RESUMEN
The existing methods for reclamation of saline-sodic soils are expensive, time-consuming, and require skilled engineering approaches. Therefore, new and fast techniques should be developed for the reclamation of these soils. This study was undertaken to evaluate if harvesting excessive salts via the soil with ammonium hexacyanoferrate (II) (AH) and ammonium perchlorate (AP) [0, 10, 20 and 40 mmol kg-1] is possible through dendritic crystal growth above the soil surface. Application of crystallization inhibitors increased the concentration of salts on the outer surface and thereby increased pHe at the top of the soil. Whereas the pHe of 0-5 cm layers were obtained as 7.30, 7.36 and 7.84, it increased to 9.94, 9.84 and 8.45 in 15-20 cm layers with 10, 20 and 40 mmol kg-1 AH application doses, respectively. Except for 5-10 cm of control and 10 mmol kg-1 AP application, the lowest pHe values were obtained from the 0-5 cm and gradually increased from bottom to top. For all AH and AP application doses, the highest electrical conductivity (ECe) values were obtained from the 15-20 cm and significantly increased from bottom to top. Application of AH and AP have transformed exchangeable Na+ to water-soluble Na+ and this situation has caused an increase in the concentration of water-soluble Na+ throughout the soil column. AH and AP applications have decreased exchangeable sodium percentage (ESP) in all of the layers. Whereas the ESP of control was 70.07% in 0-5 cm layer, it decreased to 62.44, 55.63 and 53.76% with 10, 20 and 40 mmol kg-1 AH application doses, respectively. Similar decreases were obtained for 5-10, 10-15 and 15-20 cm layers. Results obtained have shown that application of AH and AP to saline-sodic soil is an effective reclamation material to remove salts from soil surface within a short time, particularly in arid climates.
Asunto(s)
Compuestos de Amonio , Suelo , Sales (Química) , Sodio/química , Suelo/química , Agua/análisisRESUMEN
A flexible and free-standing graphene-based hybrid paper was successfully fabricated by successive applications of vacuum filtration and electropolymerization. First, a suspension including graphene oxide (GO) and silver nanoparticles (AgNPs) was prepared, and GO/AgNPs paper was obtained by vacuum-filtration of this suspension through a membrane. This GO/AgNPs paper was transformed to rGO/AgNPs paper by using both chemical reduction with HI and thermal annealing procedures. rGO/AgNPs/poly(PyY) hybrid paper electrode was formed by electropolymerization of Pyronin Y (PyY) on rGO/AgNPs paper electrode from a PyY monomer-containing (pH 1.0) solution. Structural, chemical, and morphological characterization of this hybrid paper was carried out by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, infrared spectroscopy, UV-vis absorption spectroscopy, four-point probe conductivity measurement, and cyclic voltammetry techniques. Electrooxidation of nitrite on rGO/AgNPs/poly(PyY) hybrid paper electrode has been achieved at 860 mV with a linear range of 0.1-1000 µM, sensitivity of 13.5 µAµM(-1)cm(-2), and a detection limit of 0.012 µM. Amperometry studies have shown that the hybrid paper electrode is suitable for amperometric determination of nitrite in both standard laboratory samples and real samples. Moreover, this paper electrode selectively detects nitrite even in the presence of 100-fold common ions and exhibits an excellent operational stability and good flexibility.