Optimization of Chitosan Surface Response Methodology (Natural and Commercial) Used for Chromium Ion Removal from Wastewater across Different Parameters

Chromium is one of the most significant metals used in the industry. There are many techniques for treating different types of industrial waste water that include chromium ion. In this study, the authors successfully adsorbed the chromium ion from alkaline aqueous solutions using different prepared types of chitosan as adsorbent materials. For the simultaneous sorption behaviour, the adsorption potential of the produced adsorbent was investigated for Cr+6 in a batch system. Natural chitosan was extracted from shrimp shell as it contains about 8–10% chitin which is used in the production of chitosan. The removal percentage of Cr+6 reached 99% after grafting natural and commercial chitosan at specific conditions. Several isotherm models have been used for mechanistic studies. The results indicated that the adsorption data for commercial chitosan is well-fitted by the Freundlich isotherm, Langmuir for commercial grafted, natural and natural grafted chitosan. Kinetic and equilibrium studies showed that the experimental data of Cr+6 were better described by the pseudo-first-order model for commercial chitosan and fitted the pseudo-second-order model for different types of chitosan used. Significantly, in order to scale this effective strategy on an industrial scale, response surface methodology (RSM) was used as a modelling tool to optimise process parameters such as ion concentrations, utilising Statistica Software.

Influence of Pt, Ag and Au electrodes on Cr (III) electrofiltration with current density

The metals Pt, Au and Ag as electrodes were studied at electrofiltration Cr3+ ion. The system of three half-cells were used. The Cr3+ migration from the central half-cell to the others half-cells where are electrodes was evaluated. Current density and the configurations of metals such as anode - cathode, is determined. The electrodes activity varies with current density as well as cathode or anode. The Cr3+ electromigration to cathodic half-cell increase when anode activity to generate H3O+ ions was higher than cathode (OH- ions). Instead, the migration of Cr3+ to the anode is by electroosmosis. The presence of Au as an electrode generates greater electromigration of the chromium ion to the cathode.

2,6-Bis(E)-4-Methylbenzylidine)-Cyclohexan-1-One As A Fluorescent-On Sensor For Ultra-Selective Detection Of Chromium Ion In Aqueous Media

In current decade, curcumin and its analogues have been broadly used in biological field. However, there are relatively fewer studies regarding their fluorescence based applications for chromium ion sensing in water samples. This article, hereby, reports the synthesis, FTIR and 1H-NMR spectroscopic analyses and optical description of 2,6-bis(E)-4-methylbenzylidine)-cyclohexan-1-one (sensor C), as a fluorescence-on sensor for trace level sensing of chromium. The sensor C exhibited an ultra-selective response to chromium among the tested heavy metal ions. Different parameters were optimized like pH, effect of concentration of sensor C, metal ion and contact time. The binding stoichiometry of C :Cr3+ was calculated to be 2:1 (Job’s plot) with a significantly low detection limit of 2.3×10− 9 M. Sensor C were practically employed for detection of chromium in spiked water samples.

The Catalytic Activity of Biosynthesized Magnesium Oxide Nanoparticles (MgO-NPs) for Inhibiting the Growth of Pathogenic Microbes, Tanning Effluent Treatment, and Chromium Ion Removal

Magnesium oxide nanoparticles (MgO-NPs) were synthesized using the fungal strain Aspergillus terreus S1 to overcome the disadvantages of chemical and physical methods. The factors affecting the biosynthesis process were optimized as follows: concentration of Mg(NO3)2·6H2O precursor (3 mM), contact time (36 min), pH (8), and incubation temperature (35 °C). The characterization of biosynthesized MgO-NPs was accomplished using UV-vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy—energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), and dynamic light scattering (DLS). Data confirmed the successful formation of crystallographic, spherical, well-dispersed MgO-NPs with a size range of 8.0–38.0 nm at a maximum surface plasmon resonance of 280 nm. The biological activities of biosynthesized MgO-NPs including antimicrobial activity, biotreatment of tanning effluent, and chromium ion removal were investigated. The highest growth inhibition of pathogenic Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans was achieved at 200 μg mL–1 of MgO-NPs. The biosynthesized MgO-NPs exhibited high efficacy to decolorize the tanning effluent (96.8 ± 1.7% after 150 min at 1.0 µg mL–1) and greatly decrease chemical parameters including total suspended solids (TSS), total dissolved solids (TDS), biological oxygen demand (BOD), chemical oxygen demand (COD), and conductivity with percentages of 98.04, 98.3, 89.1, 97.2, and 97.7%, respectively. Further, the biosynthesized MgO-NPs showed a strong potential to remove chromium ions from the tanning effluent, from 835.3 mg L–1 to 21.0 mg L–1, with a removal percentage of 97.5%.