Transformation of Schwertmannite to erdite nanorod via an alkaline dissolution–recrystallization process for the effective adsorption of oxytetracycline

Schwertmannite (schw) is a common Fe-bearing mineral in the precipitation of mine wastewater and/or steel pickling wastewater. It could be easily converted to goethite and hematite via heating or hydrothermal treatment and could be used as adsorbent to remove contaminants from wastewater. Herein, the spherical schw was converted into erdite nanorod by a simple hydrothermal method with the addition of Na2S. Schw was spherical particle with a size of 0.4–1.5 [Formula: see text]m. After treatment, it was converted to erdite nanorod particles with 100 nm diameter and 200 nm length. By adding MnO2 at the MMn/Fe ratio of 1, erdite nanorod grew radially to 1–1.5 [Formula: see text]m, whereas MnO2 was reductively dissolved and recrystallized to rambergite. In the absence of Fe, MnO2 was directly transformed to octahedral alabandite. The product EN-0, prepared without MnO2, showed the optimal qmax of oxytetracycline (OTC, 7479.6 mg/g), which was 12 times that of schw. In OTC-bearing solution, erdite was unstable and automatically hydrolyzed to generate Fe–SH/Fe–OH-bearing flocs, and it exhibited abundant surface functional groups for OTC adsorption. Subsequently, the hydroxyl and amino groups on the side chain of OTC would also be complexed with the Fe–SH group to generate an OTC–Fe–S ligand, in the form of flake-like particles with a smooth surface. The formed Mn-bearing minerals, for example, rambergite and alabandite, also complexed with OTC as OTC–Mn–S ligands to form quadrangular prism with shoulder and length of 10 [Formula: see text]m and 20–100 [Formula: see text]m, respectively. Spherical schw was converted into a well-crystallized erdite nanorod with the addition of MnO2, and the product showed potential applications in OTC-bearing wastewater treatment.

Preparation and Characterization of Mesoporous Silica from Bagasse Bottom Ash from the Sugar Industry

A novel and sustainable process to recycle an environmentally injurious material rich in silica—waste bagasse bottom ash from the sugar industry—into mesoporous pure silica of high purity is reported. Bagasse bottom ash (BBA) is a major byproduct of the sugar industry, with very inadequate recycling possibilities due to environmentally detrimental pollutants, whose production is dramatically increasing. In this study, for the first time, more than 70% of the silica from the bottom ash could be extracted for the synthesis of mesoporous silica using a low-temperature alkaline dissolution method instead of the customary elevated-temperature process. Furthermore, the process of dissolution was thoroughly studied to obtain the essential insight into silica hydrolysis that is largely missing from the existing research literature. Under alkaline conditions, the hydrolysis of silica is hindered due to the formation of zeolites and protective layers around the etching particles. This layer becomes a protective barrier that hinders the mass transfer of silica monomers to the solution, thus halting the dissolution process. Therefore, sequential extractions with optimized conditions of 100 °C for 72 h were employed to attain maximum silica extraction efficiency.

DEVELOPMENT AND CHARACTERIZATION OF NOVEL HERBAL FORMULATION (POLYMERIC MICROSPHERES) OF SYZYGIUM CUMINI SEED EXTRACT

Objective: The purpose of the present investigation was to develop and characterize a novel herbal formulation (polymeric microspheres) of Syzygium cumini seed extract.Methods: The extract-loaded microspheres using biological macromolecule ethyl cellulose (EC) was prepared by o/w emulsion solvent evaporation technique using polyvinyl alcohol (PVA) emulsifier. The effect of various process and formulation variables (stirring speed, evaporation time, drug/polymer ratio and organic/aqueous phase ratio) on the properties of microspheres was evaluated.Results: Micromeritic properties indicated good flow properties, and scanning electron microscopy (SEM) confirmed the spherical nature of the prepared microspheres. The particle size and entrapment efficiency were varied between 34.25 to 176.25 µm and 10.51 to 42% depending upon the variables. All the formulations showed minimal drug release in an acidic environment (pH 1.2) confirming the prevention of drug release in the stomach and enteric nature of the polymer. Sustained drug release has been observed in alkaline dissolution media (pH 7.4) after 12 h of drug release study except for formulation F7 which contains a lower concentration of polymer. The fourier transform infrared spectroscopy (FTIR) analysis indicated the compatibility of the extract with the polymer. The absence of extract-polymer interaction was indicated by the differential scanning calorimetry (DSC) thermogram. x-ray diffraction (XRD) analysis revealed the amorphous nature of the extract in the microspheres which in pure form exhibits a crystalline structure.Conclusion: The findings of this present study suggest that microsphere formulation was a promising carrier for novel delivery of herbal drugs.