Metal Ions In Aqueous Solution Research Articles

Rapid Detection of Metal Ions in the Aqueous Medium by Colorimetry and Surface Enhanced Raman Scattering Using Vanillic Acid-Coated Silver Nanoparticles

Rapid and inexpensive detection of heavy metal pollution is highly required these days in order to combat pollution. Noble metal nanoparticles coated by organic molecules having surface plasmon resonance have recently played key role in conceptualizing and fabricating sensing devices for the detection of heavy metals. The present study uses the utility of vanillic acid coated silver nanoparticles (V-AgNPs) synthesized by chemical reduction for the colorimetric and surface-enhanced Raman scattering detection of heavy metal ions in aqueous solution. The synthesized V-AgNPs are of approximately 5–15 nm in size. The addition of synthesized V-AgNPs colloidal solution to control and metal ion laced water samples turns the solution color grayish black except for Cr(III) ions. The addition of V-AgNPs colloidal solution to the water samples containing Cr(III) ions turns the solution transparent. Furthermore, the addition of V-AgNPs to water samples containing Cr(III) ions and Mo(VI) creates unique Raman spectral signatures with high intensities that were used for the identification of these metal ions in aqueous solution. The addition of V-AgNPs to metal ions causes aggregation of the nanoparticles which results in change in color and Raman scattering signals. The obtained color patterns and Raman spectral signatures show the potential of V-AgNPs for low cost, timeless, affordable, convenient, sensitive, selective, and rapid detection of heavy metal ions in aqueous media.

Novel biogenic gold nanoparticles stabilized on poly(styrene-co-maleic anhydride) as an effective material for reduction of nitrophenols and colorimetric detection of Pb(II)

Biogenic gold nanoparticles (AuNPs) have been extensively studied for the catalytic conversion of nitrophenols (NP) into aminophenols and the colorimetric quantification of heavy metal ions in aqueous solutions. However, the high self-agglomeration ability of colloidal nanoparticles is one of the major obstacles hindering their application. In the present study, we offered novel biogenic AuNPs synthesized by a green approach using Cistanche deserticola (CD) extract as a bioreducing agent and stabilized on poly(styrene-co-maleic anhydride) (PSMA). The prepared Au@PSMA nanoparticles were characterized by various techniques (HR-TEM, SEAD, FE-SEM, DLS, TGA, XRD, and FTIR) and studied for two applications: the catalytic reduction of 3-NP by NaBH4 and the sensing detection of Pb2+ ions. The optimal conditions for the synthesis of AuNPs were investigated and established at 60 °C, 20 min, pH of 9, and 0.5 mM Au3+. Morphological studies showed that AuNPs synthesized by CD extract were mostly spherical with a mean diameter of 25 nm, while the size of polymer-integrated AuNPs was more than two-fold larger. Since PSMA acted as a matrix keeping the nanoparticles from coagulation and maintaining the optimal surface area, AuNPs integrated with PSMA showed higher catalytic efficiency with a faster reaction rate and lower activation energy than conventional nanoparticles. Au@PSMA could completely reduce 3-NP within 10 min with a rate constant of 0.127 min−1 and activation energy of 9.96 kJ/mol. The presence of PSMA also improved the stability and recyclability of AuNPs. Used as a sensor, Au@PSMA exhibited excellent sensitivity and selectivity for Pb2+ ions with a limit of detection of 0.03 μM in the linear range of 0–100 μM. The study results suggested that Au@PSMA could be used as a promising catalyst for the reduction of NP and the colorimetric sensor for detection of Pb2+ ions in aqueous environmental samples.

