Advances in natural polysaccharides for gold recovery from e-waste: Recent developments in preparation with structural features.

The increasing demand for gold because of its high market price and its wide use in the electronic industry has attracted interest in gold recovery from electronic waste (e-waste). Gold is being dumped as solid e-waste which contains gold concentrations ten times higher than gold ores. Adsorption is a widely used approach for extracting gold from e-waste due to its simplicity, low cost, high efficiency, and reusability of adsorbent material. Natural polysaccharides received increased attention due to their natural abundance, multi-functionality, biodegradability, and nontoxicity. In this review, a brief history, and advancements in this technology were evaluated with recent developments in the preparation and mechanism advancements of natural polysaccharides for efficient gold recovery. Moreover, we have discussed some bifunctional modified polysaccharides with detailed gold adsorption mechanisms. The modified adsorbent materials developed from polysaccharides coupled with inorganic/organic functional groups would demonstrate an efficient technology for the development of new bio-based materials for efficient gold recovery from e-waste. Also, future views are recommended for highlighting the direction to achieve fast and effective gold recovery from e-waste in a friendly and sustainable manner.

Preparation of MoS2/MXene/NC Porous Composite Microspheres with Wrinkled Surface and Their Microwave Absorption Performances.

In this paper, a MoS2/MXene/N-doped carbon (NC) porous composite microsphere with a wrinkled surface was designed and constructed. Lithium fluoride exfoliation and lithium-ion etching fabricated two types of 2D assembly elements, MXene (Ti3C2Tx) and MoS2 nanosheets. The two nanosheets were self-assembled by an ultrasonic spray technique with high-temperature reduction, and MoS2/MXene microspheres with 3Dwrinkled shapes were obtained. The coating of the surface NC layer was achieved by the carbonization of a polydopamine (PDA) precursor formed by the self-polymerization of dopamine. The amount of PDA coating and raw material ratio significantly affect the microstructure and electromagnetic wave absorption performance. The optimal MXene to MoS2 mass ratio is 5:1, and the optimal coating time and filler amount are 8 h and 40%. MoS2/MXene/NC composite microspheres exhibit excellent absorption performance with low reflection losses (RLmin) of -52.9 dB at 6.4 GHz and high adequate absorption bandwidths of 5.2 GHz. By adjusting the thickness of the absorber, the full coverage of the C-Ku band (4-18 GHz) can be achieved. As a new composite absorber, it has significant potential applications.

Co-encapsulation of multivitamins in micro & nano-sized starch, target release, capsule characterization and interaction studies.

This study aims to protect sensitive vitamins D, E, B1 and B2 by co-encapsulation in micro and nanoparticles of water chestnut starch for synergistic effects. The encapsulation efficiency, particle size, thermal properties and molecular configuration & interactions studies were analysed. The nano-sized starch with a particle size of 362 nm showed better encapsulation potential than micro-sized starch having an average particle size of 3.47 µm. The encapsulation efficiency was found to be 35 %, 81.17 %, 83.13 %, & 76.07 % and 46.27 %, 89.29 %, 84.91 %, & 77.60 % for vitamin D, E, B1 and B2 in micro and nano-sized starch, respectively. Fluorescence spectroscopy showed higher intensity for non-covalent interactions within the internal matrix of capsules. The FTIR peak at 877 cm-1 belonging to vitamin ring structures was prominent and confirmed the presence of vitamins in encapsulated powders. The nano starch capsules of vitamins showed better thermal stability with low crystallinity than micro starch capsules of vitamins. The study suggests the use of co-encapsulated vitamins in food fortification/supplementation to overcome the issues related to vitamin deficiencies.

Extraction of polysaccharide from Althea rosea and its physicochemical, anti-diabetic, anti-hypertensive and antioxidant properties.

