Determination of optimum conditions for the synthesis of activated carbon from walnut shell to be used in the removal of trace levels of Pb, Ni and Cr elements from polluted water

The goal of this thesis is to determine ppb levels of toxic elements like Cr, Ni and Pb. This is carried out by two steps 1- preparation of adsorbent (AC); 2- application to trace elements preconcentration. The first step procedure is worked by synthesize and characterize an environmentally- friendly adsorbent which has high adsorption capacity. This is achieved by choosing walnut shell which chemically modified it goes by H₂SO₄ sulfuric acid, after modification it goes under pyrolysis by (N₂) gas at (500-600 Cͦ); and so, the synthesis of activated carbon (AC). This process undergoes to the first step for preconcentrating of toxic elements by using different pH(3-6) with the same concentration for removing or decreasing the levels of these elements in contaminated water. This step was performed by determining the optimum condition such as optimum pH and optimum contact time for Cr, Ni and Pb trace elements. This procedure was carried out by the model solution and measurements were carried out by inductively coupled plasma -mass spectrometry (ICP-MS). The optimum pH was was found to be 6 for Pb, Ni and Cr. The optimum contact time was 45min for both Pb; Cr and Ni. Also characterization of AC were carried out by FTIR . Scanning electron microscope (SEM) device used for investigating the shape of surface of obtained AC and found that there are many holes and cave types found in the surface. as a result, the surface area has absolutely increased that are available for the adsorption. Also BET instrument used for AC to investigate the extent of surface area available to the adsorbate which stated that activated carbon exhibits type I. the optimized technique was applied to determination of ppb levels of Pb, Ni and Cr in model solutions for contaminated water