REMOVAL OF CHROMIUM IONS FROM INDUSTRIAL WASTE EFFLUENTS BY ADSOPTION

Abstract Heavy metals are unacceptable pollutants if present in industrial or urban wastes, due to their highly toxic effects for humanity. Chromium ions, especially if in the hexavalent form, are one of these undesirable waste contents. They may be present in industrial solid or liquid effluents, especially those from tanneries and dyeing plants, which will appear finally in the effluent liquids, and perhaps solids. The objective of the present investigation is to remove chromium ions, by the adsorption technique, from liquid and/or solid effluents in order that these may be safely disposed in rivers, canals or draining exits. Chicken feathers, were chosen to be the solid adsorbent. This will decrease land environmental pollution by feathers and will remove chromium ions from liquid wastes, as well. The factors affecting the removal process were examined such as equilibrium time, feather charges, mixing conditions and the pH of the waste solution. The best results were obtained at 1 and 2 values of the pH. Equilibrium modeling has been carried out using Langmuir, Freundlish and Redlish- Peterson models. The correlation between the three isotherms and experimental data was found to be reasonable in all cases. A simple kinetic model has been developed to explain the external mass transport of chromium from water onto chicken feathers and determine the external mass transfer coefficient, Ks under influence of a number of design variables, namely agitation seep, size and mass of chicken feathers. By log-log correlation, it has been proved that Ks varies linearly with agitation, size and mass of chicken feathers.