Synthesis of ultrasonic-assisted lead ion imprinted polymer as a selective sorbent for the removal of Pb2+ in a real water sample

A new tannin-based adsorbent synthesized for rapid and selective recovery of palladium and gold: Optimization using central composite design

A tannin-based adsorbent was synthesized by pomegranate peel tannin powder modified with ethylenediamine (PT-ED) for the rapid and selective recovery of palladium and gold. To characterize PT-ED, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS-Mapping), and Fourier transform infrared spectroscopy (FT-IR) were used. Central composite design (CCD) was used for optimization. The kinetic, isotherm, interference of coexisting metal ions, and thermodynamics were studied. The optimal conditions, including Au (III) concentration = 30 m g L - 1 , Pd (II) concentration = 30 m g L - 1 , adsorbent mass = 26 mg, pH = 2, and time = 26 min with the sorption percent more than 99 %, were anticipated for both metals using CCD. Freundlich model and pseudo-second-order expressed the isotherm and kinetic adsorption of the both metals. The inhomogeneity of the adsorbent surface and the multi-layer adsorption of gold and palladium ions on the PT-ED surface are depicted by the Freundlich model. The thermodynamic investigation showed that P d 2 + and A u 3 + ions adsorption via PT-ED was an endothermic, spontaneous, and feasible process. The maximum adsorption capacity of P d 2 + and A u 3 + ions on PT-ED was 261.189 m g g - 1 and 220.277 m g g - 1 , respectively. The probable adsorption mechanism of P d 2 + and A u 3 + ions can be ion exchange and chelation. PT-ED (26 mg) recovered gold and palladium rapidly from the co-existing metals in the printed circuit board (PCB) scrap, including Ca, Zn, Si, Cr, Pb, Ni, Cu, Ba, W, Co, Mn, and Mg with supreme selectivity toward gold and palladium. The results of this work suggest the use of PT-ED with high selectivity and efficiency to recover palladium and gold from secondary sources such as PCB scrap.

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

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

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

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

Fabrication of Fe/Bi bimetallic magnetic nano-oxides (IBBMNOs) as efficient remediator for hexavalent chromium from aqueous environment

In this study, highly efficient Fe/Bi bimetallic magnetic nanooxides (IBBMNOs) were used as adsorbent for the removal of Cr(VI) from an aqueous environment. The IBBMNOs were synthesized by a simple and facile chemical reduction method. After that, different analytical techniques were used to characterize the resultant nanomaterial. According to characterization results, the IBBMNOs are highly porous look like cotton beads with an average size of 60-69 nm. BET results show that IBBMNOs are highly porous with a high surface area. After optimizing different parameters such as pH, adsorbent dose, and time study, an excellent adsorption capacity was achieved up to 185 mg/g in 10 min. The calculated data of the adsorption process was well fitted with Langmuir and pseudo-first-order kinetic model. The prepared materials have good usability as compared to reported adsorbent materials can be used for five different cycles with good removal efficiency of chromium ion from aqueous samples. Schematic illustration of adsorption of Cr(VI) from aqueous solution by IBBMNOs.

Remediation of pharmaceuticals from contaminated water by molecularly imprinted polymers: a review

The release of pharmaceuticals into the environment induces adverse effects on the metabolism of humans and other living species, calling for advanced remediation methods. Conventional removal methods are often non-selective and cause secondary contamination. These issues may be partly solved by the use of recently-developped adsorbents such as molecularly imprinted polymers. Here we review the synthesis and application of molecularly imprinted polymers for removing pharmaceuticals in water. Molecularly imprinted polymers are synthesized via several multiple-step polymerization methods. Molecularly imprinted polymers are potent adsorbents at the laboratory scale, yet their efficiency is limited by template leakage and polymer quality. Adsorption performance of multi-templated molecularly imprinted polymers depends on the design of wastewater treatment plants, pharmaceutical consumption patterns and the population serviced by these wastewater treatment plants.

