Iminodiacetic Acid Research Articles

Polymer brush grafted immobilized metal ion affinity adsorbent based on polydopamine/polyethyleneimine-coated magnetic graphene oxide for selective enrichment of cytokinins in plants

Animmobilized metal affinity (IMAC) adsorbent was prepared for selective enrichment of adenine type CKs, via grafting polymer chain pendant with iminodiacetic acid (IDA) from polydopamine (PDA)/polyethyleneimine (PEI)-coated magnetic graphene oxide (magGO) via surface-initiated-atom transfer radical polymerization (SI-ATRP). The prepared IMAC sorbent exhibited remarkable adsorption performances and good selectivity for adenine-type CKs and was utilized as a sorbent of magnetic solid-phase extraction (MSPE) for effectiveenrichment of four adenine-type CKs in bean sprouts. Under the optimized extraction conditions, an analytical method for four adenine type CKs in bean sprouts was established by combining the MSPE combined with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The recoveries of the analytes were between 80.4 ± 1.9% and 114.6 ± 1.5% (n = 3). The limits of detection (LODs) range from 0.63 to 2.30 pg⋅mL-1. The relative standard deviations of intra-day and inter-day were less than 12.6%. Theestablished method was successfully applied to the selective extraction and sensitive detection of trace adenine-type CKs in plant samples.

Inorganic nanoparticles-modified polyvinyl chloride separation membrane and enhanced anti-fouling performance

Porous nanomaterials are important additives in the preparation of high-performance separation membranes. To prepare two nanocomposites, mesoporous silicon dioxide (MCM-41) as a carrier and zinc acetate as a zinc source, Zinc oxide-loaded mesoporous silicon dioxide (ZPP-MCM) was prepared by using polydopamine (PDA) and Polyethylenimine (PEI) as water-soluble ligands, and zinc oxide-loaded mesoporous silicon dioxide (εZI-MCM) were prepared by using iminodiacetic acid (IDA) as water-soluble ligands and coated with ε-poly-l-lysine HCl. The two nanocomposites were blended into polyvinyl chloride (PVC) membranes as modifiers. The results show that the overall porosity of the composite membrane is increased. However, the surface roughness of the composite membrane is decreased with narrow pore size distribution, which was favourable for selective filtration. εZI-MCM nanoparticles can be evenly distributed on the film due to their excellent dispersion, which solves the problem of uneven distribution of nanoparticles on the film, and the surface of the prepared composite film is relatively flat. In addition, introducing the nanoparticles significantly improves the surface hydrophilicity and water flux of the composite membrane. In the experiments of pure water flux and bovine serum albumin (SBA) flux, the flat film with nanoparticles shows higher flux than pure PVC films. The addition of nano-composites further improves the anti-fouling performance and flux recovery ratio of the modified PVC membrane, and the recovery ratio of flux was more than 90%. This work exhibits that Porous nanomaterials have successfully modified the hydrophobic PVC membrane, affording good anti-fouling performance.

Electrochemical sensing interface based on the oriented self-assembly of histidine labeled peptides induced by Ni2+ for protease detection

To construct an electrochemical sensing interface which was convenient for protease recognition and cleavage, we designed a strategy for directed self-assembly of histidine-tagged peptides on the electrode led by Ni2+ ions for electrochemical detection of prostate specific antigen (PSA). The electrode surface was first functionalized using carboxylated multiwalled carbon nanotubes and then modified with the metal ion chelating agent (5 S)–N-(5-Amino-1-carboxypentyl) iminodiacetic acid (NIA). After the Ni2+ was captured by NIA, the designed immune-functional peptide could be oriented assembly to the electrode interface through the imidazole ring of histidine at the tail, completing the construction of the recognition layer. Therefore, by adding the analyte PSA to identify and shear the immune-functional peptide, the ferrocene in its head was released, resulting in a reduction in the electrical signal, enabling sensitive detection. In addition, the self-assembly layer could be removed by pickling to realize the reconstruction of the recognition layer. Under optimal conditions, the electrochemical sensor had an ultralow detection limit of 11.8 fg mL−1 for PSA, with a wide detection range from 1 pg mL−1 to 100 ng mL−1. In this work, an electrochemical sensing interface based on the histidine-tagged peptide induced by Ni2+ was formed to enable controllable oriented assembly on the electrode surface, and the recognition layer could be reconstructed via pickling, providing a potential approach for the design of repeatable interfaces.

