Removal of Heavy Metal Ions from Aqueous Solutions by Bamboo Wastes

In the present study, the ability of wastes of 5 local bamboo species (Dendrocalamus latiflorus, Phyllostachys makinoi, P. pubescens, Bambusa stenostachya, and B. dolichoclada) to remove heavy metal ions of Cu(II), Pb(II), Cd(II) and Ni(II) from aqueous solutions, with different reaction times, particle sizes, and pH values were evaluated and compared with 4 known biosorbents of activated carbon, bark, exhausted coffee, and exhausted tea by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The results showed that the absorptive capacity of bamboo waste for heavy metal ions increased with prolongation of the reaction times and a decrease in the particle size. The optimum pH value for metal adsorption was in the range of 4~6. Phyllostachys pubescens was the most effective in removing heavy metal ions from aqueous solutions among the wastes of the 5 bamboo species. By hot-water-extraction treatment, the available volume and surface area of the raw bamboo materials greatly increased which effectively improved the metal-removal efficiency. The performance of hot-water-extracted bamboo for removing heavy metal ions was even better than those of bark, exhausted coffee, and exhausted tea. Therefore, the use of hot-water-extracted bamboo waste as an adsorbent may be an alternative to other more-costly materials.