THE COMBINED EFFECT OF HYDROGEL TYPE AND ACCOMPANYING CATION ON CHLORIDE TRANSPORT IN A SATURATED SANDY LOAM SOIL

Abstract

Chloride (Cl-) transport in soil can be affected by amendments such as sodium polyacrylate (SAP) and polyacrylamide (CLP). Four levels (0.0, 0.1, 0.3 and 0.5% w/w) for either SAP/CLP were mixed with sandy loam soil then packed in PVC columns (25 cm - long and 4.5 cm - inner diameter). Breakthrough curves (BTC) were established using a replacement fluid of either potassium or calcium chloride at a concentration of 0.1 molar under a head pressure of 2 cm then described using the program of CXTFIT. The dispersion (D), dispersivity (α), and retardation coefficient (R) of Cl- were obtained by the program. The CXTFIT described the observed data of BTC well with a determination coefficient of more than 0.97. According to the dispersivity criteria, all the studied treatment possessed a preferential flow, but the CLP 0.5% treated soil using CaCl2 soil had a matrix flow/dispersive flow. The reported results of average pore-water velocity (v), D), and α decreased significantly as the rates of both hydrogels increased. Contradictory, the observed complete breakthrough times and R increased significantly as the rates of both hydrogels increased. This time was longer using the KCl replacement solution than using that of the CaCl2 solution. It is obvious that using CaCl2 with CLP-treated soils was vital for reducing the dispersion coefficient and boosting the retardation coefficient. The use of hydrogel appears to be a good option for controlling leaching of such a compound. The results of the present work might be a platform towards controlling and managing the water resource contamination by nonorganic or organic compounds.