Journal of Food, Agriculture and Environment

The effect of calcium and sodium chloride levels on the dehydration power of hydrophilic polymer 

Author(s):

Mahdi Ramezani ¹ *, Mohammad Jafari ², Ali Tavili ², Seyed Akbar Javadi ¹, Qhavamodin Zahedi Amiri ²

Recieved Date: 2012-07-28, Accepted Date: 2013-04-16

Abstract:

Hydrogel or super absorbent of moisture is intelligent polymer that has the ability to absorb and retain water (moisture) and could contain water and some liquid fertilizers, for returning it back to the soil in a long period of time, and  this process helps plant growth and reduces water loss and irrigation costs. One of the important issues of these polymers is the effect of different salts on the change of their dehydration power during the time. Accordingly, in the present study, the expected changes of dehydration of the two polymer kinds due to the type and the viscosity of soil salts were tested. In order to evaluate the amount of polymer dehydration in condition of soil salts, the process of dehydration change at different times of dewatering and drying was studied with the salts of NaCl and CaCl₂ containing mono and bivalent cations of sodium and calcium with concentrations of 290, 1700 and 2000 mg/L and their electrical conductivities  (respectively 0.5, 2.5 and 3.5 dS/m) were measured. Polymer (1.0 g) was added to per litre of the above mentioned solutions in four replications. Considering that the maximum polymer dewatering is obtained after 24 h , the samples were left for a day until the polymer added to the saline solution reaches the maximum dewatering. The used polyacrylamide polymer, with the commercial brand of A200, was purchased from the commercial firms of Iran Polymer Research Center. Another experiment was done in one time to study silicate polymer dehydration in the same way. The polymer gels saturated with salt water were placed over a very fine sieve for an hour to remove all the water that was not absorbed by the polymer from the sieve. The remaining polymer gel on the sieve was weighed with the accuracy of 0.01 g. Based on the findings, in the first dehydration, each gram of Iranian made commercial  polyacrylamide polymer absorbs 183.65 g distilled water. The dehydration of this polymer, with the water having 290, 1700, 2000 mg of salts (CaCl₂ and NaCl ), is with  NaCl 47, 68 and 70%, respectively,  and with  CaCl₂  74, 91 and 91% lesser than the dehydration with distilled water. After 3 times drying the polymer saturated from the distilled water and redehydration, finally polymer ability was decreased for dehydration with the distilled water and NaCl was reduced 51, 69 and 71% and with CaCl₂ was reduced 80, 92 and 92% lesser than the fourth times of the dehydration. The destructive effect of monovalent sodium cation on the polymer dehydration was lesser than with  divalent calcium cation and the dehydration level of silicate polymer was low against the polymer A200 (in 130 g of silicate, only 40 g was absorbed). 

Keywords:

Hydrogel, polymer A200, silicate, CaCl₂, NaCl, dehydration

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Journal: Journal of Food, Agriculture and Environment
Year: 2013
Volume: 11
Issue: 2
Category: Environment
Pages: 896-898

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