Preparation of graphene oxide/chitosan/ferrite nanocomposite for Chromium(VI) removal from aqueous solution

Efficient removal of chromate from wastewater using a one-pot synthesis of chitosan cross-linked ceria incorporated hydrous copper oxide bio-polymeric composite

Remediating hexavalent chromium [Cr(VI)] from contaminated water systems is a significant concern due to its harmful effects on human health, aquatic life, and plants. To tackle this issue, scientists have created a chitosan cross-linked hydrous ceria incorporated cupric oxide bio-polymeric composite (CHCCO) by combining chitosan biopolymer with corresponding metal ions using glutaraldehyde as a cross-linker. The composite was characterized using advanced analytical instruments such as FTIR, p-XRD, SEM, XPS, etc. The synthesized composite (CHCCO) was then tested for its efficiency in removing Cr(VI) from synthetic Cr(VI) aqueous samples. The parameters examined included pH, material dose, contact time, concentration, temperature, and co-existing ions. The experimental data showed that the kinetics and equilibrium data fit well with the pseudo-second-order and the Freundlich isotherm models, respectively. Thermodynamic analysis demonstrated that the investigated surface adsorption process is spontaneous and endothermic. Except for the SO42- ion, no other species imparts adverse influence significantly on the reaction. The CHCCO bio-composite surfaces were refreshed using a dilute NaOH (1.0 M) solution and effectively recycled five times for Cr(VI) adsorption, indicating no significant surface activity deterioration. This study highlights the high effectiveness of CHCCO bio-polymeric composites in Cr(VI) remediation and the potential for this technology as an easy-to-use technique for environmental restoration.

Recovery of organic matters by activated sludge from municipal wastewater: Performance and characterization

Municipal wastewater treatment processes consume a significant amount of energy and generate substantial carbon emissions. However, organic matters existing in municipal wastewater hold the potential as a valuable carbon source. Activated sludge has the potential to capture and recover the organic matters, thereby enriching carbon sources and facilitating subsequent sludge anaerobic digestion as well as in line with the concept of sustainable development. Based on above, this study investigated the enrichment and recovery characteristics and mechanisms of activated sludge adsorption on carbon sources in municipal wastewater, while optimizing the recovery conditions. The results indicated that insoluble organic matters, as well as a fraction of dissolved organic matters, can be effective recovered within approximately 40 min. Specifically, 74.1% of insoluble organic matters and 25.8% of soluble organic matters were successfully captured by the activated sludge, resulting in a 5.0% increase in sludge organic matter content. Moreover, activated sludge demonstrated remarkable recovery of particulate organic matters across various particle sizes, particularly larger particles (>5 μm) with high protein content. Notably, the dissolved biodegradable organics such as tryptophan and tyrosine protein-like substances according to 3D-EEM and lipids, proteins/amino sugars, and carbohydrates according to FT-ICR MS can be effectively recovered. Finally, the study revealed that the recovery of organic matters from the wastewater by activated sludge followed the pseudo-second-order kinetics model, with surface binding, hydrogen bonding and interparticle diffusion in sludge flocs as the primary adsorption mechanisms. This approach had abroad application prospects for improving the profitability of wastewater treatment plants.

Graphene materials in pollution trace detection and environmental improvement

Water scarcity is a pressing issue experienced in numerous countries and is expected to become increasingly critical in the future. Anthropogenic activities such as mining, agriculture, industries, and domestic waste discharge toxic contaminants into natural water bodies, causing pollution. Addressing these environmental crises requires tackling the challenge of removing pollutants from water. Graphene oxide (GO), a form of graphene functionalized with oxygen-containing chemical groups, has recently garnered renewed interest due to its exceptional properties. These properties include a large surface area, mechanical stability, and adjustable electrical and optical characteristics. Additionally, surface functional groups like hydroxyl, epoxy, and carboxyl groups make GO an outstanding candidate for interacting with other materials or molecules. Because of its expanded structural diversity and enhanced overall properties, GO and its composites hold significant promise for a wide range of applications in energy storage, conversion, and environmental protection. These applications encompass hydrogen storage materials, photocatalysts for water splitting, the removal of air pollutants, and water purification. Serving as electrode materials for various lithium batteries and supercapacitors. Graphene-based materials, including graphene, graphene oxide, reduced graphene oxide, graphene polymer nanocomposites, and graphene nanoparticle metal hybrids, have emerged as valuable tools in energy and environmental remediation technologies. This review article provides an overview of the significant impact of graphene-based materials in various areas. Regarding energy-related topics, this article explores the applications of graphene-based materials in supercapacitors, lithium-ion batteries, and catalysts for fuel cells. Additionally, the article investigates recent advancements in detecting and treating persistent organic pollutants (POPs) and heavy metals using nanomaterials. The article also discusses recent developments in creating innovative nanomaterials, nanostructures, and treatment methods for addressing POPs and heavy metals in water. It aims to present the field's current state and will be a valuable resource for individuals interested in nanomaterials and related materials.

Synthesis of graphite/rGO-modified fungal hyphae for chromium (VI) bioremediation process

Bioremediation is a promising technology that can eliminate the drawbacks of conventional treatment methods in removing harmful toxic metals including chromium(VI). Therefore, in this study, fungal hyphae modified with graphite and reduced graphene oxide were synthesized and assessed for their potential to bioremediate heavy metals for the first time in the literature. The effects of the carbon-based materials on microbial structure were characterized using scanning electron microscopy analysis. Thermogravimetric, RAMAN, X-ray diffraction, and enzymatic analyzes were performed to determine the role of functional groups. In addition, batch adsorption experiments utilizing response surface methodology were conducted to optimize operating parameters such as time (1-11 h), chromium (10-50 mg/L), and graphite/reduced graphene oxide (0.1-1 g/L). The maximum adsorption capacity with the graphene fungal hyphae was determined to be 568 mg.g-1, which is 9.7 times that of the crude fungal hyphae. The Cr(VI) removal for fungal hyphae-graphite and fungal hyphae-reduced graphene oxide biocomposites was 98.25% and 98.49%, respectively. The isothermal and kinetic results perfectly matched the 2nd order pseudo-model and Langmuir model in terms of the nature of the adsorption process. The laboratory scale test results indicate that fungal hyphae modified with graphite and reduced graphene oxide have a high adsorption capacity, suitable for the removal of chromium (VI) from wastewater.