New method for recovery of nickel and cadmium from the ”black mass” of spent Ni-Cd batteries by solvent extraction

The paper presents experiments with solid–liquid-liquid extraction of heavy metals from the “black mass” (BM) of waste batteries related to the recycling of nickel and cadmium, as well as cobalt (for several samples) from spent Ni-Cd batteries. The extraction and separation of Ni(II) and Cd(II) from the solid BM with Deep Eutectic Solvents (DESs) and other extractants dissolved in toluene or naphtha (kerosene) have been investigated in detail. It has been shown that the extraction efficiency of DESs, contrary to ionic liquids (ILs), is at the level of 30 wt% Ni(II) and 100 wt% Cd(II) from the BM, without the primary process of leaching with sulphuric acid. Solvent extraction has been proposed with two DESs (choline chloride + lactic acid and choline chloride + malonic acid), with ionic liquids (ILs): trihexyltetradecylphosphonium chloride [P6,6,6,14][Cl] (Cyphos IL 101) and trihexyltetradecylphosphonium thiocyanate [P6,6,6,14][SCN], and with organophosphorous-based acids (OPBAs) such as bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) and di-(2-ethylhexyl) phosphoric acid (D2EHPA). Process factors such as extracting solvents and additives, solvent concentration, holding time, pH and liquid/solid, as well as organic/aqueous (O:A) ratios were studied. For all the systems, the extraction efficiency (E) and the distribution ratio (D) were specified. The metal content in the solid BM was analyzed by the SEM/EDS method and with the use of the UltraWAVE digestion system combined with an atomic absorption spectrometer (FAAS and FAES techniques). An inductively coupled plasma optical emission spectrometer (ICP-OES) was used to determine the concentration of metal ions in aqueous solutions and stripped organic solutions.

Spectroscopic properties and fluorescent recognition of dye sensitized layered lutetium-terbium hydroxides

The layered rare earth hydroxides have attracted increasing interests due to their diverse chemical composition and tunable spectroscopic properties. In this paper, a novel Tb3+ activated layered lutetium hydroxide (LLuH:Tb) was fabricated, in which the inorganic NO3− ions were ion-exchanged with organic (ibuprofen or dodecylsulfonate) anions. After the ion-exchange reaction, the organic anions intercalated LLuH:Tb showed the distinct lamellar structure with the interlayer distance of about 2.56 nm, confirming the formation of inorganic/organic hybrid assembly. The dye ibuprofen-intercalated hybrid effectively promoted the characteristic 5D4 → 7F5 green emission of Tb3+ in the host but failed to be exfoliated into nanosheet colloid. On the contrary, the dodecylsulfonate-intercalated hybrid was readily to be exfoliated into nanosheet colloid by dissolving in formamide solvent, but the green emission of Tb3+ was too weak to be observed. To take advantage of their respective merits and explore the practical uses, certain amounts of dye ibuprofen were directly added to the dodecylsulfonate-intercalated hybrid colloid. Excited with the ultraviolet light, the characteristic green fluorescence of Tb3+ was dramatically enhanced, indicating that the dye was a superior light-harvesting antenna to sensitize the activator Tb3+. The dye sensitized hybrid colloid was very stable at ambient temperature and exhibited excellent fluorescent recognition for Cu2+ ions over other metal ions in aqueous solution due to the large fluorescence quenching. The detection limit for Cu2+ ion reaches 7.63 × 10−7 mol/L, which is far lower than the limitation of Cu2+ in drinking water recommended by the World Health Organization (1.57 × 10−5 mol/L). The fluorescence enhanced/quenched sensor with excellent stability exhibits a high potential for the detection of Cu2+ in routine environmental water.

Binary adsorption of chromium and cadmium metal ions by hemp (Cannabis sativa) based adsorbents

