Diacetylmonoxine modified chitosan derived ion-imprinted polymer for selective solid-phase extraction of nickel (II) ions

Preparation and Adsorption Properties of a Three-Dimensional Superhydrophilic Mercury-Ion-Imprinted Polymer with Dual Recognition Site Based on MoS2/SBA-15

Water pollution resulting from Hg(II) ions has garnered significant global concern for public health. The flexibility and simplicity of design, cost savings, and ease of operation with adaptive designs provide adsorption with a considerable advantage over other processes. However, MoS2 is hydrophobic in nature, which limits its efficiency in the removal of Hg(II) ions from water. Therefore, the incorporation of hydrophilic SBA-15 as supporting material, combined with a nanoflower-like layered MoS2 and its highly reactive exposed edges, produces hydrophilic properties that effectively eliminate Hg(II) from water . A mercury-ion-imprinted polymer (Hg(II)-IIP) was synthesized on the MoS2/SBA-15 surface using N-allylthiourea (ATU) as a functional monomer to enhance material selectivity and create dual recognition sites. Characterization investigation using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and water contact angle showed the successful synthesis of Hg(II)-IIP, excellent hydrophilicity, and close interaction between MoS2 and SBA-15. The maximum adsorption capacity of Hg(II)-IIP for Hg(II) under optimized adsorption conditions was 567.78 mg·g-1 in 90 min, which was 6 times greater than that of the IIP solely based only on SBA-15, and followed by pseudo-second-order and aligned more closely fits with the Langmuir adsorption isotherm. Furthermore, the adsorption capacity of the synthesized Hg(II)-IIP was greater than that of three other common monomers IIP. Hg(II)-IIP possesses a strong ability to regenerate, while also showing better selectivity for Hg(II) in the presence of other interfering ions, indicating its robust anti-interference capability in the multivariate mixed solution. The analysis of the actual sample indicated that Hg(II)-IIP attained recoveries between 97.92 and 100.28% in water samples. Theoretical calculations using density functional theory (DFT) and frontier molecular orbital (FMO) indicated that the binding energy of the sulfur atom forming a tetra-ligand with Hg(II) on ATU was 0.6511 eV greater than that of a diligand. The energy gap was determined to be 0.1550 eV, supporting the preference for S-Hg tetra-ligand adsorption.

Synthesis and characterization of magnetic aluminum metal-organic frameworks encapsulated with chitosan and carboxymethyl cellulose for effective elimination of atrazine from aqueous solutions: Adsorption evaluation, DFT calculations and Box-Behnken design optimization

The discharge of herbicides is a primary contributor to water contamination, presenting significant environmental and public health hazards. Encapsulating herbicides in a chemical compound called MAl-MOF/CS-CMC hydrogel bead (MACC) made from magnetic aluminum metal-organic frameworks (MAl-MOF) and crosslinked with chitosan (CS) and carboxymethyl cellulose (CMC) shows promise for potential use. The research successfully developed and examined MACC microspheres, utilizing various analytical techniques including PXRD, FESEM, TEM, FT-IR, and XPS. The efficiency of MACC in eliminating atrazine (ATZ) from wastewater was also simulated. Additionally, density functional theory (DFT) was employed to assess the electrical characteristics, reactivity, and arrangement of ATZ at a structural level. The results of the DFT analysis demonstrate a significant relationship between the locations of nucleophilic and electrophilic attacks and the molecular orbitals of the HOMO and LUMO. Using MACC as an adsorbent provides considerable advantages due to its expansive surface area of 860.92 m2/g and a pore size of 1.48 nm, meeting the mesoporous classification criteria outlined by IUPAC standards. In addition, it possesses a pore volume of 1.22 cm3/g. Nevertheless, following the adsorption procedure, the pore volume reduced to 0.78 cm3/g, and the surface area decreased to 650.42 m2/g. Several factors contributing to the capacity to attract and retain substances were analyzed. These factors encompass temperature, duration of contact, quantity of the attracting substance, initial atrazine (ATZ) concentration, and solution pH. The primary method of adsorption that was determined is chemisorption, as evidenced by the calculated adsorption energy of 29.3 kJ per mole. The thermodynamic analysis indicates that the adsorption of ATZ by the micropores of MACC occurs spontaneously and is characterized as endothermic, as evidenced by the positive ΔHo value and negative ΔGo value. It has been proposed that a range of adsorption mechanisms, including chemisorption, π-π interactions, pore filling, hydrogen bonding, and electrostatic interactions, may be responsible for removing the herbicide from the MACC material.

