The use of tea and coffee for the removal of heavy metal from aqueous lead solutions has been reported. However, those studies were limited to expended dry biomass of coffee and tea and the lead concentration in those studies range from 10 - 100 ppm of aqueous lead solution. This study compared the effectiveness of aqueous extracts of instant coffee (IC), coffee ground (CG), coffee bean (CB), Lipton tea (Tea), and spinach puree (SP) in removing lead from 1300 PPM of aqueous lead solution. After 24 hr of agitation at room temperature followed by centrifugation, the lead concentration (in ppm) in the liquid from each reaction tube was analyzed using EPA Method 6010 (Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES)). The results suggest that the order of lead removal was Spinach (99%) > Instant coffee (95%) >Tea (91%), > CG (62%) > CB (59%). In comparing the brewed versus the boiled extracts, the results demonstrated that temperature of the aqueous extract affected the lead removal potential of coffee and tea in decreasing order: IC (95%:79%), > Tea (91%:88%) > CG (62%:53%) > CB (59%:53%).

There is a growing global concern for the environmental and health hazards posed by heavy metal contaminants, especially lead in the soil and ground water. The potential for plant and animal uptake, metabolism, and propagation into food-chain poses great health risks. World communities face a common need to a cheap, efficient, and effective technology to mitigate the growing problem of heavy metal contaminations. The present investigation was undertaken to evaluate the potential of using aqueous extracts of edible vegetables and fruits for the in-situ remediation of lead contaminated water (1300 ppm). The plants used in this study include Mustard Green (Brassica juncea), Spinach (Spinacea oleracea), Collard Green (Brassica oleracea), Bitter Leaf (Vernonia amygdalina), Carrot (Daucus Carota Sativus), Red, Green, and Yellow Bell Pepper (Capsicum Annuum), Tomatoes (Lycopersicon esculentum), Red and White Grape (Vitis vinifera), and Lime (Citrus aurantifolia). After shaking triplicate reaction mixtures lead contaminated water and each substrate for 22 hours at room temperature, lead removal by the substrates were analyzed by EPA Method 6010, using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Results suggest that the order of lead removal is Collard Green (99.8%) > Spinach (98.7%) > Mustard Green (98.2%) > Green Bell Pepper (97.8%) > Yellow Bell Pepper (97.75%) > White Grape (96.7%) > Carrot (95.5%) > Red Bell Pepper (94.28%) > Red Grape > 93.5% > Tomatoes (84%) > Bitter Leaf (61%). The study concludes that liquid substrates such as the supernatants from pureed edible tuberous, leafy, and fruity vegetables can effectively remove lead from contaminated water.

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