Previous research has documented that solid biomaterials such as charcoal or waste coffee and tea have been used to remove heavy metals from contaminated aqueous solutions through adsorption. However, these studies used very low heavy metal concentrations between 10 to 100 ppm. Recently published research work reported that extracts of edible plants and fruits were able to effectively remove lead from contaminated aqueous solution. This paper evaluates the ability of charcoal, un-brewed coffee and tea, fishbone, and caffeine to remove lead from contaminated aqueous solutions. The order of lead removal from 1300 ppm of lead solution is Charcoal (100%) > Tea (97%) > Coffee Ground (88%) > Instant Coffee (83.5%) > Coffee Bean (82%) > Fishbone (76%) > Caffeine (1.3%). These results clearly demonstrate that not all solid biomaterials can adsorb lead and that caffeine, a component of coffee and tea does not participate in the removal of lead from contaminated solutions. Furthermore, the results suggest that two possible processes may be involved in the reactions presented here: adsorption of lead by the solid substrates and precipitation of lead by the solubilized biochemical components of the substrates.

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%).