Removal Of Copper From Waste Water Using Low Cost Adsorbent

Abstract

In this study, Experiments were conducted in the laboratory to study the influence of important factors like adsorbent dosage and time of contact under the room temperature conditions (27℃ ±3℃). The experiments were conducted for batch adsorption study using pulp and paper mill sludge and cement kiln dust as low cost adsorbents on industrial wastewater. Based on results for quantification of adsorbent dosage for copper, it was observed that the equilibrium was attained for dosage of 4g/L and 2g/L and for contact time of 20 min and 40 min for pulp and paper mill sludge and cement kiln dust respectively. In equilibrium system the removal efficiency was 65% and 98% for pulp and paper mill sludge and cement kiln dust respectively. Adsorption equilibrium study was investigated by Freundlich, Langmuir and Tempkin isotherms for which ultimate adsorption capacity for pulp and paper mill sludge and cement kiln dust for adsorption of copper and zinc were calculated. The adsorption process was well fitted with the isotherms and best fitted for Langmuir isotherm. The maximum monolayer coverage from Langmuir isotherm was 15.47 mg/g for pulp and paper mill sludge and 50 mg/g for cement kiln dust. The calculations of thermodynamic parameters indicated that the adsorption is spontaneous and exothermic. Kinetic studies were analysed using pseudo first order and second order kinetics, and results showed that the pseudo-second order kinetic model gave a better fits than pseudo-first order kinetic model for adsorption. Comparing both pulp and paper mill sludge and cement kiln dust as adsorbents, the cement kiln dust showed more efficiency than pulp and paper mill sludge. Keywords: I sotherm, kinetics, cement kiln dust (CKD), paper mill sludge (PMS). 1.INTRODUCTION Environmental pollution is currently one of the most important issues facing humanity. It was increased exponentially in the past few years and reached alarming levels in terms of its effects on living creatures. Toxic heavy metals are considered one of the pollutants that have direct effect on man and animals. Rapid growth in human population is one of the major causes of environmental pollution. Increased industrialization and urbanization throughout the world results in consistent release of toxic effluents, several industrial processes generate metal containing wastes. Heavy metals are non-degradable metals. Several industrial wastewater streams may contain heavy metals such as Cr, Cu, Pb, Zn, Ni, etc., including the waste liquids generated by metal finishing or the mineral processing industries. Heavy metals are natural components of the Earth's crust. They cannot be degraded or destroyed. To a small extent they enter our bodies via food, drinking water. Heavy metals can enter a water supply by industrial and consumer waste, or even from acidic rain breaking down soils and releasing heavy metals into streams, lakes, rivers and groundwater. As trace elements, some heavy metals (e.g. copper, selenium, zinc) are essential to maintain the metabolism of the human body. However, at higher concentrations they can lead to poisoning. Heavy metals poisoning could result, for instance, from drinking water contamination. The removal of heavy metals can be accomplished by a variety of techniques. Conventional methods typically involve the use of processes such as coagulation, precipitation, ion-exchange, electro-chemical methods, membrane processes, extraction, adsorption, etc. Among these methods, adsorption is currently considered to be very suitable for wastewater treatment because of its simplicity and cost effectiveness. Some widely used adsorbents for adsorption of heavy metals include activated carbon[3], clay minerals, biomaterials, industrial solid wastes and zeolites. The aim of this investigation was to compare adsorption efficiency of copper from wastewater using two different types of adsorbents, pulp and paper mill sludge and cement kiln dust. The pseudo-first order and pseudo-second order kinetic models were used to describe kinetic of adsorption of Cu and lead onto pulp and paper mill sludge and cement kiln dust.