Cesium and cobalt adsorption on synthetic nano manganese oxide: A two dimensional infra-red correlation spectroscopic investigation

Unveiling the multiscale structural dynamics and retrogradation behavior of potato starch via integrated enzymatic hydrolysis enhanced by microwave

This research investigated the physicochemical properties and retrogradation behaviors of mashed potato (MP) after treatment with microwave-assisted enzymatic hydrolysis (BHMW). The changes in starch's multi-scale structure and the underlying mechanisms were also elucidated. The introduction of microwave significantly enhanced the hydrolysis efficiency of potato starch and reduced amylose content, thereby decreasing both the storage modulus and loss modulus. Texture profile analysis indicated that the anti-retrogradation ability of MP improved by 5 % of BHMW, compared to the traditional water bath enzymatic hydrolysis (BHWB). During simulated reheating, Fourier-transform infrared spectroscopy, X-ray diffraction, particle size distribution analysis, and scanning electron microscopy revealed that the starch structure was more susceptible to disruption under microwave reheating conditions. Furthermore, enzymatic hydrolysis induced further degradation of starch's crystalline structure. In the retrogradation process, MP treated with BHWB exhibited a 2.17 % increase in crystallinity, a significant change corroborated by variations in retrogradation enthalpy measured via differential scanning calorimetry.

Removal of Cr(VI) from aqueous solutions by activated carbon and its composite with P2W17O61: A spectroscopic study to reveal adsorption mechanism

Molecular scale information is needed to understand ions coordination to mineral surfaces and consequently to accelerate the design of improved adsorbents. The present work reports on the use of two-dimensional correlation Fourier Transform infra-red spectroscopy (2D-COS-FTIR) and hetero 2D-COS-FTIR- X-ray diffraction (XRD) to probe the mechanism of Cr(VI) removal from aqueous solutions by activated carbon (AC) and its composite with P2W17O61 (AC-composite). The adsorption data at an initial Cr(VI) concentration of 320 mg L-1 (320 ppm) revealed maximum adsorption capacities of 65 mg g-1 for AC and 73 mg g-1 for AC-composite, corresponding to removal percentages of 83 % and 94 %, respectively. The adsorption mechanism of Cr(VI) onto AC involved electrostatic attraction of charged ions, reduction of Cr(VI), orientation of O-H groups, complex formation and ion exchange reaction. On the other hand, ion exchange reactions were not observed in the case of AC-composite, but increasing reduction and complex formation due to the presence of W were more pronounced. Moreover, a monosubstituted compound; i.e. K6P2CrW17 O61·nH2O, having chromium in its maximum oxidation state (Cr(VI)) was formed. These resulted in an improved adsorption capacity of AC-composite towards Cr(VI) in comparison to AC, and could explain the differences in adsorption thermodynamics and capacity of the two studied adsorbents. High value information could be extracted from both FTIR spectroscopy and XRD patterns when combined with available 2D-COS routines and subsequently powerful tools to investigate the mechanisms of adsorption are obtained.

The effects of pH on U(VI)/Th(IV) and Ra(II)/Ba(II) adsorption by polystyrene-nano manganese dioxide composites: Fourier Transform Infra-Red spectroscopic analysis

Fourier Transform Infra-Red (FTIR) spectroscopy provides structural information of prime importance to understand ions coordination to adsorbents. This consequently aids in the design of improved ion exchange materials and help in deriving the optimum adsorption conditions. In the present work, the adsorption mechanism of both U(VI)/Th(IV) and Ra(II)/Ba(II) radionuclides couples onto polystyrene-nano manganese dioxide (PS-NMO) composite is reported in relation to the effect of working solution pH. The separation of each radionuclide couple; i.e. U(VI)/Th(IV) and Ra(II)/Ba(II); could be effectively achieved at pH = 3 and pH = 1 respectively. The pH values not only determine the species of the respected elements that are mainly present in aqueous solution before applying the adsorbent, but it also alters the structure of the composite adsorbent. FTIR spectroscopy showed that Th(IV) formed inner sphere complexes and occupied the A site in the dioxide layer, while U(VI) formed outer sphere complexes on the surface of the composite. Spectra subtraction showed that some aromatic bands and vinyl C-H bands were split or shifted to lower wavenumbers with the loading of Ba(II). This was attributed to changes in the composite stereochemistry to accommodate Ba(II). The working solution pH could be the key in the separation process of both U(VI)/Th(IV) and Ra(II)/Ba(II) from their mixture, and FTIR spectroscopy stands as a useful technique to explain the difference between metal ions responses to adsorbants.

