Sulfite Activation by Glucose-Derived Carbon Catalysts for As(III) Oxidation: The Role of Ketonic Functional Groups and Conductivity

In this study, a series of glucose-derived carbon catalysts were developed and applied for the activation of sulfite for the oxidation of As­(III). The process of sulfite activation with the carbon catalysts is based on the production of oxysulfur free radicals such as SO3•–, SO5•–, and SO4•–. The factors responsible for the sulfite activation performance of carbon catalysts are conductivity and ketonic functional groups. A complex is formed between the sulfite and carbon catalysts, and the electron transfer that takes place within the complex leads to the generation of semiquinone and oxysulfur radicals, and finally, the oxysulfur radicals are converted into SO4•– by means of O2, which results in the As­(III) oxidation. The efficiency of the sulfite/carbon system is enhanced under normoxia conditions due to the reversible transformation cycle occurring among CO/C–O•/C–OH triads. The present study is of great environmental significance as sulfite is a source of SO4•– generated, and the activation is achieved by a metal-free carbon material, which makes the process viable and environmentally friendly

Cardanol and bisphenol-F based benzoxazines with zirconium phosphate reinforced composites coating for protecting the mild steel surface from corrosion

The present work is to develop and characterize the benzoxazines from cardanol and bisphenol-F with imdazole core based amine in order to utilize them in the form of (50/50 wt%) blended composites coating for corrosion resistance application. The benzoxazine blends were reinforced with varying weight percentages of (0.5, 1, 1.5, 2.0 and 2.5 wt%) of 3-glycidoxypropyltrimethoxysilane (GPTMS) functionalized zirconium phosphate (ZrP) to obtain respective composites blended coatings. The thermal stability of composites was studied by thermogravimetric analysis (TGA). In order to ascertain their hydrophobic behavior the water contact angle studies were carried out and the values obtained for 0.5, 1, 1.5, 2.0 and 2.5 wt% GPTMS functionalized ZrP reinforced (50/50 wt% of C-ima/BF-ima) benzoxazines blended composites are 114,116,117,119,120 and 123° respectively. The UV shielding behavior of ZrP reinforced polybenzoxazine blended composites material was also studied by UV-Vis spectroscopic technique and the results obtained infer that these materials possess good UV shielding behavior. ZrP reinforced benzoxazine blended composites were coated on the mild steel specimens and their corrosion resisting behavior was studied. Results of Nyquist plot and Tafel plot, ascertain that among the coated specimens, the specimen coated with 2.5 wt% ZrP reinforced poly(C-ima/BF-ima) blended composites exhibits highest corrosion resisting efficiency.</p