Chitosan/mangiferin particles for Cr(VI) reduction and removal

Influence of Physicochemical Properties and Parent Material on Chromium Fractionation in Soils

Chromium is an element that possess several oxidation states and can easily pass from one to another, so its behavior in soils is very complex. For this reason, determining its fate in the environment can be difficult. In this research work we tried to determine which factors affect the chromium fractionation in natural soils, conditioning chromium mobility. We paid special attention to the parent material. For this purpose, extraction experiments were carried out on spiked soils incubated for 50–60 days, using H2O, CaCl2 and diethylenetriaminepentaacetic acid (DTPA). The most efficient extraction rate in all soils was achieved using water, followed by CaCl2 and DTPA. We obtained models with an adjusted R2 of 0.8097, 0.8471 and 0.7509 for the H2O Cr, CaCl2 Cr and DTPA Cr respectively. All models were influenced by the amount of chromium added and the parent material: amphibolite and granite influenced the amount of H2O Cr extracted, and schist affected the other two fractions (CaCl2 and DTPA). Soil texture also played an important role in the chromium extraction, as well as the amounts of exchangeable aluminum and magnesium, and the bioavailable phosphorus. We concluded that it is possible to make relatively accurate predictions of the behavior of the different Cr fractions studied, so that optimized remediation strategies for chromium-contaminated soils can be designed on the basis of a physicochemical soil characterization.

Magnetite Functionalized Nigella Sativa Seeds for the Uptake of Chromium(VI) and Lead(II) Ions from Synthetic Wastewater

The aim of the present study was to utilise pristine and magnetite-sucrose functionalized Nigella Sativa seeds as the adsorbents for the uptake of chromium(VI) and lead(II) ions from synthetic wastewater. Prestine Nigella Sativa seeds were labelled (PNS) and magnetite-sucrose functionalized Nigella Sativa seeds (FNS). The PNS and FNS composites were characterized by Fourier-transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The FTIR analysis of both adsorbents revealed the presence of vibrations assigned to 1749 and 1739 cm-1 (-C=O) for ketonic group for both adsorbents. The amide (-NH) peak was observed at 1533 and 1527 cm-1 on FNS and PNS composites, respectively, whilst the carboxyl group (-COOH) were observed at 1408 cm-1 on both adsorbents. The XRD results of FNS and PNS composites showed a combination of spinel structure and$y$-Fe2O3 phase confirming the formation of iron oxide. The influence of operational conditions such as initial concentration, temperature, pH, and contact time was determined in batch adsorption system. The kinetic data of Cr(VI) and Pb(II) ions on both adsorbents was described by pseudo-first-order (PFO) model which suggested physisorption process. The sorption rate of Cr(VI) ions was quicker, it attained equilibrium in 20 min, and the rate of Pb(II) ions was slow in 90 min. Freundlich isotherm described the mechanism of Pb(II) ions adsorption on PNS and FNS composites. Langmuir best fitted the uptake of Cr(VI) ions on PNS and FNS. The results for both adsorbents showed that the removal uptake of Pb(II) ions increased when the initial concentration was increased; however, Cr(VI) uptake decreased when the initial concentration increased. The adsorption of Cr(VI) and Pb(II) ions on both adsorbents increased with temperature.

Mangiferin as New Potential Anti-Cancer Agent and Mangiferin-Integrated Polymer Systems-A Novel Research Direction

For a long time, the pharmaceutical industry focused on natural biologically active molecules due to their unique properties, availability and significantly less side-effects. Mangiferin is a naturally occurring C-glucosylxantone that has substantial potential for the treatment of various diseases thanks to its numerous biological activities. Many research studies have proven that mangiferin possesses antioxidant, anti-infection, anti-cancer, anti-diabetic, cardiovascular, neuroprotective properties and it also increases immunity. It is especially important that it has no toxicity. However, mangiferin is not being currently applied to clinical use because its oral bioavailability as well as its absorption in the body are too low. To improve the solubility, enhance the biological action and bioavailability, mangiferin integrated polymer systems have been developed. In this paper, we review molecular mechanisms of anti-cancer action as well as a number of designed polymer-mangiferin systems. Taking together, mangiferin is a very promising anti-cancer molecule with excellent properties and the absence of toxicity.