Nanostructured materials via green sonochemical routes - Sustainability aspects

The production of environmentally friendly nanostructured materials with well-defined properties is a major challenge. Characteristics of the nanomaterials such as dimensionality, size and morphology strongly affect their performance in various applications. Additionally, sustainability considerations require an acceptable level of efficiency while being economically feasible and environmentally benign. The use of ultrasonic irradiation (UI) is a green and powerful technology, which can be applied for the synthesis of a variety of nanostructured materials. This review critically discusses the progress made in the fabrication of environmentally benign engineered nanomaterials with various dimensionalities (i.e., zero, one, two, or three dimensions) assisted by UI. The evolution and current status in this area are further illustrated using a scientometric approach. Application of UI for the synthesis of nanostructured materials has been also assessed according to the main sustainability pillars including the performance and environmental compatibility, as well as the relevant economic and social considerations. The outlook as well as recommendations for future research has been also provided and discussed towards the promotion of sustainable nanomaterials synthesis and application in various fields.

Nano-manganese oxide-functionalized-oleyl amine as a simple and low cost nanosorbent for remediation of ZnII/CoII and their radioactive nuclides 65Zn and 60Co from water

The contribution of oleyl amine as a biodegradable and simple aliphatic compound containing amine functional group (-NH₂) was discussed in this work with respect to the remediation process of heavy metal ions from aqueous solution. Manganese oxide nanoparticles were synthesized via combustion synthesis and then functionalized with oleyl amine to form a new nanosorbent (NMn₃O₄-OA).The characteristics of this nanosorbent were examined using different instruments, such as Fourier-transform infrared spectroscopy, thermal gravimetric analysis, X-ray powder diffraction and high-resolution transmission electron microscopy. The HR-TEM images confirmed nanoscale range for NMn₃O₄-OA between 41.30 and 61.86 nm. The influence of diverse parameters on remediation of Zn^II/Co^II was examined, involving pH of metal ion solutions (pH 1-7), reaction time (1-60 min), solid amount (5-100 mg) and ionic concentration (0.1-2.0 mol/L). The optimum conditions were found pH 7 and 5-20 min reaction time for the two metal ions. The maximum capacities for adsorptive remediation were found 202 and 100 mgg^-1for Zn^II and Co ^II, respectively.

Slow-releasing permanganate ions from permanganate core-manganese oxide shell particles for the oxidative degradation of an algae odorant in water

In this work, potassium permanganate particles (KMnO₄) were modified with a manganese oxide (MnOx) shell comprising passages for the slow release of permanganate ions (MnO₄^-) in aquatic systems. The bare particle (KMnO₄) and KMnO₄ core-MnOx shell particles (CP-60) were characterized by attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The CP-60 were evaluated as a slow source of MnO₄^- for the oxidative treatment of pure and lake water containing dimethyl trisulfide (DMTS), a water odorant produced by cyanobacteria in many eutrophic waters. XPS and ATR-FTIR results confirmed the presence of MnOx surface shell (diameter ∼ 1 μm) on CP-60. SEM images revealed cracks on CP-60, which serve as outlets for MnO₄^-. Approximately 0.76 ± 0.07 g KMnO₄/g of CP-60 was released from the core of CP-60 after 120 min. The CP-60 degraded 88.9 ± 2.5% and 70.8 ± 6.3% of DMTS in pure water and lake water matrix within 120 min, respectively. The degradation was slightly more effective than the degradation using aqueous KMnO₄ (74.2%) reported in literature. The release kinetics of the particles is consistent with a pseudo-first order equation with correlation coefficients of 0.99 and 0.97 in pure water and lake water matrix, respectively. The CP could serve as low cost slow-release particles for the degradation of micropollutants, even in cyanobacteria laden water. Notably, the in situ MnOx formed during the KMnO₄ oxidation reaction can facilitate adsorption of organics and metal ions, improving water quality.

