Levels of awareness and concentrations of heavy metals in the blood of electronic waste scavengers in Nigeria

Background - Electronic waste (e-waste) contains both valuable and hazardous materials. E-waste scavengers specialize in the collection and crude recycling of waste electronics to retrieve valuable metals, which are then sold. These activities provide an income for scavengers, but also expose them to toxic heavy metals such as lead (Pb) and copper (Cu). Objectives - The aim of the present study was to investigate the level of awareness and concentrations of heavy metals (Pb, Cu, zinc (Zn) and manganese (Mn)) in the blood levels of e-waste scavengers at Jakande dumpsite, Alaba International Market, Lagos, Nigeria. Methods - Material and data were collected by empirical survey with the use of a questionnaire to obtain information from e-waste scavengers. Blood samples of the scavengers in the present study (30 adult males exposed to recycling processes) were collected and concentrations of heavy metals were determined through acid digestion and the use of an atomic absorption spectrophotometer (AGILENT 55B AA, 2010). Results - The geometric means of blood levels of Pb, Cu, Zn and Mn were 11.0, 33.85, 126.15 and 19.38 µg / dL, respectively. High concentrations of Pb and Mn (11.0 and 19.38 µg / dL) were found in the blood samples, while Zn and Cu (126.15 and 33.85 µg / dL) showed low concentrations. The maximum blood level of lead (BPb) (24.0 µg / dL) was extremely high compared to the maximum BPb of occupationally exposed males. Statistical analysis of the questionnaires showed that all of the respondents were male, and more than half (56.7%) were between 21-30 years of age and had been involved in recycling of e-waste for 1-5 years. The results showed that 83% of the respondents were aware that hazardous fractions in e-waste require special treatment, while 76.7% were aware of the possible negative impact on their health. Conclusions - Lack of education, poverty and lack of effective enforcement of e-waste management and regulations are the major contributors to the current situation and thus scavengers carry on with their activities unhindered. The authors recommend the use of protective clothing, sensitization visits and awareness campaigns on the safe disposal of hazardous components

Morphology and Properties of Zn-Al-TiO2 Composite on Mild Steel

The influence of TiO2 composite and dispersed pure Al particle on zinc alloy electrodeposited on mild steel was studied from chloride bath solution.Microstructural and mechanical properties of the alloy were investigated. The structure, surface morphology, and surface topography of the deposited alloys were characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM).In addition, hardness of the coated alloys was measured. It was found that the obtained Zn-Al-TiO2 alloyexhibited more preferred surface morphology and mechanical strength compared tothe substrate. The result shows the existence of interaction between TiO2 compounds and zinc alloy particulate. It also exhibited well bright dominate zinc coating on steel surface

Inhibitive effect of ferrous gluconate on the electrochemical corrosion of aluminium alloy in H2SO4 solution

The use of ferrous gluconate as corrosion inhibitor on aluminium alloy in 0.5M H2SO4 solution was studied using gravimetric and potentiodynamic polarization measurements. The surface morphology of the aluminium alloy was studied after exposure to 0.5 M H2SO4 solution in the presence and absence of inhibitor using high resolution scanning electron microscopy equipped with energy dispersive spectroscopy (HRSEM – EDS). The adsorption behaviour of the inhibitor was investigated. The results of the investigation show that increase in concentration of ferrous gluconate corresponds to an improvement on inhibition efficiency. Equally, the results showed the ferrous gluconate to be an effective corrosion inhibitor for the aluminium in the acidic medium. The results obtained from the two methods used were found to correlate with each other

Physio-Chemical and Mechanical Behaviour of(Pinussylvestris) as Binders on Foundry Core Strength

The mechanical potential of sand core binders made withPinussylvestris has been examined. Ota silica base sand bonded with 6% of cassava starch in admixed proportion of Pinussylvestris was tested for tensile, compressive strength and permeability to establish the binding efficiency. Tensile strength of the green baked core were oven baked at 50°C, 100°C, 150°C and 200°C.The cylindrically shaped permeability specimens were tested with permeability meter. Study revealed thatPinussylvestris showed an improve properties at 6% cassava starch at 200°C

Electrochemical and Mechanical Properties of Mild Steel Electro-plated with Zn-Al.

Surface enhancement of engineering materials is necessary for preventing service failure and corrosion attack in the industries. Deposition was performed to obtain a better surface adherent coating using electroplating technique. Zn-Al film was developed with zinc and aluminum powder particles dissolved in nitric acid and sodium hydroxide respectively, to form solutions containing Zn2+ and Al3+ ions. Anomalous co-deposition on mild steel resulted into surface modification attributed to the complex alloys that was developed. The effect of deposition potential was systematically studied using Focused-ion beam scanning electron microscope (FIB-SEM), Atomic force microscope (AFM), X-ray diffraction (XRD) and Fourier transform infra-red (FTIR). Thick, adherent, smooth and uniform Zn-Al coating was deposited with relatively high deposition rate of 1.0 V. Experimental results indicated that the introduction of Al into the coating does significantly alter the chemical and mechanical properties of the mild steel. The microhardness value was increased by 92%; wear rate was decreased by 90% and a significant increase in the corrosion resistance was achieved based on the formation of stable deposited particles of Zn-Al

Comparative Studies of Microstructural, Tribological and Corrosion Properties of Plated Zn and Zn-alloy Coatings

Difficulties in choosing appropriate material(s) for a particular application and the control of environmental menaces cannot be over emphasized. Films of Zn and Zn–Al were electrodeposited on mild steel substrates using Zn and Zn–Al alloy plating solutions respectively. Focus ion beam scanning electron microscope (FIB-SEM) images and Atomic force microscope (AFM) were used to study the surface morphology, the topography and the surface adherent properties of the coatings. The elemental composition and the phases evolved in composite coatings were measured by means of X-ray diffractometer (XRD) and energy dispersive spectrometer (EDS). The cyclic voltammetry techniques were used to explain deposition process. The microhardness measurements and the electrochemical and wear behaviours of the deposits were investigated. Experimental results showed that Zn-Al coatings had homogeneous distribution of the fine particles deposited. These coatings had higher corrosion and wear resistances over the Zn deposited coatings as well as the substrate