Removal of arsenic by metal organic framework/chitosan/carbon nanocomposites: Modeling, optimization, and adsorption studies

Highly Efficient Adsorption of Cr(VI) by Mechanically Enhanced Chitosan Oligosaccharide Aerogel with Hierarchical Porosity

A three-dimensional porous aerogel was synthesized by combining soft chitosan oligosaccharide to hard multi-walled carbon nanotubes (MWCNTs) under mild conditions. Owing to the support of MWCNTs, mesopores can be detected on the inner surfaces of the aerogel. The cross-linking by tetraethylenepentamine forms a macropore structure after freeze drying, using water as the template. The hydrogel can bear 30% recoverable compression with the aid of hydrogen bonds between the amide groups. The aerogel exhibits excellent adsorption capabilities for Cr(VI) in water. The adsorption capacity can reach 367.6 mg/g within 100 min. Notably, the aerogel demonstrated an extremely high efficiency in removal for trace Cr(VI). Soluble Cr(VI) of 1 mg/L can be completely removed by the aerogel at a dosage of 0.2 g/L. This work provides a new strategy to synthesize adsorbents with hierarchical pores that exhibit high porosity and a fast mass transfer rate.

Modified chitosan: Insight on biomedical and industrial applications

Chitosan (CS), a by -product of chitin deacetylation can be useful in a broad range of purposes, to mention agriculture, pharmaceuticals, material science, food and nutrition, biotechnology and of recent, in gene therapy. Chitosan is a highly desired biomolecule due to the existence of many sensitive functional groups inside the molecule and also because of its net cationicity. The latter provides flexibility for creating a wide range of derivatives for particular end users across various industries. This overview aims to compile some of the most recent research on the bio-related applications that chitosan and its derivatives can be used for. However, chitosan's reactive functional groups are amendable to chemical reaction. Modifying the material to show enhanced solubility, a greater range of application options and pH-sensitive targeting and others have been a major focus of chitosan research. This review describes the modifications of chitosan that have been made to improve its water solubility, pH sensitivity, and capacity to target chitosan derivatives. Applying the by-products of chitosan as antibacterial, in targeting, extended release and as delivery systems is also covered. The by-products of chitosan will be important and potentially useful in developing new biomedical drugs in time to come.

Lanthanum-based magnetic biopolymers for brilliant green removal from aqueous solutions

In this study, lanthanum (La)-based magnetic biopolymers were synthesized, and the first adsorption study was conducted on the removal of brilliant green dye from aqueous water with these biopolymers. For the adsorption study, adsorption parameters were investigated and the ideal adsorption conditions determined for the removal of brilliant green dye from aqueous solutions are pH 11, t 60 min, m 10 mg, C0 25 mg/L, T 298 K. It was determined that the adsorption process was compatible with the single-layer Langmuir isotherm, and maximum adsorption capacity obtained according to the Langmuir isotherm was calculated as 256.41 mg/g. The adsorption process was found to be in accordance with the pseudo-second-order, and the adsorption process was explained by intra-particle diffusion. According to studies of adsorption thermodynamics, it has been established that the nature of the adsorption reaction is spontaneous, and this process is endothermic and has increasing randomness. Moreover, the reusability of magnetic lanthanum/alginate (La/Alg) biopolymers was investigated, and it was determined that the biopolymers could be used successfully. In summary, brilliant green dye has been successfully removed with simple, low-cost, environmentally friendly, and easily obtained magnetic La/Alg biopolymers. It can be stated that even low amounts of these biopolymers can be effective in the treatment of highly concentrated dye wastewaters.

Biomimetic ZIF-8 Nanoparticles: A Novel Approach for Biomimetic Drug Delivery Systems

Metal-organic frameworks (MOFs) are porous materials resulting from the coordination of metal clusters or ions with organic ligands, merging macromolecular and coordination chemistry features. Among these, zeolitic imidazolate framework-8 (ZIF-8) stands out as a widely utilized MOF known for its robust stability in aqueous environments owing to the robust interaction between its constituent zinc ions (Zn2+) and 2-methylimidazole (2-MIM). ZIF-8 readily decomposes under acidic conditions, serving as a promising candidate for pH-responsive drug delivery systems. Moreover, biomimetic materials typically possess good biocompatibility, reducing immune reactions. By mimicking natural structures or surface features within the body, they enhance the targeting of nanoparticles, prolong their circulation time, and increase their bioavailability in vivo. This review explores the latest advancements in biomimetic ZIF-8 nanoparticles for drug delivery, elucidating the primary obstacles and future prospects in utilizing ZIF-8 for drug delivery applications.