Cashew apple pectin as a carrier matrix for mangiferin: Physicochemical characterization, in vitro release and biological evaluation in human neutrophils

In this work, cashew apple pectin (CP) of the species Anacardium occidentale L. was used as an encapsulation matrix for hydrophobic drugs. The model drug chosen was mangiferin (Mf), a glycosylated C-xanthone which has antioxidant properties but low solubility in aqueous medium. CP (1-100 μg mL^-1) was not toxic to human neutrophils and also did not significantly interfere with the pro-inflammatory mechanism of these cells in the concentration range of 12.5 and 100 μg mL^-1. The results are promising because they show that pectin encapsulated mangiferin after spray drying presented an efficiency of 82.02%. The results obtained in the dissolution test, simulating the release of mangiferin in the gastrointestinal tract (pH 1.2, 4.6 and 6.8) and using Franz diffusion cells (pH 7.4), showed that cashew pectin may be a promising vehicle in prolonged drug delivery systems for both oral and dermal applications.

A pervasive scientific overview on mangiferin in the prevention and treatment of various diseases with preclinical and clinical updates

Natural products are increasing used in preventing and treating various diseases. Mangiferin belongs to the xanthone family, and has potential antiangiogenic, anticancer, immunomodulatory and anti-inflammatory activity along with the antioxidant activity. It is also used in the treatment of cardiac problem, diabetes and neurodegenerative disease. Finding of various researchers proves that mangiferin has a broad spectrum therapeutic application. Motive of this review is to describe the various studies performed on mangiferin for its different pharmacological activities. It also discusses various challenges associated with mangiferin such as stability and bioavailability. Strategies and approaches to improve bioavailability of mangiferin have also been discussed. Both research and review articles were used to write the manuscript. They were collected from various search engines like Pub Med, Science Direct and Google Scholar, using keywords like mangiferin, polyphenol, bioavailability enhancement, solubility enhancement, and antioxidant. Mangiferin being a potent antioxidant is effective in the treatment of various diseases. With novel drug delivery approaches we can overcome poor solubility and bioavailability problem which eventually can result to better utilisation of mangiferin in treating a variety of diseases and make mangiferin a revolutionary drug.

Chitosan-iron oxide hybrid composite: mechanism of hexavalent chromium removal by central composite design and theoretical calculations

In this study, the synthesis of iron oxide stabilized by chitosan was carried out for the application and optimization in the removal process of aqueous Cr(VI) by central composite design (CCD). The calculation of these effects allowed to know, quantitatively, the variables and the interaction between them that could affect the Cr(VI) removal process. It was also verified that the most favorable conditions for chromium removal were the following: pH 5.0, Cr(VI) concentration of 130 mg L^-1, adsorbent mass of 5 mg, and Fe(II) content of 45% (w/w) in the CT-Fe beads. The adsorption kinetics performed under these conditions showed that the chitosan/iron hybrid composite is an adsorbent material with high chromium removal capacity (46.12 mg g^-1). It was found that all variables were statistically significant. However, it was observed that the variable that most affected Cr(VI) removal was the pH of the solution, followed by the concentration of chromium ions in solution and the interaction between them. Therefore, the studied experimental conditions are efficient in chromium adsorption, besides the operational simplicity coming from statistical design. Theoretical calculations showed that the most stable chitosan was that with Fe(II) in the structure, that is, in the reaction mechanism, there is no competition of Fe(II) with Cr(III, VI) in the available sites of chitosan. Thus, the theoretical calculations show that the proposed Cr(VI) removal is effective.