A novel approach to environmental pollution management/remediation techniques using derived advanced materials

The carbon dioxide (CO2) crisis is one of the world's most urgent issues. Meeting the worldwide targets set for CO2 capture and storage (CCS) is crucial. Because it may significantly reduce energy consumption compared to traditional amine-based adsorption capture, adsorption dependant CO2 capture is regarded as one of the most hopeful techniques in this paradigm. The expansion of unique, critical edge adsorbent materials has received most of the research attention to date, with the main objective of improving adsorption capacity and lifespan while lowering the temperature of adsorption, thereby lowering the energy demand of sorbent revival. There are specific materials needed for each step of the carbon cycle, including capture, regeneration, and conversion. The potential and efficiency of metal-organic frameworks (MOFs) in overcoming this obstacle have recently been proven through research. In this study, we pinpoint MOFs' precise structural and chemical characteristics that have contributed to their high capture capacity, effective regeneration and separation processes, and efficient catalytic conversions. As prospective materials for the next generation of energy storage and conversion applications, carbon-based compounds like graphene, carbon nanotubes, and fullerenes are receiving a lot of interest. Their distinctive physicochemical characteristics make them suitable for these popular study topics, including structural stability and flexibility, high porosity, and customizable physicochemical traits. It is possible to precisely design the interior of MOFs to include coordinatively unsaturated metal sites, certain heteroatoms, covalent functionalization, various building unit interactions, and integrated nanoscale metal catalysts. This is essential for the creation of MOFs with improved performance. Utilizing the accuracy of MOF chemistry, more complicated materials must be built to handle selectivity, capacity, and conversion all at once to achieve a comprehensive solution. This review summarizes, the most recent developments in adsorption-based CO2 combustion capture, the CO2 adsorption capacities of various classes of solid sorbents, and the significance of advanced carbon nanomaterials for environmental remediation and energy conversion. This review also addresses the difficulties and potential of developing carbon-based electrodes for energy conversion and storage applications.

Effective removal of Cr (VI) from aqueous solution by reinforced sodium alginate/polyethyleneimine/graphene oxide composite aerogels

A reinforced composite aerogel absorbent was synthesized using a green chemistry method and an environmentally friendly freeze-drying technique. The absorbent consisted of sodium alginate, polyethyleneimine (PEI), and graphene oxide (GO). The ability of the absorbent to remove Cr (VI) ions from aqueous solutions was studied. PEI was a nitrogen source for Cr (VI) removal and a cross-linking agent for GO sheets, while SA was a reinforcing material. The aerogel was investigated using X-ray diffraction, scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, texture analysis, Raman spectroscopy, and thermogravimetric analysis (TGA). Batch studies were conducted to investigate the effect of pH and contact time on adsorption. The results indicated that the SA/PEI/GO aerogel had a maximum adsorption capacity of 174.05 mg·g-1 for Cr (VI) at pH 2. The adsorption mechanism was described using the Langmuir isotherm and pseudo-second-order kinetic models. Thermodynamic studies revealed that the adsorption process was spontaneous and endothermic. The aerogel demonstrated good regeneration ability and satisfactory recovery for Cr (VI) even after five cycles. These findings suggest that the composite aerogel could be a promising adsorbent for efficiently removing Cr (VI) from wastewater.

Green synthesis of chitosan/erythritol/graphene oxide composites for simultaneous removal of some toxic species from simulated solution

In this study, chitosan (Ch) is adapted via green methodology including sonication induced crosslinking with different weight ratios of erythritol (Er) from (Ch-Er)1 to (Ch-Er)4. The products were casted in the form of thin films. The chemical modification was proved via FTIR spectroscopy. Then, the modified products were verified via an atomic force microscopy (AFM) investigation for their topography and surface properties. The data revealed that the optimized sample was (Ch-Er)3. This sample was further modified by different weight ratios of graphene oxide 0.1, 0.2, 0.4, and 0.8 wt./wt. (symbolized as (Ch-Er)3GO1, (Ch-Er)3GO2, (Ch-Er)3GO4, and (Ch-Er)3GO8 respectively). The prepared samples were investigated by different analytical tools. Then, the adjusted sample (Ch-Er)3GO2 was irradiated by electron beam (e-beam) at 10 and 20 kGy of irradiation doses to give samples (Ch-Er)3GO2R10 and (Ch-Er)3GO2R20, respectively. The AFM data of the irradiated samples showed that the pore size decreases, and surface roughness increases at higher energy e-beam due to the formation of more crosslinking points. The optimum samples of the prepared formulations were tested as sorbent materials for simultaneous elimination of methylene blue (MB) dye and mercury cation (Hg2+) from simulated solutions. The maximum removal of both MB dye and Hg2+ cation was achieved by (Ch-Er)3GO2R10 (186.23 mg g-1 and 205 mg g-1) respectively.

Synthesis of graphene oxide-modified porous chitosan cross-linked polyaniline composite for static and dynamic removal of Cr(VI)

A novel ternary composite was synthesized comprising graphene oxide-modified porous chitosan cross-linked polyaniline (GO@CS-PANI) by improved Hummers method, followed by cross-linking and grafting. The morphological, structural, and electrical properties of the composite were characterized by FESEM, BET, XRD, RAMAN, FTIR spectra, and zeta potential. It was found that the composite shows excellent Cr(VI) removal performance both in static and dynamic adsorption. The optimal adsorption parameters were solution at pH of 2.0, adsorbent dosage of 0.4 g/L, time of 45 min, and temperature of 35 °C. The Langmuir isotherm model was the best-fitted model, indicating homogeneous adsorption with maximum uptake of 539.83 mg/g. Pseudo-second-order was the best-fitted kinetic model, and the rate was controlled by film diffusion. Thermodynamic data demonstrated that the process was spontaneous, endothermic, and feasible. From the dynamic study, it was witnessed that a lower flow rate and a higher bed height were suitable for maximum adsorption performance. The Thomas model was the best-fitted model for data obtained from the dynamic study. Competition from interfering ions showed that anions have little effect on Cr(VI) removal, whereas cations have no such effect. The adsorption mechanism involved electrostatic attraction, π-π interaction, ion exchange, and metal ion complexion. After five cycles of adsorption-desorption study, the composite still removed 76% Cr(VI). These findings of the present study and the reusable nature of GO@CS-PANI composite signify the innovative and excellent adsorbent for wastewater treatment.

Bio-fabrication of porous magnetic Chitosan/Fe3O4 nanocomposite using Azolla pinnata for removal of chromium - Parametric effects, surface characterization and kinetics

In this research, a novel porous nanocomposite, namely Chitosan-iron-oxide @ Azolla pinnata nanocomposite, has been synthesized by co-precipitation and hydrothermal method. The effect of process parameter on adsorption process was investigated. Batch removal of chromium (Cr) was optimized with respect to solution pH, batch stirring time, sorbent dose, initial chromium concentration and temperature. The maximum removal efficiency was found to be 98.58%. The Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM) analysis of the nano composite confirmed the presence of characteristic functional groups and porous structure of synthesized nanocomposite. The adsorption data fitted well with Langmuir adsorption isotherm (R² = 0.996) confirming mono layer sorption and the maximum uptake was found to be 294.12 mg/g. The adsorption was found to follow pseudo second order model (R² = 0.997). Thermodynamic studies revealed that adsorption is endothermic and spontaneous. Reusability studies have confirmed that removal efficiency attained was 85% after completion of five adsorption-desorption cycles. Electrostatic attraction, ion exchange, coordination bonding and reduction are the major mechanisms responsible for removal of chromium. Surface modification of Azolla pinnata with chitosan and iron oxide improved the ability of Azolla in the adsorption of chromium from aqueous media. The combined effects of facile synthesis, improved adsorption features and easier magnetic separation promotes Chitosan-iron-oxide @ Azolla pinnata nanocomposite as a novel adsorbent.