Chemical functionalization of Chitosan biopolymer with diacetyl monoxime for enhanced Cr(VI) removal from aqueous media

Hexavalent chromium is known for high toxicity as well as carcinogenicity and leads to contamination of water bodies through various anthropogenic activities. Chitosan biopolymer has limited adsorption capacity towards this toxicant. In order to boost hexavalent chromium adsorption, diacetylmonoxime was used to modify thiolated chitosan. The resulting material was extensively characterized using Fourier Transform Infrared, Energy Dispersive X-ray, Scanning Electron Microscopic and X-ray Diffraction investigations. To comprehend the adsorption mechanism in better way, various adsorption isotherms like Langmuir and Freundlich were investigated. In order to maximize the efficiency of adsorbent, response surface approach was used to optimize the several adsorption parameters, such as pH, adsorbent dose, adsorbate concentration, duration, and temperature. The results indicated that, 98 ± 0.5 % adsorption takes place at pH 5.0 with an adsorbent dosage of 20 mg and an adsorbate concentration of 20 mg L-1 at 298 K temperature within a short period of 60 min. According to the Langmuir monolayer isotherm, the material was observed to have Cr(VI) adsorption capacity of 430.73 mg g-1 under optimized operational conditions. Adsorption of Cr(VI) proceeds with pseudo-second-order kinetics. Because of the increasing unpredictability at interaction sites, it was discovered that adsorption efficiency decreased with rising temperature. Negative values of Gibbs free energy and enthalpy pointed towards the spontaneous and exothermic behaviour of the adsorption process. To find out if the material was suitable for greater sample volumes, column tests were conducted that showed excellent results for continuous column adsorption experiments.

Construction of 1, 10-phenanthroline functionalized magnetic starch as a lead (II) tagged surface imprinted biopolymer for highly selective targeting of toxic lead ions

In this research 1, 10 - phenanthroline functionalized CaFe₂O₄ - starch was employed as a magnetic ion-imprinted polymer (IIP) for highly selective targeting toxic Pb²⁺ ions from aqueous media. VSM analysis revealed that the sorbent has magnetic saturation of 10 emu g^-1 which is appropriate for magnetic separation. Moreover, TEM analysis confirmed that the adsorbent is composed of particles with a mean diameter of 10 nm. According to XPS analysis, lead coordination with phenanthroline is the main adsorption mechanism that is along with electrostatic interaction. A maximum adsorption capacity of 120 mg g^-1 was obtained within 10 min at a pH of 6 and an adsorbent dosage of 20 mg. Kinetic and isotherm studies showed that lead adsorption followed the pseudo-second-order and Freundlich models, respectively. The selectivity coefficient of Pb (II) relative to Cu(II), Co(II), Ni(II), Zn(II), Mn(II), and Cd(II) was 4.7, 14, 20, 36, 13 and 25, respectively. Moreover, the IIP represents the imprinting factor of 1.32. The sorbent showed good regeneration after five cycles of the sorption/desorption process with an efficiency of >93 %. Finally represented IIP was used for lead preconcentration from various matrices i.e., water, vegetable, and fish samples.

Construction of amino-thiol functionalized ion-imprinted chitosan for lead (II) ion removal

Ion-imprinting technique was used to create a lead ion-imprinted sorbent from an amino-thiol chitosan derivative (Pb-ATCS). First, 3-Nitro-4-sulfanylbenzoic acid (NSB) unit's amidized the chitosan, and then the -NO₂-residues were selectively reduced to -NH₂. Imprinting was accomplished by cross-linking with epichlorohydrin and removing the Pb (II) ions from the across-linked polymeric complex formed from the amino-thiol chitosan polymer ligand (ATCS) and Pb (II) ions. The synthetic steps have been investigated by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR), and the sorbent was tested for its ability to selectively bind Pb (II) ions. The produced Pb-ATCS sorbent had a maximum capacity of roughly 300 mg/g, and it showed a greater affinity for the Pb (II) ions than the control NI-ATCS sorbent particle. The pseudo-2nd-order equation was also consistent with the adsorption kinetics of the sorbent, which were quite rapid. This demonstrated that metal ions were chemo-adsorbed onto the Pb-ATCS and NI-ATCS solid surfaces via coordination with the introduced amino-thiol moieties.