The valorization of new polymer sources from underutilized plants as structuring, encapsulating, and texturizing agents for food and nutraceutical applications is gaining attention. This provides an opportunity where inexpensive plant-sourced biopolymers can play an impactful role, on both ecological and economic aspects performing equivalently effectual yet cost-effective substitutes to synthetic polymers. With this aim, we explored the use of mucilage from Althea rosea and reveal its physicochemical, in vitro antidiabetic and antihypertensive activity. Besides, structural, micrometric, crystallization, and anti-microbial properties was also seen. We determined the probable structure of the extracted mucilage by FTIR which confirmed the residues of saccharides as galactose and uronic acid with α and ß configurations. It consists of 78.26% carbohydrates, 3.51% ashes, and 3.72% proteins. Here, we show that the mucilage offered protection to DNA against the oxidative damage caused by (-OH) radicals and the morphology of the mucilage particles displayed a fibrillary material settled in a net-like, tangled structure. Our results demonstrate that the reconstituted mucilage powder exhibited good water holding capacity (2.89 g water/g mucilage), solubility (27.33%), and oil holding capacity (1.79 g oil/g mucilage). Moreover, high emulsifying property (95.83%) and foaming capacity (17.04%) was noted. Our results indicate that A.rosea mucilage can potentially serve as economical and eco-friendly hydrocolloid substitute for the food and nutraceutical industry owing to its functional, hypo-lipidemic, anti-hyperglycemic, antioxidant, and anti-bacterial properties.

The Imperative Need of Metal Salt for the Treatment of Industrial Wastewater via the Synergic Coagulation-Flocculation Method.

Tile industry wastewater is known to contain a high concentration of TSS and turbidity resulting from various raw materials. In the present study, the effectiveness of the coagulation process on turbidity and TSS removal from Kuwait ceramic tile industry wastewater was investigated using ferric chloride as a coagulant. The experiments were conducted using jar tests to determine the optimum operating conditions of coagulant dosages, pH, and settling time. It was found that the coagulant dosage and medium pH greatly affect the efficiency of the coagulation process. A gradual increase in coagulant dosage from 10 to 50 mg/L increased the efficiency of turbidity removal from 95.6% to 99.5%. The efficiency of the coagulation process was also found to be dependent on pH values, where higher pH improved the efficiency of turbidity removal. It was found that a medium pH of 10, 1 h settling time, and 50 mg/L of coagulant dosage are the optimum process conditions to achieve almost complete removal of turbidity (99.5%) and TSS (99.8%). This study concluded that coagulation might be useful as a primary wastewater treatment process for tile industry wastewater.

Preparation of core-shell C@TiO2 composite microspheres with wrinkled morphology and its microwave absorption.

In this work, we successfully synthesize the core-shell structure carbon@titanium dioxide (C@TiO2) composite microspheres with wrinkled surface through a three-step method and build up the relationship between the TiO2 layer thickness and the microwave absorption property. The absorbing mechanism of the novel microsphere is revealed. Interface polymerization is applied for preparation of wrinkled poly glycidyl methacrylate/divinylbenzene polymer microspheres (PGMA/PDVB); Then, TiO2 layer is controllably coated on the surface of PGMA/PDVB microspheres by hydrolysis of tetrabutyl titanate (TBT); C@TiO2 composite microspheres are obtained by vacuum carbonization with PGMA/PDVB@TiO2 microspheres as the precursor. TiO2 layer thickness on the surface of C@TiO2 composite microspheres can be effectively adjusted by controlling the amount of TBT. When the amount of TBT is 0.75 mL, C@TiO2 composite microspheres exhibit the outstanding electromagnetic loss performance. The maximum reflection loss value (RLmax) reaches -49.21 dB at the thickness of 2 mm, corresponding effective absorption bandwidth is 5.27 GHz. The maximum effective absorption bandwidth is 5.5 GHz at 2.2 mm. The results show that the introduction of TiO2 can regulate electromagnetic parameters and enhance interface polarization ability. Meanwhile, the surface wrinkle structure offers more opportunities for multiple reflections of electromagnetic and introduces a large number of defective skeleton structure. The synergy of multiple advantages makes the absorbing performance of C@TiO2 composite microspheres significantly improved. This work plays a guiding role for the composition and the structure optimization of existing microwave absorbers.

