Adsorption Properties Of Cu Research Articles

Fluorescent cellulose nanofibrils hydrogels for sensitive detection and efficient adsorption of Cu2+ and Cr6+

Increasing chromium and copper pollution poses a significant threat to the global environment and human health. It is crucial to detect and remove Cu (II) and Cr (VI) from water. Cellulose nanofibrils (CNF)-based hydrogels were a natural, abundant, and biocompatible material that has attracted great attention for bio adsorption applications. In this work, a new fluorescent CNF-based hydrogel (PAA-CNF-W) was prepared for the high-efficiency adsorption and sensitive detection of Cu (II) and Cr (VI). CNF was introduced as a natural backbone to construct a three-dimensional porous structure, which increased the specific surface area and provided additional active sites, exhibiting excellent adsorption properties for Cu (II) (159.24 mg/g) and Cr (VI) (173.87 mg/g). Moreover, the synthesized dansyl chloride derivatives with fluorescent properties were introduced to the hydrogel and formed chelates with the metals leading to fluorescence quenching. PAA-CNF-W hydrogels showed high sensitivity to the detection limit (LOD) of Cu (II) (28.70 mg/L) and Cr (VI) (1.45 mg/L). The kinetic study revealed that pseudo-second order kinetics was the best-fitting model. The Langmuir isotherm was the best adjustment model. The study provides a new idea for efficient detection and removal of Cu (II) and Cr (VI) from wastewater by cellulose materials.

Effects of Gamma-Synthesized Chitosan on Morphological, Thermal, Mechanical, and Heavy-Metal Removal Properties in Natural Rubber Foam as Sustainable and Eco-Friendly Heavy Metal Sorbents

The properties of natural rubber foam (NRF) containing gamma-synthesized chitosan (CS) powder were investigated to address the growing demand for efficient methods to treat industrial wastewater contaminated with heavy metals. The CS powder was prepared by irradiating chitin (CT) powder with varying doses of gamma rays (0–100 kGy), followed by deacetylation using 40% sodium hydroxide (NaOH) at 100 °C for 1 h. The resulting CS powders were then mixed with natural rubber latex (NRL) at different contents (0, 3, 6, and 9 parts per hundred parts of rubber by weight; phr) and processed using Dunlop techniques to prepare the foam samples. The experimental findings indicated that the degree of deacetylation (%DD) of the CS powder increased initially with gamma doses up to 60 kGy but then decreased at 80 and 100 kGy. In addition, when the CS powder was incorporated into the NRF samples, there were increases in total surface area, density, compression set, and hardness (shore OO), with increasing gamma doses and CS contents. Furthermore, the determination of heavy metal adsorption properties for Cu, Pb, Zn, and Cd showed that the developed NRF sample exhibited high adsorption capacities. For instance, their removal efficiencies reached 94.9%, 82.5%, 91.4%, and 97.0%, respectively, in NRF containing 9 phr of 60 kGy CS. Notably, all adsorption measurements were determined using 3 cm × 3 cm × 2.5 cm specimens submerged in respective metal solutions, with an initial concentration of 25 mg/L. However, the removal capacity per unit mass of the sample (mg/g) showed less dependencies on CS contents, probably due to the higher density of CS/NRF composites in comparison to pristine NRF, resulting in a smaller volume of the former being submerged in the solution, subsequently suppressing the effects from CS in the adsorption. Lastly, tests on the reusability of the developed NRF indicated that the samples could be reused for up to three cycles, with the Cu removal capacity remaining relatively high (83%) in the sample containing 9 phr of 60 kGy CS. The overall outcomes implied that the developed NRF with the addition of gamma-synthesized CS not only offered effective and eco-friendly heavy metal adsorption capacity to improve public health safety and the environment from industrial wastewater but also promoted greener and safer procedures for the synthesis/modification of similar substances through radiation technologies.

DFT Study of Zn-Modified SnP3: A H2S Gas Sensor with Superior Sensitivity, Selectivity, and Fast Recovery Time.

