Synthesis of hydrophilic macroporous chelating polymers and their versatility in the preconcentration of metals in seawater samples

Advances in gum-based hydrogels and their environmental applications

Gum-based hydrogels (GBHs) have been widely employed in diverse water purification processes due to their environmental properties, and high absorption capacity. More desired properties of GBHs such as biodegradability, biocompatibility, material cost, simplicity of manufacture, and wide range of uses have converted them into promising materials in water treatment processes. In this review, we explored the application of GBHs to remove pollutants from contaminated waters. Water resources are constantly being contaminated by a variety of harmful effluents such as heavy metals, dyes, and other dangerous substances. A practical way to remove chemical waste from water as a vital component is surface adsorption. Currently, hydrogels, three-dimensional polymeric networks, are quite popular for adsorption. They have more extensive uses in several industries, including biomedicine, water purification, agriculture, sanitary products, and biosensors. This review will help the researcher to understand the research gaps and drawbacks in this field, which will lead to further developments in the future.

Synthesis and Characterization of Chelating Hyperbranched Polyester Nanoparticles for Cd(II) Ion Removal from Water

Chelating hyperbranched polyester (CHPE) nanoparticles have become an attractive new material family for developing high-capacity nanoscale chelating agents with highly branched structures and many functional groups in the main chains and end groups that can be used to remove heavy metals from water. In this study, a hyperbranched polyester with a particle size of 180–643 nm was synthesized with A₂+B₃ interfacial polymerization, using dimethylmalonyl chloride as the difunctional monomer (A₂) and 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) as the trifunctional monomer (B₃). FTIR and NMR were used to characterize the CHPE and confirm the structure. The CHPE nanoparticles were generally considered hydrophilic, with an observed swelling capacity of 160.70%. The thermal properties of the CHPE nanoparticles were studied by thermal gravimetric analysis (TGA) with 1% mass loss at temperatures above 185 °C. The XRD of the CHPE nanoparticles showed a semi-crystalline pattern, as evident from the presence of peaks at positions ~18° and 20°. The nature of the surface of the CHPE was examined using SEM. Batch equilibrium was used to investigate the removal properties of the CHPE nanoparticles towards Cd(II) ions as a function of temperature, contact time, and Cd(II) concentration. The Cd(II) ion thermodynamics, kinetics, and desorption data on the CHPE nanoparticles were also studied.

Methacrylate-Based Polymeric Sorbents for Recovery of Metals from Aqueous Solutions

The industrialization and urbanization expansion have increased the demand for precious and rare earth elements (REEs). In addition, environmental concerns regarding the toxic effects of heavy metals on living organisms imposed an urgent need for efficient methods for their removal from wastewaters and aqueous solutions. The most efficient technique for metal ions removal from wastewaters is adsorption due to its reversibility and high efficiency. Numerous adsorbents were mentioned as possible metal ions adsorbents in the literature. Chelating polymer ligands (CPLs) with adaptable surface chemistry, high affinity towards targeted metal ions, high capacity, fast kinetics, chemically stable, and reusable are especially attractive. This review is focused on methacrylate-based magnetic and non-magnetic porous sorbents. Special attention was devoted to amino-modified glycidyl methacrylate (GMA) copolymers. Main adsorption parameters, kinetic models, adsorption isotherms, thermodynamics of the adsorption process, as well as regeneration of the polymeric sorbents were discussed.

A Review of Adsorbents for Heavy Metal Decontamination: Growing Approach to Wastewater Treatment

Heavy metal is released from many industries into water. Before the industrial wastewater is discharged, the contamination level should be reduced to meet the recommended level as prescribed by the local laws of a country. They may be poisonous or cancerous in origin. Their presence does not only damage people, but also animals and vegetation because of their mobility, toxicity, and non-biodegradability into aquatic ecosystems. The review comprehensively discusses the progress made by various adsorbents such as natural materials, synthetic, agricultural, biopolymers, and commercial for extraction of the metal ions such as Ni2+, Cu2+, Pb2+, Cd2+, As2+ and Zn2+ along with their adsorption mechanisms. The adsorption isotherm indicates the relation between the amount adsorbed by the adsorbent and the concentration. The Freundlich isotherm explains the effective physical adsorption of the solute particle from the solution on the adsorbent and Langmuir isotherm gives an idea about the effect of various factors on the adsorption process. The adsorption kinetics data provide valuable insights into the reaction pathways, the mechanism of the sorption reaction, and solute uptake. The pseudo-first-order and pseudo-second-order models were applied to describe the sorption kinetics. The presented information can be used for the development of bio-based water treatment strategies.