Advances in Sorptive Removal of Hexavalent Chromium (Cr(VI)) in Aqueous Solutions Using Polymeric Materials

Sorptive removal of hexavalent chromium (Cr(VI)) bears the advantages of simple operation and easy construction. Customized polymeric materials are the attracting adsorbents due to their selectivity, chemical and mechanical stabilities. The mostly investigated polymeric materials for removing Cr(VI) were reviewed in this work. Assembling of robust functional groups, reduction of self-aggregation, and enhancement of stability and mechanical strength, were the general strategies to improve the performance of polymeric adsorbents. The maximum adsorption capacities of these polymers toward Cr(VI) fitted by Langmuir isotherm model ranged from 3.2 to 1185 mg/g. Mechanisms of complexation, chelation, reduction, electrostatic attraction, anion exchange, and hydrogen bonding were involved in the Cr(VI) removal. Influence factors on Cr(VI) removal were itemized. Polymeric adsorbents performed much better in the strong acidic pH range (e.g., pH 2.0) and at higher initial Cr(VI) concentrations. The adsorption of Cr(VI) was an endothermic reaction, and higher reaction temperature favored more robust adsorption. Anions inhibited the removal of Cr(VI) through competitive adsorption, while that was barely affected by cations. Factors that affected the regeneration of these adsorbents were summarized. To realize the goal of industrial application and environmental protection, removal of the Cr(VI) accompanied by its detoxication through reduction is highly encouraged. Moreover, development of adsorbents with strong regeneration ability and low cost, which are robust for removing Cr(VI) at trace levels and a wider pH range, should also be an eternally immutable subject in the future. Work done will be helpful for developing more robust polymeric adsorbents and for promoting the treatment of Cr(VI)-containing wastewater.

Chitosan-the miracle biomaterial as detection and diminishing mediating agent for heavy metal ions: A mini review

Proliferation of heavy metal ions as aquatic pollutants has been a matter of growing concern now a days. Several anthropogenic activities have fueled higher concentration of heavy metal ions in aquatic bodies above threshold values, as set by World Health Organization. Of late, chitosan for its exquisite properties has been widely used in tackling this burning problem of aquatic pollution caused by heavy metal ions. Accordingly, this mini review appraises the detection as well as diminution activities where chitosan plays the major contributing part. Starting from the intrinsic properties of chitosan, the detection strategy via chitosan composites is comprehensively delineated. Likewise, the removal activities via chitosan mediating agents are also overviewed, followed by future recommendations. It is believed that this mini review will give researchers a brief appraisal of two prominent activities related to controlling of heavy metal ion pollution.

A review on current progress of graphene-based ternary nanocomposites in the removal of anionic and cationic inorganic pollutants

The current review aims to summarize the ongoing advances in high-performing graphene-based ternary nanocomposites for removing cationic and anionic inorganic pollutants. Graphene derivatives are extensively utilized for the development of composites due to their high synergism with co-functional materials, rational design, flexible surface chemistry, high mobile charge carriers, improved binding properties, and many more. The past ten years have witnessed progressive research on graphene-based ternary nanocomposites in a multitude of pollution remediation applications. Therefore, the focus falls on understanding how these ternary nanocomposites are tailored to capture the inorganic cationic and anionic contaminants with particular emphasis on graphene derivatives as base matrix and filler. The review investigates the synthesis, categorization, and characterization techniques of graphene-based ternary composites. Besides, the study broadens the understanding of the binding mechanism of the pollutants onto graphene ternary composites. The review also assesses the separation and recycling efficacy of the composites in detail. The future prospects in improving the practical application of the ternary systems also have been discussed. The comprehensive review on graphene based ternary systems detailing their structural and functional aspects, as well as their performance as inorganic decontaminants can provide deep insights for researchers in improvising wastewater treatment technologies.

Preparation of Graphene Oxide-Maghemite-Chitosan Composites for the Adsorption of Europium Ions from Aqueous Solutions

The adsorption of Eu(III) on composites synthesised from graphene oxide (GO), maghemite (MGH), and chitosan (CS) has been studied using different approaches. The physicochemical and morphological characteristics of the composites GO-MGH, GO-CS, GO-MGH-CS I, II, and III were determined by XRD, Mössbauer spectroscopy, FTIR, Raman spectroscopy, and TEM. According to the results of batch experiments, the maximum experimental adsorption capacity was 52, 54, 25, 103, and 102 mg/g for GO-MGH, GO-CS, GO-MGH-CS I, II, and III, respectively. The data obtained are in better agreement with the Langmuir, pseudo-second-order, and pseudo-first-order models only for GO-MGH. Thus, the adsorption of Eu(III) on the composites was a favourable, monolayer, and occurred at homogeneous sites. The nature of adsorption is chemical and, in the case of GO-MGH, physical. Tests of the composites in natural waters showed a high removal efficiency for Eu(III), Pu(IV), and Am(III), ranging from 74 to 100%. The ANFIS model has quite good predictive ability, as shown by the values for R², MSE, SSE, and ARE. The GO-MGH-CS composites with the high adsorption capacity could be promising candidates for the removal of Eu(III) and the pre-concentration of Pu(IV) and Am(III) from natural waters.

Graphene-Based Adsorbents for Arsenic, Fluoride, and Chromium Adsorption: Synthesis Methods Review

Water contamination around the world is an increasing problem due to the presence of contaminants such as arsenic, fluoride, and chromium. The presence of such contaminants is related to either natural or anthropogenic processes. The above-mentioned problem has motivated the search for strategies to explore and develop technologies to remove these contaminants in water. Adsorption is a common process employed for such proposals due to its versatility, high adsorption capacity, and lower cost. In particular, graphene oxide is a material that is of special interest due to its physical and chemical properties such as surface area, porosity, pore size as well as removal efficiency for several contaminants. This review shows the advances, development, and perspectives of materials based on GO employed for the adsorption of contaminants such as arsenite, arsenate, fluoride, and hexavalent chromium. We provided a detailed discussion of the synthesis techniques and their relationship with the adsorption capacities and other physical properties as well as pH ranges employed to remove the contaminants. It is concluded that the adsorption capacity is not proportional to the surface area in all the cases; instead, the synthesis method, as well as the functional groups, play an important role. In particular, the sol-gel synthesis method shows better adsorption capacities.