New ion-imprinted polymer for selective removal of Cu2+ ion in aqueous solution using extracted Aloe vera leaves as a monomer

The objective of this project is to create a unique type of polymer known as an ion imprinted polymer (IIP) and a non-imprinted polymer (NIP) utilizing natural waste biosorbent materials. One example of this type of waste is Aloe vera, a plant with many medicinal uses that is grown globally. Aloe vera is considered one of the most valuable medicinal plants with a wide range of applications. Extracted Aloe vera was used as functional monomers for the first time to prepare new IIPs, epichlorohydrin, and Cu²⁺ ion as the cross-linking agent and template, respectively. The NIP was also synthesized for comparison, without the use of the Cu²⁺ salt. Following polymerization, the IIP particles were cleansed of template ions through a 0.1 M EDTA leaching process, resulting in the formation of cavities within the particles, these cavities in the polymer provide selective linking zones for these specific template ions. The synthesized IIPs were characterized using the most recent identification instruments. The experimental parameters for adsorption, such as pH of a solution, contact time, initial copper concentration, adsorbent dosage, and temperature have been optimized. The most effective conditions for metal adsorption onto the ionic imprinted polymer were found to be a pH of 8.0, a temperature of 30 °C, a concentration of 0.03 g/100 mL, and a contact time of 50 min. Based on the ANOVA statistical value, the adsorption of Cu²⁺ ion on IIP is significant with very low probability (p) values (<0.001). The Langmuir isotherm model and a second-order reaction were both used in the adsorption process. According to thermodynamic characteristics, Cu²⁺ adsorption over IIPs and NIP was an endothermic, spontaneous process. Compared to NIP, the imprinted polymer exhibits a significantly better capacity and selectivity for Cu²⁺ adsorption, the maximum removal percentage of IIPs and NIP was 96.02 % and 74.3 % respectively. Moreover, the research showed that ion imprinting can be a promising technique for preparing selective adsorbents to separate and preconcentrate metal in a medium of multiple competitive metals (Co²⁺, Cd²⁺, Ni²⁺, Zn²⁺, Fe²⁺, and Pb²⁺) The most important point for this new Cu²⁺-IIPs was shown superior reusability up to 8 cycles with small decrees in uptake capability.

Synthesis process and adsorption performance of temperature-sensitive ion-imprinted porous microspheres (ReO4−-TIIM) for the selective separation of ReO4−

The adsorption–desorption process of imprinted microspheres is controlled by changing the temperature conditions of the external environment.

A Critical Review of Analytical Applications of Chitosan as a Sustainable Chemical with Functions Galore

Biomass and biowastes stand as sustainable and cost-effective environmentally benign alternative feedstock. Chitosan is a biocompatible, bioactive, and biodegradable biopolymer derived from chitin to achieve eight aspects out of the 12 green chemistry principles. Chitosan got significant attention in several fields including chemical analysis, in addition to chemical functionally, which enabled its use as adsorbent and its structural crosslinking using various crosslinkers. The physicochemical, technological, and optical properties of chitosan have been extensively exploited in analysis. Mainly, deacetylation degree and molecular weight are controlling its properties and hence controlling its functions. This review presents a structure, properties, and functions relationships of chitosan. It also aims to provide an overview of the different functions that chitosan can serve in each analytical technique such as supporting matrix, catalyst…etc. The contribution of chitosan in improving the ecological performance is discussed in each technique.

Selective biosorption of U(VI) from aqueous solution by ion-imprinted honeycomb-like chitosan/kaolin clay composite foams

The radioactive pollution caused by the discharge of radioactive wastewater poses a serious threat to public health and ecosystem stability owing to its long-term detriments. Herein, the ion-imprinted honeycomb-like chitosan/kaolin clay (ICK) composite foams were successfully fabricated and applied to the selective biosorption of U(VI) from aqueous solution. It was found that the ICK-2 was the best among various ICK foams owing to its well-developed honeycomb-like structure and the presence of abundant functional groups. As compared to the non-imprinted sorbent (NICK-2), the ion-imprinted sorbent (ICK-2) presents higher sorption and better selectivity since it can smartly recognize the target ions. The sorption isotherms was well-fitted with Langmuir model, and the maximum sorption capacity of ICK-2 was evaluated as 286.85 mg/g for U(VI) at 298 K and pH 5.0. The kinetic data could be described by pseudo-second order model. The FTIR and XPS results suggest that both amine and hydroxyl groups are responsible for U(VI) coordination. The ICK-2 presents high sorption capacity, good selectivity and fast kinetic rate, and thus it has potential application for U(VI) separation from radioactive wastewater.

