CHROMIUM

The study was designed to assess the concentrations of zinc and chromium in some commercially available green and Black sold teas they include Lipton, Top tea, Richmond tea, Cinnamon Tea and Natural green tea within Benin City, Nigeria. Five of the most popular brands among consumers were purchased in the open market. They were digested, infused (cold and hot) and analyzed for their heavy metal content using the atomic absorption spectrophotometer. The heavy metal concentration varied among the different brands of tea in the study. In the tea samples zinc concentration ranged between 35mg/ kg to 70mg/kg while chromium gave the lowest value of 0.65mg/kg and maximum concentration of 22mg/kg. The cold and hot infusion samples revealed very low concentrations of both zinc and chromium (most of them below detectable limits) ranging between 0.03 mg/l to 0.10 mg/l. In conclusion, the risk of heavy metal exposure via the consumption of these tea is low, with no significant health implications to onsumers and thus does not pose a threat to food safety

Chromium is one of the most notorious heavy metals released by various industries such as tanning and leather industries, manufacturing industries, catalyst and pigments, fungicides, ceramics, crafts, glass, photography, electroplating industry and corrosion control application. This study was aimed at sorption of chromium(VI) ion from aqueous solution by adsorbent derived from used tyres. Waste tyre was collected from Uwelu spare part market in Edo state. The collected tire was washed and rinsed with distilled water to remove debris, oven dried for 3hours at 180oC and ground into powder. This dried powder was carbonized and activated by charging into a muffle furnace for 2hrs at 500oC and then treated with 4M nitric acid. The efficacy of chromium removal of the adsorbent is determined by investigating the various parameters such as adsorbent dose, agitation time and shaking speed. The adsorbent was characterized by Scanning Electron Microscopy (SEM), Energy dispersive X-ray (EDX) and Fourier Transform Infra-Red (FTIR) spectroscopy. The total pore volume of the adsorbent was observed to bet P/P0=0.988646762:0.624668 cm3/g. The percentage of C and O was found to be 30.50% and 20.23%. Analysis of Variance for the response surface quadratic model showed that the Model F-value of 75.25 implies that the model is significant. The Lack of Fit F-value of 0.9763 implies that the Lack of Fit is not significant relative to the pure error. The high R-square value (coefficient of determination) of 0.9898 indicates that the fitted model predicts the metal ion removal with reasonable precision