Potential Removal of Chromium from Tannery Wastewater by Water Hyacinth Roots

Continuous discharge of untreated wastewater with high chromium contents from tanning industries causes severe environmental pollution in different aquatic systems as well as poses a variety of health risks. To reduce harmful chromium pollution in various water bodies, it is imperative to develop a method that is both affordable and environmentally benign. In the present study, chromium was successfully removed from tannery effluents using the roots of the water hyacinth (Eichhornia Crassipes). Chromium status in wastewater bodies before and after the biosorption processes was evaluated using standard spectrophotometric techniques such as UV–Vis and atomic absorption spectroscopy (AAS). The metal removal capacity of water hyacinth roots was determined by varying the biosorbent dosages, temperature, and starting chromium ion concentrations. The maximum removal of chromium was found 95% from dilute tannery wastewater and 72% of chromium was extracted directly from raw tannery effluents by using different quantities of water hyacinth. The Langmuir and Freundlich type isotherms were used to study the chromium biosorption process, and the results were found to be highly consistent with the Langmuir monolayer biosorption type isotherm. The results of kinetic investigation showed that the removal of chromium by water hyacinth roots followed a pseudo-second-order kinetic with a R2 of 0.99618. The biosorption of chromium on water hyacinth roots was exothermic and spontaneous which were confirmed from the evaluation of thermodynamic parameters such as ΔG°, ΔH°, and ΔS°. The present research findings revealed that this naturally available plant could be utilized as very promising, environmentally friendly, and cost-effective biosorbent for removing chromium species from raw as well as diluted industrial wastewater systems.