Selective heavy metal removal and water purification by microfluidically-generated chitosan microspheres: Characteristics, modeling and application

Many industrial wastewater streams contain heavy metals, posing serious and irreversible damage to humans and living organisms, even at low concentrations due to their high toxicity and persistence in the environment. In this study, high-performance monodispersed chitosan (CS) microspheres were prepared using a simple microfluidic method and evaluated for metal removal from contaminated water. Batch experiments were carried out to evaluate the adsorption characteristics for the removal of copper ions, one representative heavy metal, from aqueous solutions. The inherent advantages of microfluidics enabled a precise control of particle size (CV = 2.3%), while exhibiting outstanding selectivity towards target ions (adsorption capacity 75.52 mg g^-1) and fair regeneration (re-adsorption efficiency 74% after 5 cycles). An integrated adsorption mechanism analytic system was developed based on different adsorption kinetics and isotherms models, providing an excellent adsorption prediction model with pseudo-second order kinetics (R² = 0.999), while the isotherm was fitted best to the Langmuir model (R² = 0.998). The multi-step adsorption process was revealed via quantitative measurements and schematically described. Selective adsorption performance of CS microspheres in the present of other competitive metal ions with different valence states has been demonstrated and studied by both experimental and density functional theory (DFT) analysis.

Chromium (VI) remediation in aqueous solution by waste products (peel and seed) of mango (Mangifera indica L.) cultivars

The surface group characteristics of mango cultivar peels and seeds were evaluated by infrared spectra, PZC, and functional group composition. The adsorption/reduction of chromium (VI) in aqueous solutions was investigated by varying pH, contact time, initial Cr(VI) concentration, and adsorbent amount. The results show that both peel and seed powders of the mango cultivars showed significant adsorption/reduction capacity for Cr(VI) and that the desorption process obeys pseudo-second-order kinetics. Optimal adsorption occurred at pH 1.0, using a Cr(VI) concentration of 100 mg/L. On average, at pH 1.0, and a concentration of 3 g/L, the maximum adsorption/reduction capacity of Cr(VI) was 83% (peels 76%, seeds 90%). Of the mango powders tested, the most efficient were Tommy seed (100%) and Coite peel (98%) followed by Coite seed (96%) and Tommy peel powders (95%). The adsorption/reduction of Cr(VI) was complete (100%) by the mango seed, in comparison to the peel powders (97%) after 180 min. The data indicates that mango waste products, such as seed and peel powders, are both excellent candidates for the remediation of Cr(VI) from aqueous systems and due to the higher concentration of gallates and galloyl glucosides, the mango seed powders should be the powders of choice for future remediation projects.

Concurrent reduction-adsorption of chromium using m-phenylenediamine-modified magnetic chitosan: kinetics, isotherm, and mechanism

Magnetic chitosan particles (MCS) were chemically grafted by m-phenylenediamine (mPD) forming a distinctive shell layer with abundant nitrogenous functional groups and used as an adsorbent for the effective removal of Cr(VI) from aqueous solution. By interaction among functional groups in the facile oxidative polymerization process, the grafting of mPD and its polymers on MCS surface was innovatively realized. Through Fourier-transformed infrared spectroscopy, energy dispersive spectrometer, X-ray photoelectron spectroscopy, etc., the chemical properties of MCS before and after modification were characterized and the concurrent reduction-adsorption mechanism in Cr(VI) adsorption by mPD-MCS was carefully analyzed. The maximal Cr(VI) removal performance of mPD-MCS reached 227.27 mg/g, which was significantly better than that of the original MCS. The analysis indicated that Cr(VI) could be efficiently reduced to Cr(III) and the removal of Cr(VI) and Cr(III) was through adsorption and chelation simultaneously by mPD-MCS. Results also indicated that the concurrent reduction-adsorption was enhanced by protonation of nitrogenous functional groups under low pH. The obtained results suggest that mPD-MCS has a good potential in removal and detoxication of Cr(VI) from aqueous solutions.

Removal of phosphate and hexavalent chromium from aqueous solutions by engineered waste eggshell

In this work, a novel adsorbent derived from waste eggshell (ES) was used for phosphate and hexavalent chromium adsorption.