Enantioselective chitosan-based racemic ketoprofen imprinted polymer: Chiral recognition and resolution study

This work presented a novel racemic imprinting process employing the chiral properties of chitosan monomer. The preparation of racemic ketoprofen (RS-KTP) imprinted polymer (RS-MIP) was conducted using glutaraldehyde as a crosslinker. The nature of elution solvent affected the % desorption ratio suggesting a heterogenous nature of the formed binding sites. Good imprinting was indicated by an imprinting factor of 3.50 for S-KTP. The enantioselectivity of the RS-MIP was indicated by enantioselectivity coefficient of 2.31 and % enantiomeric excess (%ee) of 28.55%. A SPE cartridge packed with RS-MIP enabled resolution of RS-KTP using gradient elution solvent system. Scatchard plot revealed two binding sites types of different affinity towards S-KTP and density observed for the RS-MIP. The binding capacity of RS-MIP showed observed dependence on the % ee of S-KTP indicating its enantioselectivity. The success of using racemic template for the preparation of enantioselective MIP brings a new possibility to achieve enantioseparation of racemic mixtures having very expensive or unavailable pure enantiomers.

Epichlorohydrin and tripolyphosphate-crosslinked chitosan-kaolin composite for Auramine O dye removal from aqueous solutions: Experimental study and DFT calculations

Chitosan (Ch, a natural polymer) and kaolin (K, a natural mineral) composite (Ch-K) was produced with the help of two crosslinkers, epichlorohydrin and tripolyphosphate, and then moulded into uniform beads in tripolyphosphate solution. The synthesis was proved by the analyses involving FT-IR and SEM-EDX. The beads were then used as the natural adsorbent for removal of the auramine O (AO), a frequently-used industrial dye, in aqueous solutions. Adsorbent performance of the Ch-K composite for AO dye molecules was optimized: 500 mg L^-1 at pH 7.5 at 25 °C. The Langmuir model found 0.118 mol kg^-1 for the maximum adsorption capacity of the Ch-K and the D-R isotherm model showed that the nature of the adsorption process was physical. Kinetics of the adsorption could be explained by using both IPD (intraparticle diffusion) and PSO (pseudo second order) models. Thermodynamic parameters demonstrated that the behaviour of the adsorption was an endothermic and spontaneous. The activity of the composite adsorbent was recovered (88%) after the five sequential adsorption/desorption cycles. Supported by experimental findings, the results obtained from in silico modeling at M06-2X/6-31+G (d,p) level helped hypothesise a mechanism for the formation of the Ch-K composite, and shed some light onto the adsorption behaviour of AO dye by assuming several favourable intermolecular interactions.

Smart ion imprinted polymer for selective adsorption of Ru(Ⅲ) and simultaneously waste sample being transformed as a catalyst

In this work, a temperature-sensitive block polymer PDEA-b-P(DEA-co-AM) was synthesized and then introduced into the preparation of a smart Ru(Ⅲ) imprinted polymer (Ru-IIP) to selectively adsorption Ru(Ⅲ) first. Then the waste Ru-IIP was converted into a catalyst in-situ for recycle. The structure and morphology of the prepared polymer were characterized by Fourier transform infrared spectrometer, Scanning electron microscope, BET surface area and Thermogravimetric analysis. The adsorption properties of the synthesized smart material were investigated in terms of adsorption pH, adsorption kinetics and adsorption isotherm. Results documented that the optimal adsorption temperature and pH were 35 °C and 1.5 respectively, the maximum adsorption capacity was 0.153 mmol/g, and the adsorption processes of Ru-IIP were more suitable to be expressed by pseudo-first-order kinetic and Langmuir model. The selectivity studied in different binary mixed solutions showed that Ru-IIP has good selectivity, and reusability results showed that Ru-IIP still maintains a good adsorption effect after 8 cycles. In addition, the waste Ru-IIP, a Ru(Ⅲ) remained waste sample was employed as the catalyst for the synthesis of imines, and result showed the mass of adsorbent would reduce after the completion of catalysis, which could not only catalyze the reaction but also reduce pollution.

