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1.
Int J Biol Macromol ; 149: 404-416, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-31935405

RESUMO

This paper highlights the efficacy of carboxymethyl chitosan (CMCh), a bio-degradable water-soluble derivative of chitosan for the separation of a mixture of heavy metal ions such as copper, nickel, zinc and lead from aqueous streams, as they constitute, the major industrial pollutants present in wastewater. The experimental studies are conducted using commercially available ultrafiltration module using synthetic solutions of the contaminants. The design of experiments was performed by Response Surface Methodology (RSM) with split-plot D-optimal design. Parametric studies were carried out using initial pH of the feed solution, loading ratio (P/M) and initial metal ion concentration to assess the percentage rejection and recovery of metal ions. The maximum percentage rejection of Cu(II), Ni(II), Zn(II) and Pb(II) with CMCh were found to be 100%, 100%, 95%, and 98% respectively under optimum conditions. Subsequently the metal ions were recovered collectively by reversing the pH to 2. The results show that CMCh could be an effective size enhancing species for the removal and recovery of mixture of metals by SEUF.


Assuntos
Quitosana/análogos & derivados , Metais Pesados/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Água/química , Cádmio/química , Cádmio/isolamento & purificação , Quitosana/química , Cobre/química , Cobre/isolamento & purificação , Humanos , Metais Pesados/química , Níquel/química , Níquel/isolamento & purificação , Eliminação de Resíduos Líquidos , Águas Residuárias , Poluentes Químicos da Água/química , Purificação da Água/métodos , Zinco/química , Zinco/isolamento & purificação
2.
Int J Biol Macromol ; 132: 278-288, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30940581

RESUMO

N­N­N­triethylammonium chitosan (TEAC) and carboxymethyl chitosan (CMCh), the two water-soluble chitosan derivatives were utilized for the removal and recovery of heavy metals by size enhanced ultrafiltration (SEUF). The strong positive quaternary ammonium [-N+(C2H5)3] cation in TEAC interacts with Cr(VI), which exists as a strong chromate anion thereby enabling the efficient removal of chromate through ultrafiltration. CMCh consists of COOH and NH2 moieties, which facilitate interactions with heavy metals such as Cu(II) and Ni(II). FTIR, SEM, and EDAX were used to characterize the chitosan derivatives before and after the removal of metals. The experiments were designed with the central composite design (CCD) of response surface methodology (RSM). The metal ion removal experiments were conducted as per the statistical design to determine the optimum process conditions; initial pH of the feed solution, polymer to metal loading ratio (P/M), and initial concentration of the feed solution. The optimization study was conducted to maximize the heavy metal rejection and binding capacity of the chitosan derivatives. The analysis of variance (ANOVA) was performed to validate the developed regression models.


Assuntos
Quitosana/análogos & derivados , Metais Pesados/química , Metais Pesados/isolamento & purificação , Ultrafiltração/métodos , Quitosana/química , Concentração de Íons de Hidrogênio
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