Abstract
Background: At present scenario, there is the global issue due to the environment pollution caused by waste effluent bearing organic dyes such as Methyl Violet (MV) while getting mixed into the surface water. Such organic dye uses in industries like textile, paper, leather, food, pharmaceutical, cosmetics etc. is extensive leading to increase the contamination level and therefore, the removal of above dye is warranted by adopting suitable adsorbent to minimize the level of contamination. Present investigation accomplishes the study on removal of Methyl Violet (MV) dye from aqueous solution using low cost bioadsorbent as activated Phragmites karka (APK).
Methods: The adsorbent APK was derived from Phragmites karka (PK) by charring with 25 % H2SO4 appears to be effective while enhancing MV loading efficiency than PK without activation. Operating variables such as contact time (1- 300 min), dye concentration (100-500 ppm), pH (2-11), sorbent dose (0.25-5.0 g) and temperature (293-333K) affecting to the adsorption of MV were studied. Adsorption Iso-therm, thermodynamics and kinetics are studied to ascertain the mechanism for the adsorption of MV on to APK.
Results: Phase characterization study results of APK, MV loaded APK, and MV by FTIR and UV-VIS, respectively, ensured the adsorption process and mechanism. The maximum adsorption capacity of APK was resulted as 371.6 mg/g at ambient condition. The value of separation factor (RL) from Langmuir equation and Freundlich constant (n) indicated on favorability of adsorption. Positive value of ΔHo (4.9 kJ mol-1) indicated that adsorption was of endothermic and the negative value of ΔGo confirmed about feasibility of dye adsorption. Kinetics result revealed that adsorption of MV is of pseudo second-order ascertaining the chemisorptions type.
Conclusion: The adsorption of MV with APK was critical with the influence of time, temperature and pH. The pH of the solution affects the surface charge of the adsorbent and the degree of ionization of adsorbate and adsorption was efficient at merely neutral pH range (pH-6.0). The adsorption of MV was also enhanced while increasing APK dose as well as initial MV concentration. Experimental equilibrium data showed best fit with Freundlich isotherm and Thermodynamic data showed the relevance on favoring the adsorption process. The present investigation ensured that APK can be used as an effective adsorbent while applying on purification of contaminated water / process aqueous solution.
Keywords: Activated bio-adsorbent, adsorption, APK, isotherm, kinetics, methyl violet (MV).
Graphical Abstract
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