On As(III) Adsorption Characteristics of Innovative Magnetite Graphene Oxide Chitosan Microsphere

A magnetite graphene oxide chitosan (MGOCS) composite microsphere was specifically prepared to efficiently adsorb As(III) from aqueous solutions. The characterization analysis of BET, XRD, VSM, TG, FTIR, XPS, and SEM-EDS was used to identify the characteristics and adsorption mechanism. Batch experiments were carried out to determine the effects of the operational parameters and to evaluate the adsorption kinetic and equilibrium isotherm. The results show that the MGOCS composite microsphere with a particle size of about 1.5 mm can be prepared by a straightforward method of dropping FeCl2, graphene oxide (GO), and chitosan (CS) mixtures into NaOH solutions and then drying the mixed solutions at 45 °C. The produced MGOCS had a strong thermal stability with a mass loss of <30% below 620 °C. The specific surface area and saturation magnetization of the produced MGOCS was 66.85 m2/g and 24.35 emu/g, respectively. The As(III) adsorption capacity (Qe) and removal efficiency (Re) was only 0.25 mg/g and 5.81% for GOCS, respectively. After 0.08 mol of Fe3O4 modification, more than 53% of As(III) was efficiently removed by the formed MGOCS from aqueous solutions over a wide pH range of 5−10, and this was almost unaffected by temperature. The coexisting ion of PO43− decreased Qe from 3.81 mg/g to 1.32 mg/g, but Mn2+ increased Qe from 3.50 mg/g to 4.19 mg/g. The As(III) adsorption fitted the best to the pseudo-second-order kinetic model, and the maximum Qe was 20.72 mg/g as fitted by the Sips model. After four times regeneration, the Re value of As(III) slightly decreased from 76.2% to 73.8%, and no secondary pollution of Fe happened. Chemisorption is the major mechanism for As(III) adsorption, and As(III) was adsorbed on the surface and interior of the MGOCS, while the adsorbed As(III) was partially oxidized to As(V) accompanied by the reduction of Fe(III) to Fe(II). The produced As(V) was further adsorbed through ligand exchange (by forming Fe−O−As complexes) and electrostatic attraction, enhancing the As(III) removal. As an easily prepared and environmental-friendly composite, MGOCS not only greatly adsorbs As(III) but also effectively removes Cr(VI) and As(V) (Re > 60%) and other metals, showing a great advantage in the treatment of heavy metal-contaminated water.

Removal of Cr(VI) from Wastewater Using Graphene Oxide Chitosan Microspheres Modified with α-FeO(OH)

Graphene oxide and chitosan microspheres modified with α−FeO(OH) (α−FeO(OH)/GOCS) are prepared and utilized to investigate the performance and mechanism for Cr(VI) removal from aqueous solutions and the possibility of Fe secondary pollution. Batch experiments were carried out to identify the effects of pH, mass, and volume ratio (m/v), coexisting ions, time (t), temperature (T), and Cr(VI) initial concentration (C0) on Cr(VI) removal, and to evaluate adsorption kinetics, equilibrium isotherm, and thermodynamics, as well as the possibility of Fe secondary pollution. The results showed that Cr(VI) adsorption increased with C0, t, and T but decreased with increasing pH and m/v. Coexisting ions inhibited Cr(VI) adsorption, and this inhibition increased with increasing concentration. The influence degrees of anions and cations on the Cr(VI) adsorption in descending order were SO42− > PO42− > NO3− > Cl− and Ca2+ > Mg2+ > Mn2+, respectively. The equilibrium adsorption capacity of Cr(VI) was the highest at 24.16 mg/g, and the removal rate was 97.69% under pH = 3, m/v = 1.0 g/L, T = 298.15 K, and C0 = 25 mg/L. Cr(VI) adsorption was well fitted to a pseudo-second-order kinetic model and was spontaneous and endothermic. The best fit of Cr(VI) adsorption with the Langmuir and Sips models indicated that it was a monolayer and heterogeneous adsorption. The fitted maximum adsorption capacity was 63.19 mg/g using the Sips model under 308.15 K. Cr(VI) removal mainly included electrostatic attraction between Cr(VI) oxyanions with surface Fe−OH2+, and the adsorbed Cr(VI) was partially reduced to Cr(III) and then precipitated on the surface. In addition, there was no Fe secondary pollution during Cr(VI) adsorption.

Enhanced adsorption of copper ions from aqueous solution by two-step DTPA-modified magnetic cellulose hydrogel beads

Copper contamination of water is one of the most pressing environmental problems which has attracted extensive concern in recent decades. In this study, a series of magnetic adsorbents were synthesized by two-step modified cellulose with N-[3-(trimethoxysilyl)propyl]ethylenediamine (KH-792) and diethylenetriaminepentaacetic acid (DTPA) using for removal of Cu(II) from aqueous solutions. Adsorption performance of Cu(II) was systematically investigated under various treatment conditions as the effect of solution pH, contact time, initial concentration and temperature. The adsorption process was found to match better with the pseudo-second-order kinetics model, and the equilibrium adsorption data were well described by Langmuir model, which meant predominant governance of monolayer chemical adsorption. The analysis of FTIR and XPS confirmed the possible adsorption mechanism between Cu(II) and the synthesized adsorbents was electrostatic attraction and the chemical coordination. Compared with MCCs and APMC, DPMC showed higher adsorption capacity of Cu(II), reaching maximum adsorption capacity of 298.62 mg·g^-1 at pH 6. Given this, ease of preparation, low cost and excellent reusability, DPMC will be promising adsorbent for application in Cu(II) removal from wastewater.

A facile modification of cation exchange resin by nano-sized goethite for enhanced Cr(VI) removal from water

A novel macroporous strong acidic cation exchange resin (D001) modified by nano-sized goethite (nFeOOH@D001) was fabricated by using a facile ethanol dispersion and impregnation method, and its efficiency for Cr(VI) removal was tested thereafter. Due to the dispersing effect of ethanol, FeOOH particles of 20-150 nm were coated on the D001 surfaces. The nFeOOH@D001 obtained a Cr(VI) removal efficiency and capacity of 80.2% and 7.4 mg/g respectively, 5 times and 8 times higher than that of the pristine D001. The Cr(VI) removal by nFeOOH@D001 followed the pseudo second-order kinetics and the Langmuir adsorption model. Column experiments also demonstrated that the nFeOOH@D001 exhibited a much better ability to remove Cr(VI) as compared to the D001. Additionally, the nFeOOH@D001 showed a potential for reusability and renewability. The adsorbed nFeOOH@D001 could be easily desorbed by 0.1 M acetic acid and a reuse efficiency of 92.7% could be maintained after 4 desorption-adsorption cycles. The used nFeOOH@D001 could be eluted by 0.1 M HCl to remove nFeOOH, and the renewed D001 could be recoated by nFeOOH and achieved a regeneration rate of 97.8% for Cr(VI) removal. The above results indicated that nano-sized goethite modification is a promising method to endow D001 with the ability to remove Cr(VI) from water.