The adsorption properties of Cu, Ag, Zn, and Cd-modified SnP3 monolayers for H2S have been studied using density functional theory (DFT). Based on phonon spectrum calculations, a structurally stable intrinsic SnP3 monolayer was obtained, based on which four metal-modified SnP3 monolayers were constructed, and the band gaps of the modified SnP3 monolayers were significantly reduced. The adsorption capacity of Cu, Zn-modified SnP3 was better than that of Ag, Cd-modified SnP3. The adsorption energies of Cu-modified SnP3 and Zn-modified SnP3 for H2S were -0.749 eV and -0.639 eV, respectively. In addition, Cu-modified SnP3 exhibited chemisorption for H2S, while Zn-modified SnP3 exhibited strong physisorption, indicating that it can be used as a sensor substrate. Co-adsorption studies showed that ambient gases such as N2, O2, and H2O had little effect on H2S. The band gap change rate of Zn-modified SnP3 after adsorption of H2S was as high as -28.52%. Recovery time studies based on Zn-modified SnP3 showed that the desorption time of H2S was 0.064 s at 298 K. Therefore, Zn-modified SnP3 can be used as a promising sensor substrate for H2S due to its good selectivity, sensitivity, and fast recovery time.

Efficient removal of Cu2+ and methylene blue pollutants from an aqueous solution by applying a new hybrid adsorbent based on alginate-chitosan and HAP derived from Moroccan rock phosphate.

Alginate-chitosan/hydroxyapatite (Alg-Cs/HAP) beads were prepared as adsorbent to remove methylene blue (MB) and copper ions from an aqueous solution using a batch system. FTIR, TGA, point of zero charge (pHpzc), SEM, XRD, and BET analysis were used to characterize the elaborated material. The effect of several parameters such as initial pH value, adsorbent dose, temperature, contact time, and initial pollutant concentration were also investigated. The obtained results showed that Alg-Cs/HAP exhibit excellent adsorption properties for Cu (II) and MB removal, with high adsorption capacities of copper ions (208.34mg/g) and methylene blue (454.54mg/g). The kinetic of the adsorption process is correlated with the pseudo-first-order for methylene blue and the pseudo-second-order for copper ions. The equilibrium data for MB dye fitted the Freundlich isotherm model, thus implying that the adsorption process consists of multilayer adsorption as well as interactions between the adsorbate and the adsorbent. The equilibrium data for copper ions corresponds closely with the Langmuir model which suggests that the adsorbed molecules occur over a monolayer. Various thermodynamic parameters such as the standard Gibbs energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) were calculated. All results indicated that Alg-Cs/HAP material has a good potential for the treatment of wastewater.

One-step synthesis of lychnophora residue-derived porous carbon sheets for highly efficient removal of copper(Ⅱ)

In this study, the lychnophora residue-derived porous carbon sheets (LRPCSs) were synthesized using a facile one-step pyrolysis method, and the physicochemical properties of LRPCSs were analyzed via various characterization apparatus, its adsorption behaviors and mechanism for copper(Ⅱ) (Cu(II)) were also investigated. The LRPCSs possessed three-dimensional honeycomb sheet structure, a specific surface area of 14.6 m2·g−1, abundant mineral elements (K, Ca, and Mg), and the oxygen- and sulfur-containing functional groups, which would offer more active sites for the fast adsorption of Cu(II). Batch experiments demonstrated that the adsorption properties of Cu(II) by LRPCSs raised with the raising of biochar dose, pH value (2−6), Cu(II) concentration, and temperature. The isotherms and kinetics studies showed that the adsorption data conformed very well to Langmuir isotherm (R2 ≥0.9975) and pseudo-second-order kinetic models (R2 ≥0.9941). The maximum Cu(II) adsorption capacities of LRPCSs were respectively 103.09, 120.48, and 153.85 mg·g−1 at 298, 308, and 318 K, which were superior to previously reported biochar adsorbents. The thermodynamic studies indicated that the Cu(II) adsorption with LRPCSs was an automatic, endothermal, and entropy-raising process (ΔG° = −6.82∼−8.47 kJ·mol−1, ΔH° = 17.89 kJ·mol−1, ΔS° = 83.07 J·(mol·K)−1). The adsorption capacity of Cu(II) with LRPCSs still remained 85% after four adsorption-desorption cycles. Furthermore, the ion exchange and surface complexation were the predominant mechanism for the Cu(Ⅱ) adsorption by LRPCSs, with cation-π interaction and pore capture playing a secondary role. This study showed that LRPCSs could be an effective, low-cost, and reusable adsorbent with great potential for application in remediating the Cu(II)-containing wastewater pollution.