Efficient removal of Pb(II) by iminodiacetic acid modified magnetic mesoporous carbon

Magnetic mesoporous adsorbent carbon modified with iminodiacetic acid (Fe3O4@mC-IDA), was prepared to remove Pb(II). The magnetic mesoporous carbon (Fe3O4@mC) was first synthesized by in-situ growing carbon layers on the surface of ferrosoferric oxide, which exhibited large specific surface area and mesoporous structure, and the template molecule and carbon source are both from rich and cheap magnesium citrate. Then, iminodiacetic acid (IDA) was attached to Fe3O4@mC by a ring opening reaction. Multiple characterization techniques were applied to demonstrate the synthesis of the adsorbent. The composite could achieve adsorption equilibrium of Pb(II) in 65 min, and had a maximum adsorption capacity of 429.23 mg g−1 for Pb(II). Langmuir isothermal, pseudo-2nd-order kinetics model and Elovich model could be relatively suitable for simulating the adsorption process. In addition, the adsorbent had fine reusability, and the removal rate of Pb (II) reached 90.67% after 5 cycles. The adsorption mechanistic study showed that COO− and tertiary amine formed tridentate chelates with Pb(II), and hydroxyl groups combined with Pb(II) through electrostatic attraction. These results suggested that Fe3O4@mC-IDA was a potential adsorbent for Pb(II) removal with fast adsorption speed, easy separation ability and fine reusability.

Features of doxorubicin adsorption on Fe3O4 magnetic nanoparticles coated with SiO2 or SiO2/aminopropylsilane

New nanocomposites based on Fe3O4 magnetic nanoparticles coated with SiO2 or SiO2/aminopropylsilane (APS), including those using N-(phosphonomethyl)iminodiacetic acid (PMIDA), were obtained, and the immobilization of the antitumor agent doxorubicin (Dox) on nanocomposites was examined. It has been shown that the binding of Dox to the negatively charged surface of SiO2 particles occurs more efficiently than that to the APS-modified surface with positively charged amino groups; the presence of PMIDA molecules on the surface significantly increased the loading content. Based on DFT calculations, a mechanism for Dox binding to the surface of the synthesized nanocomposites was proposed.

Chimeric Hepatitis B core virus-like particles harboring SARS-CoV2 epitope elicit a humoral immune response in mice

BackgroundVirus-like particles are an interesting vector platform for vaccine development. Particularly, Hepatitis B virus core antigen has been used as a promising VLP platform. It is highly expressed in different recombinant expression systems, such as E. coli, and self-assembled in vitro. It effectively improves the immunogenicity of foreign antigenic epitopes on its surface. Various foreign antigens from bacteria, viruses, and protozoa can be genetically inserted into such nanoparticles. The effective immunogenicity due to VLP vaccines has been reported. However, no research has been performed on the SARS-CoV2 vaccine within this unique platform through genetic engineering. Considering the high yield of target proteins, low cost of production, and feasibility of scaling up, E. coli is an outstanding expression platform to develop such vaccines. Therefore, in this investigation, we planned to study and develop a unique HBc VLP-based vaccine against SARS-Cov2 utilizing the E. coli expression system due to its importance.ResultsInsertion of the selected epitope was done into the major immunodominant region (MIR) of truncated (149 residues) hepatitis B core capsid protein. The chimeric protein was constructed in PET28a+ and expressed through the bacterial E. coli BL21 expression system. However, the protein was expressed in inclusion body forms and extracted following urea denaturation from the insoluble phase. Following the extraction, the vaccine protein was purified using Ni2 + iminodiacetic acid (IDA) affinity chromatography. SDS-PAGE and western blotting were used to confirm the protein expression. Regarding the denaturation step, the unavoidable refolding process was carried out, so that the chimeric VLP reassembled in native conformation. Based on the transmission electron microscopy (TEM) analysis, the HBC VLP was successfully assembled. Confirming the assembled chimeric VLP, we explored the immunogenic effectivity of the vaccine through mice immunization with two-dose vaccination with and without adjuvant. The utilization of adjuvant was suggested to assess the effect of adjuvant on improving the immune elicitation of chimeric VLP-based vaccine. Immunization analysis based on anti-spike specific IgG antibody showed a significant increase in antibody production in harvested serum from immunized mice with HBc-VLP harboring antigenic epitope compared to HBc-VLP- and PBS-injected mice.ConclusionsThe results approved the successful production and the effectiveness of the vaccine in terms of humoral IgG antibody production. Therefore, this platform can be considered a promising strategy for developing safe and reasonable vaccines; however, more complementary immunological evaluations are needed.

