A Novel Biosorbent Lagenaria vulgaris Shell - ZrO2for the Removal of Textile Dye From Water.

A new biosorbent, abbreviated as LVB-ZrO2, was synthesized by chemically modifying Lagenaria vulgaris shell with ZrO2. The removal of textile dye RB19 from aqueous solution by LVB-ZrO2was studied. Characterization by SEM, FTIR and XRD confirmed the chemical modification of the biomaterial, which showed significant improvement of removal efficiency compared with unmodified Lagenaria vulgaris shell. LVB-ZrO2point of zero charge is 5.49. The biosorption process is highly pH dependent and the optimal pH is 2.0, at which complete dye removal was attained. The results are the best by a pseudo-second order kinetic model. The optimal adsorbent dosage is 4 mg/dm³.The RB19 biosorption follows the Langmuir isotherm model (R² = 0.9978), with the maximum sorption capacity of 75.12 mg/g. LVB-ZrO2is a mechanically stable, easy to synthesize, cost-effective, biocompatible and environmentally-friendly biosorbent with the high potential for the removal of RB19 from aqueous solution.

Identification of intermediates and ecotoxicity assessment during the UV/H2O2 oxidation of azo dye Reactive Orange 16.

Degradation of azo dye Reactive Orange 16, a widely used textile dye, was carried out with UV light in the presence of H2O2. The experiments were conducted in the batch mode using low-pressure mercury lamps, emitting at 253.7 nm. Liquid-chromatography tandem mass spectrometry (LC/MS/MS) and high resolution mass spectrometry (FT-ICR) were employed in order to identify some of degradation products as well as to suggest possible degradation pathways. According to the mass spectrum characterization of RO16 dye and MS(n) fragmentation (up to MS(4)), its possible fragmentation pattern was proposed. The results revealed that degradation occurred mainly via hydroxylation, cleavage of the C‒S bond between the aromatic ring and the sulfonate group, cleavage of the azo bond, cleavage of the C‒N bond between azo group and naphthalene ring and aromatic ring opening. Toxicity test with marine photobacterium Vibrio Fisheri was performed to consider whether or not the UV/H2O2 treatment of RO16 dye results in the products with enhanced toxicity for aquatic life.