A Review on Green Synthesis of Nanoparticles and Their Diverse Biomedical and Environmental Applications

In recent times, metal oxide nanoparticles (NPs) have been regarded as having important commercial utility. However, the potential toxicity of these nanomaterials has also been a crucial research concern. In this regard, an important solution for ensuring lower toxicity levels and thereby facilitating an unhindered application in human consumer products is the green synthesis of these particles. Although a naïve approach, the biological synthesis of metal oxide NPs using microorganisms and plant extracts opens up immense prospects for the production of biocompatible and cost-effective particles with potential applications in the healthcare sector. An important area that calls for attention is cancer therapy and the intervention of nanotechnology to improve existing therapeutic practices. Metal oxide NPs have been identified as therapeutic agents with an extended half-life and therapeutic index and have also been reported to have lesser immunogenic properties. Currently, biosynthesized metal oxide NPs are the subject of considerable research and analysis for the early detection and treatment of tumors, but their performance in clinical experiments is yet to be determined. The present review provides a comprehensive account of recent research on the biosynthesis of metal oxide NPs, including mechanistic insights into biological production machinery, the latest reports on biogenesis, the properties of biosynthesized NPs, and directions for further improvement. In particular, scientific reports on the properties and applications of nanoparticles of the oxides of titanium, cerium, selenium, zinc, iron, and copper have been highlighted. This review discusses the significance of the green synthesis of metal oxide nanoparticles, with respect to therapeutically based pharmaceutical applications as well as energy and environmental applications, using various novel approaches including one-minute sonochemical synthesis that are capable of responding to various stimuli such as radiation, heat, and pH. This study will provide new insight into novel methods that are cost-effective and pollution free, assisted by the biodegradation of biomass.

Nanomaterials as adsorbents for As(III) and As(V) removal from water: A review

Freshwater demand will rise in the next couple of decades, with an increase in worldwide population growth and industrial development. The development activities, on one side, have increased the freshwater demand. However, the ground water has been degraded. Among the various organic and inorganic contaminants, arsenic is one of the most toxic elements. Arsenic contamination in ground waters is a major issue worldwide, especially in South and Southeast Asia. Various methods have been applied to provide a remedy to arsenic contamination, including adsorption, ion exchange, oxidation, coagulation-precipitation and filtration, and membrane filtration. Out of these methods, adsorption of As(III)/As(V) using nanomaterials and biopolymers has been used on a wide scale. The present review focuses on recently used nanomaterials and biopolymer composites for As(III)/As(V) sorptive removal. As(III)/As(V) adsorption mechanisms have been explored for various sorbents. The impacts of environmental factors such as pH and co-existing ions on As(III)/As(V) removal, have been discussed. Comparison of various nanosorbents and biopolymer composites for As(III)/As(V) adsorption and regeneration of exhausted materials has been included. Overall, this review will be useful to understand the sorption mechanisms involved in As(III)/As(V) removal by nanomaterials and biopolymer composites and their comparative sorption performances.

Polymeric Nanocomposites for Environmental and Industrial Applications

Polymeric nanocomposites (PNC) have an outstanding potential for various applications as the integrated structure of the PNCs exhibits properties that none of its component materials individually possess. Moreover, it is possible to fabricate PNCs into desired shapes and sizes, which would enable controlling their properties, such as their surface area, magnetic behavior, optical properties, and catalytic activity. The low cost and light weight of PNCs have further contributed to their potential in various environmental and industrial applications. Stimuli-responsive nanocomposites are a subgroup of PNCs having a minimum of one promising chemical and physical property that may be controlled by or follow a stimulus response. Such outstanding properties and behaviors have extended the scope of application of these nanocomposites. The present review discusses the various methods of preparation available for PNCs, including in situ synthesis, solution mixing, melt blending, and electrospinning. In addition, various environmental and industrial applications of PNCs, including those in the fields of water treatment, electromagnetic shielding in aerospace applications, sensor devices, and food packaging, are outlined.

Preparation and applications of chitosan and cellulose composite materials

Chitosan is a natural fiber, chemically cellulose-like biopolymer, which is processed from chitin. Its use as a natural polymer is getting more attention because it is non-toxic, renewable, and biocompatible. However, its poor mechanical and thermal strength, particle size, and surface area restrict its industrial use. Consequently, to improve these properties, cellulose and/or inorganic nanoparticles have been used. This review discusses the recent progress of chitosan and cellulose composite materials, their preparation, and their applications in different industrial sectors. It also discusses the modification of chitosan and cellulose composite materials to allow their use on a large scale. Finally, the recent development of chitosan composite materials for drug delivery, food packaging, protective coatings, and wastewater treatment are discussed. The challenges and perspectives for future research are also considered. This review suggests that chitosan and cellulose nano-composite are promising, low-cost products for environmental remediation involving a simple production process.

Improved catalytic activity and bactericidal behavior of novel chitosan/V2O5 co-doped in tin-oxide quantum dots

The novel V₂O₅/chitosan (CS) co-doped tin oxide (SnO₂) quantum dots (QDs) were synthesized via co-precipitation technique. The optical, structural, morphological, and catalytic properties of the concerned specimens were examined by UV-Vis, PL, FTIR, X-ray diffraction, HR-TEM, and EDS. Structural analysis through XRD confirmed the tetragonal structure of SnO₂; meanwhile, HR-TEM measurements unveiled quantum dot morphology. Rotational and vibrational modes related to functional groups of (O–H, C–H, Sn–O, and Sn–O–Sn) have been assessed with FTIR spectra. Through UV-Vis spectroscopy, a reduction in band-gap (4.39 eV to 3.98 eV) and redshift in co-doped spectra of SnO₂ were identified. Both CS/SnO₂ and V₂O₅-doped CS@SnO₂ showed promising catalytic activity in all media. Meanwhile, CS/SnO₂ showed higher activity for use in hospital and industrial dye degradation in comparison to dopant-free Ch/SnO₂. For V₂O₅/CS@ SnO₂ QDs, inhibition domains of G –ve were significantly confirmed as 1.40–4.15 mm and 1.85–5.45 mm; meanwhile, for G +ve were noticed as 2.05–4.15 mm and 2.40–5.35 mm at least and maximum concentrations, correspondingly. These findings demonstrate the efficient role of V₂O₅/CS@SnO₂ QDs towards industrial dye degradation and antimicrobial activity.

Figure showing bactericidal mechanism exhibited by the prepared pristine and co-doped SnO₂.