Characterization of amphoteric bentonite-loaded magnetic biochar and its adsorption properties for Cu2+ and tetracycline.

To realize simultaneous adsorption of heavy metal and antibiotic pollutants by a BC-based recyclable material, Fe3O4 magnetic biochar (MBC) was prepared by co-precipitation method. Then different ratios of dodecyl dimethyl betaine (BS-12)-modified bentonite (BS-B) were loaded on the surfaces of biochar (BC) and MBC to prepare BS-B-loaded BC and MBC composites, called BS-B/BC and BS-B/MBC, respectively. The physicochemical and structural properties of the composites were characterized by scanning electron microscopy, Fourier transform infrared spectrometry, thermogravimetric analysis, specific surface area (SBET) analysis, and vibrating sample magnetometry, and the adsorption efficiencies of BS-B/BC and BS-B/MBC to Cu2+ and tetracycline (TC) were studied. The following results were obtained. (1) Compared with BS-B/BC, BS-B/MBC had decreased pH and cation exchange capacity (CEC) and increased SBET. The pH, CEC, and SBET of BS-B/BC and BS-B/MBC decreased with the increase in the BS-12 proportion of BS-B. The surface of BS-B/MBC became rough after Fe3O4 loading. (2) The residual rate of BS-B/MBC was higher than that of BS-B/BC after high-temperature combustion, and the residual rate decreased with the increase in the BS-12 proportion of BS-B. The 2D infrared spectra showed that Fe3O4 and BS-12 were modified on the surface of BS-B/MBC. MBC and BS-B/MBC had splendid magnetism and could be separated by external magnetic field. (3) Compared with unmagnetized ones, the adsorption effects of Cu2+ and TC on different BS-B/MBCs improved, and the average adsorption rate reached the largest value of 91.92% and 97.76%, respectively. Cu2+ and TC adsorptions were spontaneous, endothermic, and entropy-increasing processes. The pH and SBET of the material had a great influence on Cu2+ and TC adsorptions, respectively, than CEC.

Preparation of chitosan-like magnetic composite microspheres and their adsorption properties for Cu (II)

The novel magnetic composite microspheres (Fe3O4/HAD-C) coated with Fe3O4 were fabricated by inverse suspension cross-linking method, where glutaraldehyde was used as a crosslinking agent. Magnetic Fe3O4 particles and Hexamethylene Diamine Cellulose was prepared respectively by the chemical coprecipitation method and grafting amino group onto microcrystalline Cellulose. The scanning electron microscope, laser particle size analyzer, X-ray diffractometer, and thermogravimetric analyzer were used to characterize the magnetic Fe3O4/HAD-C composite microspheres. The findings demonstrate that the Fe3O4/HAD-C composite microspheres were spherical and well dispersed with the size range between 0.3 μm and 1.2 μm, and possessed super paramagnetic property with 39.72 emu·g−1. The mass of Fe3O4 in the composite is about 37.11 %. By using an adsorption study, the removal of Cu (II) from heavy metal wastewater by Fe3O4/HAD-C was examined. The findings showed that the composite microsphere made of Fe3O4/HAD-C effectively absorbed Cu (II). The entire adsorption procedure follows the Langmuir isothermal adsorption model and pseudo-second order kinetics. Fe3O4/HAD-C also had high reusability and stability. Even after 5 cycles of adsorption and desorption, Fe3O4/HAD-C still achieve 32.45 mg g−1. Environmentally friendly and effective, the unique magnetic chitosan-like composite microspheres (Fe3O4/HAD-C) developed in this study.