Adsorption Behavior of Organoarsenicals over MnFe2O4-Graphene Hybrid Nanocomposite: The Role of Organoarsenic Chemical Structures

As a kind of emerging contaminant, organoarsenic compounds have drawn wide concern because of their considerable solubilities in water, and the highly toxic inorganic arsenic species formed during their biotic and abiotic degradation in the natural environment. Thus, the effective removal and studying of the adsorption mechanism of organoarsenic compounds are of significant urgency. In this work, MnFe2O4 and MnFe2O4/graphene were prepared through a facile solvothermal method. From the results of the Transmission Electron Microscope (TEM) characterization, it can be found that MnFe2O4 nanoparticles were uniformly distributed on the surface of the graphene. And the specific surface area of the MnFe2O4/graphene was about 146.39 m2 g-1, much higher than that of the MnFe2O4 (86.15 m2 g-1). The interactions between organoarsenic compounds and adsorbents were conducted to study their adsorption behavior and mechanism. The maximum adsorption capacities of MnFe2O4/graphene towards p-arsanilic acid (p-ASA) and roxarsone (ROX) were calculated to be 22.75 and 30.59 mg g-1. Additionally, the ionic strength, negative ions, and humus were introduced to investigate the adsorption performance of organoarsenic compounds. Electrostatic adsorption and surface complexation are the primary adsorption mechanisms on account of X-ray photoelectron spectroscopy (XPS) and the Fourier-transform infrared spectroscopy (FT-IR) analysis. This research extends the knowledge into studying the interaction between organoarsenic species and hybrid nanomaterials in the natural environment.

Recent advances in removal of inorganic anions from water by chitosan-based composites: A comprehensive review

Chitosan is a modified natural carbohydrate polymer that has been found in the exoskeletons of crustaceans (e.g., lobsters, shrimps, krill, barnacles, crayfish, etc.), mollusks (octopus, oysters, squids, snails), algae (diatoms, brown algae, green algae), insects (silkworms, beetles, scorpions), and the cell walls of fungi (such as Ascomycetes, Basidiomycetes, and Phycomycetes; for example, Aspergillus niger and Penicillium notatum). However, it is mostly acquired from marine crustaceans such as shrimp shells. Chitosan-based composites often present superior chemical, physical, and mechanical properties compared to single chitosan by incorporating the benefits of both counterparts in the nanocomposites. The tunable surface chemistry, abundant surface-active sites, facilitation synthesize and functionalization, good recyclability, and economic viability make the chitosan-based materials potential adsorbents for effective and fast removal of a broad range of inorganic anions. This article reviews the different types of inorganic anions and their effects on the environment and human health. The development of the chitosan-based composites synthesis, the various parameters like initial concentration, pH, adsorbent dosage, temperature, the mechanism of adsorption, and regeneration of adsorbents are discussed in detail. Finally, the prospects and technical challenges are emphasized to improve the performance of chitosan-based composites in actual applications on a pilot or industrial scale.

Functional MOF-Based Materials for Environmental and Biomedical Applications: A Critical Review

Over the last ten years, there has been a growing interest in metal-organic frameworks (MOFs), which are a unique category of porous materials that combine organic and inorganic components. MOFs have garnered significant attention due to their highly favorable characteristics, such as environmentally friendly nature, enhanced surface area and pore volume, hierarchical arrangements, and adjustable properties, as well as their versatile applications in fields such as chemical engineering, materials science, and the environmental and biomedical sectors. This article centers on examining the advancements in using MOFs for environmental remediation purposes. Additionally, it discusses the latest developments in employing MOFs as potential tools for disease diagnosis and drug delivery across various ailments, including cancer, diabetes, neurological disorders, and ocular diseases. Firstly, a concise overview of MOF evolution and the synthetic techniques employed for creating MOFs are provided, presenting their advantages and limitations. Subsequently, the challenges, potential avenues, and perspectives for future advancements in the utilization of MOFs in the respective application domains are addressed. Lastly, a comprehensive comparison of the materials presently employed in these applications is conducted.

