Selective Removal Of Cd Research Articles

Selective removal of Cd(II), As(III), Pb(II) and Cr(III) ions from water resources using novel 2-anthracene ammonium-based magnetic ionic liquids

Facile synthesis of two 2-anthracene ammonium-based magnetic ionic liquids (MILs), 2-anthracene ammonium tetrachloroferrate (III) ([2A-A]FeCl 4 ) and 2-anthracene ammonium trichlorocobaltate (II) ([2A-A]CoCl 3 ) was performed by protonation of 2-aminoanthracene, followed complexation with FeCl 3 /CoCl 2 . The MILs were tested in the adsorptive removal of Cd 2+ , As 3+ , Pb 2+ and Cr 3+ from water sources. Upon treatment with 10 mg dosage of MILs in 10 mL aqueous solution of 50 ppm each of Cd 2+ , As 3+ , Pb 2+ and Cr 3+ , adsorption capacity (mg/g) in the range of 5.73–55.5 and 23.6–56.8 for [2A-A]FeCl 4 and [2A-A]CoCl 3 respectively were recorded. Thus, the optimization, kinetic and isotherms studies were conducted using the [2A-A]CoCl 3 adsorbent. The [2A-A]CoCl 3 was more effective in pH 7–9, and equilibrium adsorption was achieved after 60 min contact time. The adsorption process proceeded via the Pseudo-second order pathway and the Langmuir isotherm model is the best fit for the adsorption process (with q max = 227 – 357 mg/g) of all the targeted metal ions. The [2A-A]CoCl 3 adsorbent demonstrated practicality with large distribution and selectivity coefficients of the targeted ions, and up to six times regeneration.

Electrochemically-assisted removal of cadmium ions by redox active Cu-based metal-organic framework

• Electrochemical capture and release of Cd 2+ were conducted using Cu-MOF-74. • Selective removal of Cd 2+ (>95%) was feasible under Na/Cd ~ 2 × 10 4 in molar ratio. • Redox of Cu within the MOF enables energy-efficient electrosorption/regeneration. • Excellent electrosorption (>100 mg/g) and regeneration (>90%) were achieved. An electrochemically-assisted wastewater treatment using Faradaic materials offers a promising technique for the selective removal of hazardous substances. Here, we demonstrate the reversible capture and release of cadmium ions in aqueous solutions, using a redox-active metal-organic framework (MOF) electrode. As-synthesized copper-based MOF (Cu-MOF-74; copper 2,5-dihydroxyterephthalate) is a highly attractive candidate for Faradaic electrosorption due to its large surface area, water stability, and redox-active metal nodes. Our work demonstrates the reversible capture and release of Cd 2+ ions assisted by the electrochemical redox reaction of Cu 2+ /Cu + within the MOF structure. Combined material characterization and electrosorption tests were carried out to determine the operational conditions for maximizing adsorption capacity, energy efficiency, and material stability, thus leading to excellent electrosorption (>100 mg g −1 ) and regeneration efficiency (>90%). This study demonstrates the feasibility of leveraging MOFs containing redox-active metal nodes for the selective separation of toxic cations, and paves the way for promising future applications of these 3-D porous structures for wastewater treatment and environmental remediation.

Selective removal of Cd(II) ion using synthesised Poly(o-anisidine)–Sn(IV)silicophosphate nanocomposite

ABSTRACT A nanocomposite cation exchanger, poly(o-anisidine)–Sn(IV)silicophosphate, was synthesised using the sol-gel method by the incorporation of Sn(IV)silicophosphate into the poly(o-anisidine) matrix. The physicochemical properties were investigated using FTIR, simultaneous TGA-DTA, SEM and TEM. Characterisation of the polymer-based nanocomposite has shown granulometric nature of the composite with uniform surface morphology and appreciable thermal and chemical stability. The ion-exchange capacity (Na+ ion) of the cation exchanger synthesised at an optimum pH of 0.75 was found to be 1.92 meq g−1. The nanocomposite can withstand temperature as high as 400 with retention of 81.8% of its initial ion-exchange capacity and a mere weight loss of 11.2%. Metal sorption study carried out in different solvent shows the selectivity of the nanocomposite for Cd2+ and Th4+ in all solvent media. Analytically important quantitative binary separations of metal ions were achieved using the synthesised cation exchanger with recovery almost 99.0%. The limit of detection (LOD) and limit of quantification (LOQ) for Cd2+ were found to be 1.60 µg L−1 and 5.33 µg L−1 respectively. Selective removal of hazardous Cd2+ from the industrial effluent reflects the potential utility of the synthesised nanocomposite in environmental pollution control and wastewater treatment.