Biogenic Synthesis of Iron Oxide Nanoparticles Using Enterococcus faecalis: Adsorption of Hexavalent Chromium from Aqueous Solution and In Vitro Cytotoxicity Analysis

The biological synthesis of nanoparticles is emerging as a potential method for nanoparticle synthesis due to its non-toxicity and simplicity. In the present study, a bacterium resistant to heavy metals was isolated from a metal-contaminated site and we aimed to report the synthesis of Fe3O4 nanoparticles via co-precipitation using bacterial exopolysaccharides (EPS) derived from Enterococcus faecalis_RMSN6 strains. A three-variable Box-Behnken design was used for determining the optimal conditions of the Fe3O4 NPs synthesis process. The synthesized Fe3O4 NPs were thoroughly characterized through multiple analytical techniques such as XRD, UV-Visible spectroscopy, FTIR spectroscopy and finally SEM analysis to understand the surface morphology. Fe3O4 NPs were then probed for the Cr(VI) ion adsorption studies. The important parameters such as optimization of initial concentration of Cr(VI) ions, effects of contact time, pH of the solution and contact time on quantity of Cr(VI) adsorbed were studied in detail. The maximum adsorption capacity of the nanoparticles was found to be 98.03 mg/g. The nanoparticles could retain up to 73% of their efficiency of chromium removal for up to 5 cycles. Additionally, prepared Fe3O4 NPs in the concentration were subjected to cytotoxicity studies using an MTT assay. The investigations using Fe3O4 NPs displayed a substantial dose-dependent effect on the A594 cells. The research elucidates that the Fe3O4 NPs synthesized from EPS of E. faecalis_RMSN6 can be used for the removal of heavy metal contaminants from wastewater.

Clean approach for chromium removal in aqueous environments and role of nanomaterials in bioremediation: Present research and future perspective

Chromium is an insidious ecological pollutant that is of huge value for its toxicity. The existing ecological objective to lower the heights of toxic materials in marine systems and to stimulate the existing water to recycle after suitable treatment of wastewater. Chromium is a hazard element that appears in discharges of numerous industries that must be diminished to accomplish the goals. Nearly all of the findings described in the literature related to the usage of various materials such as fungal, algal, bacterial biomass, and nanomaterials for chromium adsorption. The current work evaluates the findings of research commenced in the preceding on the use of a variety of adsorbents to decrease chromium concentrations in contaminated waters. This review article focuses on the issue of chromium contamination, its chemistry, causes, consequences, biological agent remediation techniques, and the detailed process of chromium detoxification in microbial cells. It also lists a description of the in situ and ex situ chromium bioremediation methods used. This can help design more effective Cr(VI) removal methods, thus bridging the difference between laboratory discoveries and industrial chromium remediation applications.

Detection, Contamination, Toxicity, and Prevention Methods of Ochratoxins: An Update Review

Ochratoxins (OTs) with nephrotoxic, immunosuppressive, teratogenic, and carcinogenic properties are thermostable fungal subordinate metabolites. OTs contamination can occur before or after harvesting, during the processing, packing, distribution, and storage of food. Mold development and mycotoxin contamination can occur in any crop or cereal that has not been stored properly for long periods of time and is subjected to high levels of humidity and temperature. Ochratoxin A (OTA) presents a significant health threat to creatures and individuals. There is also a concern of how human interaction with OTA will also express the remains of OTA from feedstuffs into animal-derived items. Numerous approaches have been studied for the reduction of the OTA content in agronomic products. These methods can be classified into two major classes: inhibition of OTA adulteration and decontamination or detoxification of food. A description of the various mycotoxins, the organism responsible for the development of mycotoxins, and their adverse effects are given. In the current paper, the incidence of OTA in various fodder and food materials is discussed, which is accompanied by a brief overview of the OTA mode of synthesis, physicochemical properties, toxic effects of various types of ochratoxins, and OTA decontamination adaptation methods. To our knowledge, we are the first to report on the structure of many naturally accessible OTAs and OTA metabolism. Finally, this paper seeks to be insightful and draw attention to dangerous OTA, which is too frequently neglected and overlooked in farm duplication from the list of discrepancy studies.

Diethylenetriaminepentaacetic acid-thiourea-modified magnetic chitosan for adsorption of hexavalent chromium from aqueous solutions

Chromium pollution is a serious environmental problem given that like most heavy metals, Cr tends to persist and accumulate in the environment. In this study, diethylenetriaminepentaacetic acid-thiourea-modified magnetic chitosan (DTCS-Fe₃O₄) was synthesized for use as an adsorbent for Cr(VI) removal from aqueous solutions. The effects of various treatment conditions on the Cr(VI) adsorption performance of DTCS-Fe₃O₄ composite as well as the kinetics were elucidated. Moreover, by observing the structure and morphology of DTCS-Fe₃O₄, the possible Cr(VI) adsorption mechanism was proposed. DTCS-Fe₃O₄ exhibited a maximum adsorption capacity of 321.3 ± 6.0 mg g^-1. Further, the adsorption process, which followed the Langmuir model for monolayer adsorption, was predominantly governed by chemical adsorption, and could be fitted using the pseudo-second-order kinetics model. Furthermore, given its ease of preparation, low cost, and remarkable performance, it is expected that the DTCS-Fe₃O₄ composite would find wide practical application in the removal of toxic Cr(VI) from wastewater.

Enhanced sequestration of Cr(VI) onto plant extract anchored on carbon-coated aluminium oxide composite

Aluminium oxide (ALU) and carbon-coated aluminium oxide modified with Kigelia africana leaf extract (KECA) were employed for the removal of toxic hexavalent chromium (Cr(VI)) from the aqueous phase. The adsorbents (ALU and KECA) were characterized by TGA, BET, FESEM, FTIR, Raman and XRD spectroscopic techniques. The potential of KECA and ALU to remove Cr(VI) from simulated wastewater was optimum at pH 2, sorbent dose of 0.025 g and a contact time of 200 min. Meanwhile, the uptake capacity of KECA and ALU was enhanced with an increase in sorbent dose, contact time and initial Cr(VI) concentration. The uptake of Cr(VI) onto the adsorbents ALU and KECA was kinetically best described by the pseudo-second-order and Elovich models, respectively. Besides, the equilibrium data acquired for ALU and KECA obeyed Freundlich and Langmuir isotherm models, respectively. ALU and KECA were observed to have optimum adsorption capacity of 56.45 mg g^-1 and 258.2 mg g^-1, respectively. The adsorption of Cr(VI) onto the adsorbents was thermodynamically feasible, endothermic in nature and entropy-driven. A decrease in efficiency was observed on regeneration of the absorbents, thus limiting their reusability. However, the presence of functional groups with reducing property in the extract of Kigelia africana leaves was noticed to enhance the capacity of the adsorbent to abstract Cr(VI) from the solution. Hence, this study demonstrates the potential of KECA to sequestrate Cr(VI) from an aqueous solution and provides a reference for its application to the treatment of Cr(VI)-laden industrial wastewater.