Analysis of trace metals in water samples using NOBIAS chelate resins by HPLC and ICP-MS

The pre-concentration of major constituents is crucial to accurate and precise determination of trace metals in water samples by inductively coupled plasma mass spectrometry (ICP-MS). In this work, NOBIAS chelate resins were used in the sample concentration for both HPLC and ICP-MS detection. 4-(2-Pyridylazo) resorcinol (PAR) was selected as a precolumn chelating reagent for this research. 520 nm wavelength was used as to minimize the peak of PAR and to reduce baseline noise for HPLC analysis. The sample pre-treatment step was achieved by enrichment and Cd(II), Co(II), Cu(II), Mn(II), Ni(IV), Pb(II), and Zn(II) were detected in the bottled water and tap water samples. The results of two detection methods of ICP-MS and HPLC were compared. Results showed that by acquiring 50-time pre-concentrates of test samples using 250 mg of the Nobias-chelate PA1 chelating resin, the metal contents could be accurately detected using both ICP-MS and HPLC. And the approach of HPLC enables the quantitative detection of bottled water and tap water at different concentrations with determination coefficient (R²) greater than 0.9990. This simple and cost-effective quantitative detection approach using NOBIAS chelate resins and HPLC may widen the application of NOBIAS chelate resins for quantitative detection of more water samples.

Structural modification of acrylonitrile–butadiene–styrene waste as an efficient nanoadsorbent for removal of metal ions from water: isotherm, kinetic and thermodynamic study

An environmentally benign approach for the structural modification of ABS waste and its use for the removal of heavy metal ions from aqueous solutions have been described using isotherm, kinetics and thermodynamic studies.

Application of magnetic nanoparticles modified with poly(2-amino thiophenol) as a sorbent for solid phase extraction and trace detection of lead, copper and silver ions in food matrices

We are introducing magnetic nanoparticles modified with poly(2-amino thiophenol) as a new solid-phase for the extraction of heavy metals ions, including lead(ii), copper(ii) and silver(i).

Removal of metal ions from water using nanohydrogel tragacanth gum-g-polyamidoxime: isotherm and kinetic study

A new biosorbent was prepared by grafting polyacrylonitrile onto iranian tragacanth gum (ITG), a naturally and abundantly available polysaccharide, and subsequent amidoximation in the presence of hydroxylamine hydrochloride. This nanohydrogel with amidoxime functional groups [C(NH2)NOH], named polyamidoxime-g-tragacanth (ITG-g-PAO), was characterized and used for the removal of metal ions from aqueous solution. The effect of pH, agitation time, concentration of adsorbate and amount of adsorbent on the extent of adsorption was investigated. The experimental data were analyzed by four isotherms and kinetics equations, and the results were fitted well with the Temkin isotherm and pseudo-second-order model. The maximum adsorption capacities (Qm) of ITG-g-PAO as obtained from Langmuir adsorption isotherm were found to be 100.0, 76.92, 71.42 and 66.67 (mgg(-1)) for the adsorption of metal ions in order of Co(II)>Zn(II)>Cr(III)>Cd(II). The experimental results demonstrate that the above selective order of adsorption capacity is due to formation of stable chelating ring between the bidentate amidoxime ligand and metal ion.

A strontium-90 sequestrant for first-aid treatment of radiation emergency

In this study, hydrophilic porous polymer beads with phosphonic acid groups (PGMA-EGDMA-TTA-MP) were synthesized, and assessed as a radioactive strontium-90 sequestrant for the treatment of the radiation emergency. Strontium ions were rapidly absorbed into the blood from the gastrointestinal (GI) tract after oral administration to rats, and distributed to the target organ, i.e., bones. Over 40% of the administered strontium was absorbed into the blood, while the remainder was discharged in the feces within 48 h after the administration. When the PGMA-EGDMA-TTA-MP beads were administered to rats subsequent to the strontium solution, the strontium had accumulated less in the femur. Consequently, the oral administration of the PGMA-EGDMA-TTA-MP beads was effective in suppressing the absorption of strontium from the GI tract.

SP70-alpha-benzoin oxime chelating resin for preconcentration-separation of Pb(II), Cd(II), Co(II) and Cr(III) in environmental samples

In the presented work, alpha-benzoin oxime immobilized SP70 chelating resin was synthesized for separation and preconcentration of Pb(II), Cd(II), Co(II) and Cr(III). The optimization procedure for analytical parameters including pH, eluent type, flow rate, etc. was examined in order to gain quantitative recoveries of analyte ions. The effects of foreign ions on the recoveries of studied metal ions were also investigated. The detection limits (3sigma) were found to be 16.0, 4.2, 1.3, 2.4microgL(-1) for Pb, Cd, Co and Cr, respectively. The preconcentration factor was 75 for Pb, 100 for Cd, Co and Cr. The optimized method was validated with certified reference materials and successfully applied to the waters, crops and pharmaceutical samples with good results (recoveries greater than 95%, R.S.D. lower than 10%).