Search

Rice straw is the most abundant agricultural waste material in Thailand. Therefore, this research was interested in utilizing rice straw and adding value by preparing a reactive dye bio adsorbent. The aims of this research were to prepare rice straw nonwovens by the wet-laid process, study chitosan-coated nonwovens by the dip coating method, and evaluate the reactive dye adsorption capacity of the coated nonwovens. The ratio of weight per unit area of the prepared nonwovens was controlled. The nonwovens were dipped in chitosan solutions (0.5, 1, and 1.5 wt% of chitosan) to prepare chitosan-coated nonwovens. Reactive dye adsorption capacity, chemical structure, morphology, and physical properties of the nonwovens were investigated. It was found that rice straw nonwoven coated with chitosan increased in thickness, hardness, and water resistance properties with increasing chitosan concentration. Chitosan-coated nonwoven, at 15% chitosan concentration and a contact time of 72 hours, was able to adsorb 38.40% of the reactive azo dye, C.I. Reactive Blue 194 (50 mg/L). The dye absorbency of the chitosan-coated nonwovens increased with the increase in the chitosan-coated concentration and the contact time. In addition, the chitosan-coated nonwovens could remain on rice straw cellulose nonwoven surfaces under reactive dye immersion for at least 72 hours without change. The results indicated that rice straw nonwovens coated with chitosan by the dip coating method had reactive dye adsorption abilities. [ABSTRACT FROM AUTHOR]

Wastewater released from textile and dye-based industries is one of the major concerns for human and aquatic beings. Biological decolorization using ligninolytic bacteria has been considered as an effective and alternative approach for the treatment of dyeing wastewater. This study aimed to assess the isolation, characterization and application of soil bacteria isolated from mangrove wetlands in Thailand. Four active bacteria were genetically identified and designated as Klebsiella pneumoniae strain RY10302, Enterobacter sp. strain RY10402, Enterobacter sp. strain RY11902 and Enterobacter sp. strain RY11903. They were observed for ligninolytic activity and decolorization of nine reactive dyes under experimental conditions. All bacteria exhibited strong decolorization efficiency within 72 h of incubation at 0.01% ( w / v ) of reactive dyes. The decolorization percentage varied from 20% (C.I. Reactive Red 195 decolorized by K. pneumoniae strain RY10302) to 92% (C.I. Reactive Blue 194 decolorized by Enterobacter sp. strain RY11902) in the case of bacterial monoculture, whereas the decolorization percentage for a mixed culture of four bacteria varied from 58% (C.I. Reactive Blue 19) to 94% (C.I. Reactive Black 1). These findings confer the possibility of using these bacteria for the biological decolorization of dyeing wastewater., Competing Interests: The authors declare no conflicts of interest.