天然棕色棉对亚铁离子的吸附行为OA

Naturally brown cotton refers to a general category of cotton that naturally acquires a brown hue during the maturation of its fibers.Because it does not require dyeing or printing processes during manufacturing,it can effectively shorten production procedures and reduce environmental pollution,making it a green and environmentally friendly fiber material.However,the impure color and poor stability of naturally brown cotton greatly hinder its subsequent applications.Therefore,it is urgent to enrich the color variety of naturally brown cotton.Existing research shows that treatment with Fe(II)ions can improve the color intensity and achieve color-fastening effects in brown cotton.Nevertheless,the mechanism underlying the adsorption of Fe(II)ions by brown cotton is still unclear,lacking theoretical guidance for practical applications and thus constraining its industrial promotion.To address this,this paper explores the adsorption mechanism of brown cotton greige fabric on Fe(II)ions. In this study,ammonium ferrous sulfate was employed as the source of Fe(II)ions to investigate the differences in Fe(II)ion adsorption between white cotton bleached fabric and brown cotton greige fabric.The effects of reaction time,adsorption reaction environmental temperature,and the initial mass concentration of Fe(II)ions in the solution on the Fe(Ⅱ)ion adsorption characteristics of brown cotton greige fabric were examined.The adsorption kinetics process and isothermal adsorption characteristics of Fe(Ⅱ)ions onto brown cotton greige fabric were elucidated.Subsequently,pigments were extracted from brown cotton,and a brown cotton pigment-Fe2+complex was prepared using ammonium ferrous sulfate.Through characterization techniques such as infrared spectroscopy,X-ray photoelectron spectroscopy,and colorimetric analysis,the chemical structural alterations and color variations in both the fabric and the pigments before and after Fe(II)ion treatment were studied.This approach aimed to unveil the underlying adsorption mechanism of Fe(II)ions by brown cotton greige fabric. Research findings indicate that the adsorption capacities of both white cotton bleached fabric and brown cotton greige fabric for Fe(Ⅱ)ions increase progressively with time.The adsorption capacity of brown cotton greige fabric for Fe(Ⅱ)ions is always greater than that of white cotton bleached fabric,and the first hour of adsorption is a fast reaction process,reaching adsorption equilibrium at 3 hours.During the color-fixing treatment of brown cotton greige fabric with ammonium ferrous sulfate,the kinetic behavior of Fe(Ⅱ)ion adsorption adheres closely to the pseudo-second-order kinetic model(R2=0.9994).Additionally,the adsorption efficiency escalates with rising temperatures,plateauing at 70℃.The isothermal adsorption characteristics can be well described by the Langmuir isotherm model(R2=0.9998),indicating that the adsorption process is predominantly chemical in nature.Mechanistically,Fe(Ⅱ)ions undergo complexation reactions with the phenolic hydroxyl groups of proanthocyanidins present in brown cotton pigments,generating proanthocyanidin-Fe2+complexes.A portion of these Fe2+complexes are further oxidized to proanthocyanidin-Fe3+complexes.The synergistic effect of these complexes results in a visible darkening of the brown cotton color,enhanced green and blue light,and reduced lightness and saturation.