Hexavalent chromium Cr(VI) and divalent cadmium Cd(II) are among the most dangerous metal ions in aqueous solutions. The removal of Cr(VI) and Cd(II) from aqueous media requires serious attention. This study reports on the potential of adsorbents produced from hemp seeds to simultaneously remove Cr(VI) and Cd(II) from a synthetic aquatic medium. Pristine hemp seeds (PHS) were carbonized to obtain carbonized hemp seeds (CHS). The surface of the CHS was impregnated with Fe3O4 nanoparticles to yield a composite CHN. The biomaterials were characterized by SEM-EDX, FTIR, XRD and BET. The characterization revealed that CHS and CHN differed from the PHS adsorbent by exhibiting distinct properties such as higher cation exchange capacity, larger surface area, and porous surface morphology. The SEM images of CHS and CHN were porous. FTIR results of the adsorbents exhibited functional groups such as –OH, –COOH, –C=O and –NH2 that could easily bind to the metals ions. XRD spectra revealed that cellulose materials disintegrated in CHS and CHN. The adsorption data were fitted into kinetics and isotherm models for assessing the uptake mechanism(s). The adsorption rate was rapid in the initial stages until equilibrium was reached after 40 min. The rate data correlated with the pseudo-second-order (PSO) model. The average removal efficiency of Cr(VI) was 19.29, 33.43, and 48.28 mg/g and for Cd(II) 20.19, 40.16, and 42.12 mg/g by PHS, CHS, and CHN respectively. CHS and CHN were better adsorbents than PHS.

Relationship between Surface Hydroxyl Complexation and Equi-Acidity Point pH of MnO2 and Its Adsorption for Co2+ and Ni2.

MnO2 has shown great potential in the field of adsorption and has a good adsorption effect on heavy metal ions in aqueous solution, but there have been problems in the adsorption of heavy metal ions in high-concentration metal salt solutions. In this paper, different crystal forms of MnO2 (α-MnO2, β-MnO2, γ-MnO2, δ1-MnO2, δ2-MnO2, and ε-MnO2) were prepared and characterized by XRD, SEM, EDS, XPS, ZETA, and FT-IR. The reasons for the equi-acidity point pH change of MnO2 and the complex mechanism of surface hydroxylation on metal ions were discussed. The results showed that the equi-acidity point pHs of different crystalline MnO2 were different. The equi-acidity point pH decreased with the increase of reaction temperature and electrolyte concentration, but the reaction time had no effect on it. The equi-acidity point pHs of MnO2 were essentially equal to the equilibrium pH values of adsorption and desorption between surface hydroxyl and metal ions on them. The change of equi-acidity points was mainly due to the complexation of surface hydroxyl, and the equi-acidity point pHs depended on the content of surface hydroxyl and the size of the complexation ability. According to the equi-acidity point pH characteristics of MnO2, more hydroxyl groups could participate in the complexation reaction by repeatedly controlling the pH, so that MnO2 could adsorb heavy metals Co2+ and Ni2+ in high-concentration MnSO4 solution, and the adsorption rates of Co2+ and Ni2+ could reach 96.55 and 79.73%, respectively. The effects of MnO2 dosage and Mn2+ concentration on the adsorption performance were further investigated, and the products after MnO2 adsorption were analyzed by EDS and FT-IR. A new process for MnO2 to adsorb heavy metals Co2+ and Ni2+ in high-concentration MnSO4 solution was explored, which provided a reference for the deep purification of manganese sulfate solutions.

Mercaptocarboxylic acid intercalated MgAl layered double hydroxide adsorbents for removal of heavy metal ions and recycling of spent adsorbents for photocatalytic degradation of organic dyes

Adsorption is considered aneffectiveway for the removal of heavy metal ions in aqueous solutions; however, recycling of spent adsorbents is a formidable challenge. We synthesized mercaptocarboxylic acid/layered double hydroxide (MPA/LDH) adsorbents for the removal of heavy metal ions from wastewater, and it demonstrated excellent adsorption capacities; the maximum adsorption capacities for Hg2+, Pb2+, and Cu2+ were 250.30, 122.10, and 105.33 mg/g at adsorbent dosage of 0.2 g/L and pH of 5.5. The excellent adsorption performance was attributedtothe inner-sphere surface complexation between the heavy metal ions and the S-S and COO– groups in MPA/LDH. Moreover, host–guest interactions between MPA and the LDH laminate may have enhanced the adsorptionefficiencyand selectivity of MPA/LDH. After the adsorption of Hg2+, Pb2+, and Cu2+, highlydispersed metal sulfide NPs were spontaneously formed in the LDH interlayer via confined base catalysis, providing excellent photocatalytic activity for the degradation of organic dyes. High photocatalytic activity was attributed to the suitable energy band and high dispersity of metal sulfides. MPA/LDH-absorbed Hg2+ showed the best photodegradation performance of 99.2% for methylene blue. Notably, MPA/LDH can be used for the simultaneous removal of heavy metals and organic dyes under visible light irradiation. The findings of this study provide insights for developing an environmentally friendly method for conversion from adsorbent to photocatalyst, demonstrating wide prospects in industrial applications.

