The Ultraviolet Absorptions Of Coastal Seawater Of China, COD Direct Determination Of Seawater By Ultraviolet Spectrophotometry And As (v) Removal With Chitosan As Adsorbent

The ultraviolet absorptions of coastal seawater of China , COD direct determination of seawater by ultraviolet spectrophotometry and the removal of the soluble As( v ) with chitosan as adsorbent were studied in this paper. 1. The ultraviolet absorptions of coastal seawater of China and COD direct determination of seawater by ultraviolet spectrophotometryUltraviolet absorption is an important character of seawater. It is not found that the ultraviolet absorptions of coastal seawater of China has been determined.The ultraviolet absorption of hundreds of seawater samples from the Bohai Sea, the Northern Yellow Sea, Jiaozhou Bay, the East China Sea, the estuary of the Yangtse River,the South China Sea and the estuary of the Zhujiang River were determined by ultraviolet spectrophotometry. Because of the result of photochemistry, chemistry, wave, tide and ocean current, the reductive matter such as organic contamination is distributinged rather equality in seawater. The results show that all the absorption peaks appear between 200 and 220 nm. Or, to be more exact, appear between 208 and 220 nm for samples from the Bohai Sea, northern Yellow Sea and Jiaozhou Bay, and at about 205 nm for samples from the other waters. Thus it can be seen that similarly reductive matter exists in different sea area, which puts up the similar ultraviolet absorption.It is found that the results have a good linear relation, which indicates that the two methods have little difference in this regard.Ultraviolet spectrophotometry presents the practical dates and a simpler method to determine the waste in water, which realizes UV monitoring and reflect the organiccontamination in seawater samples. 2. As( v ) removal by adsorptionThe adsorption of soluble As( v ) with three adsorbents, chitosan powder, chitosan sphere, chitosan-active carbon sphere and the influence of pH, temperature, time and ionic strength to adsorption were studied in this paper.It is found that the adsorption of three different adsorbents has resemblance: the best pH is between 3.5 and 5.0, and adsorption quantity decreases with the increase of ionic strength and temperature. The adsorption curve preferably accords with Langmuir isotherm, and partition coefficient falls with the increase of temperature, which indicates that heat is given out in the course of adsorption, so the increase of the temperature is beneficial to desorption while not to adsorption. In the meanwhile, the chitosan sphere and chitosan-active carbon sphere can be reused repeatly without the reduction of adsorption quantity. However, the three adsorbent have also some differences. The saturated adsorption quantity of chitosan powder is 14.77mg/g on conditions of pH = 5.0, 25, 1 = 0. The saturated adsorption quantity of chitosan sphere is 24.94mg/g on conditions of pH=4.5, 20, 1=0. On conditions of pH=4.0, 20, 1=0 and a 53.76% chitosan percentage, the saturated adsorption quantity of chitosan-active carbon sphere is 22.17mg/g, while it can account to 41.24mg/g when calculated with chitosan of the equal mass.The chitosan is inartificial adsorbent, which has the point of innocuity and supernal security. It especially suits to As( v) removal in foodstuff industry.