Self-Assembly by Tridentate or Bidentate Ligand: Synthesis and Vapor Adsorption Properties of Cu(II), Zn(II), Hg(II) and Cd(II) Complexes Derived from a Bis(pyridylhydrazone) Compound.

Four complexes, [Cu4L2(OCH3)2(CH3OH)2]·2H2O (1), [Zn2L2Cl4]·2H2O·2CH3OH (2), [Hg2L2Br4]·4CH3OH (3), and {[CdL2Cl2]·4H2O·4CH3OH}n (4), have been synthesized and characterized from a bis(pyridylhydrazone) ligand (L) with copper(II), zinc(II), mercury(II) or cadmium(II), respectively. Complex 1 exists as a centrosymmetric tetranuclear dimer with L as deprotonated tridentate ligand. Complexes 2 and 3 exist as centrosymmetric metallamacrocycles with L as bidentate ligand. Complex 4 exists as a 1D looped-chain coordination polymer. The thermal stabilities and vapor adsorption properties of the four complexes were investigated as well.

Preparation of Hydrated Calcium Silicate Gel and its Adsorption Properties for Cu(II)

Calcium silicate hydrate gel (CSH) was synthesized by calcium acetate and sodium silicate. The structure and morphology of CSH were characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy and Scanning electron microscopy. The adsorption performance of CSH was measured by static adsorption method. The results show that CSH has porous structure and large specific surface area, and the optimum reaction conditions is the reaction temperature of 25°C and calcium-silicon ratio of 1.2. It has the maximum adsorption capacity of more than 150 mg/g and the removal rate of more than 86% with Cu2+. And it shows the excellent adsorption performance, even when the concentration of Cu2+ is less than 200mg/L, the removal rate is above 90%. The research may provide a low-cost and high-efficiency adsorbent.

造纸污泥制备功能陶粒(GTL)及其对Cu<sup>2+</sup>吸附性能的研究

造纸污泥制备功能陶粒(GTL)及其对Cu<sup>2+</sup>吸附性能的研究

Biofilm alters tetracycline and copper adsorption behaviors onto polyethylene microplastics

• Co-adsorption of Cu(II) and TC on PE microplastics with biofilm was first studied. • Biofilm enhanced the adsorption and stabilization of Cu(II) and TC on microplastics. • Competition and complexation interactions were involved in the adsorption process. • Microplastics with biofilm act as carriers of heavy metals and antibiotics in water. In this study, the adsorption properties of Cu(II) and tetracycline (TC) onto virgin and biofilm-developed polyethylene (PE) microplastics were investigated in batch sorption experiments. PE microplastics were placed at sewage outlets (Shanghai, China) for 20 days to develop biofilm on their surface. The adsorption and desorption isotherms of Cu(II) and TC were well fitted by the Freundlich model, and revealed that biofilm could enhance the adsorption and stabilization of Cu(II) and TC on microplastics. The linearity test of the film diffusion model in kinetic experiments suggested that the adsorption on virgin and biofilm-developed microplastics was dominated by intra-particle diffusion and film diffusion, respectively. Compared with the virgin microplastics, the adsorption of Cu(II) and TC on biofilm-developed microplastics was additionally affected by pH-dependent complexation interactions in the biofilm and competition interactions. Cu(II) pre-adsorbed on the biofilm could be released into solution because of competition effects of TC. Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) further confirmed that the enhanced adsorption of TC on the biofilm could be attributed to the complexation of TC, Cu(II) and components in biofilm. This study illustrated that biofilms could enhance the role of microplastics in the Cu(II) and TC migration by changing their adsorption properties on microplastics.