Synthesis of a copper (II) metal-organic framework for photocatalytic degradation of rhodamine B dye in water

The Cu(II) metal-organic frameworks (MOFs) based on 1,3,5-benzenetricarboxylic acid (Cu₃(BTC)₂) was synthesized by the hydrothermal method. The synthesized Cu₃(BTC)₂ exhibited pyramid-shaped morphology and showing an average specific area of 32.16 m² g^-1. The Cu₃(BTC)₂ photocatalysts were characterized using Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), field emission scanning electron microscopy-energy-dispersive X-ray spectroscopy (FESEM-EDX), UV-Vis diffusive reflectance spectra, and Brunauer-Emmett-Teller (BET). The photocatalytic activity of Cu₃(BTC)₂ was examined on Rhodamine B (RhB) degradation under visible light irradiation. The outcomes displayed exceedingly enhanced photocatalytic activity under visible light. In addition, its recyclability was also confirmed for multiple cycles. The easiness of construction and high photocatalytic performance of Cu₃(BTC)₂ photocatalysts can be capable in environmental applications to treat water contamination.

Quantitative Nanomechanical Mapping of Polyolefin Elastomer at Nanoscale with Atomic Force Microscopy

Elastomeric nanostructures are normally expected to fulfill an explicit mechanical role and therefore their mechanical properties are pivotal to affect material performance. Their versatile applications demand a thorough understanding of the mechanical properties. In particular, the time dependent mechanical response of low-density polyolefin (LDPE) has not been fully elucidated. Here, utilizing state-of-the-art PeakForce quantitative nanomechanical mapping jointly with force volume and fast force volume, the elastic moduli of LDPE samples were assessed in a time-dependent fashion. Specifically, the acquisition frequency was discretely changed four orders of magnitude from 0.1 up to 2 k Hz. Force data were fitted with a linearized DMT contact mechanics model considering surface adhesion force. Increased Young's modulus was discovered with increasing acquisition frequency. It was measured 11.7 ± 5.2 MPa at 0.1 Hz and increased to 89.6 ± 17.3 MPa at 2 kHz. Moreover, creep compliance experiment showed that instantaneous elastic modulus E₁, delayed elastic modulus E₂, viscosity η, retardation time τ were 22.3 ± 3.5 MPa, 43.3 ± 4.8 MPa, 38.7 ± 5.6 MPa s and 0.89 ± 0.22 s, respectively. The multiparametric, multifunctional local probing of mechanical measurement along with exceptional high spatial resolution imaging open new opportunities for quantitative nanomechanical mapping of soft polymers, and can potentially be extended to biological systems.

Graphene-Based Materials Immobilized within Chitosan: Applications as Adsorbents for the Removal of Aquatic Pollutants

Graphene and its derivatives, especially graphene oxide (GO), are attracting considerable interest in the fabrication of new adsorbents that have the potential to remove various pollutants that have escaped into the aquatic environment. Herein, the development of GO/chitosan (GO/CS) composites as adsorbent materials is described and reviewed. This combination is interesting as the addition of graphene to chitosan enhances its mechanical properties, while the chitosan hydrogel serves as an immobilization matrix for graphene. Following a brief description of both graphene and chitosan as independent adsorbent materials, the emerging GO/CS composites are introduced. The additional materials that have been added to the GO/CS composites, including magnetic iron oxides, chelating agents, cyclodextrins, additional adsorbents and polymeric blends, are then described and discussed. The performance of these materials in the removal of heavy metal ions, dyes and other organic molecules are discussed followed by the introduction of strategies employed in the regeneration of the GO/CS adsorbents. It is clear that, while some challenges exist, including cost, regeneration and selectivity in the adsorption process, the GO/CS composites are emerging as promising adsorbent materials.

Pentaclethra macrophylla stem bark extract anchored on functionalized MWCNT-spent molecular sieve nanocomposite for the biosorption of hexavalent chromium

nsufficient innovative research on the sequestration of Cr(VI) from the aquatic ecosystem has made Cr(VI) a recalcitrant water contaminant that often affects water sources. In this work, a novel plant anchor-nanocomposite was fabricated from the spent molecular sieve, multi-walled carbon nanotubes, and the extract from the stem bark of Pentaclethra macrophylla. It was envisaged that due to the phytochemical constituent of the modifier, this nanocomposite could also act as potent adsorbents for the treatment of Cr(VI) polluted water. To the best of our knowledge, the application of Pentaclethra macrophylla stem bark extract as a modifier for the green fabrication of nanocomposite has not been reported. The resulting composites showed good uptake capacity for Cr(VI) as well as efficient reusability.

Functionalized MWCNTs-quartzite nanocomposite coated with Dacryodes edulis stem bark extract for the attenuation of hexavalent chromium

Multiwalled carbon nanotubes/quartzite nanocomposite modified with the extract of Dacryodes edulis leaves was synthesized and designated as Q, which was applied for the removal of Cr(VI) from water. The adsorbents (PQ and Q) were characterized using the SEM, EDX, FTIR, TGA, XRD, and BET analyses. The XRD revealed the crystalline composition of the nanocomposite while the TGA indicated the incorporated extract as the primary component that degraded with an increase in temperature. The implication of the modifier was noticed to enhance the adsorption capacity of Q for Cr(VI) by the introduction of chemical functional groups. Optimum Cr(VI) removal was noticed at a pH of 2.0, adsorbent dose (50 mg), initial concentration (100 mg dm^-3), and contact time (180 min). The kinetic adsorption data for both adsorbents was noticed to fit well to the pseudo-second-order model. The adsorption equilibrium data were best described by the Langmuir model. The uptake of Cr(VI) onto PQ and Q was feasible, endothermic (ΔH: PQ = 1.194 kJ mol^-1 and Q = 34.64 kJ mol^-1) and entropy-driven (ΔS : PQ = 64.89 J K^-1 mol^-1 and q = 189.7 J K^-1 mol^-1). Hence, the nanocomposite demonstrated potential for robust capacity to trap Cr(VI) from aqueous solution.

Immobilization of cellulase enzymes on nano and micro-materials for breakdown of cellulose for biofuel production-a narrative review

Cellulose is a very abundant polymer that is found in nature. Cellulose has been used as a raw material for production of biofuels for many years. However, there are multiple processing steps that are required so that cellulose can be used as a raw material for biofuel production. One of the most important steps is the breakdown of cellulose into intermediate sugars which can then be a viable substrate for biofuel production. Cellulases are enzymes which play a role in the catalysis of the breakdown of cellulose into glucose. Nanomaterials and micromaterials have been gaining a lot of attention over the past few years for its potential in immobilizing enzymes for industrial procedures. Immobilization of enzymes on these nanomaterials has been observed to be of great value due to the improvement in thermal stability, pH stability, regenerative capacity, increase in activity and the reusability of enzymes. Similarly, there have been multiple reports of cellulase enzymes being immobilized on various nanoparticles. The immobilization of these cellulase enzymes have resulted in very efficient processing and provide a great and economic solution for the processing of cellulose for biofuel production. Hence in this paper, we review and discuss the various advantages and disadvantages of enzymes on various available nanomaterials.

