M. A. Islam
Department of Chemistry, University of Rajshahi, Rajshahi-6205, Bangladesh
S. Sarker
Department of Chemistry, University of Rajshahi, Rajshahi-6205, Bangladesh
M. S. Nasri
Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh
M. A. Hoque
Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi-6205, Bangladesh
M. S. Islam
Department of Chemistry, University of Rajshahi, Rajshahi-6205, Bangladesh
M. N. Islam
Department of Chemistry, University of Rajshahi, Rajshahi-6205, Bangladesh
Electrical conductivity; pH; Surface water pollution; Surfactant mitigation; Vermicompost.
Rajshahi University campus in Rajshahi, Bangladesh.
Risk Management in Agriculture
Water pollution, Vermicompost and vermiculture
Sodium dodecyl sulfate (SDS, purity, 99 %), methylene chloride (purity, 99.9 %), tin(II) chloride (purity, 97%), NaOH (purity, 98 %), NaCl (purity, 99 %), H2SO4 (purity, 98 %), KH2PO4 (purity, 99.5 %), HCl (purity, 37 %), were procured from Loba Chemie Private Limited, India. Methylene blue (purity, 98.9 %) was obtained from Merck, Darmstadt, Germany. All the chemicals were used without further purification. Redistilled and deionized water was used for solution preparation. Working solutions were prepared by sequential dilution of each standard solution with ultrapure water. Soil sample was collected from non-cultivated area of Rajshahi University campus in Rajshahi, Bangladesh. The samples taken from the upper 15 cm soil layer were air-dried, ground and sieved through 2-mm sieve to increase the uniformity of the experiment and preserved in a polyethylene plastic packet. The particle size distribution of the used soil was 42.01 % silt, 44.04 % sand and 13.94 % clay with texture grade of sandy loam. Vermicompost were collected from a home-based farm situated in Chapainawabganj district in Bangladesh. The moisture contents of soil and vermicompost were 20.67 % and 75.28 % respectively. The potentiality of vermicompost on surfactant removal was studied using six trials with different proportions of soil, vermicompost and phosphate keeping the surfactant concentration constant. The change in the physicochemical properties of the samples was monitored by measuring surfactant concentration, pH and conductivity for nine days. Six experimental trials T0, T1, T2, T3, T4 and T5 were constructed in 3 L glass bottles among which T1, T2, T3, T4 and T5 were considered as simulated ponds and T0 as control. The ratio of surfactant (Surf.) to phosphate (P) concentrations was chosen from the recent report on Surf Excel composition [9] and the ratio of soil to vermicompost (VC) was chosen from the report on the potentiality of organic fertilizers on phosphorous management. A standard method [10,11] was used for the estimation of surfactant content using UV- visible spectrophotometer, where methylene blue was used as cationic dye and methylene chloride as organic solvent. The methylene blue complexing solution of 100 mL in redistilled and deionized water was prepared by well mixing 3 mL of 1000 mg/L methylene blue stock solution, 4 mL of 3 M sulphuric acid solution and 5 g of KH2PO4.H2O. 100 mL of washing solution was made by adding 0.7 mL of concentrated sulphuric acid and 5 g of KH2PO4.H2O in redistilled and deionized water. All sample solutions were diluted 50 times before analysis and the SDS standard solutions (1, 5, 10, 20, 30 and 40 mg/L) from 100 mg/L standard SDS stock solution were prepared in redistilled and deionized water. Then 2 mL of diluted sample solution from each trial or SDS standard solution was taken in a vial. The pH of the solution was adjusted to 8.3 by adding drop wise sodium hydroxide or hydrochloric acid solution. To the solution, 0.5 mL of the methylene blue complexing solution and 2 mL of methylene chloride were added and the vial was immediately closed with the cap tightly. The solution was shaken for 20 sec. The anionic surfactant present in standard SDS solutions or trial solubilized in organic solvent through complex formation with the positively charged methylene blue by electrostatic interaction. The contents in the vial were allowed to stand for phase separation and the organic phase was collected into another vial using a long-tip pasteur pipette with a rubber bulb. For complete transfer of methylene blue- surfactant complex from aqueous phase to organic phase, three more extractions were performed using 2 mL of methylene chloride each time. The extracted organic phase was washed once with 5 mL of washing solution and the tracer of the methylene blue- surfactant complex in the washing solution was extracted with 2 mL of methylene chloride. The extracted organic phase was transferred to a 10 mL volumetric flask and made up to mark by methylene chloride. The organic phase was then analyzed by UV- visible spectrophotometer at 652 nm. A Shimadzu UV-1800 UV-visible spectrophotometer was used for UV-visible absorption measurement. pH of the supernatant liquid of the trials was measured with the help of pH meter (Hanna Instruments, HI 2211). Before using, pH meter was calibrated according to manufacturer's instructions using the buffer at pH 4.00 and 7.00 buffer. The conductivity was measured by a conductivity meter (Jenway Conductivity Meter 4310). The conductivity meter was calibrated and cell constant was determined with 0.1 M and 0.01 M standard KCl solution.
J. Sci. Res. 12 (3), 411-417 (2020)
Journal