Preparation of Polyacrylonitrile-Based Immobilized Copper-Ion Affinity Membranes for Protein Adsorption.

A polyacrylonitrile (PAN)-based immobilized metal-ion affinity membrane (IMAM) was prepared with a high capacity for protein adsorption. PAN was selected as the substrate due to its excellent thermal and chemical stability. The cyano groups on the PAN membrane were substituted with carboxyl groups, followed by reactions with ethylenediamine (EDA) and ethylene glycol diglycidyl ether (EGDGE) to produce the terminal epoxy groups. The chelating agent iminodiacetic acid (IDA) was then bound to the modified PAN membrane and further chelated with copper ions. The immobilized copper ion amount of membrane was analyzed to obtain the optimal reaction conditions, which were 60 °C/3 h for EDA coupling and 60 °C/4 h for EGDGE grafting. Furthermore, under the use of minor IDA and copper ion concentrations, the immobilized copper ion capacity of the IMAM was 4.8 μmol/cm2 (253.4 µmol/mL, or 1.47 μmol/mg). At a neutral pH, the cationic lysozyme exhibited a large adsorption capacity with the IMAM (1.96 μmol/mL), which was most likely multilayer binding, whereas the adsorption capacity for bovine serum albumin (BSA) and histidine-tagged green fluorescent protein (GFP-His6) was 0.053 μmol/mL and 0.135 μmol/mL, respectively, with a monolayer adsorption arrangement. The protein desorption efficiency was greater than 95%, implying that the prepared IMAM could be reused for protein adsorption.

Heterometallic uranyl (hydroxyethyl)iminodiacetic acid (heidi) complexes: Molecular models for U(VI) uptake in complex media.

Amidoximated absorbents (AO-PAN) effectively remove U(VI) from aqueous solution, but previous studies reported more variability for complex natural waters that contain additional confounding ions and molecules. Ternary phases containing U(VI), M(III) (M = Fe(III), Al(III), Ga(III)), and organic molecules exist under these conditions and cause heterogeneous U(VI) uptake on AO-PAN. The goal of the current study is to provide additional insights into the structural features ternary complexes using N-(2-hydroxyethyl)-iminodiacetic acid (HEIDI) as the model organic chelator and explore the relevance of these species on U(VI) capture. Three model compounds ([(UO2)(Fe)2(μ3-O)(C6NO5H8)2(H2O)4] (UFe2), ([(UO2)(Al)2(μ2-OH)(C6NO5H8)2(H2O)3] (UAl2) and [(UO2)(Ga)2(μ2-OH)(C6NO5H8)2(H2O)3] (UGa2)) were characterized by single-crystal X-ray diffraction. Raman spectra of the model compounds were compared with solution data and the ternary phases were noted in the case of Al(III) and Ga(III), but not in the Fe(III) system. U(VI) adsorption onto AO-PAN was not impacted by the presence of HEIDI or the trivalent metal species.

Poly (polyethylene glycol diacrylate‐co‐allyl glycidyl ether) cryogels: Preparation, modification with iminodiacetic acid, and application of Cu(II) removal

AbstractIn this study, poly (polyethylene glycol diacrylate‐co‐allyl glycidyl ether) cryogels (p(PEGDA‐co‐AGE)) was synthesized by low‐temperature polymerization using polyethylene glycol diacrylate (PEGDA), allyl glycidyl ether (AGE), and N,N′‐methylenebisacrylamide (MBAAm). The cryogel was then modified with iminodiacetic acid (IDA) by a ring‐opening reaction of AGE to attach carboxyl groups on the surface. The modified cryogel (p(PEGDA‐co‐AGE)‐IDA) was characterized by scanning electron microscope, energy dispersive X‐ray spectra, infrared spectra, X‐ray photoelectron spectroscopy, and compression test, as well as its absorption performance. It was found that the adsorption efficiency and the reusability of cryogels for Cu(II) was related to pH, and the maximum adsorption capacity was 76.49 mg g−1 (pH = 6). In addition, the kinetics of Cu(II) adsorption on cryogels was investigated to clarify the adsorption mechanism.

