Assessment of chromite ore wastes for methylene blue adsorption: Isotherm, kinetic, thermodynamic studies, ANN, and statistical physics modeling.

This research investigates the adsorption potential of chrysotile and lizardite, two minerals derived from chromite ore wastes, for the uptake of Methylene Blue (MB) dye from waste streams. The characterization of these minerals involves XRD, XRF, FTIR, and SEM. Results confirm the dominance of polymorphic magnesium silicate minerals, specifically chrysotile and lizardite, in the samples. The FTIR spectra reveal characteristic vibration bands confirming the presence of these minerals. The SEM analysis depicts irregular surfaces with broken and bent edges, suggesting favorable morphologies for adsorption. N2 adsorption-desorption isotherms indicate mesoporous structures with Type IV pores in both adsorbents. The Central Composite Design approach is employed to optimize MB adsorption conditions, revealing the significance of contact time, adsorbent mass, and initial MB concentration. The proposed models exhibit high significance, with F-values and low p-values indicating the importance of the studied factors. Experimental validation confirms the accuracy of the models, and the optimum conditions for MB adsorption are determined. The influence of solution acidity on MB uptake is investigated, showing a significant enhancement at higher pH values. Isothermal studies indicate Langmuir and Freundlich models as suitable descriptions for MB adsorption onto chrysotile and lizardite. The maximum adsorption capacities of MB for chrysotile and lizardite were found to be 352.97 and 254.85, respectively. Kinetic studies reveal that the pseudo-first-order model best describes the adsorption process. Thermodynamic analysis suggests an exothermic and spontaneous process. Statistical physics models further elucidate the monolayer nature of adsorption. Additionally, an artificial neural network is developed, exhibiting high predictive capability during training and testing stages. The reusability of chrysotile and lizardite is demonstrated through multiple regeneration cycles, maintaining substantial adsorption potential. Therefore, this research provides comprehensive insights into the adsorption characteristics of chrysotile and lizardite, emphasizing their potential as effiective and reusable sorbents for MB uptake from wastewater.

Enhancing the efficiency of Ni(II), Cd(II), and Cu(II) adsorption from aqueous solution using schist/alginate composite: batch and continuous studies.

The main aim of this research is focused on the synthesis of schist/alginate composite (SC/AL) adsorbent and its utilization for the removal of Ni(II), Cu(II), and Cd(II) from waste streams using batch and column processes. The characterization of developed adsorbent was performed by X-ray fluorescence, X-ray diffraction, FTIR, and BET analyses. The most influential operating parameters (pH, contact time, temperature and initial adsorbate concentration) on the adsorption capacity of pollutants were examined to evaluate the performance of developed adsorbent. The kinetic and equilibrium adsorption results at pH 5.0 indicated that SC/AL composite had good adsorption capacity (qmax) for Ni(II), Cu(II), and Cd(II) estimated at 124.79 mg/g, 111.78 mg/g, and 119.78 mg/g, respectively. From the kinetic viewpoint, the good fit of pseudo-first-order kinetic model to the kinetic adsorption data indicated that dominant interaction of heavy metals with SC/AL composite was physisorption. The results of thermodynamic studies indicated that the adsorption of heavy metals onto SC/AL composite was endothermic and spontaneous in nature. The adsorption capacity of developed adsorbent could still reach relatively 85% of the original one after completing fifth cycle. Therefore, the reusability results of SC/AL composite were quite satisfied, making the developed adsorbent a commercially attractive and green method. Finally, in column studies, the effect of initial concentration of pollutants at pH 5.0 on the removal of heavy metal ions was investigated. The Thomas and Yoon-Nelson models provided a satisfactory explanation for the results of column data.

Nitrate adsorption onto surface-modified red mud in batch and fixed-bed column systems: equilibrium, kinetic, and thermodynamic studies.

This research aimed to develop a novel composite as a low-cost adsorbent for the removal of nitrate ion from aqueous solutions. The characterization of this composite (composition of red mud with dimethyldioctadecylammonium bromide (DDAB)) was performed by XRF, XRD, FTIR, and BET analyses. The most influential variables on nitrate adsorption, including contact time, solution acidity, adsorbent amount, and temperature were studied. The maximum amount of nitrate adsorbed onto the prepared adsorbent was obtained at pH 5.5 and contact time 30 min. The heterogeneous adsorption occurred during the uptake of nitrate. The results of kinetic study revealed that intra-particle diffusion was the major limitation for nitrate adsorption rate. The values of thermodynamic parameters illustrate the non-spontaneous, associative, and exothermic adsorption process. Increasing the temperature enhances the tendency of the process to non-spontaneously. Research on fixed-bed column has been done under different initial nitrate concentrations. The adsorption capacity of nitrate was increased with an increase in the initial concentration of nitrate. The results of column data were successfully explained using the Thomas and Yoon-Nelson models.

Improving the 6-Aminopenicillanic acid release process using vermiculite-alginate biocomposite bead on drug delivery system.