Magnetic Ion Imprinted Polymers (MIIPs) for Selective Extraction and Preconcentration of Sb(III) from Environmental Matrices

Antimony(III) is a rare element whose chemical and toxicological properties bear a resemblance to those of arsenic. As a result, the presence of Sb(III) in water might have adverse effects on human health and aquatic life. However, Sb(III) exists at very ultra-trace levels which may be difficult for direct quantification. Therefore, there is a need to develop efficient and reliable selective extraction and preconcentration of Sb(III) in water systems. Herein, a selective extraction and preconcentration of trace Sb(III) from environmental samples was achieved using ultrasound assisted magnetic solid-phase extraction (UA-MSPE) based on magnetic Sb(III) ion imprinted polymer-Fe3O4@SiO2@CNFs nanocomposite as an adsorbent. The amount of antimony in samples was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The UA-MSPE conditions were investigated using fractional factorial design and response surface methodology based on central composite design. The Sb(III)-IIP sorbent displayed excellent selectivity towards Sb(III) as compared to NIIP adsorbent. Under optimised conditions, the enrichment factor, limit of detection (LOD) and limit of quantification (LOQ) of UA-MSPE/ICP-OES for Sb(III) were 71.3, 0.13 µg L-1 and 0.44 µg L-1, respectively. The intra-day and inter-day precision expressed as relative standard deviations (%RSDs, n = 10 and n = 5) were 2.4 and 4.7, respectively. The proposed analytical method was applied in the determination of trace Sb(III) in environmental samples. Furthermore, the accuracy of the method was evaluated using spiked recovery experiments and the percentage recoveries ranged from 95-98.3%.

Fabrication of nickel-tagged magnetic imprinted polymeric network for the selective extraction of Ni(II) from the real aqueous samples

A new nickel ion, magnetic imprinted polymer was fabricated through the precipitation polymerization process, using amine-functionalized silica-capped iron oxide particles as a core material, and 4-vinyl pyridine as complexing agent methacrylic acid as functional monomer. The resulted magnetic adsorbent was employed to eliminate toxic Ni²⁺ ions from industrial wastewater. The different parameters were optimized, such as pH, shaking speed, and adsorbent dose, to obtain the maximum adsorption capacity. The synthesized material showed high selectivity coefficient for Ni⁺² ions in the presence of other competitive ions and followed pseudo-second-order kinetics and Langmuir isotherm. A good adsorption capacity of 158.73 mg g^-1 was obtained at optimized pH 6 in the concentration of 5 mg L^-1 nickel ions aqueous solution. The limit of detection, quantification, and the percent relative standard deviation was found to be 0.58, 1.93, and 3.4%. This proves the excellent performance of prepared magnetic Ni(II) ion-imprinted polymer for selective detoxification of Ni²⁺ ions from real aqueous samples. Due to tunable magnetic properties, the prepared MMIPs are highly selective and sensitive and highly porous in nature; due to excellent magnetic properties, there is no need for centrifugation. Just use external magnetic field, it has good reusability. Showing preparation of Ni (II) imprinted magnetic polymer.

Characterization and adsorption capacity of modified 3D porous aerogel from grapefruit peels for removal of oils and organic solvents

With the rapid industrialization, especially offshore oil exploitation, frequent leakage incidents of oils/organic solvents have adversely affected ecological systems and environmental resources. Therefore, great interest has been shown in developing new materials to eliminate these organic pollutants, which have become worldwide problems. In this study, a cost-effective, environmentally friendly porous aerogel with three-dimensional (3D) structure was prepared from grapefruit peel by a facile hydrothermal method as the adsorbent of oils/organic solvents. The as-prepared modified grapefruit peel aerogel (M-GPA) showed mesoporous structure with high specific surface area of 36.42 m²/g and large pore volume of 0.0371 cm³/g. The excellent hydrophobicity of M-GPA with a water contact angle of 141.2° indicated a strong potential for adsorption of oils and organic solvents. The high adsorption capacity of M-GPA for a series of oils and organic solvents was 8 to 52 times as much as its own weight. Moreover, the M-GPA was easily regenerated and a high adsorption capacity recovery above 97% was maintained after five adsorption-regeneration cycles. Therefore, the M-GPA is a promising recyclable adsorbent for the removal of oils/organic solvents from polluted water.

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

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

Fabrication of chromium-imprinted polymer: a real magneto-selective sorbent for the removal of Cr(vi) ions in real water samples

Graphical representation (a and b) show the procedure for the synthesis of Cr(vi) ion-imprinted magnetic polymer.