Ligand-Capped Cobalt(II) Multiplies the Value of the Double-Histidine Motif for PCS NMR Studies.

In structural studies by NMR, pseudocontact shifts (PCSs) provide both angular and distance information. For proteins, incorporation of a di-histidine (diHis) motif, coordinated to Co2+, has emerged as an important tool to measure PCS. Here, we show that using different Co(II)-chelating ligands, such as nitrilotriacetic acid (NTA) and iminodiacetic acid (IDA), resolves the isosurface ambiguity of Co2+-diHis and yields orthogonal PCS data sets with different Δχ-tensors for the same diHis-bearing protein. Importantly, such capping ligands effectively eliminate undesired intermolecular interactions, which can be detrimental to PCS studies. Devising and employing ligand-capping strategies afford versatile and powerful means to obtain multiple orthogonal PCS data sets, significantly extending the use of the diHis motif for structural studies by NMR.

Interaction between [(η6-p-cym)M(H2O)3]2+ (MII = Ru, Os) or [(η5-Cp*)M(H2O)3]2+ (MIII = Rh, Ir) and Phosphonate Derivatives of Iminodiacetic Acid: A Solution Equilibrium and DFT Study.

The pH-dependent binding strengths and modes of the organometallic [(η6-p-cym)M(H2O)3]2+ (MII = Ru, Os; p-cym = 1-methyl-4-isopropylbenzene) or [(η5-Cp*)M(H2O)3]2+ (MIII = Rh, Ir; Cp* = pentamethylcyclopentadienyl anion) cations towards iminodiacetic acid (H2Ida) and its biorelevant mono- and diphosphonate derivatives N-(phosphonomethyl)-glycine (H3IdaP) and iminodi(methylphosphonic acid) (H4Ida2P) was studied in an aqueous solution. The results showed that all three of the ligands form 1:1 complexes via the tridentate (O,N,O) donor set, for which the binding mode was further corroborated by the DFT method. Although with IdaP3- and Ida2P4- in mono- and bis-protonated species, where H+ might also be located at the non-coordinating N atom, the theoretical calculations revealed the protonation of the phosphonate group(s) and the tridentate coordination of the phosphonate ligands. The replacement of one carboxylate in Ida2- by a phosphonate group (IdaP3-) resulted in a significant increase in the stability of the metal complexes; however, this increase vanished with Ida2P4-, which was most likely due to some steric hindrance upon the coordination of the second large phosphonate group to form (5 + 5) joined chelates. In the phosphonate-containing systems, the neutral 1:1 complexes are the major species at pH 7.4 in the millimolar concentration range that is supported by both NMR and ESI-TOF-MS.

Binding of His-tagged molecules to giant vesicles via anchor lipids.

Giant unilamellar vesicles (GUVs) are versatile biomimetic membrane compartments made of a lipid bilayer. For the biofunctionalization of the membranes, proteins can be attached peripherally to membranes using anchor lipids. One such anchor lipid is the 1,2-dioleoyl-sn-glycero-3-[(N-(5-amino-1-carboxypentyl) iminodiacetic acid) succinyl] (DGS-NTA) lipid, which has a head group that can bind to metal cations and subsequently to proteins via a six-histidine (6H) chain. The proteins are tagged with fluorescent molecules to visualize them in the confocal microscope. We use two molecules with a 6H tag - fluorescein isothiocyanate (FITC) and green fluorescent protein (GFP). The binding affinity of the protein to the NTA lipid is affected by the size of the molecule and the choice of the metal cation in the head group. In this study, we use a microfluidic device to expose the GUVs with NTA lipids to a constant His-tagged fluorophore concentration in the exterior solution. The equilibrium dissociation constant for the NTA chelated to divalent nickel cation (Ni2+) is measured to be 37.5 nM for 6H-GFP and 18.5 nM for 6H-FITC (Soft matter, 2022, 18, 6372). We also establish a DGS-NTA lipid system that chelates to trivalent cobalt cation (Co3+) and compare it to the Ni2+ system. We achieve such a system without oxidizing reagents, keeping the lipids and the protein unaffected.