Wrinkled Fe3O4@C magnetic composite microspheres: Regulation of magnetic content and their microwave absorbing performance.

In this work, we develop a novel synthetic strategy for wrinkled magnetic composite microspheres (Fe3O4@C). Firstly, hydrophobic oleic acid modified Fe3O4 (OA-Fe3O4) nanoparticles acted as the magnetic component are prepared by synchronous modification coprecipitation method. The macromolecular emulsifier with initiating activity is obtained by means of soap-free emulsion polymerization under the presence of 1,1-diphenylethylene (DPE). Then, interfacial polymerization is employed to synthesis Fe3O4@polymethylglycidyl ester/divinylbenzene composite microspheres (Fe3O4@PGMA/DVB). Fe3O4@C composite microspheres are obtained by vacuum carbonization of the microspheres. The effect of magnetic content on the microwave absorbing properties of Fe3O4@C composite microspheres is explored. The results show that Fe3O4@C composite microspheres exhibit the excellent application performance at the Fe3O4 content of 0.15 g. The reflection loss can reach -53.7 dB at only thickness of 1.7 mm. The Maximum effective absorption bandwidth is up to 5.26 GHz with a thickness of 1.9 mm. The microwave attenuation mechanism of Fe3O4@C composite microspheres is revealed. The excellent absorbing performance is attributed to the enhanced interfacial polarization ability, the surface wrinkled structure and the good synergy between dielectric and magnetic losses. This work provides an effective strategy for the design and preparation of new magnetic composite materials.

Development of novel functional snacks containing nano-encapsulated resveratrol with anti-diabetic, anti-obesity and antioxidant properties.

In this study, functional snacks with addition of nanoenapsuated resveratrol were prepared to evaluate the nutraceutical and physical properties. The nanoencapsulated resveratrol was prepared from horse-chestnut (HRP), water-chestnut (WRP) and lotus-stem starch particles (LRP) and added to the wheat flour at the level of 0.4% for preparation of snacks by extrusing process. After extrusion, 43-53% and 5.42% of resveratrol was retained in snacks containing encapsulated and free resveratrol (FRP), respectively. The HRP, WRP and LRP showed significantly less peak viscosities and less elastic behaviour than native product (NP) which can influence the human sensory perception. The shift of few peaks towards higher wavelength and presence of additional peaks at 1384, 1229, 1513 and 1613 cm-1 depicts change in molecular pattern and presence of resveratrol in functional snacks. The functional snacks containing encapsulated resveratrol showed significantly higher antioxidant, anti-diabetic and anti-obesity properties than snacks containing no or free resveratrol.

Ultrasonicated resveratrol loaded starch nanocapsules: Characterization, bioactivity and release behaviour under in-vitro digestion.

In this study, the resveratrol was nano-encapsulated in three different sources of starch like Water chestnut Horse chestnut and Lotus stem to safeguard it from gastric conditions and to improve its bioavailability and bioactivity upon digestion. The nano-capsules were prepared using safe and eco-friendly ultra-sonication method and studied for encapsulation-efficiency, particle-size and zeta-potential measurement. These were also characterized by ATR-FTIR, SEM, XRD and DSC. The release behaviour of resveratrol and its activity against anti-diabetic and anti-obesity were also studied. The particle size of HSR, LSR and WSR was found to be 419, 797 and 691 nm with a zeta potential of -16.09, -24.28 and -14.77 and encapsulation efficiency of 81.46, 75.83 and 79.37 %, respectively. The nanoparticles showed porous or film-like structures with decreased crystallinity and higher transition temperatures. The maximum percentage of resveratrol was released in intestinal juice and exhibited higher anti-obesity and anti-diabetic activities than free resveratrol after digestion.

Development of surface imprinted heterogeneous nitrogen-doped magnetic carbon nanotubes as promising materials for protein separation and purification.