Research progress of adsorption and removal of heavy metals by chitosan and its derivatives: A review

Chitosan has received widespread attention as an adsorbent for pollutants because of its low cost and great adsorption potentials. Chitosan has abundant hydroxyl and amino groups that can bind heavy metal ions. However, it has defects such as sensitivity to pH, low thermal stability, and low mechanical strength, which limit the application of chitosan in wastewater treatment. The functional groups of chitosan can be modified to improve its performance via crosslinking and graft modification. The porosity and specific surface area of chitosan in powder form are not ideal, therefore, physical modification has been attempted to generate chitosan nanoparticles and hydrogel. Chitosan has also been integrated with other materials (e.g. graphene, zeolite) resulting in composite materials with improved adsorption performance. This review mainly focuses on reports about the application of chitosan and its derivatives to remove different heavy metals. The preparation strategy, adsorption mechanism, and factors affecting the adsorption performance of adsorbents for each type of heavy metal are discussed in detail. Recent reports on important organic pollutants (dyes and phenol) removal by chitosan and its derivatives are also briefly discussed.

A mesoporous melamine/chitosan/activated carbon biocomposite: Preparation, characterization and its application for Ni (II) uptake via ion imprinting

A novel imprinted biocomposite and its non-imprinted form were developed by melaminating and crosslinking of chitosan coated onto a bio-based activated carbon and characterized using FTIR, BET, FESEM-EDS and XRD. Nickel, 4-Toluenesulfonyl chloride, and glutaraldehyde were used as a template, converter of hydroxyl and amine groups to good leaving groups, and cross-linker, respectively. The factors affecting adsorptivity and imprinting factor were optimized by using the Taguchi method for the subsequent comparative adsorptivity, kinetics, isotherms, selectivity, and reusability studies of imprinted biocomposite with its non-imprinted one. The pseudo-first-order and Langmuir models were best fitted to the experimental kinetics and equilibrium isotherm data, respectively. The maximum Ni (II)) adsorptivity of 109.86 mg/g, the imprinting factor (I·F) of 5.45 and Ni (II) selectivity coefficients values of 3.13, 4.48, 3.72, 2.51 for Ni (II) toward Zn (II), Cd (II), Cu (II) and Pb (II), respectively, were obtained at optimum conditions. After five consecutive adsorption-desorption cycles, the biocomposites still presented a high adsorptivity (>83%), indicating their excellent reusability.

Development of superabsorbent hydrogel based on Gum Arabic for enhanced removal of anxiolytic drug from water

The growing consumption of anxiolytic drugs like diazepam (DZP) has aggravated the problem of persistent organic pollutants in water. Due to its characteristics, the removal of DZP from water and wastewater is a challenging task. As an effort to deals with this issue, in this study, we report the development of a hydrogel based on Gum Arabic (GA) grafted with poly(acrylic acid) (GA-g-PAAc) to be used in the adsorptive removal of DZP from water. The hydrogel formation was confirmed by Fourier-transform infrared (FTIR) spectroscopy and thermal analysis (TGA/DTG) analyses. Images obtained by scanning electron microscopy (SEM) revealed that GA-g-PAAc hydrogel exhibits a porous morphology while swelling experiments suggest a superabsorbent characteristic (degree of swelling> 600%). From batch experiments, it was found that the removal of DZP reached remarkable percentages (>80%) before 300 min in moderate experimental conditions (pH 7, 25 °C, 150 mg of adsorbent). The adsorption of DZP on GA-g-PAAc followed the pseudo-first order kinetics, and the mechanism was described by the linear Langmuir isotherm. The maximum adsorption capacity (q_max) was calculated to be 15.16 mg g^-1 (at 25 °C), which is comparable or superior to other adsorbent materials used in DZP removal. Reuse experiments showed that GA-g-PAAc keeps appreciable adsorption ability even after five reuse cycles. The results reported here suggest this superabsorbent hydrogel could be a promising adsorbent material to treat water contaminated by anxiolytic drugs, like DZP.