Adsorption of Cu(II) on soil humin: batch and spectroscopy studies

Understanding the interactions of humic substances with metal ions is of great importance in forecasting the behaviors and fates of trace metals in the environment. Humin is the least understood humic substance fraction due to its close association with the mineral matrix in soil. In this study, humin was prepared from three zonal soils (i.e., dark brown soil, yellow brown soil, and latosol) in eastern China by demineralization using HF–HCl solution after removing alkaline-soluble humic substance fractions. The adsorption properties of Cu(II) onto both humin and humic acid were examined using batch and spectroscopy (SEM, EDS, FTIR, XPS, and XAS) techniques. With respect to humic acid, humin was more aliphatic and less polar. The adsorption kinetics of humin and humic acid were best fit with pseudo-second-order kinetics equation, and the adsorption isotherms were well depicted by the Langmuir model. However, the quantity of adsorbed Cu(II) on humin was inferior to that of Cu(II) adsorbed onto humic acid. After adsorption, the surface morphology of humin and humic acid changed. Carboxyl, hydroxyl, aromatic N, and primary amine N on the surfaces of the two humic substance fractions took part in Cu(II) adsorption, and Cu(II) was bound with O/N and C atoms via inner-sphere complexation. Our results suggested that humin and humic acid had different adsorption capacity but similar adsorption mechanisms toward Cu(II).

The polyaminocarboxylated modified hydrochar for efficient capturing methylene blue and Cu(II) from water

The polyaminocarboxylated modified hydrochar (ACHC) was synthesized to introduce abundant amino, hydroxyl and carboxylate multifunctional groups onto the surface of hydrochar by etherification, amination and carboxylated reaction. The ACHC was systematically characterized and used to evaluate adsorption properties of Cu(II) and methylene blue (MB) by batch sorption tests. The adsorption process toward Cu(II) and MB by ACHC obeyed the pseudo-second-order kinetic model and Langmuir model. Characteristic analysis indicated the surface chelation was mainly contribute to Cu(II) adsorption by large amounts of amino and carboxylate groups while π-π interaction, hydrogen bonding and electrostatic attraction dominated MB adsorption. The maximum adsorption capacities of ACHC were 140.65 and 1238.66 mg·g−1 for Cu(II) and MB at 303 K, respectively. Approximately 97% of the adsorptive uptakes for two pollutants were removed within merely 5 min for kinetic experiment. Competitive adsorption of Cu(II) and MB, and treatment of electroplating wastewater by ACHC were also investigated.

Effect of metal-ligand ratio on the CO2 adsorption properties of Cu-BTC metal-organic frameworks.

Initially, in the synthesis of Cu–BTC MOFs some fraction of Cu was expected to be replaced with Mg to enhance its CO2 adsorption properties. Indeed, an enhancement in the specific surface area, microporosity and CO2 adsorption capacity was observed; however, Mg was not detected. Therefore, additional syntheses of Cu–BTC MOFs with the same Cu to BTC ratios were performed but in the absence of Mg to explain the observed enhancement. It was found that the adjustment of the Cu–BTC ratio to 1.09 : 1.0, which differs from that reported in the literature, resulted in a Cu–BTC MOF with higher specific BET surface area, larger micropore volume, and consequently, superior CO2 adsorption of 9.33 mmol g−1 at 0 °C and 1 bar.

