Comparison of synthesis of chelating resin silica-gel-supported diethylenetriamine and its removal properties for transition metal ions

Evaluation of Dithiocarbamate-Modified Silica for Cisplatin Removal from Water

Despite the globally increasing use of platinum-based cytostatic drugs in the treatment of several types of cancer, only limited attention has been paid to developing a treatment for contaminated liquid samples originating from hospitals, laboratories and manufacturing facilities before and after their administration. In this work, we assess the efficiency of a low-cost adsorbent material, a dithiocarbamate-functionalized silica, in removing cisplatin from a solution containing it in the 0.5–150 mg L−1 concentration range. The advantage of having a surface-functionalized silica is that adsorption can occur by either non-covalent interaction or surface complexation. In the latter case platinum(II) is de-complexed and the original drug is no longer present. Adsorption occurs through a first rapid step, followed by a second slower process. This is likely due to the fact that in our operating conditions (0.9% w/v NaCl), only the original compound is present, for which ligand substitution is known to proceed slowly. The interesting performance, even at low metal concentration, and facile synthesis of the material mean it could be adapted for other applications where the recycling of platinum can be realized.

Lead electrodeposition from aliphatic polyamines solutions

Hydrometallurgical and pyrometallurgical processing of ores and concentrates generates large amount of various solid residues. These may contain significant amount of heavy metals, particularly lead is of great importance. It is present in form of anglesite, cerrusite or lead oxides. Hydrometallurgical processing of leaching residues, dusts, and fly ashes is used to recover valuable metals from these streams. Acid leaching in sulfuric acid solutions or spent electrolyte results in producing high amount of lead sulfate that is still very attractive material to fulfill demand of lead acid battery market. Aliphatic linear polyamines are solvent extracting agents very selective towards lead sulfate. Here we report the comparative tests of four different linear aliphatic homologs, namely ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine as potential extracting agents of lead sulfate. The core research was devoted to the possibility of direct electrodeposition of lead from various polyamines solutions. Electrochemical tests performed at current density 200 A/m2, 60 °C, with an addition of selected inhibitor showed the possibility to produce metal layer with 97.2% purity for triethylenetetramine.

Graphical abstract

Lead Electrodeposition from Triethylenetetramine Solution Containing Inhibitors

Lead can be efficiently electrodeposited from a number of common leaching agents such as mineral acids, carboxylic acids, and bases (hydroxides and ammonia). This paper reports the possibility to deposit lead from a triethylenetetramine solution, which is also a powerful extracting agent for lead sulfate. The high affinity of triethylenetetramine towards lead sulfate molecules makes it a promising candidate for lead recovery from various solid materials, including industrial secondary resources, sewages, and wastes. A popular methodology that can be found in the literature to recover metal from amine is based on purging a solution with carbon dioxide, resulting in lead carbonate precipitation. Here, the direct electrodeposition of lead from an amine solution was reported. The effects of the main process parameters, i.e., current density, temperature, and presence of additives, were examined to enhance the product quality. Bone glue, ethylene glycol, and polyvinylpyrolidone were used as perspective inhibitors of dendritic lead formation. It was shown that the addition of ethylene glycol can significantly reduce their formation as well as discoloration resulting from amine, producing lead metal with a 99.9% purity.

Surface Modification of Attapulgite by Grafting Cationic Polymers for Treating Dye Wastewaters

In this study, the cationic polymer poly-epichlorohydrin-dimethylamine was immobilized on natural attapulgite to improve the dye adsorption capacities. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, nitrogen adsorption-desorption isotherms, scanning electron microscope (SEM) analysis, zeta potential analysis, and particle size analysis were used to determine the characteristics of modified attapulgite. Results showed that the poly-epichlorohydrin-dimethylamine had been successfully grafted onto the surface of attapulgite without altering its crystal structure. After cationic modification, the specific surface area of attapulgite obviously decreased, and its surface zeta potentials possessed positive values in the pH range from 3 to 11. The cation-modified attapulgite displayed high adsorption capacities for anionic dyes, and its maximum adsorption capacities were 237.4 mg/g for Reactive Black 5 and 228.3 mg/g for Reactive Red 239; this is corroborated by Langmuir’s isotherm studies. It was demonstrated that the two reactive dyes could be 100% removed from effluents when cation-modified attapulgite was used in column operation modes. Its treatment capacities were more than three times larger than that of activated carbon. The regeneration study verified better utilization and stability of the fabricated adsorbent in column operation. This work has conclusively confirmed the potential of the new modified attapulgite for effectively treating dye wastewaters.