Identification and determination of multiple heavy metal ions using a miniaturized paper-based optical device

A simple colorimetric paper-based sensor array (optical tongue), which can quickly and accurately identify and discriminate twenty-five kinds of heavy metal ions, is developed. It functions by immobilizing six metal indicators on the paper substrate using polyvinyl chloride. Exposing the device to the aqueous solution of metal ions produces a unique colorimetric signature for each ion, enabling discrimination of the ions by visual inspection. Further analysis of the colorimetric patterns by chemometrics data analysis methods leads to a clustering map for accurate classifying of the metal ions at different concentrations (10.0, 5.0, 2.5, and 1.0 mg L−1). In addition, the device was applied to analyze binary and ternary mixtures of metal ions as well. An interesting feature of this tasting device is speciation analysis of an element of different oxidation states and their mixtures. Beside to qualitative analysis, it represented quantitative analysis ability, e.g., for Zn2+ and Co2+, in the concentration ranges of 0.10–10.00 mg L−1 (R2 = 0.99) and 0.25–12.50 mg L−1 (R2 = 0.99) and detection limits of 0.03 and 0.08 mg L−1, respectively. This optoelectronic tongue shows promising results to be used potentially of on-site analysis of water for its quality.

Evaluation of Aerogel Spheres Derived from Salix psammophila in Removal of Heavy Metal Ions in Aqueous Solution

Heavy metal wastewater treatment is a huge problem facing human beings, and the application degree of Salix psammophila resources produced by flat stubble is low. Therefore, it is very important to develop high-value products of Salix psammophila resources and apply them in the removal heavy metal from effluent. In this work, we extracted the cellulose from Salix psammophila, and cellulose nanofibers (CNFs) were prepared through TEMPO oxidation/ultrasound. The aerogel spheres derived from Salix psammophila (ASSP) were prepared with the hanging drop method. The experimental results showed that the Cu(II) adsorption capacity of the ASSP composite (267.64 mg/g) doped with TOCNF was significantly higher than that of pure cellulose aerogel spheres (52.75 mg/g). The presence of carboxyl and hydroxyl groups in ASSP enhanced the adsorption capacity of heavy metals. ASSP is an excellent heavy metal adsorbent, and its maximum adsorption values for Cu(II), Mn(II), and Zn(II) were found to be 272.69, 253.25, and 143.00 mg/g, respectively. The abandoned sand shrub resource of SP was used to adsorb heavy metals from effluent, which provides an important reference value for the development of forestry in this sandy area and will have a great application potential in the fields of the adsorption of heavy metals in soil and antibiotics in water.

Graphene oxide modified tilted fiber Bragg grating for 10<sup>–12</sup> level heavy metal ion sensing