Optical detection/collection of toxic Cd(II) ions using cubic Ia3d aluminosilica mesocage sensors

Optical sensors for selective removal and detection of extremely toxic ions such as cadmium (CdII) in aquatic samples were successfully fabricated via simple strategy. Aluminosilica-based network platforms are used as selective mesopore shape and size carriers in order to fabricate optical sensors through the direct functionalization of α, β, γ, and δ-tetrakis(1-methylpyridinium-4-yl)porphine ρ-toluenesulfonate (TMPyP) moieties without any prior surface modification using silane or thiol agents. In turn, the key advantage of a heretical three-dimensional (3D) cubic Ia3d mesocage is the facile access of target ions such as ion transports and the high affinity responses of TMPyP receptor-Cd(II) analyte binding events, which result in the easy generation and transduction of optical signals even at the trace level of the Cd(II) ion. The optical sensor design-based aluminosilica cages enable the sensitive detection and selective removal of Cd(II) ions even at ultra-trace concentrations of 10−10mol/dm3 with rapid response time (in minutes). This rational strategy is crucial to the development of optical mesocollectors (i.e., probe surface-mounted naked-eye ion-sensor strips) with highly selective Cd(II) ion removal from aqueous water. These new classes of optical mesocollectors exhibit long-term stability and reusability of deleterious Cd(II) ions, which makes them efficient for various analytical applications.

Functional, mesoporous, superparamagnetic colloidal sorbents for efficient removal of toxic metals

γ-Fe(2)O(3) incorporated mesoporous silica particles of 50-100 nm size have been synthesized which are functionalized with chelating agents of metal ions. These particles are water dispersible but aggregate in response to the external magnetic field and have been used for high performance and selective removal of Cd, Pb, Hg and As.

Facilitated Transport of Cd(II) Through a Supported Liquid Membrane with Aliquat 336 as a Carrier

Selective removal of cadmium from wastewaters is very important, because cadmium is toxic for the environment and for human health. This work is a comprehensive study on the selective removal of Cd(II) from aqueous solutions by using a co-current flow flat sheet supported liquid membrane system. 4.4 × 10−4 M Cd(II) concentration was used as a feed solution in the experiments. Toluene containing Aliquat 336 was used as the membrane liquid in the membrane system. Parameters such as the properties of feed and stripping solutions, carrier concentration, and flow rate, which have roles in transport of Cd(II) ions, were optimized. The efficiency of the system is expressed in terms of permeability and flux values, and transport efficiency. The optimum process conditions for the Cd(II) transport are experimentally found as follows: The feed solution as 2 M HCl, the carrier concentration as 0.1 M Aliquat 336, the stripping solution as 0.06 M EDTA, and the flow rates for the feed and stripping solutions as 50 mL/min and 80 mL/min, respectively. Under these conditions, the Cd(II) transport efficiency is found to be 82%.

Cadmium removal out of human plasma using ion-imprinted beads in a magnetic column

The aim of this study is to utilize ion-imprinted magnetic beads in the selective removal of Cd 2+ ions out of human plasma overdosed with Cd 2+ ions. The Cd 2+ imprinted magnetic poly(HEMA-MAC) (mPHEMAC-Cd 2+) beads were produced by suspension polymerization in the presence of magnetite Fe 3O 4 in a nano-powder form. The template Cd 2+ ions could be reversibly detached from the matrix to form mPHEMAC-Cd 2+ beads using 0.1 M thiourea solution. The specific surface area of the mPHEMAC-Cd 2+ beads was found to be 24.7 m 2/g. The MAC and Fe 3O 4 contents of the mPHEMAC-Cd 2+ beads were found to be 41.8 µmol/g polymer and 8.2% on the average. The Cd 2+ adsorption capacity of mPHEMAC-Cd 2+ columns decreased drastically from 48.8 µmol/g to 20.0 µmol/g as the flow rate is increased from 0.50 ml/min to 3.0 ml/min. The maximum adsorption capacity of the mPHEMAC-Cd 2+ beads was determined to be 48.8 µmol Cd 2+/g on the average. The relative selectivity coefficients of the mPHEMAC beads for Cd 2+/Pb 2+ and Cd 2+/Zn 2+ were 22.6 and 160.7 times greater than those of the non-imprinted magnetic PHEMAC (mPHEMAC) beads, respectively. The mPHEMAC-Cd 2+ beads are reusable for many times with no significant decrease in their adsorption capacities.

An Integrated Process for the Removal of Cd and U from Wet Phosphoric Acid

In this work, an integrated process based on the application of two membrane technologies for the selective recovery of the U and the Cd contained in wet phosphoric acid is presented. The process is based on the removal of U by ion exchange using the Purolite S940 resin as ion-exchange resin followed by the selective removal of Cd by means of membrane-assisted solvent extraction with Aliquat 336 as the selective extractant. After sorption of U, the elution step was carried out with a 1 M solution of Na{sub 2}CO{sub 3} whereas the back extraction of Cd was efficiently achieved by simply using water in the back-extraction phase. Because of working with acidic solutions containing initially 200 mg/l of U and 50 mg/l of Cd, the viability of the process for reduction of the U and Cd concentration below 2 mg/l has been checked, obtaining the kinetic models and parameters of the removal steps, thus, establishing the basis for the process design and optimization.

Analysis of a NDSX Process for the Selective Removal of Cd from Phosphoric Acid

In this work an analysis of the separation process of Cd from phosphoric acid by means of nondispersive solvent extraction technology and by using Aliquat 336 as the selective extractant and water as the backextractant solution is presented. Based on the results of a previous literature report for a different type of extractant, experimental planning has been carried out to determine the feasibility of cadmium removal in a continuous process that includes a regeneration step of the extractant to its chloride form. A chemical mechanism for the separation process has been proposed. Analysis of the steady-state results of Cd transport from the feed acidic phase to the stripping phase led to evaluation of the membrane mass transport parameter, K m = 1.76 × 10−8m/s.