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Query: UMLS:C0267964 (PAA)
 2,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cadmium (II) or lead (II) complex formation with two poly(acrylic acids) of high molecular weight (Mw=2.5 x 10(5) and 3 x 10(6)) was investigated in dilute aqueous solution (NaNO(3) 0.1 mol l(-1); 25 degrees C). Potentiometric titrations were carried out to determine the stability constants of the MA and MA(2) complex species formed. Bjerrum's method, modified by Gregor et al. (J. Phys. Chem. 59 (1955) 34-39), for the study of polymeric acids was used. The results were compared to those previously obtained in the same conditions with copper (II) and nickel (II) [1]. It appeared that the two polymers under study present similar binding properties and that the stability constants of the complex species formed increased in the following order, depending on the metal ion: Ni(II)<Cd(II)<Cu(II)<Pb(II). Lead (II) ions seemed to be particularly well bound to PAAs (the global stability constant log beta(102) was found to be close to 7.0) and allowed the formation of the predominant PbA(2) species in a quite large pH domain. Finally, the greater stability of PAA complexes compared to those of their monomeric analogs, glutaric and acetic acids, was confirmed.
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PMID:Potentiometric study of Cd(II) and Pb(II) complexation with two high molecular weight poly(acrylic acids); comparison with Cu(II) and Ni(II). 1896 60

In this study, chitosan-g-poly(acrylic acid) (CTS-g-PAA) hydrogel with crosslinked polymeric networks was prepared from an aqueous dispersion polymerization and then used as the adsorbent to recover a valuable metal, Ni2+. The adsorption capacity of CTS-g-PAA for Ni2+ was evaluated and the adsorption kinetics was investigated using Voigt-based model and pseudo-second-order model. In addition, the effects of pH values and coexisting heavy metal ions such as Cu2+ and Pb2+ on the adsorption capacity were studied. The results indicate that the as-prepared adsorbent has faster adsorption rate and higher adsorption capacity for Ni2+ recovery, with the maximum adsorption capacity of 161.80 mg g(-1). In a wide pH range of 3-7, the adsorption capacity keeps almost the same, and even under competitive conditions, the adsorption capacity of CTS-g-PAA for Ni2+ is observed to be as high as 54.47 mg g(-1). Finally, the adsorption performance of CTS-g-PAA for Ni2+ in real water sample and the reusability of the as-prepared adsorbent were evaluated, and also the controlled adsorption mechanism was proposed.
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PMID:Chitosan-g-poly(acrylic acid) hydrogel with crosslinked polymeric networks for Ni2+ recovery. 2127 22

The increasing extent of heavy metal pollution all over the world has resulted in many serious environmental and public health problems. To solve these problems, effective technologies for water treatment are urgently needed. Recent efforts have focused on the development of self-driven micro/nanomotors for eliminating inorganic and organic pollutants in an aqueous system. These synthetic micro/nanomotors can increase mass transfer through the transportation of reactive species, leading to higher decontamination rates. Here, we report a surface-tunable poly(amino acid) (PAA)-based micromotor. The property of the outer layer can be adjusted by changing the type and proportion of amino acids according to real requirements. Three kinds of micromotors are fabricated, which consist of a microtube composed of PAAs (i.e., polyaspartic acid (PAsp), polycysteine (PCys) or a copolymer of both (PAsp-Cys)), a thin Ni intermediate layer, and a Pt inner layer. Due to the presence of various side-chain functional groups (e.g., amino, carboxyl, and sulfhydryl) on the surface of the poly(amino acid)s, these micromotors can be used as effective scavengers for the removal of heavy metals (i.e., Cd2+, Pb2+ and methylmercury). Compared with PAsp and PCys micromotors, the PAsp-Cys micromotor shows good acid resistance and can simultaneously adsorb various kinds of heavy metals with high removal efficiency. The outer layer of the surface-tunable micromotor has good biocompatibility and adsorption efficiency, which holds considerable promise for environmental and biomedical applications.
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PMID:Effective removal of inorganic and organic heavy metal pollutants with poly(amino acid)-based micromotors. 3207 22