REMOVAL OF LEAD(II) IONS FROM AQUEOUS SOLUTION UNDER DIFFERENT PHYSICOCHEMICAL CONDITIONS USING VARIOUS SORBENTS

Heavy metals and other toxic pollutants are considered extremely pernicious because they are toxic, nondegradable, and environmentally persistent. Electroplating, metal finishing, and/or leather tanning produce wastewater streams contaminated with heavy metals such as chromium, zinc, cadmium, lead, nickel, and mercury [1]. Heavy metals when introduced into water are either remains in dissolved form or are leached down with excess water, or else partially fixed temporarily or permanently in sediments. Those elements which move downward through the sediment contaminate groundwater, which is often used for drinking purposes, so they may be injurious to humans and animals [2,3]. Lead is one of these heavy metals, and can be introduced into liquid wastes from different industries. In water, lead tends to accumulate in aquatic organisms through the food chain and by direct uptake [4]. Lead can damage practically all tissues, particularly the kidneys and the immune system. Intense exposure to high lead levels (from 100 to 200 gmlday) causes encephalopathy with the following symptoms: vertigo, insomnia, migraine, irritability, and even convulsions, seizures, and coma [5,6]. There is a need to treat the waste water to bring the concentration of toxic elements below the recommended release limit [7]. Adsorption is one of the methods commonly used to remove heavy metal ions from various aqueous solutions with relatively low metal ion concentrations. The efficiency of adsorption relies on the capability of the adsorbent to adsorb metal ions from the solutions onto its surfaces. Different naturally occurring adsorbents like activated carbon [8-11], tea waste [12], egg shells [13], mineral mixtures [14], and rice husks [15] are used as adsorbents for industrial waste management.