Adsorptive Removal of Malachite Green Using Water Hyacinth from Aqueous Solution

Abstract

Effluent from dye industries contains the reactive dye in large amount, which imparts color to the water and causes harm to the wellbeing of humans and aquatic animals. Malachite green (MG) is one of the dyes used in the dye industry, which is mutagenic, carcinogenic and therefore toxic. Water hyacinth (WH) is an aquatic weed, which is known for its proliferating growth. This leads to the eutrophication of water bodies. Water hyacinth (Eichhornia crassipes) powder is used as bio adsorbent to remove malachite green dye from aqueous solution. The adsorptive removal capacity of malachite green using water hyacinth powder was studied by carrying out the batch study on synthetic samples to assess malachite green removal efficiency. The effect on the removal was a function of various parameters like agitation speed, adsorbent dose, contact time, initial concentration, particle size and pH. At pH 7 adsorption reaches equilibrium at an agitation speed of 130 rpm at a contact time of 30 min at temperature of 27 °C. The pseudo-second-order kinetics and both Freundlich and Langmuir isotherms with R2 0.9987, 0.9970 and 0.9923, respectively, fit the kinetics and isotherm models. The water hyacinth characterization was carried out with SEM and EDX, which suggests adsorption of malachite green. From the results obtained it can be observed that water hyacinth powder can adsorb the malachite green dye under optimum conditions which are easy to maintain. Therefore, water hyacinth can be potentially applied for the removal of malachite green dye from dye wastewater.