Preparation of cross-linked magnetic chitosan particles from steel slag and shrimp shells for removal of heavy metals

ABSTRACTIn this study, a new method for preparation of cross-linked magnetic chitosan particles (MCPs) from steel slag and shrimp shells using green tea extract as crosslinking reagent has been presented. The MCPs obtained were characterized by means of X-ray diffraction analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy and magnetic properties, and then were used to investigate the adsorption properties of Cu(II) and Ni(II) ions in aqueous solutions. The influence of experimental conditions such as contact time, pH value, adsorbent dose and initial metal concentration, and the possibility of regeneration were studied systematically. The Cu(II) and Ni(II) adsorption isotherms, kinetics and thermodynamics have been measured and discussed. The results show that the synthesized MCPs have high adsorption capacity for both metal ions (126.58 mg/g for Cu(II) and 66.23 mg/g for Ni(II)), and have excellent regeneration stability with efficiency of greater than 83% after five cycles of the adsorption–regeneration process. The adsorption process of Ni(II) and Cu(II) on MCPs was feasible, spontaneous and exothermic, and better described by the Langmuir model and pseudo-second-order kinetic equation. The MCPs can be applied as a low cost and highly efficient adsorbent for removal of heavy metals from wastewater due to its high adsorption capacity, easy recovery and good reusability.

From naturally low-grade palygorskite to hybrid silicate adsorbent for efficient capture of Cu(II) ions

A new eco-friendly hybrid Mg, Al-silicate adsorbent with superior adsorption properties for Cu(II) was prepared by a one-step hydrothermal process using earth-abundant low-grade palygorskite (PAL) as the starting materials and non-toxic sodium carbonate as the assistant. The structural characterizations by scanning electronic microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), BET adsorption-desorption isotherms and Zeta potential analyses confirm that part of rod-like PAL crystals were in-situ transformed as smectite sheets, and the hybrid silicate adsorbents with rod/sheet transition formulation were formed. Under the action of alkaline, some inert SiOSi(or M) bonds were broken as –Si–O− groups, which not only make the adsorbent having extremely negative surface charge (−46.4mV), but also strengthen the chelating and holding capability of the adsorbent to Cu(II). The silicate adsorbent shows high adsorption capacity of 229.9mg/g for Cu(II), which can capture 98.95% of Cu(II) from 200mg/L of Cu(II) solution at the dosage of 2.6g/L (only 64.5% for raw PAL). The intensified electrostatic attraction, ion-exchange, and chemical association of Si-O− surface groups with Cu(II) primarily contribute to the improved capture capability for Cu(II).

Adsorption properties of Ni, Cu, and Zn in young alkaline lake sediments in south Hungary (Lake Fehér, Szeged)

Halmos L., Bozso G., Pal-Molnar E. (2015): Adsorption properties of Ni, Cu, and Zn in young alkaline lake sediments in south Hungary (Lake Feher, Szeged). Soil & Water Res., 10: 244–251. Adsorption properties of Cu, Ni, and Zn in alkaline sediments of Lake Feher at Szeged (Hungary) were inves tigated. The effects of pollution of these three chosen phytotoxic elements in sodic sediments were primarily examined. These elements are strongly adsorbed in the soils and sediments with relatively high pH values for a long time without any influence on the geochemical processes. However, the salinization (indicated by the global climate change) of soils and sediments can strongly change the original geochemical status. For the adsorption experiments, the horizons with the highest organic matter contents were selected from two profiles. The pH, electrical conductivity (EC), particle size distribution, carbonate content, quality and quantity of organic matter, and clay mineral content of the selected samples were also determined. Efficiency of the adsorption is reduced in Cu >> Zn > Ni and Cu > Ni >> Zn order based on the calculated maximum and specific adsorption values. The adsorption properties of heavy metals are dependent on the content of soil constituents. The results showed that Cu has the highest but not the same affinity to each of the sorbent materials. Ni is strongly while Zn is less bounded to the organic matter. In most cases the results showed that the most effective fixative soil constituent is carbonate, followed by clay minerals and, last, organic matter regarding to the investigated elements.