Fabrication of Triethylenetetramine Terminal Hyperbranched Dendrimer-Like Polymer Modified Silica Gel and Its Prominent Recovery Toward Au (III)

To further increase the quantity and density of functional groups on adsorbent, terminal triethylenetetramine hyperbranched dendrimer-like polymer modified silica-gel (SG-TETA and SG-TETA2) was synthesized. The hyperbranched dendrimer-like polymer was successfully introduced onto silica gel and new cavities were formed, which was demonstrated by FTIR, SEM, and BET. The highest adsorption capacities of SG-TETA and SG-TETA2 obtained from Langmuir model toward Au(III) were 2.11, and 2.27 mmol g⁻¹, respectively, indicating that SG-TETA2 possessing more functional groups had a better adsorption ability. Moreover, the adsorbents combined with Au(III) ion through chelation and electrostatic attraction mechanism, after which reduction reactions for Au(III) ion loaded on adsorbents proceeded. SG-TETA2 had better adsorption selectivity than SG-TETA in removing Au(III) in Au-existed ion solution systems. SG-TETA2 had higher overall adsorption capacities compared to silica-gel-based hyperbranched polymers functionalized by diethylenetriamine. Therefore, the effective recovery makes SG-TETA2 a practical adsorbent in removing Au(III) ion from e-wastes and industrial effluents with much prospect.

Syntheses and catalytic activities of new metallodendritic catalysts

Metallodendritic catalysts showed high selectivity in the epoxidation of olefins even after being used for at least five cycles.

Uptake of Fe(iii), Ag(i), Ni(ii) and Cu(ii) by salicylic acid-type chelating resin prepared via surface-initiated atom transfer radical polymerization

With chloromethylated PS being the base material, a new type of ASA/PGMA/PS resin with high capacity was prepared by grafting GMA on the surface of the resin via surface-initiated atom transfer radical polymerization and followed by the derivatization with 5-ASA.

Amine-functionalized mesoporous polymer as potential sorbent for nickel preconcentration from electroplating wastewater

In this study, mesoporous glycidyl methacrylate-divinylbenzene-based chelating resin was synthesized and grafted with diethylenetriamine through epoxy ring-opening reaction. The synthesized resin was characterized by elemental analysis, infrared spectroscopy, surface area and pore size analysis, scanning electron microscopy, energy-dispersive spectroscopy, and thermogravimetry. The resin was used for the first time as an effective sorbent for the preconcentration of nickel in electroplating wastewater samples. The analytical variables like pH, flow rate for sorption/desorption, and eluate selection were systematically investigated and optimized. The uniform and monolayer sorption behavior of resin for nickel was proved by an evident fit of the equilibrium data to a Langmuir isotherm model. Under optimized conditions, the resin was observed to show a good sorption capacity of 20.25 mg g(-1) and >96% recovery of nickel even in the presence of a large number of competitive matrix ions. Its ability to extract trace amount of nickel was exhibited by low preconcentration limit (5.9 μg L(-1)). The calibration curve was found to be linear (R(2) = 0.998) in the concentration range of 6.0-400.0 μg L(-1). Coefficient of variation of less than 5 for all the analysis indicated good reproducibility. The reliability was evaluated by the analysis of standard reference material (SRM) and recovery experiments. The applicability of the resin for the systematic preconcentration of nickel is substantiated by the analysis of electroplating wastewater and river water samples. Graphical abstract ᅟ.

Synthesis of silica gel supported salicylaldehyde modified PAMAM dendrimers for the effective removal of Hg(II) from aqueous solution

A series of silica gel supported salicylaldehyde modified PAMAM dendrimers (SiO2-G0-SA ∼ SiO2-G2.0-SA) were synthesized and their structures were characterized by FTIR, XRD, SEM, TGA, and porous structure analysis. The feasibility of these adsorbents for the removal of Hg(II) from aqueous solution was first described and the adsorption mechanism was proposed. The adsorption was found to depend on solution pH, the generation number of salicylaldehyde modified PAMAM dendrimers, contact time, temperature, and initial concentration. Results showed that the optimal pH was about 6 and the adsorption capacity increased with the increasing of generation number. Density functional theory (DFT) method was used to investigate the coordination geometries and the chelating mechanism. Adsorption kinetics was found to follow the pseudo-second-order model with film diffusion process as rate controlling step. Adsorption isotherms revealed that adsorption capacities increased with the increasing of temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models were employed to analyze the equilibrium data. The adsorption can be well described by Langmuir isotherm model and took place by chemical mechanism. The thermodynamics properties indicated the adsorption processes were spontaneous and endothermic nature. The maximum adsorption capacity of SiO2-G0-SA, SiO2-G1.0-SA, and SiO2-G2.0-SA were 0.91, 1.52, and 1.81 mmol g(-1), respectively. The considerable higher adsorption capacity compared with other adsorbents indicates SiO2-G0-SA ∼ SiO2-G2.0-SA are favorable and useful for the uptake of Hg (II), and can be potentially used as promising adsorbents for the effective removal of Hg(II) from aqueous solution.