Graphene oxide (GO) is an ideal label-free sensing material with its super large specific surface area and abundant surface functional groups. Considering its insulating characteristic, the GO is suitable for optics-based heavy metal ion sensing. However, given the large surface tension of water and the hydrophilicity of GO, the agglomeration or wrinkles of GO nanosheets is usually inevitable during coating with aqueous dispersion. This reduces the accessible surface area and surface functional groups of GO, thereby degrading the sensing performance. Here, an ultra-sensitive GO functionalized tilted fiber Bragg grating (TFBG) sensor is designed to detect heavy metal ions in aqueous solutions. Firstly, a strategy of free energy manipulation is employed to avoid the wrinkles and agglomeration of GO nanosheets. In the scenario of aqueous dispersion, the GO nanosheets will wrinkle as the water droplets evaporate and shrink. In contrast, using the lower-surface-tension ethanol as the dispersant and a high-surface-energy substrate processed by oxygen plasma, the dispersion will evenly spread on the substrate instead of forming droplets. When ethanol evaporates, GO nanosheets are attached to the substrate in largest possible area to reduce the free energy of the system, by which a GO film without agglomeration or wrinkles can be obtained. Secondly, the intrinsic sensitivity of TFBG is conducive to the detection of heavy metal ions in water. Mode interference occurs between the cladding mode and the core mode in the TFBG, and the wavelength and intensity of the interference are highly sensitive to the surrounding temperature, stress, and refractive index. Combining the above characteristics, the GO functionalized TFBG is highly sensitive to Pb<sup>2+</sup>, Cd<sup>2+</sup>, and Cu<sup>2+</sup> ions in water. These heavy metal ions are adsorbed by the GO, and thus causing the effective refractive index to increase. The results show that the adsorption of heavy metal ions makes the interference peaks red-shifted in the transmission spectrum. The lowest detection limit for Pb<sup>2+</sup> and Cd<sup>2+</sup> can reach 10<sup>–10</sup> mol/L (ng/L level), and the corresponding sensitivities are 0.426 and 0.385 dB/(nmol·L<sup>–1</sup>) (2.06 and 3.43 dB/(μg·L<sup>–1</sup>)), respectively. These superior sensing performances benefit from the high specific surface area and accessible carbonyl groups of the unfolded GO, and also rely on the excellent intrinsic sensitivity of TFBG. The GO functionalized TFBG sensor has a promising potential application in environment monitoring.

PREPARATION OF ACTIVATED CARBON ADSORBENT FROM COCONUT HUSK FOR THE ADSORPTION OF LEAD (II) IONS FROM AQUEOUS SOLUTION

Heavy metals contamination of water and wastewater is a common phenomenon. Industrial wastewaters are usually the cause of heavy metals pollution of the environment. In this work, the adsorptive removal of lead metal ions in aqueous solution is investigated using an activated carbon derived from coconut husk. The activated carbon was modified with NaOH and characterized for functional group, micro-structure and textural properties. The activated carbons have a surface area of 304.38 m 2 /g from 600 °C activation with NaOH modification and 281.19 m 2 /g (300 °C) without modification. FTIR demonstrated the different functional groups present and the SEM images showed the pores on the surface of the activated carbon due to the NaOH modification. The maximum adsorption capacity of 91.70 and 73.90 mg/g were obtained for the coconut husk modified and unmodified adsorbents respectively. The adsorption kinetics for lead metal ions onto both adsorbents can be described by a pseudo-second-order rate model and are well fitted to the Langmuir adsorption isotherm. The results indicated that coconut husk in modified and unmodified forms can be used for the efficient removal of lead (II) ions from water and wastewater.

Preparation and application of polyethyleneimine-modified corncob magnetic gel for removal of Pb(ii) and Cu(ii) ions from aqueous solution.

As a biomass resource, corncob is a kind of agricultural by-product with wide sources and low cost. Because its composition contains a large number of functional polymers such as cellulose, chitosan, and semi chitosan, corncob can be chemically modified to prepare a variety of adsorption materials. In this study, a magnetic gel material (PEI-CC@Fe3O4) consisting of corncob modified by glutaraldehyde-crosslinked polyethyleneimine (PEI) was successfully prepared and applied to the adsorption of heavy metal ions in aqueous solutions. The structure, thermal stability, and adsorption of heavy metal ions of the magnetic gel material (PEI-CC@Fe3O4) were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction phase analysis (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The results showed that PEI was crosslinked to the corncob through Aldol reaction and Schiff-base reaction. The heavy metal ion adsorption experiment showed that the PEI-CC@Fe3O4 had better adsorption toward divalent copper ions and divalent lead ions at 303 K, and the maximum adsorption capacities reached 459.4 mg g−1 and 290.8 mg g−1, respectively. Moreover, the study of isothermal adsorption and adsorption kinetics shows that the adsorption process is pseudo-second-order kinetics model adsorption, which belongs to Langmuir isothermal adsorption. Such excellent adsorption performance will contribute to the application of corncob biomass materials in industrial polluted wastewater.