To promote the development of molecular imprinting technique in the separation and analysis of protein, novel bovine serum albumin (BSA) surface imprinted nitrogen-doped magnetic carbon nanotubes (N-MCNTs@MIPs) are developed by this paper. The imprinted materials are prepared by depositing polydopamine (PDA) on the surface of nitrogen-doped magnetic carbon nanotubes (N-MCNTs). N-MCNTs prepared by high temperature pyrolysis and chemical vapor deposition exhibit high specific surface area, positive hydrophilicity, abundant nitrogen functional groups and excellent magnetic properties. These characteristics are conducive to the increase of effective binding sites, the smooth development of the protein imprinting process in the aqueous phase, the improvement of the binding capacity and the simplification of the separation process. The amount of BSA adsorbing on the N-MCNTs@MIPs can reach 150.86 mg/g within 90 min. The imprinting factor (IF) is 1.43. The results of competitive adsorption and separation of fetal bovine serum showed that N-MCNTs@MIPs can specifically recognize BSA. The excellent reusability and separation ability for real sample prove that N-MCNTs@MIPs have the potential to be applied to the separation and purification of proteins in complex biological samples.

Fabrication of magnetic tubular fiber with multi-layer heterostructure and its microwave absorbing properties.

A new type of microwave absorbing material (TCF@Fe3O4@NCLs) with multi-layer heterostructure is designed and fabricated via a one-step pyrolysis process of the precursor (PF@Fe3O4@PDA). PF@Fe3O4@PDA is prepared by the technology of confined self-polycondensation, solvothermal method coupled with polymerization of dopamine (DA). The as-obtained material has the structure of tubular carbon nanofibers (TCF) embedded with Fe3O4 nanoparticles, dispersed Fe3O4 nanoparticles, and nitrogen-doped carbon layers (NCLs) from inside to outside. Notably, tubular carbon nanofibers provide the major dielectric loss. Fe3O4 nanoparticles significantly improve the microwave absorption ability at low frequencies and provide appropriate magnetic loss. NCLs improve the conductivity and facilitate the generation of multiple polarization effects, resulting in enhanced dielectric loss. The absorption mechanism is further elucidated. Based on the synergistic effect of double dielectric/magnetic loss composite materials, the interface introduced by multi-layer heterostructure, and conductive networks, TCF@Fe3O4@NCLs exhibits excellent reflection loss (RL) of -43.6 dB and effective absorption bandwidth (EBA) of 4.6 GHz (8.2-12.8 GHz) with a loading of 10%. The results demonstrate potentially promising prospects of TCF@Fe3O4@NCLs as new material candidate for microwave absorption.

Nano-reduction of starch from underutilised millets: Effect on structural, thermal, morphological and nutraceutical properties.

Starch nanoparticles from pearl (Pe) and proso (Pr) millets were characterised for morphological, thermal, rheological and nutraceutical properties which are important parameters to be considered for predicting applicable domain of nanoparticles in food and other industrial applications. In the present study after using collision ball milling to achieve the nano-reduction, dynamic light scattering (DLS) revealed the average hydrodynamic particle diameter of 636 nm and 417 nm for nano-reduced pearl (PeN) and proso (PrN) millet starches. Further the nano-particles produced were having greater stability, as revealed by the data obtained for zeta potential. X-ray diffraction (XRD) revealed loss of crystallinity in starch granules whereas attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) showed no difference in the basic functional groups but decrease in intensity. Scanning electron microscopy (SEM) was used to elicit the changes in surface topography of starch granules upon nano-reduction. Post nano-reduction treatment various thermal transition temperatures significantly shifted to lower values. Results of anti-oxidant assays for prediction of nutraceutical potential revealed significant increase upon nano-reduction.

Production and characterization of starch nanoparticles by mild alkali hydrolysis and ultra-sonication process.

