Research Of Cr⁶⁺ Adsorption By Composite Adsorbent In Water

The pollution of heavy metals in water becomes a big problem. The heavy metals in the environment is greatly concerned due to their toxicity. Many toxic heavy metals have been discharged into the environment as industrial wastes, causing serious soil and water pollution. Chromium(VI) is recognized to be much more toxic than chromium(â…¢). Hexavalent chromium compounds are carcinogenic and corrosive on tissues, and are found to be harmful to bacteria, plants, animals and people. The toxicity of chromium(VI) to human includes lung cancer, as well as kidney, liver, and gastric damage.In this paper, NaCl modified clinoptilolite is used as basement to prepare two kinds of new composite adsorbents. The modifying materials are chitosan and infusibility humic acid (IHA), and deacetylating degree of chitosan is 90%.The main research contents are as follows: preparation of composite adsorbents , adsorption treatment of Chromium(VI)-containing wastewater and measurement and simulation of adsorption isotherms of Chromium(VI) on composite absorbents. We analyse the surface Characteristic of composite adsorbents with scanning electron microscopy (SEM) and X-Ray Diffractometer (XRD). Through single-factor test and orthogonal test, the adsorption condition was optimized.Chitosan was supported on NaCl modified clinoptilolite to prepare composite adsorbentâ… in this experiment. pH and dosage of composite adsorbent is the most important factor for the adsorption effect of Cr(VI). The absorption effect is improved in the acid condition and with more adsorbent dosage. The composite adsorbentâ…¡, in which chitosan and IHA were supported on NaCl modified clinoptilolite, has bigger adsorbt capacity, and the adsorption effect is better when the Cr(VI) concentration is 100mg/L.Langmuir and Freundlich isotherms were developed to describe Chromium (VI) adsorption onto composite adsorbents, and the experimental results were excellently described by Freundlich isotherm. The results demonstrate that the modified clinoptilolites are good adsorbents to remove Cr(VI).Compared with NaCl modified clinoptilolite, the composite adsorbents have a faster adsorption speed, a better adsorbability and a lower cost for Cr(VI) removal. The results show that the composite adsorbents are the new materials which have relatively large adsorption spaces. So they have great application potential in wastewater treatment.