A novel 2D metal–organic framework probe: a highly sensitive and visual fluorescent sensor for Al3+, Cr3+ and Fe3+ ions

A novel 2D MOF Tb-DBA was constructed. Tb-DBA could detect Al3+, Cr3+ and Fe3+ ions rapidly, sensitively, selectively, reversibly and visually. Tb-DBA represents a promising material for the quick detection of metal ions in aqueous solution.

Effect of Aqueous Metal Ion Solutions Containing Copper on Cyanobacterial Cells: Behavior of Metal Ions and Changes in Cell Structure

Effect of Aqueous Metal Ion Solutions Containing Copper on Cyanobacterial Cells: Behavior of Metal Ions and Changes in Cell Structure

Zein adsorbents with micro/nanofibrous membrane structure for removal of oils, organic dyes, and heavy metal ions in aqueous solution

Developing multi-functional media for effectively removing different contaminants coexisted in wastewater system is highly desired. Herein, zein, a natural protein possessing abundant functional groups in molecule, is chosen to be fabricated into micro/nanofibrous membranes as adsorbents and separation media. Zein fibers with novel groove ribbon structures, which possess better structural characteristics, are designed for obtaining good adsorption performance. The adsorption performances of zein fiber membranes are evaluated. The results show that zein fiber membranes have the adsorption capacities up to 94 g/g for motor oil, 168 mg/g for Congo red, and 189 mg/g for Pb2+ ion for 1000 mg/L initial solution concentration, showing considerable competitiveness as compared with the reported adsorbents. The zein membrane with groove ribbon fiber morphology exhibits optimal adsorption capability and can be attractive multi-functional separation media.

Improving the adsorption of poly(o-phenylenediamine) to heavy metal ions in aqueous solution through its composite with carbon dots

Improving the adsorption of poly(o-phenylenediamine) to heavy metal ions in aqueous solution through its composite with carbon dots

A terpyridine-based chemosensor for detection transition metal ions in aqueous solution: Synthesis and characterization

A hydrophilic terpyridine-based copolymer chemosensor containing acrylic acid and fluorescence fragments to detect transition metal ions in aqueous solution were synthesized and well characterized. Characteristic color changes, which were resulted from chelating with specific metal ions and visible to the naked eye under natural and ultraviolet light provided possibility for real-time monitoring. Absorption and luminescence properties were adopted for further study, which exhibited unique response when treated with various metal ions. Intensity of absorption peak at 284 nm decreased with the increase of all kinds of metal ions while the secondary absorption peak at 335 nm increased with a certain concentration range. Different metal ions bring fluorescence enhancement or quenching response to the copolymer in aqueous solution. The unique fluorescence enhancing resulting from coordination of terpyridine and Zn2+ endows the polymer excellent detection ability. In particular, owing to metal-ligand charge transfer (MLCT) process, a new absorption peak appeared at 570 nm with the addition of Fe2+, and the polymer showed obvious color change.

