The First International Proficiency Testing Conference Sinaia, România 11 th − 13 th October, 2007 371 REMOVAL OF HEXAVALENT CHROMIUM FROM AQUEOUS SOLUTIONS BY ADSORPTION ON PEACH KERNEL AND NUTSHELL Cristina Modrogan, Cristina Costache, Daniela Oanamari Orbulet University Politehnica of Bucharest, str. Polizu, nr. 1-7, sector 1, Bucharest, Romania c_modrogan@yahoo.com Abstract A new process for the hexavalent chromium removal from aqueous solutions is described. The paper intend to present, on a hand how to obtain an adsorbant using unconventional materials (peach kernel and nutshell), and on the other hand the study of hexavalent chromium removal from wastewater of different industries using this adsorbant. The paper has a double purpose. In the first part, was obtained from nonconventional materials: coconut bark and peach kernel an adsorbant mass. In the second part of the paper, was studied the hexavalent chromium removal from wastewater proceeding from different industries. The authors studied the influence of the following parameters: the initial pH of solution, the contact time on the adsorption capacity. The adsorbent efficiency to the chromium removal was also studied using chromium-plating wastewater. Key words Hexavalent chromium, nutshell, aqueons solutions 1 INTRODUCTION Chromium can be acutely toxic to both plants and animals. To develop effective remediation plans for contaminated sites, it must understand the processes governing the transport and fate of chromium in the environment. Since both the mobility and toxicity of Cr depend on its oxidation state, redox reactions involving Cr are extremely important in determining its fate in the environment and its risk to human health (12). Until a few years ago, it also was the favored corrosion control agent in cooling towers whose water blow down (waste) was dumped into rivers, pits, lakes, and oceans. Cr occurs in wastewaters resulting from these operations in both trivalent [Cr(III)] and hexavalent [Cr(VI)] forms. The hexavalent form is more hazardous to animals than the trivalent form.