Preparation of polyvinyl alcohol/chitosan hydrogel compounded with graphene oxide to enhance the adsorption properties for Cu(II) in aqueous solution

A novel bio-adsorbent, composite hydrogel beads, composed of polyvinyl alcohol (PVA), chitosan (CS) and graphene oxide (GO) was prepared by an instantaneous gelation method. The micromorphology and thermal stability of the PVA/CS/GO hydrogel beads were characterized by scanning electronic microscope (SEM) and thermo gravimetric analysis (TGA) respectively. Adsorption of Cu(II) onto PVA/CS/GO hydrogel beads was investigated with respect to pH, initial concentration, temperature and adsorption time. Adsorption data were well matched by Langmuir isotherm and pseudo-second-order kinetic model at the optimum pH 5.5. The maximum adsorption capacities of PVA/CS/GO hydrogel beads were found to be 162 mg g−1 for Cu(II) at 30 °C, which was much higher than that of PVA/CS hydrogel. Thermodynamic studies indicated that the adsorption was spontaneous and endothermic process in nature. Besides, desorption efficiency and reusability of the adsorbents were assessed on basis of six consecutive adsorption-desorption cycles. Based on these studies, it can be seen that PVA/CS/GO hydrogel beads will be a potential recyclable adsorbent for removal of hazardous metal ions in waste water.

Zeolite X/chitosan hybrid microspheres and their adsorption properties for Cu(II) ions in aqueous solutions

The preparation of zeolite X/chitosan (CS) hybrid microspheres for efficient removal of Cu(II) ions by an impregnation-gelation-hydrothermal synthesis technique is reported here. Characterizations by various techniques indicate that the microspheres show porous structures and intimate interaction between zeolite and CS. The adsorption experiments are performed to evaluate the adsorption capacity of zeolite X/CS hybrid microspheres and comparisons are made with binderless zeolite X microspheres, pure CS microspheres and mechanical mixed zeolite X/CS microspheres. The effects of Cu(II) solution concentration and the pH are investigated. The results indicate that zeolite X/CS hybrid microspheres with the zeolite content of 60 wt% show the highest adsorption capacity, which is 90 mg/g at the initial Cu(II) concentration of 10 mg/L and 150.4 mg/g at Cu(II) concentration of 500 mg/L. The adsorption capacity increases with increasing initial pH and reaches a maximum at pH 5.5 in the range of 0–6.0. The equilibrium adsorption data are well described by the Langmuir isotherm model, exhibiting a maximum adsorption capacity of 152.0 mg/g, and the kinetic data are well fitted with the pseudo-second-order equation. Complete removal of Cu(II) ions can be obtained even at very low concentrations. The microspheres show high adsorption capacity and efficiency for Cu(II) ions, exhibiting potential practical application in the treatment of water pollution of heavy metal ions.

Immobilization of 5-aminopyridine-2-tetrazole on cross-linked polystyrene for the preparation of a new adsorbent to remove heavy metal ions from aqueous solution

Novel 5-aminopyridine-2-tetrazole-functionalized polystyrene resin (APTZ-PS) was prepared by anchoring 5-aminopyridine-2-carbonitrile onto chloromethylated polystyrene beads (CMPS) and subsequently using the cyano-tetrazole conversion reaction. The APTZ-PS resin was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and specific surface area and pore size analyses. The adsorption experiments of the prepared resin for heavy metal ions were conducted by batch methods. The effects of the experimental conditions, such as pH, contact time and initial metal ion concentration on the adsorption properties of Cu(II), Pb(II) and Hg(II) were investigated. The results showed that the resin possessed perfect adsorption capacities for Cu(II), Pb(II) and Hg(II), and the selectivity was different from the commonly used iminodiacetic acid-chelating resin. The sorption kinetics of the three metal ions followed the pseudo-second-order equation. The adsorption isotherms for Cu(II) and Pb(II) could be better fitted by the Langmuir model than the Freundlich model, whereas the Freundlich model was the best for the Hg(II) ion. Even after five consecutive adsorption–desorption cycles, no obvious change in the adsorption capacity of the resin was found, which implied that the APTZ-PS resin was suitable for the efficient removal of heavy metal ions from aqueous solution.