A Styrofoam-nano manganese oxide based composite: Preparation and application for the treatment of wastewater

Nano-composites were synthesized by the reaction of waste polystyrene (PS) and KMnO₄. The structure of the composite was controlled by the solvent/non-solvent system and the concentration of KMnO₄. The FTIR spectra indicated the functionalization of PS and the attachment of NMO with the polymer chains. The maximum adsorption capacities (q_max) were 10,000 and 5000 Bq g^-1, for U and Th respectively. Different but controllable sorption/desorption behaviours were noted between Th and U, which could be promising in the separation of Th and U from their mixture.

Copper-based nanomaterials for environmental decontamination - An overview on technical and toxicological aspects

Synthesis of the various types of engineered nanomaterials has gained a huge attention in recent years for various applications. Copper based nanomaterials are a branch of this category seem to be able to provide an efficient and cost-effective way for the treatment of the persistent effluents. The present work aimed to study the various parameters may involve in the overall performance of the copper based nanomaterials for environmental clean-up purposes. To this end, the related characteristics of copper based nanomaterials and their effects on the nanomaterials reactivity and the environmental and operating parameters have been critically reviewed. Toxicological study of the copper based nanomaterials has been also considered as a factor with high importance for the selection of a typical nanomaterial with optimum performance and minimum environmental and health subsequent effects.

Chemical fractionation of radium-226 in NORM contaminated soil from oilfields

Contamination of soil with ²²⁶Ra is a common problem in the oilfields, leading to costly remediation and disposal programmes. The present study focuses on the chemical fractionation and mobility of ²²⁶Ra in contaminated soils collected from an oilfield using a three-step sequential extraction procedure (BCR). The total activity concentrations of ²²⁶Ra in contaminated soils were measured and found to be in the range from 1030 ± 90 to 7780 ± 530 Bq kg^-1, with a mean activity concentration of 2840 ± 1840 Bq kg^-1. The correlation between the total concentration of ²²⁶Ra and soil properties, mainly pH, LOI, C_org, clay and Ca, was investigated using the principal component analysis method (PCA). The chemical fractionation of ²²⁶Ra was studied using the sequential extraction method (BCR). The highest fraction of ²²⁶Ra (27-65%) was found to be in the acid-reducible fraction, which suggests that ²²⁶Ra is mainly bound to FeMn oxides. The BCR method showed that high percentages of ²²⁶Ra were found to be in mobile soil phases (between 45 and 99%). Consequently, groundwater contamination could occur due to the remobilization of ²²⁶Ra from soils under normal environmental conditions. However, the obtained results could be useful to reduce the volume of NORM wastes generated from the oilfields and decision-making process for final treatment and disposal of NORM-contaminated soil.

A Reliable Hybrid Adsorbent for Efficient Radioactive Cesium Accumulation from Contaminated Wastewater

Cesium (Cs) removal from nuclear liquid wastewater has become an emerging issue for safeguarding public health after the accident at the Fukushima Daiichi Nuclear Power Plant. A novel macrocyclic ligand of o-benzo-p-xylyl-22-crown-6-ether (OBPX22C6) was developed and successfully immobilized onto mesoporous silica for the preparation of hybrid adsorbent. The benzene ring π electron is the part of crown ether of OBPX22C6 for easy orientation of the macrocyclic compound for making the π electron donation with Cs complexation. The potential and feasibility of the hybrid adsorbent as being Cs selective was evaluated in terms of sensitivity, selectivity and reusability. The results clarified that the Cs removal process was rapid and reached saturation within a short time. Considering the effect of competitive ions, sodium (Na) did not markedly affect the Cs adsorption whereas potassium (K) was slightly affected due to the similar ionic radii. However, the oxygen in long ethylene glycol chain in OBPX22C6 was expected to show strong coordination, including Cs-π interaction with Cs even in the presence of the high amount of K and Na. Due to its high selectivity and reusability, significant volume reduction is expected as this promising hybrid adsorbent is used for Cs removal in Fukushima wastewater.

Granulous KMS-1/PAN composite for Cs+ removal

A novel KMS-1/PAN composite was successfully fabricated simply by combining KMS-1 with PAN. The KMS-1/PAN combines the efficient, rapid adsorption of Cs⁺ by KMS-1 with granulation for easy separation after adsorption.