Removal and recovery of heavy metals using fresh water algae
Removal – Recovery- Heavy metals- fresh water algae
Removal and recovery of Cadmium, Lead and zinc ions were determined from aqueous solution using sun dried, oven dried and activated biomasses of Nile water algae and three isolated algae which are belonging to three major phytoplankton groups in the river Nile (Chlamydomonas variabilis (green algae), Anabaena constricta (blue-green), and Nitzschia linearis (diatoms)).The oven dried Nile water algae were powdered and activated by CaCl2, Na2CO3, Na2SO4, and H2SO4, commercially activated carbon also used. Nile water and isolated algal biosorbents were characterized for metal binding using Fourier Transform Infra-Red spectroscopy (FT-IR), High resolution Transmission Electron Microscope (TEM), and Energy Dispersive X-ray microanalysis (EDX). The optimum adsorption condition obtained at pH (4), 150 min contact time, and 2 g/l adsorbent dose. The initial concentrations for Cadmium, Lead and zinc ions of dried and activated algal biomass were 9.8, 10, and 9 mg/l, respectively. The maximumefficiencies of metal removal take place by using activated Nile water algae by H2SO4 with percentage removal 99.28. Almost all analytical results of the isotherm models (Langmuir and Freundlich) for metals removals withsun dried, oven dried and activated Nile water, and isolated algal biosorbents were well fitted with R2 more than 0.9. On the other hand the results show that there are no clear differences between the percentage removals of metals for sun dried, oven dried , and activated dried . It was found that the recovery of metals by using 0.1 M HNO3 takes place through two adsorption / desorption runs in all biosorbents, in 1st runs the recovery was more effective, while at 2nd cycle the effectiveness of recovery was decreased, also there are no clear differences between the percentage recovery of metals for sun dried, oven, so that it is recommended to use the sun dried biosorbent of Nile water algae for metal removal and recovery.