A novel fluorescent metal-organic framework based on porphyrin and AIE for ultra-high sensitivity and selectivity detection of Pb2+ ions in aqueous solution

Lead (Pb2+) ion, as a heavy metal pollutant in water, is harmful to human health, and may cause various diseases. Therefore, it is of great necessity for people to find a new and quick way to detect Pb2+ ions in water. Based on this condition, a zinc porphyrin-based metal-organic framework (ZnTCPP-MOF) with aggregation-induced emission (AIE) was successfully synthesized via coordination polymerization of zinc (Zn2+) ions, H2TCPP and TPE-2COOH, and shows a great fluorescent phenomenon which can be used as a fluorescent probe to detect metal ions in aqueous solution. So, the ZnTCPP-MOF with a highly selective and sensitive property can be employed to detect Pb2+ ions. The experiment results exhibit that the color change of ZnTCPP-MOF could be directly discovered from bright red to colorless after adding Pb2+ ions by naked eyes. Meanwhile, the quenching curves, at lower concentrations of Pb2+ ions, exhibited an excellent linear relationship between fluorescence quenching efficiency and concentrations. The highlight of this study is that the ZnTCPP-MOF could explore Pb2+ ions in water, at very low concentrations, as well as the limit of detection (LOD) is 4.99 × 10−8 M which is an excellent data, compared with other MOFs.

Preparation of recyclable materials for removing heavy metal ions in aqueous solution and wastewater applications

AbstractBACKGROUNDTwo functionalized nano‐adsorbents were prepared by modifying carbon nanotubes and graphene oxide with active carboxyl groups, and used to remove Pb(II) heavy metal ions in aqueous solutions. The adsorbent combines the advantages of the active groups that can easily capture heavy metal ions and the high specific surface area of nanomaterials, has high adsorption capacity and affinity and is easily separated from the sample solution by centrifugation.RESULTSBoth scanning and transmission electron microscopy images show that the walls of the carbon tubes are oxidized and the ports at both ends are also opened, and the graphene oxide surface has more folds, producing more active groups such as carboxyl and hydroxyl groups, which provide suitable active sites for the attachment of heavy metals. X‐ray photoelectron spectroscopy shows that characteristic peak of lead appears in the energy spectrum after adsorption. Raman and infrared spectra show that the surface defects of the two materials have increased. The adsorption capacity calculated using the Langmuir equation was 118.82 and 178.23 mg g−1 at pH = 5, and equilibrium adsorption capacity was reached at 120 min. The adsorption capacity of the materials for Pb2+ reaches the equilibrium concentration value when the concentration is 50 mg L−1. Wastewater experiments were carried out to prove that the materials can meet the relevant national standards for lead ions in actual wastewater.CONCLUSIONSThe adsorption results for the two materials demonstrated that the materials prepared in the optimum conditions exhibited strong adsorption ability and high stability and with promise for practical applications. © 2021 Society of Chemical Industry

Synthesis and Self-Assembling Properties of Peracetylated β-1-Triazolyl Alkyl D-Glucosides and D-Galactosides

Carbohydrate-based low-molecular-weight gelators (LMWGs) are useful classes of compounds due to their numerous applications. Among sugar-based LMWGs, certain peracetylated sugar beta-triazole derivatives were found to be effective organogelators and showed interesting self-assembling properties. To further understand the structural influence towards molecular assemblies and obtain new functional materials with interesting properties, we designed and synthesized a library of tetraacetyl beta-1-triazolyl alkyl-D-glucosides and D-galactosides, in which a two or three carbon spacer is inserted between the anomeric position and the triazole moiety. A series of 16 glucose derivatives and 14 galactose derivatives were synthesized and analyzed. The self-assembling properties of these new triazole containing glycoconjugates in different solvents were analyzed. Several glucose derivatives were found to be effective LMWGs, with compound 7a forming gels in a variety of organic solvents as well as in the presence of metal ions in aqueous solutions. The organogels formed by several compounds were characterized using optical microscopy, atomic force microscopy (AFM) and UV-vis spectroscopy, etc. The co-gels formed by compound 7a with the Fmoc derivative 7i showed interesting fluorescence enhancement upon gelation. Several gelators were also characterized using powder X-ray diffraction and FT-IR spectroscopy. The potential applications of these sugar-based gelators for drug delivery and dye removal were also studied.