Casca De Arroz Quimicamente Tratada Como Adsorvente De Baixo Custo Para A Remoção De íons Metálicos (co2+ And Ni2+)

Rice husk is an agricultural byproduct and its final disposition has been a serious environmental problem. However, it can be conveniently applied to the sorption of undesirable species from aqueous medium. This work investigated the sorption characteristics for Co2+ (aq) and Ni2+ (aq) ions and the best conditions of the sorption processes onto in nature (IN) and modified rice husks. Chemical treatments were performed by treating rice husk with phosphoric acid (AF) and phosphoric acid/urea (AFU). The experiments were conducted in aqueous solution, pH 4.8, and under constant temperature (28 ± 1 °C) and stirring. Kinetics and isotherms models were applied to the experimental data. The observed order for the maximum adsorption capacities (mmol.g-1) were: Co2+: 0.10 IN < 0.80 AF < 1.60 AFU, and Ni2+: 0.08 IN < 0.55 AFU < 0.75 AF.8358860

Estudos Cinéticos, Isotérmicos e Termodinâmicos Referentes à Adsorção do Corante Têxtil Rubi 2G Dianix sobre Quitosana.

Kinetic, Isothermal and Thermodynamic Studies from Adsorption of Textile Dye Ruby 2G Dianix onto Chitosan. Kinetic, isothermal and thermodynamic equilibrium experiments from adsorption of textile dye ruby 2G Dianix onto chitosan in aqueous medium were studied, as well as biopolymer characterization. Bath adsorptions experiments were realized and the pH results indicated the best range adsorption is between 4,0 and 6,0. The kinetic reaction suggests a second order rate law and the isotherm results agree with the Langmuir model. The thermodynamic parameters (ΔGº, ΔHº and ΔSº) also are presented in this work

Isotermas de Adsorção de Diferentes Corantes Têxteis sobre Quitosana

Adsorption isotherm of some textile dyes onto chitosan. The biopolymer chitosan was employed as adsorbent material to remove some textile dyes (blue R 160% Rcmazol, ru.bine S-2G Dianix, turquoise G 133% Remazol, red RB gran 133% Remazol and brilliant violet 5R Remawl) from aqueous solutions at pH 6.0. The obtained isothenns pointed out the following adsorption capacity sequence: (mg.g-I ): blue (952.4) > violet (699.3) > red (418.4) > rubine (294.1) > turquoise (245.1). The experimental data for all textile dyes studied showed that the equilibrium isotherms correlated very well with the Langmuir isotherm equation

High Performance Maleated Lignocellulose Epicarp Fibers For Copper Ion Removal

Natural lignocellulosic fiber epicarp extracted from the babassu coconut (Orbignya speciosa) was chemically modified through reaction with molten maleic anhydride without solvent, with incorporation of 189.34 mg g-1 of carboxylic acid groups into the biopolymer structure. The success of this reaction was also confirmed by the presence of carboxylic acid bands at 1741 and 1164 cm-1 in the infrared spectrum. Identically, the same group is observed through13C NMR CP/MAS in the solid state, via high field signals in the 167 pm region. Both the precursor and the immobilized maleated biopolymers presented nearly the same thermal stability and similar crystallinity to cellulose. However, the pendant carboxylic groups have the ability to remove copper with maximum sorption through a batchwise process at pH 6.0, as expected from the point of zero charge, determined to be 6.45. 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