Chromium (VI) removal from aqueous solutions using Eichhornia as an adsorbent

The study was carried out to check the potential of water hyacinth, Eichhornia crassipes, to remove chromium (VI) in batch process. Powder was prepared from dried Eichhornia (particle size 0.3 mm and 1.0 mm). The influence of various parameters on adsorption (pH, dose, contact time, temperature) was studied. The Cr(VI) removal was 60.9% and 79.2% for 1.00 mm and 0.3 mm particles of Eichhornia treated (ET) after 30 min contact time and 52.7% and 53.4% for 1.00 mm and 0.3 mm particles of Eichhornia untreated (EU) after 75 min contact time respectively. The optimum pH for both adsorbents was found to be 2.0 and optimum dose was found to be 0.4 g 100 ml(-1) for ET and 0.6 g 100 ml(-1) for EU. Maximum adsorption occurred at room temperature (26 +/- 1 degrees C) in case of both ET and EU, respectively. The adsorption process followed the first order mechanism as well as the Langmuir isotherm. Finally, it was concluded that the adsorbent prepared from Eichhornia is very effective in removing Cr(VI) and it can be used for industrial wastewater treatment.