Adsorption of Copper and Arsenic from Water Using a Semi-Interpenetrating Polymer Network Based on Alginate and Chitosan

New biobased hydrogels were prepared via a semi-interpenetrating polymer network (semi-IPN) using polyacrylamide/chitosan (PAAM/chitosan) hydrogel for the adsorption of As(V) or poly acrylic acid/alginate (PAA/alginate) hydrogel for the adsorption of Cu(II). Both systems were crosslinked using N,N'-methylenebisacrylamide as the crosslinker and ammonium persulfate as the initiating agent. The hydrogels were characterized by SEM, Z-potential, and FTIR. Their performance was studied under different variables, such as the biopolymer effect, adsorbent dose, pH, contact time, and concentration of metal ions. The characterization of hydrogels revealed the morphology of the material, with and without biopolymers. In both cases, the added biopolymer provided porosity and cavities' formation, which improved the removal capacity. The Z-potential informed the surface charge of hydrogels, and the addition of biopolymers modified it, which explains the further metal removal ability. The FTIR spectra showed the functional groups of the hydrogels, confirming its chemical structure. In addition, the adsorption results showed that PAAM/chitosan can efficiently remove arsenic, reaching a capacity of 17.8 mg/g at pH 5.0, and it can also be regenerated by HNO3 for six cycles. On the other hand, copper-ion absorption was studied on PAA/alginate, which can remove with an adsorption capacity of 63.59 mg/g at pH 4.0, and the results indicate that it can also be regenerated by HNO3 for five cycles.

Progresses in lignin, cellulose, starch, chitosan, chitin, alginate, and gum/carbon nanotube (nano)composites for environmental applications: A review

Water sources are becoming increasingly scarce, and they are contaminated by industrial, residential, and agricultural waste-derived organic and inorganic contaminants. These contaminants may pollute the air, water, and soil in addition to invading the ecosystem. Because carbon nanotubes (CNTs) can undergo surface modification, they can combine with other substances to create nanocomposites (NCs), including biopolymers, metal nanoparticles, proteins, and metal oxides. Furthermore, biopolymers are significant classes of organic materials that are widely used for various applications. They have drawn attention due to their benefits such as environmental friendliness, availability, biocompatibility, safety, etc. As a result, the synthesis of a composite made of CNT and biopolymers can be very effective for a variety of applications, especially those involving the environment. In this review, we reported environmental applications (including removal of dyes, nitro compounds, hazardous materialsو toxic ions, etc.) of composites made of CNT and biopolymers such as lignin, cellulose, starch, chitosan, chitin, alginate, and gum. Also, the effect of different factors such as the medium pH, the pollutant concentration, temperature, and contact time on the adsorption capacity (AC) and the catalytic activity of the composite in the reduction or degradation of various pollutants has been systematically explained.

Recent advancements in engineered biopolymeric-nanohybrids: A greener approach for adsorptive-remediation of noxious metals from aqueous matrices

Industrial wastewater is causing serious health problems due to presence of large concentrations of toxic metals. Removal of these metals is still a big challenge using pristine natural biopolymers due to their low surface area, water solubility, and poor recovery. Developing biopolymeric composites with other materials has attained attention because they possess a high surface area and structural porosity, high reactivity, and less water solubility. In simple words, biopolymeric nanohybrids have great adsorption capacity for heavy metals. Biopolymeric materials are abundant, low cost, biodegradable, and possess different functional moieties (carboxyl, amine, hydroxyl, and carbonyl) which play a vital role to adsorb metal ions through various inter-linkages (i.e., electrostatic, hydrogen bonding, ion exchange, chelation, etc.). Biopolymeric nanohybrids have been proven a potent tool in environmental remediation such as the abatement of heavy metal ions from polluted water. Herein, we have reported the adsorption potential of various biopolymers (cellulose, chitosan, pectin, gelatin, and silk proteins) for the removal of heavy metals. This review discusses the suitability of biopolymeric nanohybrids as an adsorbent for heavy metals, their synthesis, modification, adsorption potential, and adsorption mechanism along with best fitted thermodynamic and kinetic models. The influence of pH, contact time, and adsorbent dose on adsorption potential has also been discussed in detail. Lastly, the challenges, research gaps and recommendations have been presented. This review concludes that biopolymers in combination with other materials such as metal-based nanoparticles, clay, and carbon-based materials are excellent materials to remove metallic ions from wastewater. Significant adsorption of heavy metals was obtained at a moderate pH (5-6). Contact time and adsorbent dose also affect the adsorption of heavy metals in certain ways. The Pseudo-first order model fits the data for the initial period of the first step of the reaction. Kinetic studies of different adsorption processes of various biopolymeric nanohybrids described that for majority of bionanohybrids, Pseudo-second order fitted the experimental data very well. Functionalized biopolymeric nanohybrids being biodegradable, environment friendly, cost-effective materials have great potential to adsorb heavy metal ions. These may be the future materials for environmental remediation.