Benchmarking computational chemistry approaches on iminodiacetic acid

In the present study, theoretical harmonic vibrational frequencies (IR and Raman), carbon and proton NMR chemical shifts, geometric parameters, atomic charges (only for heteroatoms), reactivity indices (eLUMO, eHOMO, electronegativity, and hardness), and thermodynamical data (inner energy, enthalpy, Gibbs free energy, and entropy) of iminodiacetic acid (IDA) molecule have been investigated. We utilized ORCA software for B3LYP and HF (combined with Pople and Karlsruhe basis sets) calculations and MOPAC2016 software for semi-empirical calculations (AM1, PM3, and PM6). Theoretical vibrational frequencies and carbon and proton NMR chemical shifts have been compared with the corresponding experimental data. Although there was a strong correlation between the experimental and computational vibrational frequencies at low frequencies (<2200 cm−1), the computational predictions of vibrational frequencies were unsuccessful at high frequencies (>2200 cm−1). Distinctly, the studied computational approaches appeared to perform better in the prediction of carbon and proton NMR chemical shifts. Theoretical vibrational frequencies were also compared to each other to understand the impact of method choice (HF vs B3LYP D3 vs semi-empirical methods), dispersion correction (B3LYP D3 vs B3LYP), water solvation (SMD supplemented vs non-supplemented calculations), the family of basis set (Pople vs Karlsruhe basis sets), numbers of zeta (double vs triple zeta), polarization function (polarized vs nonpolarized basis sets), and diffusion function (diffusion supplemented vs non-supplemented basis sets). Moreover, geometric parameters, heteroatom charges, reactivity indices, and thermodynamical data produced by distinct computational approaches, as well, were compared to each other. Based on these comparisons, we detected critical factors (such as water solvation) acting on the computation of geometries, energies, and charges.

Benchmarking polymeric cryogels for immobilized metal affinity chromatography

Cryogels are polymers prepared in frozen environment and seen as new separation matrices with their applications in many bioseparation methods. They have significant benefits including supermacroporosity, short diffusion path, low pressure, and low resistance to both adsorption and elution. Macro and connected pores give cryogels a unique spongy structure. Immobilized metal affinity chromatography (IMAC) is a generally employed analytical separation method for the purification of biomolecules. Several transition ions create stable complexes with electron-rich compounds. IMAC sorbent is obtained by complexing first-order transition metal ions over chelating agents. Lysozyme is an enzyme found in various vertebrate cells and secretions. Common applications include its use as a cell disrupting agent, as an anti-bacterial agent, as a food additive, and as a medicine for the treatment of infections and ulcers. In this study, cryogel-based polymeric material prepared by free-radical polymerization method with hydroxyethyl methacrylate/glycidyl methacrylate monomer pair were covalently interacted with iminodiacetic acid metal chelating agent, and regions showing affinity for lysozyme enzyme were formed by binding with Ni(II) ions. The cryogel was first characterized by Fourier transform infrared spectrophotometer, scanning electron microscopy, thermal gravimetric analysis, X-ray photoelectron spectroscopy and swelling test. Then, the effects of pH, lysozyme concentration, temperature, ionic strength and flow rate on lysozyme adsorption capacity were explored and optimum conditions were found.

Clinical, Laboratory, Radiological, and Genetic Characteristics of Pediatric Patients with Alagille Syndrome.

Alagille syndrome (ALGS) is an autosomal dominant disease caused by JAG1 or NOTCH2 mutation. It is diagnosed by the presence of three out of five features: characteristic facies, posterior embryotoxon, peripheral pulmonary stenosis, vertebral defects, and interlobular bile duct paucity. This study aimed to review the prevalence, clinical presentations, diagnosis, treatment, and outcome of patients with ALGS. This is a retrospective review of patients with ALGS at the Pediatric Department, Salmaniya Medical Complex, Bahrain, between August 1994 and October 2022. The diagnosis was based on clinical, laboratory, radiological, histopathological, and genetic findings. Five patients were found to have ALGS. The prevalence of ALGS in Bahrain was 1.04 patients per 100,000 (0.001%). Four were Bahraini and three were females. Median birth weight was 2.3 (2.3-2.5) kg. All patients presented at the time of birth with low birth weight, cholestatic jaundice, clay-colored stool, heart murmur, and dysmorphic facial features. All had congenital heart diseases, two had butterfly vertebrae, and one had posterior embryotoxon. All had elevated liver enzymes and normal abdominal ultrasound. Three had positive hepatobiliary iminodiacetic acid scan and one had bile duct paucity in liver biopsy. Three had intraoperative cholangiogram. Four were positive for JAG1 mutation. All received ursodeoxycholic acid and fat-soluble vitamins. Two required liver transplantation. ALGS is a rare disorder in Bahrain. Diagnosis is challenging as the disease can be associated with or misdiagnosed as biliary atresia. Patients with ALGS are at high risk of morbidity either by unnecessary intraoperative cholangiogram or unavoidable liver transplantation.