A review on cleaner strategies for extraction of chitosan and its application in toxic pollutant removal

Existence of human beings in this world require a cleaner environment, in which, water is the main requirement for living. Owing to the considerable development in civilisation and considerable population explosion, an increase in the contamination of natural water resources by means of non-biodegradable contaminants like heavy metals is observed thereby increasing the need for treatment of water before usage. Despite the existence of specific limits for disposal of heavy metals in water resources, studies still show high contamination of heavy metals in all these water resources. This review provides a brief note on sources and toxicity of different heavy metals in various oxidation states, their effects as well as highlights the numerous available and advanced techniques for heavy metals removal. Of all techniques adsorption is found to be beneficial as it doesn't inculcate any secondary pollutants to the environment. Additionally, this article has investigated the advantages of polymer nanocomposites in adsorption and mainly focused on biopolymer chitosan owing to its abundance in natural environment. The cleaner techniques for the extraction of chitosan and its functionalisation using different types of nanofillers are comprehensively discussed in this review. This article suggests a better alternative for conventional adsorbents as well as aids in remediation of wastes.

Graphene Oxide-Doped MgO Nanostructures for Highly Efficient Dye Degradation and Bactericidal Action

Various concentrations (0.01, 0.03 and 0.05 wt ratios) of graphene oxide (GO) nanosheets were doped into magnesium oxide (MgO) nanostructures using chemical precipitation technique. The objective was to study the effect of GO dopant concentrations on the catalytic and antibacterial behavior of fixed amount of MgO. XRD technique revealed cubic phase of MgO, while its crystalline nature was confirmed through SAED profiles. Functional groups presence and Mg-O (443 cm-1) in fingerprint region was evident with FTIR spectroscopy. Optical properties were recorded via UV-visible spectroscopy with redshift pointing to a decrease in band gap energy from 5.0 to 4.8 eV upon doping. Electron-hole recombination behavior was examined through photoluminescence (PL) spectroscopy. Raman spectra exhibited D band (1338 cm-1) and G band (1598 cm-1) evident to GO doping. Formation of nanostructure with cubic and hexagon morphology was confirmed with TEM, whereas interlayer average d-spacing of 0.23 nm was assessed using HR-TEM. Dopants existence and evaluation of elemental constitution Mg, O were corroborated using EDS technique. Catalytic activity against methyl blue ciprofloxacin (MBCF) was significantly reduced (45%) for higher GO dopant concentration (0.05), whereas bactericidal activity of MgO against E. coli was improved significantly (4.85 mm inhibition zone) upon doping with higher concentration (0.05) of GO, owing to the formation of nanorods.

Fe(II) and Tannic Acid-Cloaked MOF as Carrier of Artemisinin for Supply of Ferrous Ions to Enhance Treatment of Triple-Negative Breast Cancer

Suppression of tumor development by inducing ferroptosis may provide a potential remedy for triple-negative breast cancer, which is sensitive to intracellular oxidative imbalance. Recently, artemisinin (ART) and its derivatives have been investigated as potential anticancer agents for the treatment of highly aggressive cancers via the induction of ferroptosis by iron-mediated cleavage of the endoperoxide bridge. Owing to its poor water solubility and limited intracellular iron content, it is challenging for further application in antitumor therapy. Herein, we developed ferrous-supply nano-carrier for ART based on tannic acid (TA) and ferrous ion (Fe(II)) coated on the zeolitic imidazolate framework-8 (ZIF) with ART encapsulated (TA-Fe/ART@ZIF) via coordination-driven self-assembly. Drug release experiments showed that ART was not nearly released in pH 7.4, while 59% ART was released in pH 5.0 after 10 h, demonstrating the excellent pH-triggered release. Meanwhile, a high level of intracellular ROS and MDA, accompanied with decreasing GSH and GPX4, displayed a newly developed nano-drug system displayed markedly enhanced ferroptosis. Compared with monotherapy, in vitro and vivo tumor inhibition experiments demonstrated higher efficiency of tumor suppression of TA-Fe/ART@ZIF. This work provides a novel approach to enhance the potency of ferroptotic nano-medicine and new directions for TBNC therapy.

Antagonistic effect of VDR/CREB1 pathway on cadmium-induced apoptosis in porcine spleen

Cadmium (Cd) is a toxic trace element that can enter the environment with industrial waste and accumulate in the body but the health effects of Cd on ternary pigs are still lacking in research. In order to explore the effect of Cd on the apoptosis of pig spleen and its mechanism, this study chose ternary pig as the research object to detect relevant indicators in pig spleen under Cd exposure. The results of this study showed that Cd exposure can induce apoptosis by promoting the absorption of various toxic trace elements in the spleen and inducing oxidative stress. We also found that the mechanism of Cd-induced apoptosis is closely related to the VDR/CREB1 pathway. On the one hand, Cd exposure can activate VDR, and indirectly regulate the CYP family, affecting the normal function of the spleen. On the other hand, VDR and its downstream genes antagonize the toxicity of Cd by maintaining the stability of the mitochondrial-related endoplasmic reticulum membrane structure. Our research will help researchers to further understand the physiological toxicity of Cd.

Recent Developments in Chitosan-Based Adsorbents for the Removal of Pollutants from Aqueous Environments

The quality of water is continuously under threat as increasing concentrations of pollutants escape into the aquatic environment. However, these issues can be alleviated by adsorbing pollutants onto adsorbents. Chitosan and its composites are attracting considerable interest as environmentally acceptable adsorbents and have the potential to remove many of these contaminants. In this review the development of chitosan-based adsorbents is described and discussed. Following a short introduction to the extraction of chitin from seafood wastes, followed by its conversion to chitosan, the properties of chitosan are described. Then, the emerging chitosan/carbon-based materials, including magnetic chitosan and chitosan combined with graphene oxide, carbon nanotubes, biochar, and activated carbon and also chitosan-silica composites are introduced. The applications of these materials in the removal of various heavy metal ions, including Cr(VI), Pb(II), Cd(II), Cu(II), and different cationic and anionic dyes, phenol and other organic molecules, such as antibiotics, are reviewed, compared and discussed. Adsorption isotherms and adsorption kinetics are then highlighted and followed by details on the mechanisms of adsorption and the role of the chitosan and the carbon or silica supports. Based on the reviewed papers, it is clear, that while some challenges remain, chitosan-based materials are emerging as promising adsorbents.