Polymer-Supported Phosphoric, Phosphonic and Phosphinic Acids-From Synthesis to Properties and Applications in Separation Processes

Efficient separation technologies are crucial to the environment and world economy. The challenge posed to scientists is how to engineer selectivity towards a targeted substrate, especially from multicomponent solutions. Polymer-supported reagents have gained a lot of attention in this context, as they eliminate a lot of inconveniences concerning widely used solvent extraction techniques. Nevertheless, the choice of an appropriate ligand for immobilization may be derived from the behavior of soluble compounds under solvent extraction conditions. Organophosphorus compounds play a significant role in separation science and technology. The features they possess, such as variable oxidation states, multivalence, asymmetry and metal-binding properties, highlight their status as a unique and versatile class of compounds, capable of selective separations proceeding through different mechanisms. This review provides a detailed survey of polymers containing phosphoric, phosphonic and phosphinic acid functionalities in the side chain and covers main advances in the preparation and application of these materials in separation science, including the most relevant synthesis routes (Arbuzov, Perkow, Mannich, Kabachnik-Fields reactions, etc.), as well as the main stages in the development of organophosphorus resins and the most important achievements in the field.

Amidrazone modified acrylic fabric activated with cyanuric chloride: A novel and efficient support for horseradish peroxidase immobilization and phenol removal

In this study, hydrazine treated acrylic fabrics (polyacrylonitrile, PAN) activated with cyanuric chloride was developed as supporting material for horseradish peroxidase (HRP) immobilization. The immobilization of HRP onto the modified supporting material was achieved after being end-over-end incubated for 12 h. Field emission scanning electron microscopy and Fourier-transform infrared spectroscopy techniques were used to confirm the successful immobilization. Reusability experiment was performed to estimate the ability of the immobilized HRP to recover the reaction medium, in which it was observed to retain 78% of its original activity after 10 cycles. Relative to the soluble HRP, the optimum pH and temperature for the immobilized HRP were shifted to 7-7.5 and 50 °C, respectively. The kinetic parameters of guaiacol and H₂O₂ for the immobilized HRP were determined to be Km/Vmax = 57.61, 11.35 and Kcat/Km = 1.87, 1.86, respectively, while the values for the free form were Km/Vmax = 41.49, 6.23 and Kcat/Km = 1.87, 1.86, respectively. Compared to the soluble form, the immobilized HRP exhibited higher resistance toward metal ions and some organic solvents. For an application perspective. The immobilization of HRP using this procedure has the potential to be used for industrial application and wastewater treatment.

α-Amylase immobilization on amidoximated acrylic microfibres activated by cyanuric chloride

Enzyme immobilization is one of the most important techniques for industrial applications. It makes the immobilized enzyme more stable and advantageous than the free form in different aspects. α-Amylase was immobilized on 4% cyanuric chloride-activated amidoximated acrylic fabric at pH 7.0 with (79%) maximum efficiency. A field emission scanning electron microscope and Fourier transform infrared were used to confirm the immobilization process. Even after being recycled 10 times, the immobilized enzyme lost just 28% of its initial activity. Owing to immobilization, the pH of the soluble α-amylase was shifted from 6.0 to 6.5. The immobilized α-amylases showed thermal stability at 60°C, and became more resistant to heavy metal ions. The k _m values of the immobilized and soluble α-amylases were 9.6 and 3.8 mg starch ml^-1, respectively. In conclusion, this method shows that the immobilized α-amylase proved to be more efficient than its soluble form, and hence could be used during saccharification of starch.

Immobilization of Trichoderma harzianum α-amylase on treated wool: optimization and characterization

α-Amylase from Trichoderma harzianum was covalently immobilized on activated wool by cyanuric chloride. Immobilized α-amylase exhibited 75% of its initial activity after 10 runs. The soluble and immobilized α-amylases exhibited maximum activity at pH values 6.0 and 6.5, respectively. The immobilized enzyme was more thermally stable than the soluble one. Various substrates were hydrolyzed by immobilized α-amylase with high efficiencies compared to those of soluble α-amylase. The inhibition of the immobilized α-amylase by metal ions was low as compared with soluble enzyme. On the basis of the results obtained, immobilized α-amylase could be employed in the saccharification of starch processing.

Comparison of covalent immobilization of amylase on polystyrene pellets with pentaethylenehexamine and pentaethylene glycol spacers

α-Amylase from Aspergillus oryzae was covalently immobilized onto polystyrene pellets with pentaethylenehexamine (PS-PEHA-Ald) and pentaethylene glycol (PS-PG-Ald) carrying a terminal aldehyde group. Optimum immobilization occured at pH 8.0 and 25 °C, and at pH 7.0 and 35 °C for PS-PEHA-Ald and PS-PG-Ald, respectively. PS-PEHA-Ald immobilized enzyme retained approximately 75% of the initial activity over 45 days of storage, 70% of the initial activity after nine runs of recycling and displayed the better resistance to detrimental metal ions. PS-PG-Ald immobilized enzyme retained approximately 50% of the initial activity in 8h at 70 °C. The catalytic efficiencies of PS-PEHA-Ald immobilized and PS-PG-Ald immobilized amylase were 1.42 and 1.29 times higher than that of native enzyme. The activation energy of the reaction mediated by the amylase was reduced by 58.1% and 57.3% when PS-PEHA-Ald and PS-PG-Ald used as support respectively.

The synergistic effect between hydrophobic and electrostatic interactions in the uptake of amino acids by strongly acidic cation-exchange resins

The goal of this work was to investigate the synergistic effect between the electrostatic and hydrophobic interactions upon the uptake of organic ions with hydrophobic moieties by ion-exchange resins with hydrophobic matrixes. The uptake of neutral amino acids by a macroporous polystyrene-based strongly acidic cation-exchange resin (D001) and two strongly acidic cation-exchange resins (poly(2-acrylamido-2-methyl propanesulfonic acid) and poly(vinylsulfonic acid)) with much less hydrophobic matrixes essentially follow an ion exchange stoichiometry. However, the thermodynamic parameters of the uptakes indicate that besides electrostatic interaction, hydrophobic interaction also contributes to the affinity of the amino acids with hydrophobic side chains for D001. No detectable uptake capacities for the amino acids by D001AM, which was obtained by amidation of the sulfonic acid groups of D001, can be determined. Thus, it is deduced that the hydrophobic interaction alone contributes little to the uptake of these amino acids by D001, of which hydrophobicity is the same with or lower than that of D001AM. These results indicate that synergistic effect exists between the electrostatic and hydrophobic interactions when the two interactions exist in a chelate manner and the hydrophobic interaction contributes to the uptake even if the hydrophobic interaction is so weak that it contributes little to the uptake when it acts alone.