Superhydrophilic microfibrous adsorbent with broad-spectrum binding affinity to effectively remove diverse pollutants from aqueous solutions

The diversity of pollutants in wastewater, such as heavy metal ions, dyes, and antibiotics, has threatened the ecological environment and human health for decades. To tackle this harsh issue, we developed a superhydrophilic microfibrous adsorbent to remove diverse pollutants by functionalizing electrospun poly(glycidyl methacrylate) fibers with a high density of iminodiacetic acid (IDA) functional groups. Thanks to strong and broad-spectrum binding affinity of the IDA group and good surface wettability, the resulting superhydrophilic microfibrous adsorbent exhibits excellent adsorption performance toward cationic organic dyes, heavy metal ions, and antibiotics via electrostatic interaction or coordination. It can achieve extraordinarily high adsorption capacities of 2569.70 mg/g, 1621.49 mg/g, 2420.18 mg/g, 175.44 mg/g, 123.46 mg/g, and 389.53 mg/g towards methylene blue, malachite green, methyl violet, Cu2+, Cr3+, and tetracycline, respectively. The absorbent can realize more than 98 % removal rate of these pollutants from water within 20 min. Moreover, its porous membrane structure and pH-dependent adsorption selectivity provide the developed adsorbent with outstanding recyclability. The spent adsorbent can be easily regenerated via a dilute acid solution and reused at least 10 times without apparent loss in performance.

Iron(Ⅲ)-modified resin YZS60 combined with laser-induced fluorescence spectra for the detection of phosphorus after solid-phase extraction in aqueous solutions

Phosphorus elements were extracted from aqueous solutions by iron-modified chelate resin YZS60. The characterization of the iron-modified chelate resin by using scanning electron microscopy, energy disperse spectroscopy, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy showed that iron(Ⅲ) was successfully grafted onto the iminodiacetic acid functional group of chelating resin. The resin chelated with phosphorus emitted strong fluorescence after excited by very low power semiconductor laser, which was used for the detection of phosphorus in aqueous solutions, resulting in improving the sensitivity significantly for the detection of phosphorus in aqueous solutions. The fluorescence intensities of the chelates were proportional to the phosphorus concentrations with highly linear correlation coefficients R2 = 0.991 and the limit of detection of 0.018 mg/L was achieved. This work provides a simple, low-cost, and non-destructive method for the extraction and detection of phosphorus in aqueous solutions.

Selective adsorption of Pd(II) over Ag(I) in nitric acid solutions using nitrogen-donor-type adsorbents

The HNO3 leaching process is used in recycling Pd metal from spent products that primarily contain Ag, and most Pd residues are separated from solutions containing Ag(I). However, a small amount of Pd(II) remains in these Ag(I) solutions. Therefore, the separation of Pd(II) and Ag(I) in HNO3 solutions is essential for promoting efficient Pd recycling. In this study, the separation of Pd(II) and Ag(I) in HNO3 solutions was investigated using four N-donor-type adsorbents bearing amine (R-Amine), iminodiacetic acid (R-IDA), pyridine (R-Py), and bis-picolylamine (R-BPA) functional groups. R-IDA and R-Py demonstrated efficient separation of Pd(II) (82 %–99 %) from Ag(I), Cu(II), Ni(II), and Fe(III) (<3%) over a range of HNO3 concentrations (0.5–7 M for R-IDA and 0.3–7 M for R-Py). R-Amine showed similar selectivity but lower Pd(II) adsorption (<65 %). By contrast, R-BPA adsorbed Pd(II), Ag(I), and Cu(II) efficiently and non-selectively (>90 %; 0.3–5 M HNO3). Structural analyses of the adsorbed metal ions using Fourier-transform infrared and extended X-ray absorption fine structure spectroscopies revealed the separation mechanisms of the N-donor-type adsorbents. Pd(II) adsorption on R-IDA, R-Py, and R-BPA occurred via Pd(II) coordination with their respective functional groups, whereas that on R-Amine occurred via anion exchange of NO3− with [Pd(NO3)4]2−. The coordinative adsorption mechanisms resulted in higher Pd(II) adsorption of R-IDA, R-Py, and R-BPA. HCl (5.0 M) eluents desorbed 83 % of Pd(II) from R-IDA, whereas thiourea eluents (0.1 M) desorbed 95 % of Pd(II) from R-Py. R-Py was the most effective Pd(II) adsorbent based on adsorption selectivity and desorption efficiency.