In this report, synthesis of the starch nanoparticles from underutilized and cheap sources viz: Horse chestnut (HS), Water chestnut (WS) and Lotus stem (LS) by using mild alkali hydrolysis and ultra-sonication process has been presented. The particles were characterized by Differential scanning colorimeter (DSC), X-Ray Diffraction (XRD), Rheology, Scanning electron microscopy (SEM) and Fourier transform infra-spectroscopy (ATR-FTIR). The particle size measurements, functional properties and antioxidant potential of starch nanoparticles were also analyzed. The experimental results revealed that the average particle size diameter of Horse chestnut starch nanoparticles (HSP), Water chestnut starch nanoparticles (WSP) and Lotus stem starch nanoparticles (LSP) was found to be 420, 606 and 535 nm, respectively. We observed a notable increase in the water absorption capacity but decreased capacity for oil absorption in the starch nano-particles. SEM images revealed damaged starch granules after size reduction. Additionally, loss of crystallinity and molecular order was observed from XRD and ATR-FTIR spectra. It was concluded that the starch nanoparticles have better thermal stability, increased viscosity and antioxidant properties.

Influence of ball milling on the production of starch nanoparticles and its effect on structural, thermal and functional properties.

The starch nanoparticles from water chestnut (WS), lotus stem (LS) and horse chestnut (HS) starch were synthesized using planetary ball milling. The starch nanoparticles were investigated by using various techniques like particle size analyser, differential scanning colorimeter (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), rheometer, and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The particle size of horse chestnut starch nanoparticles (HNS), water chestnut starch nanoparticles (WNS) and lotus stem starch nanoparticles (LNS) was found to be 343,271 & 855 nm with zeta potential of -18.75, -20.45 & -12.2 mV, respectively. SEM revealed small and damaged starch granules. The relative crystallinity was decreased from 13.13 to 6.22, 22.27 to 7.96 and 26.16 to 7.98% in HS, LS and WS starch after ball milling and average crystallite size of starch nanoparticles was found to be 9-12 nm. The starch nanoparticles also showed increase in transition temperature and viscosity as analysed by DSC and rheometer, respectively. These properties could be useful in particular food and drug formulations.

Novel synthetic method for magnetic sulphonated tubular trap for efficient mercury removal from wastewater.

Highly efficient Hg(II) adsorption from wastewater remains a crucial task for human health and environment protection. In present work, a simple method was used to develop a carbon-based mercury magnetic "trap" (magnetic sulphonated tubular trap, MSTT) as proved by increasing surface area and wide diameter porous magnetic trap with a high density of strong Hg(II) chelating groups. Various parameters including the initial concentration of Hg(II), pH, contact time and adsorbent dosage are analyzed. The adsorption results of MSTT and sulphonated tubular trap (STT) are closely fitted with the Langmuir adsorption isotherm with maximum adsorption capacities were 970.87 (mg/g) and 952.38 (mg/g). It reveals 99.9 ± 0.5% Hg(II) adsorption occurs at pH 6.8, which is close to neutral pH. These traps can efficiently reduce Hg(II) from 10 (mg/L) to 0.3 (µg/L) in a short time of 10 min. This level is lower than the permissible limit for the drinking water. The calculated thermodynamic parameters ΔH°, ΔG°, and ΔS° indicate that the adsorption of Hg(II) onto MSTT and STT are endothermic, spontaneous and random adsorption process. The regeneration of adsorbents and high Hg(II) adsorption efficiencies in the presence of other metal ions will endow the prepared MSTT and STT with a promise for efficient Hg(II) adsorption for environmental remediation.

Correction: Removal of Pb(ii) and Cd(ii) from wastewater using arginine cross-linked chitosan-carboxymethyl cellulose beads as green adsorbent.

[This corrects the article DOI: 10.1039/C9RA00356H.].

Bioactive compounds from date fruit and seed as potential nutraceutical and functional food ingredients.

Date palm is an important fruit bearing tree grown widely in the arid and semi-arid regions of the world. The date fruit and its by-products, such as seeds, have both nutritional and medicinal value. However, date fruit and seeds have not been fully considered as potential functional food ingredients to develop foods with promising health benefits. Based on the available information in the literature, fruit and seed of date palm are rich in phytochemicals, such as phenolics, anthocyanin, carotenoids, tocopherols, tocotrienols, phytosterols and dietary fiber. In addition, they were reported to possess several beneficial health properties explored under in-vitro and in-vivo conditions. Further research in this area would provide valuable information for the potential utilization of date fruit and seed as functional food ingredients. This review presents a comprehensive information about the bioactive compounds and nutraceutical properties of different varieties of date fruit and seed, as well as the potential for using them as functional food ingredients.

