Photocatalytic degradation of Eosin B dye in aqueous solution by cadmium oxide nanoparticles

Cadmium oxide (CdO) and potassium (K) doped CdO nanoparticles (NPs) were synthesized by the chemical co-precipitation method and were used as photocatalysts for the degradation of Eosin B dye. The X-ray diffraction results presented that the crystallite size of undoped CdO and K doped CdO NPs were 43.74 and 42.31 nm, respectively. The morphological study and percent composition of synthesized undoped CdO and K doped CdO NPs was done by scanning electron microscope and energy dispersive X-ray analysis. The formation of NPs was confirmed by Fourier transform infrared spectroscopy. The precursor decomposition to CdO after annealing at ∼500 °C was studied by thermogravimetric analysis. The undoped CdO and K doped CdO nanoparticles degraded about 80% and 90% of the dye, respectively, in 140 min. The maximum degradation efficiency of the dye was achieved at a pH of 4, dye initial concentration of 15 ppm, catalyst dose of 20 mg, and a temperature of 45 °C. The degradation efficiency observed for recovered undoped CdO and recovered doped CdO nanoparticles was found to be 63% and 77%, respectively.

Effective Removal of Amido Black and Eosin B Dyes in Aqueous Solution by MWCNT/ZrO2/Pb Nanocomposites: Isotherm, Reusability and Kinetic Studies

This research illustrates modification of multi-walled carbon nanotubes (MWCNT) by ZrO2/Pb to construct nanocomposites (MWCNT/ZrO2/Pb-NCs) by simple precipitation technique and subsequently examine its ability for adsorption of Amido black (AB) and Eosin B (EB) dyes in binary system. The present nanocomposites investigation by FESEM, XRD, FTIR, and EDX analysis, reveal its as-synthesized crystalline nature with cubic morphology and average particle size 30–50 nm. The present nano-adsorbent represent high efficiency for AB and EB adsorption from aqueous solution, while dependency of variables including pH, initial concentration of dyes, contact time and MWCNT/ZrO2/Pb-NCs mass were analyzed by central composite design (CCD). The predicted maximum removal percentage was 95% removal for both dyes is consequence of adjustment of operational conditions at pH of 6.0; 0.05 g MWCNT/ZrO2/Pb-NCs; 15 min stirring at 15 mg L-1 for both dyes. The Langmuir as applicable for representation and description of reveal data of adsorption with adsorption capacity of 15.46 and 16.92 mg g-1 for AB and EB, respectively. Pseudo-first order model owing to its high correlation coefficient and closeness of experimental and theoretical data well represented behavior of corresponding adsorption system. Mechanism examination strongly proof high contribution of external mass transference as the main rate-controlling step. The successful regeneration of MWCNT/ZrO2/Pb-NCs suggested their usefulness in wastewater treatment and its ability of environmental management.

Synthesis of metal–organic frameworks (MOFs) MIL-100(Fe) functionalized with thioglycolic acid and ethylenediamine for removal of eosin B dye from aqueous solution

The interaction of eosin B dye from aqueous solution with MIL-100(Fe) and functionalized MIL-100(Fe) metal–organic frameworks (MOFs) is reported in this study. MIL-100(Fe) was prepared and functionalized with thioglycolic acid (TH) and ethylenediammine (ED) separately by incorporating the thiol (–SH) and the amine (–NH2) group of the functionalizing agents into the open metal sites of the MIL-100(Fe) to obtain the acidic (TH-MIL-100) and basic (ED-MIL-100) forms of the MOF respectively. Characterization of the MOFs was done by melting point analysis, elemental analysis, spectroscopic techniques, scanning electron microscopy (SEM), and powdered X-ray diffraction (PXRD) analysis. The adsorption experiments were carried out at different conditions such as pH, adsorbent dosage, contact time, temperature, and initial concentration of the dye to estimate the optimum conditions and the maximum adsorption capacities. Adsorption capacities were observed to increase in the order of ED-MIL-100 < MIL-100 < TH-MIL-100, while the TH-MIL-100 was the most effective in the removal process due to acid–base interaction between the acidic thiol group (–SH) and the alkaline medium of eosin B dye solution. The Langmuir Isotherm was seen to fit well to adsorption data obtained for all three adsorbent materials studied, and adsorption processes followed the pseudo-second order kinetics. This study, therefore, indicates the suitability of functionalization of MIL-100(Fe) towards improving its adsorption capacity.

Protoenzymes: The Case of Hyperbranched Polymer-Scaffolded ZnS Nanocrystals

Enzymes are biological catalysts that are comprised of small-molecule, metal, or cluster catalysts augmented by biopolymeric scaffolds. It is conceivable that early in chemical evolution, ancestral enzymes opted for simpler, easier to assemble scaffolds. Herein, we describe such possible protoenzymes: hyperbranched polymer-scaffolded metal-sulfide nanocrystals. Hyperbranched polyethyleneimine (HyPEI) and glycerol citrate polymer-supported ZnS nanocrystals (NCs) are formed in a simple process. Transmission electron microscopy (TEM) analyses of HyPEI-supported NCs reveal spherical particles with an average size of 10 nm that undergo only a modest aggregation over a 14-day incubation. The polymer-supported ZnS NCs are shown to possess a high photocatalytic activity in an eosin B photodegradation assay, making them an attractive model for the study of the origin of life under the “Zn world” theory dominated by a photocatalytic proto-metabolic redox reaction network. The catalyst, however, could be easily adapted to apply broadly to different protoenzymatic systems.

A Study of Synergy of Combination of Eosin B with Chloroquine, Artemisinin, and Sulphadoxine-Pyrimethamine on Plasmodium falciparum In Vitro and Plasmodium berghei In Vivo

Background and Objectives. Artemisinin is the popular antimalarial medication, but it has to be used in combination with other drugs as its monotherapy causes resistance. The effectiveness of eosin B, a laboratory stain, as a competent antimalarial agent was identified earlier. It was tested in combination with different antimalarial drugs such as artesunate (a derivative of artemisinin) or chloroquine or sulphadoxine-pyrimethamine in vitro on Plasmodium falciparum and in vivo on Plasmodium berghei using Peter’s suppression test. Methods. Drug assessment was carried out singly or in combination on Plasmodium falciparum in vitro using the candle jar method at three inhibitory concentrations. Percent parasitemia of live cells was obtained by microscopic counting. Peter’s suppression test was carried out on mice infected with Plasmodium berghei after 3 administration of the drugs singly and in combination, and parasites were counted by microscopy for 10 days. Results. Synergy was exhibited by isobolograms of eosin B combined with artesunate and sulphadoxine-pyrimethamine with more than 10 fold reduction of all drugs in vitro. A good combination index was obtained with artesunate at 50% inibitory concentration with 3.4 nM eosin B and 1.7 nM artesunate in contrast to 124 nM eosin B and 7.6 nM artesunate singly. In vivo studies also showed a considerable lowering of the effective dose of eosin B 30 mg/kg: artesunate 3 mg/kg with 200 mg/kg eosin B and 60 mg/kg artesunate separately. Sulphadoxine-pyrimethamine seemed to have the greatest synergistic effect with a combination index of 0.007, but this could be due to it consisting of a combination of three drugs. Eosin B’s combination index with chloroquine was fair, and in vivo tests too did not show as much competence as the other two drugs. Conclusion and Interpretation. It can be concluded that eosin B can be used in combination with antimalarial drugs with favorable results.