Processing swellable clay adsorbers charged with heavy metals - by desorption of heavy metal e.g. with acid and testing heavy metal adsorption capacity of regenerated clay to indicate reuse or removal from system

摘要

To treat swellable clay materials loaded with heavy metals in a waste water treatment system, the adsorbed heavy metals (HM) are desorbed in a first desorption by means of an acid (step 1), which gives a regenerated clay (step 3). The heavy metal soln. is sepd. from the regenerated clay and the regenerated clay is reused for the adsorption of heavy metals (step 5) and its HM-adsorption tested (step 6). If the HM-adsorption capacity is satisfactory, the HM-loaded clay is re-circulated to a further desorption (step 7), whereas if the HM-adsorption capacity is insufficient, the HM-loaded clay is withdrawn from the system for further processing. USE/ADVANTAGE - Process allows the clay to be reused in the process after desorption of the heavy metal until its adsorption capacity is exhausted, at which point it may be subjected to a more rigorous desorption of the heavy metals to give a prod. which can be utilised as a bleaching clay, or it may be converted into a modified bentonite such as an organophilic bentonite which can be used for adsorption of organic substances, thus avoiding the necessity for disposing of clay contaminated with heavy metals.