A chitosan-based composite for adsorption of uranyl ions; mechanism, isothems, kinetics and thermodynamics

The present paper describes a green and cost-effective approach to investigate chitosan-sepiolite (Ch-Sep) composite as an adsorbent for removal of UO₂²⁺ ions in aqueous solution. The Ch-Sep composite was prepared as a beads using with two cross-linking agents: tripolyphosphate (TPP) and epichlorohydrin (ECH). Their adsorption properties for the removal of UO₂²⁺ ions in aqueous solution by batch experimental conditions were studied. The adsorptive removal processes of UO₂²⁺ ions from aqueous solution were evaluated by Langmuir, Freundlich and Dubinin-Radushkevich isotherm models, and was found to be perfectly fit to the Langmuir model (R² = 0.971). The maximum adsorption capacity was 0.220 mol kg^-1 at 25 °C from Langmuir isotherm model. Adsorption energy was 12.1 kJ mol^-1 indicating that the adsorption process was chemical. The adsorption kinetics followed the pseudo second order and intra particle diffusion models. The thermodynamics parameters of UO₂²⁺ ions removal from aqueous solution was confirmed spontaneous, endothermic and possible at higher temperatures behavior of adsorption process. The adsorption mechanism of UO₂²⁺ ions onto Ch-Sep composite beads was investigated by FT-IR and SEM analysis. These findings revealed the effectiveness and potential of the newly synthesized Ch-Sep composite beads for the removal of UO₂²⁺ ions.

Ion-imprinted sponge produced by ice template-assisted freeze drying of salecan and graphene oxide nanosheets for highly selective adsorption of mercury (II) ion

As a kind of potential heavy metal absorbent, polysaccharide-based materials are limited by the complicated preparation method and bad selectivity toward targeted ion. Here, a fantastic sponge was produced by combining salecan and graphene oxide (GO) nanosheets via ice template-assisted freeze drying and ion-imprinting technologies. The intense intermolecular interactions between salecan and GO gave the sponge high stability. The swelling, morphology, and mechanical stiffness of the material showed highly dependent on the salecan content. Additionally, the influence of salecan content, pH, initial ion concentration, and contact time on Hg²⁺ adsorption was extensively investigated. Adsorption kinetics and equilibrium isotherms perfectly fitted in the pseudo-second-order and Freundlich models, reflecting the multilayer chemical-adsorption mediated mechanism. Most strikingly, the ion-imprinted sponge exhibited strong selectivity toward Hg²⁺ and outstanding stability with recyclability over usage of five times. These investigations provide the guidance for the construction of promising polysaccharide-based adsorbents for the remediation of Hg²⁺-polluted water.

Bionic chitosan-carbon imprinted aerogel for high selective recovery of Gd(Ⅲ) from end-of-life rare earth productions

High selective recovery of Gd(Ⅲ) from end-of-life rare earth productions is essential for cleaner production. Chitosan(CS), a biomaterial, has shown excellent results in water treatment. The amino and hydroxyl groups on the surface of CS play a vital role in adsorbing metal ions. Polydopamine has good stability, strong water dispersibility, and excellent biocompatibility. As a bio-crosslinking agent, the amino and phenolic hydroxyl groups on its surface can be combined with metal ions to help the material absorb metal ions. This paper combines the active groups of biomimetic materials and the mechanical properties of new nanomaterials multi-walled carbon nanotubes and graphene oxide, and prepared a high-performance chitosan-based aerogel MWCNT-PDA-CS-GO through heat and mass transfer at low temperature and low pressure. The adsorption mechanism of MWCNT-PDA-CS-GO for Gd(Ⅲ) was analyzed through a series of characterization and adsorption experiments. At pH 7.0, the maximum adsorption capacity of aerogel for Gd(Ⅲ) reached 150.86 mg g^-1. The relative selectivity of imprinted ions is 48.02 times higher than other ions. All the results indict MWCNT-PDA-CS-GO aerogel exhibits excellent selectivity and stability for effective recovery of Gd(Ⅲ).

Impacts of polyethylene microplastics on bioavailability and toxicity of metals in soil

In this study, we investigated the bioavailability and toxicity of metals (Cu and Ni) in the soil containing polyethylene microplastics (PE-MPs). The bioavailability of the metals determined by the five-step chemical sequential extraction method increased with the addition of MPs (0.1%, 1%, 10%) in the soil, which was confirmed by the adsorption-desorption characteristics. To further examine the bioavailability and toxicity of metals, earthworms (Eisenia fetida) were exposed to soil containing Cu²⁺ (100 mg/kg) or Ni²⁺ (40 mg/kg) with different amounts (0.01%, 0.05%, and 0.1%) of PE-MPs for 21 days. The highest concentrations of Cu²⁺ and Ni²⁺ in earthworms reached to 73.3 and 36.3 mg/kg, respectively. Moreover, metal concentrations in earthworms increased with MP contents in the soil, which was consistent with the bioavailability measured by the sequential extraction method. Furthermore, changes in biomarkers including peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD) activity, malondialdehyde (MDA) contents, and related gene expression levels in earthworms suggested that the pollutants caused toxicity to earthworms. Overall, MPs increased the bioavailability of metals in the soil and the toxic effects to earthworms. These findings provide insights regarding the impacts of MPs on the bioavailability of metals and the combined toxic effects of these two kinds of pollutants on terrestrial animals.