The present study deals with developing vermiculite (VMT)-alginate (Alg) composites with different cross-linker concentrations (CaCl2) to deliver the controlled 6-aminopenicillin acid (6-APA). The Characterization of synthesized composites was conducted by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. Optimization attempts were explored via the response surface method (RSM) to best predict the actual amount of compound. The adsorption capacity of 6-APA onto this adsorbent was found to be 208.33 mg/g, which was higher than that for other clays. The equilibrium and Kinetic studies (chemical reaction and diffusion-based models) indicated that drug absorption on VMT-Alg is homogeneous with chemical interaction. An increase in cross-linker (CaCl2) concentration leads to improvement in the drug encapsulation efficiency while having no significant effect on loading efficiency. The in-vitro release of the pure drug shows a rapid burst release followed by 100% cumulative release within 6 h. Whereas, the synthesized drug with Alg substantially showed less release of 43% after 8 h. Release experiments revealed that the presence of the CaCl2 delayed the release of the 6-APA less than 35% after 12 h. The kinetic release of 6-APA is followed by the Korsmeyer-Peppas model based on Fick's law mechanism due to the kinetic exponent (n < 0.5). All studied composites antibacterial activity after 24 h exposure against E. Coli and S. aureus. The antibacterial activities of composites were evaluated by the halo of no growth. The results showed that the VMT-Alg-6APA composite had strong activity against Gram-positive and Gram-negative bacteria.

Sorption, mechanism, and behavior of sulfate on various adsorbents: A critical review.

Sulfate decontamination has drawn widespread attention due to its harmful effects by broad human and animal exposure in recent decades. Adsorption is one of the most promising methods for sulfate decontamination. This review categorized various sulfate adsorbents, discussed the adsorption behavior, and introduced effective adsorbents in detail in terms of their preparation, characterization, and affecting factors on adsorption efficiency. Moreover, adsorption mechanisms of sulfate on different adsorbents are reviewed based on the intermolecular interaction, equilibrium, thermodynamic, and kinetic studies. Among natural bioadsorbents, synthesized-organic, and synthesized-inorganic adsorbents chitin-based shrimp shells (156 mg/g), bagasse pith cellulose-based (526.32 mg/g), and ZrO(OH)2/Y-Zeolite (284.22 mg/g) showed the significant capacity for sulfate uptake from aqueous solution, respectively. Although natural adsorbents have been proved to be inexpensive and efficient, they are not as popular as synthesized adsorbents for sulfate decontamination in recent years due to their low recoverability and reusability. The adsorption mechanism of sulfate to various adsorbents is generally attributed to electrostatic interactions, covalent or ionic bonding, and hydrogen bonding. Based on equilibrium studies, sulfate adsorption processes were done mainly homogeneously for most of the adsorbents; however, there are some exceptions of the heterogeneous adsorption process of sulfate, which is done mostly for adsorbents that remove sulfate through hydrogen and covalent bonding. The kinetic studies illustrated that both film diffusion and pore-diffusion could control sulfate uptake by the various adsorbents. The thermodynamic studies showed that the sulfate adsorption is endothermic and spontaneous except for the sulfate removal by polypyrrole-modified activated-carbons and LDH-HPI mine waste, which requires energy for adsorption.

A novel chitosan-polyethylene oxide nanofibrous mat designed for controlled co-release of hydrocortisone and imipenem/cilastatin drugs.

Antimicrobial chitosan-polyethylene oxide (CS-PEO) nanofibrous mats containing ZnO nanoparticles (NPs) and hydrocortisone-imipenem/cilastatin-loaded ZnO NPs were produced by electrospinning technique. The FE-SEM images displayed that the spherical ZnO NPs were ∼70-200nm in size and the CS-PEO nanofibers were very uniform and free of any beads which had average diameters within the range of ∼20-130nm. For all of the nanofibrous mats, the water uptakes were the highest in acidic medium but they were decreased in the buffer and the least swellings were obtained in the alkaline environment. The drug incorporated mat preserved its bactericidal activity even after it was utilized in the release experiment for 8days in the PBS buffer. The hydrocortisone release was increased to 82% within first 12h while the release rate of imipenem/cilastatin was very much slower so that 20% of the drug was released during this period of time suggesting this nanofibrous mat is very suitable to inhibit inflammation (by hydrocortisone) and infection (using imipenem/cilastatin antibiotic and ZnO NPs) principally for the wound dressing purposes.

Aqua-chloridodimethyl-phenyltin(IV)-15-crown-5 (2/1).

The Sn(IV) atom in the title compound, 2[Sn(CH(3))(2)(C(6)H(5))Cl(H(2)O)]·C(10)H(20)O(5), exists in a trans-C(3)SnClO trigonal bipyramidal geometry in which the organo substituents occupy the equatorial sites. The coordinated water mol-ecule forms two hydrogen bonds to the 15-crown-5 mol-ecule, which is disordered about a center of inversion.