Study the adsorption of methylene blue dyes by polyvinyl alcohol/activated carbon composite hydrogel beads.
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Date
2019-06
Authors
Nurul Atikah Binti Saifulqahar
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Abstract
Water pollution is one of the most undesirable environmental problems in the world and it requires solutions. Textile industries produce a lot of wastewater, which contains a number of contaminants, including acidic or caustic dissolved solids, toxic compounds, and any different dyes such as methylene blue (MB). The aim of this project is to study the adsorption of MB dyes on polyvinyl alcohol/activated carbon (PVA/AC) composite hydrogel beads. Various physiochemical parameters such as, initial concentration, contact time and adsorbent dosage were investigated in a batch adsorption technique. PVA hydrogel beads and PVA/AC composite hydrogel beads were prepared by the dropping method. The hydrogel beads were employed as adsorbents for removal of MB from aqueous solutions. The removal efficiency for PVA/AC was found to be higher at 80.24% compared to PVA hydrogel beads which is only 46.72% at the initial MB concentration of 10 mg/L. The equilibrium data were evaluated using Langmuir, Freundlich and Temkin isotherms. The Freundlich model best described the uptake of MB dye, which implies that the adsorption of textiles dyes in this study onto composite hydrogel beads is heterogenous with multi-layers. The multi-layer maximum adsorption capacity of MB onto PVA/AC was 0.19 mg/g while for PVA only 0.08 mg/g. In addition, kinetic studies of adsorption onto composite hydrogel beads best fit by pseudo-first order kinetic models. Hence, the PVA hydrogel beads and PVA/AC composite hydrogel beads can be potentially used for the removal of MB dyes from wastewater.