Functionalized Silica Gel as Green Material for Metal Remediation

Advancement in industrialization and urbanization is a good indicator of the progress of humanity. However, it has an evil side as well. This advancement is identified as being responsible for deleterious effects on the health of human beings and aquatic biodiversity. Anthropogenic activities like mining and disposal of treated/untreated waste effluents containing toxic metals have resulted in severe deterioration of water quality, rendering serious environmental problems. The basic problem is that the wastewater generated through industries is not given the necessary pretreatment and is discharged directly into water resources. The metals beyond their permissible limits cause maximum negative impacts owing to their long biological half-lives and nondegradable nature. The condition is further worsening in economically deprived countries, where this metal-contaminated wastewater is directly used in various agricultural and day-to-day practices. As a solution to this, the extraction and removal of toxic metal ions from these polluted water resources at an industrial level is of paramount importance. This chapter provides the enthusiastic efforts of the scientific community to disseminate the fundamentals and practices of green analytical methods for metal removal. These methods are based on solid-phase extraction using functionalized silica gel for the separation and preconcentration of metal ions in polluted water resources. Ease of synthesis and extensive application of these organic-inorganic hybrid materials helps to fulfil the commitment of continual environmental improvement by remediating the wastewater.

Synthesis of polyacrylonitrile-grafted cross-linked N-chlorosulfonamidated polystyrene via surface-initiated ARGET ATRP, and use of the resin in mercury removal after modification

A novel method of surface modification was developed via iron (III)-mediated atom transfer radical polymerization, with activators regenerated by electron transfer (ARGET ATRP) on the surfaces of polystyrene resin-supported N-chlorosulfonamide groups. The well-defined polyacrylonitrile (PAN) was grafted onto the surfaces of the polystyrene (PS). The graft reaction exhibited first-order kinetics with respect to the polymerization time in the low-monomer-conversion stage. The cyano group of PAN-g-PS was modified by NH(2)OH·HCl to yield amidoxime (AO) groups. The AO groups had been demonstrated to be an efficient Hg-specific sorbent, which can remove Hg(2+) from solutions. No interference arose from common metal ions, such as Pd(2+), Ag(+), and Cu(2+). Three adsorption-desorption cycles demonstrated that this resin is suitable for reuse without any considerable change in adsorption capacity.

Kinetic Investigation of Silica Gel Chemically Modified by Ethylenediamine Bis(Methylene Phosphonic Acid) for Adsorption of Au(Iii)

A novel hybrid material, silica gel chemically modified by ethylenediamine bis(methylene phosphonic acid) (denoted as SH-E-P), has been developed, and FT-IR analysis demonstrated that methylene phosphonic acid groups had been grafted successfully onto the surface of the silica gel. A detailed kinetic investigation of the adsorption of Au(III) onto SH-E-P is reported in this study. The results showed that SH-E-P could reach its saturation adsorption capacity within 4h, with an excellent adsorption capacity for Au(III) of 453.83 mg g−1 when the initial solution concentration was 2.0 mmol L−1 at 35°C. Moreover, the adsorption kinetics can be closely modelled by a pseudo second-order rate equation. The thermodynamic parameters Δ G, Δ H and Δ S were - 19.52 kJ mol−1, 4.84 kJ mol−1, and 79.43 J K−1 mol−1, respectively. It can be concluded that the adsorption of Au(III) on SH-E-P is a spontaneous, endothermic process controlled by film diffusion, which results in its higher adsorption capacity at higher temperatures.

Synthesis of porous acrylonitrile/methyl acrylate copolymer beads by suspended emulsion polymerization and their adsorption properties after amidoximation

Porous acrylonitrile (AN)/methyl acrylate (MA) copolymer beads were prepared by suspended emulsion polymerization. The cyano groups in AN/MA copolymer beads were converted to amidoxime (AO) groups by reaction with hydroxylamine hydrochloride (NH(2)OH.HCl) to remove metal ions in aqueous solution. The untreated AN/MA and amidoximated AN/MA (AO AN/MA) copolymer beads were characterized by FTIR spectroscopy, SEM, and porous structural analysis. Both mesopores and macropores were presented in AN/MA and AO AN/MA copolymer beads. Qualitative experiments of adsorption were conducted to evaluate modified and unmodified resins on fixing Hg(2+), Ag(+), Cu(2+), Fe(3+) and Pb(2+) from aqueous solution using batch extractions. It was found that AO AN/MA copolymer beads have excellent adsorption capacities for Hg(2+), Ag(+) and Cu(2+), especially for Hg(2+), and it have good selectivity for Hg(2+). The equilibrium was established in 10h through adsorption kinetics study. The Langmuir model was much better than the Freundlich model to describe the isothermal process.

Modified silica surface by phenylboronic acid derivatives as effective sugar sensor

Silica surface was modified with phenylboronic acid derivatives. The structures of the functionalized supports were characterized by FT-IR spectroscopy, 13C CP/MAS NMR spectrometry, elemental and thermogravimetric analysis. The solid supports were effectively applied as artificial receptors for sugars in aqueous solutions. Alizarin Red S. (ARS) was used to detect colour change upon carbohydrate (sugar) binding. The association constants of the supports studied-ARS complex and the functionalized silica-sugar (glucose) complex were calculated. The parameters obtained were comparable with those for the phenylboronic acids used for the silica gel modification. The competitive binding of the functionalized silica surface with ARS and sugar were studied by UV/VIS measurements.