Adsorption of methylene blue from industrial effluent using poly (vinyl alcohol

The application of poly (vinyl alcohol) (PVA) in an unmodified form as an adsorbent for methylene blue (MB) dye removal in waste water at 303–333K was investigated. Effects of operational parameters such as adsorbent dosage, initial dye concentration and pH were determined for optimum conditions for maximum dye removal. Results obtained showed that dye removal efficiency increases as the amount of adsorbent increased. Lowest initial dye concentration and at pH of 4.0 gave maximum adsorption of MB onto PVA. Adsorption parameters were found to fit well into Langmuir, Freundlich and Temkin adsorption isotherm models with correlation coefficient (R2> 0.95) in the concentration range of MB studied. Adsorption kinetics studies revealed that pseudo-second order provided the best fit to experimental data compared with pseudo-first-order model. Thermodynamic parameters revealed that the adsorption process was non-spontaneous and exothermic with an orderly mixing adherence of the dye molecules on the adsorbent surface