الفهرس 
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Abstract
Heavy metal toxicity, due to industrial wastewater, has been a threat to the environment for the past many decades, so it is needful to remove it before drainage into the environment. Laser-induced breakdown spectroscopy (LIBS) was used in this study as an alternative instrumental methodology that uses direct introduction and analysis of chromium ion in wastewater. LIBS is a laser-based, non-destructive, rapid and sensitive optical diagnostic technique used to detect certain atomic species. A measuring device by LIBS has been established which included the Nd:YAG laser, Echelle spectrograph, intensified charge-coupled device (ICCD) and liquid jet. The characteristic spectral lines of chromium ion in synthetic wastewater was analyzed using LIBS. The calibration curve of chromium ion in liquid was obtained experimentally. In the present thesis the effectiveness of using activated charcoal and treated rice husk (TRH) to remove chromium ion from synthetic wastewaters were studied using batch and fixed bed column adsorption techniques. In batch adsorption it was found that the percentage of removal of metal ion increased with increasing adsorbent dose and contact time. The adsorption efficiency increased with increasing initial metal concentration. The experimental data fitted well to Freundlich and Temkin adsorption isotherm. The kinetic study showed that it is pseudo-second order. In the fixed bed adsorption it was found that the percentage of removal of chromium ions increased with the increase of bed depth and decrease of flow rate. Although a slight increase in percentage of removal was notice when using charcoal, however, rice husk is generally preferred owing to its low cost.