layer column chromatography employing different forms of silica gel. The prepared samples were analyzed using GC-MS. The overall mean concentrations of the total PBDEs ranged from 1.80 to 9.46 ng/g. The results showed that the concentrations of the PBDEs were slightly higher during the wet season than those during the dry season. In all the studied locations, BDE28, BDE47, BDE99, BDE100, BDE153, and BDE154 were detected in all the sediment samples at concentrations that ranged from 0.73 to 10.43 ng/g. Results of this study indicated that BDE153 was the major pollutant of the Asunle stream sediments.

Speciation study of the heavy metals in commercially available recharge cards coatings in Nigeria and the health implication.

This work assessed levels of heavy metals exposure from silver coatings of mobile phones recharge cards of three major companies (designated as A, B and C) with price denominations 100, 200 and 400 from companies A, B and C respectively, which were carefully scratched using a plastic scraper into a glass tube. The coatings were acid digested for total metal concentration, while speciation experiment for Mn, Cu, Cd and Pb was carried out. Total metals and speciation analysis were done using AAS and XRF techniques. The total metal concentration from XRF analysis was in the range: Ca (70-2140 µg/g), K (20-4930 µg/g), Sc (80-270 µg/g), Ti (1530-12,580 µg/g), Fe (50-6660 µg/g), Ni (20-2040 µg/g), Cu (20-850 µg/g) and Zn (40-460 µg/g). Cr had the lowest concentration (10 µg/g) in A ( 400) while Ti had the highest concentration (12,580 µg/g) in C ( 500) for all the coatings analyzed. AAS and XRF results agreed closely except for Fe with higher concentration. A ( 100) contained high concentration of the metals compared with others. Speciation study identified Mn as the most mobile element when present in the environment.