Ion-Imprinted Polymers: Synthesis, Characterization, and Adsorption of Radionuclides

Growing concern over the hazardous effect of radionuclides on the environment is driving research on mitigation and deposition strategies for radioactive waste management. Currently, there are many techniques used for radionuclides separation from the environment such as ion exchange, solvent extraction, chemical precipitation and adsorption. Adsorbents are the leading area of research and many useful materials are being discovered in this category of radionuclide ion separation. The adsorption technologies lack the ability of selective removal of metal ions from solution. This drawback is eliminated by the use of ion-imprinted polymers, these materials having targeted binding sites for specific ions in the media. In this review article, we present recently published literature about the use of ion-imprinted polymers for the adsorption of 10 important hazardous radionuclides-U, Th, Cs, Sr, Ce, Tc, La, Cr, Ni, Co-found in the nuclear fuel cycle.

Chitosan based-nanoparticles and nanocapsules: Overview, physicochemical features, applications of a nanofibrous scaffold, and bioprinting

Recent advancements in the synthesis, properties, and applications of chitosan as the second after cellulose available biopolymer in nature were discussed in this review. A general overview of processing and production procedures from A to Z was highlighted. Chitosan exists in three polymorphic forms which differ in degree of crystallinity (α, β, and γ). Thus, the degree of deacetylation, crystallinity, surface area, and molecular mass significantly affect most applications. Otherwise, the synthesis of chitosan nanofibers is suffering from many drawbacks that were recently treated by co-electrospun with other polymers such as polyvinyl alcohol (PVA), polyethylene oxide (PEO), and polycaprolactone (PCL). Ultimately, this review focuses on the area of new trend utilization of chitosan nanoparticles as nanospheres and nanocapsules, in cartilage and bone regenerative medicine. Owing to its biocompatibility, bioavailability, biodegradability, and costless synthesis, chitosan is a promising biopolymeric structure for water remediation, drug delivery, antimicrobials, and tissue engineering.

A Critical Review on the Synthesis and Application of Ion-Imprinted Polymers for Selective Preconcentration, Speciation, Removal and Determination of Trace and Essential Metals from Different Matrices

The presence of toxic trace metals and high concentrations of essential elements in the environment presents a serious threat to living organism. Various methods have been used for the detection, preconcentration and remediation of these metals from biological, environmental and food matrices. Owing to the complexicity of samples, methods with high selectivity have been used for detection, preconcentration and remediation of these trace metals. These methods are achieved by the use of ion-imprinted polymers (IIPs) due to their impressive properties such as selectivity, high extraction efficiency, speciation capability and reusability. Because of the increase of toxic trace and essential metals in the environment, IIPs have attracted great use in analytical chemistry. This review, provide a brief background on IIPs and polymerization method that are used for their preparation. Recent applications of IIPs as adsorbents for preconcentration, removal, speciation and electrochemical detection of trace and essential metal is also discussed.

A Comparative Study on Cu2+, Zn2+, Ni2+, Fe3+, and Cr3+ Metal Ions Removal from Industrial Wastewaters by Chitosan-Based Composite Cryogels

Materials coming from renewable resources have drawn recently an increased attention in various applications as an eco-friendly alternative in the synthesis of novel functional materials. Polysaccharides, with their prominent representative - chitosan (CS), are well-known for their sorption properties, being able to remove metal ions from dilute solutions either by electrostatic interactions or chelation. In this context, we proposed here a comparative study on Cu2+, Zn2+, Ni2+, Fe3+, and Cr3+ metal ions removal from industrial wastewaters by CS-based composite cryogels using batch technique. The composite cryogels consisting of CS embedding a natural zeolite, namely clinoptilolite, were synthesized by cryogelation, and their sorption performance were compared to those of CS cryogels and of acid-activated zeolite. A deeper analysis of thermodynamics and kinetics sorption data was performed to get insights into the sorption mechanism of all metal ions onto sorbents. Based on the optimized sorption conditions, the removal of the above-mentioned ions from aqueous solutions by the composite sorbent using dynamic technique was also evaluated.