Synthesis, Characterization, Kinetics, and Thermodynamics of EDTA-Modified Chitosan-Carboxymethyl Cellulose as Cu(II) Ion Adsorbent.

A new adsorbent derived from the naturally occurring biopolymers, chitosan (CS) and carboxymethyl cellulose (CMC) was prepared by cross-linking them using EDTA. EDTA having high affinity for metal ions can be used to enhance the chelation properties of the adsorbent enormously. The product obtained (chitosan-EDTA-CMC, CSECM) was characterized by different techniques: FTIR, XRD, SEM/EDAX, TGA, and XPS. The parameters for evaluation of the adsorption properties for removal of Cu(II) ions from the aqueous solution were determined using the batch adsorption method by studying the effect of pH, contact time, initial ion concentration, and temperature on adsorption. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic models were applied to study the kinetics of the adsorption process, whereas Langmuir, Freundlich, Temkin, and D-R models were applied to evaluate the thermodynamics of the adsorption process. The kinetic adsorption parameters were in best agreement with the pseudo-second-order model, while thermodynamic parameters best fitted to the Langmuir isotherm at different temperatures for adsorption of Cu(II) ions from aqueous solution with a maximum adsorption capacity of 142.95 mg/g at pH 5.5. CSECM showed excellent regeneration capability and recovery of the Cu(II) ion up to five cycles without the loss of the adsorption efficiency, which is the best characteristic to select the appropriate choice of the adsorbent. The adsorbent was also employed in batch experiments to evaluate the adsorption of hardness, producing common metal ions in single and real wastewater solutions.

New method for hydrogel synthesis from diphenylcarbazide chitosan for selective copper removal.

In this work, a simple method was developed for hydrogel preparation from 1,5-Diphenylcarbazide (DPC) and chitosan (CS) through Diazotization reaction of CS as a selective adsorbent (DPCCS) for Cu(II) ions. CS was treated with sodium nitrate and subsequent crosslinking reaction with DPC for the preparation of DPCCS. Different techniques were used for characterization of DPCCS. Various parameters such as, temperature, pH, and concentration of Cu(II) were used for adsorption studies. Kinetics of Cu(II) ion on DPCCS follows the Pseudo second order and equilibrium of adsorption occurs in short time. The equilibrium data was best fitted with the Langmuir isotherm and the maximum adsorption capacity of DPCCS was 185.505 mg g-1. Thermodynamic parameters ΔG°, ΔH° and ΔS° suggested that the adsorption of Cu(II) ion on the surfaces of DPCCS was spontaneous, endothermic and randomness of Cu(II) ion in the solution was enhanced respectively. Regeneration of DPCCS and Cu(II) ion recovery were studied up to five cycles without the lost of the adsorption capacity.

A review on latest innovations in natural gums based hydrogels: Preparations & applications.

The prospective uses of natural gum polysaccharides in various aspects of food, water, energy, biotechnology, environment and medicine industries, have garnered a great deal of attention recently. Natural gums have gained widespread attention due to their availability, low cost, structural diversity and remarkable properties as 'green' bio-based renewable materials. Natural gums are obtainable as natural polysaccharides from various tree genera possessing exceptional properties, including their renewable, biocompatible, biodegradable, and non-toxic nature and their ability to undergo easy chemical modifications. Hydrogels based on natural gums offer several valuable properties when equated to synthetic origin. The fundamental objective of this review is to compile different strategies for the preparation of hydrogels based on several important commercially available gums (arabic, guar, gellan, ghatti, karaya, kondagogu, konjac, locust bean tamarind, tragacanth, tara and xanthan) for the greener synthesis and stabilization of metal/metal oxide NPs, production of electrospun fibers, water purification, drug delivery, tissue engineering, agriculture and for antimicrobial and biomedical applications.