Recovery of water and valuable metals using low pressure nanofiltration and sequential adsorption from acid mine drainage

Acid mine drainage (AMD) contains an array of valuable resources such as Rare Earth Elements (REE) and Copper (Cu) which can be recovered along with fresh water. Low pressure nanofiltration with NF90 membrane was first studied to recover fresh water from synthetic AMD and concentration of dissolved metals for subsequent efficient selective recovery. Organic matter (OM) present in AMD was found to cause membrane fouling which resulted in significant flux decline. Powdered eggshell was investigated as a low-cost adsorbent for OM removal. The study showed that a 0.2 mg/l dose of powdered eggshell adsorbed 100% of OM and Fe with no significant loss of other dissolved metals. A steady permeate flux of 15.5 ± 0.2 L/m 2 h (LMH) was achieved for pre-treated AMD with a solute rejection rate of more than 98%. A chromium-based metal organic framework (MOF) modified with N - (phosphonomethyl) iminodiacetic acid (PMIDA) and an amine-grafted mesoporous silica (SBA15) material was synthesized for selective recovery of REE and Cu, respectively. The two adsorbents were used sequentially to selectively adsorb REE (91%) and Cu (90%) from pH adjusted concentrated feed. The formation of coordinating complexes with carboxylate and phosphonic groups on MOF was found to be the primary driving force for selective REE adsorption. Selective uptake of Cu onto amine-grafted SBA15 was due to the formation of strong chelating bonds between Cu and amine ligands. Both adsorbents remained structurally stable over 5 regeneration cycles. The findings here highlight the practical potential of membrane/adsorption hybrid systems for water and valuable metal (REE) recovery from AMD. • Low pressure NF achieved 80% permeate recovery while concentrating dissolved ions. • Modified MOF and SBA15-NH 2 selectively adsorbed 91% of REE and 90% of Cu. • REE show high affinity to deprotonated phosphonic and carboxyl groups in MOF. • Chelating bonds between Cu and amine groups in SBA15 promotes high selectivity. • High reuse capacity over multiple cycles recorded for both adsorbents.

Effect of the Silica-Magnetite Nanocomposite Coating Functionalization on the Doxorubicin Sorption/Desorption.

A series of new composite materials based on Fe3O4 magnetic nanoparticles coated with SiO2 (or aminated SiO2) were synthesized. It has been shown that the use of N-(phosphonomethyl)iminodiacetic acid (PMIDA) to stabilize nanoparticles before silanization ensures the increased content of a SiO2 phase in the Fe3O4@SiO2 nanocomposites (NCs) in comparison with materials obtained under similar conditions, but without PMIDA. It has been demonstrated for the first time that the presence of PMIDA on the surface of NCs increases the level of Dox loading due to specific binding, while surface modification with 3-aminopropylsilane, on the contrary, significantly reduces the sorption capacity of materials. These regularities were in accordance with the results of quantum chemical calculations. It has been shown that the energies of Dox binding to the functional groups of NCs are in good agreement with the experimental data on the Dox sorption on these NCs. The mechanisms of Dox binding to the surface of NCs were proposed: simultaneous coordination of Dox on the PMIDA molecule and silanol groups at the NC surface leads to a synergistic effect in Dox binding. The synthesized NCs exhibited pH-dependent Dox release, as well as dose-dependent cytotoxicity in in vitro experiments. The cytotoxic effects of the studied materials correspond to their calculated IC50 values. NCs with a SiO2 shell obtained using PMIDA exhibited the highest effect. At the same time, the presence of PMIDA in NCs makes it possible to increase the Dox loading, as well as to reduce its desorption rate, which may be useful in the design of drug delivery vehicles with a prolonged action. We believe that the data obtained can be further used to develop stimuli-responsive materials for targeted cancer chemotherapy.