The Removal Of Iron Ions From The Waste Lye In The Pre-treatment Of Cotton Fabrics And The Recovery And Reuse Of Lye

After mercerizing cotton fabrics,a large amount of low concentration alkali liquor will be produced.Alkali liquor is usually concentrated by direct multi-effect evaporation and re-applied to the pretreatment of cotton fabrics.However,due to the presence of a large number of iron ions and organic impurities in the alkali solution,the treatment effect of cotton fabrics will be greatly affected,and even cause oxidative hole-breaking phenomenon.Therefore,it is necessary to remove iron ions and other impurities in alkali liquor to improve the purity of alkali liquor.In this study,mercerized light alkali liquor was treated and recovered by coagulation,ultrafiltration and nanofiltration.The concentration of iron ion,CODCr,turbidity,chroma and hydroxide ion in the treated alkali liquor were analyzed.Cotton fabrics were pretreated by desizing,scouring and bleaching in one bath with purified alkali solution.The whiteness,capillary effect and breaking strength of cotton fabrics were analyzed.1.In order to remove iron ions from alkali liquor efficiently,magnesium oxide and sodium styrene sulfonate were used to coagulate the alkali liquor.The results show that when the dosage of magnesium oxide is 14 g/L and sodium p-styrene sulfonate is 20 mg/L,the chroma of alkali solution decreases from 674.8 degrees to 325.9 degrees,the turbidity decreases from 232.1 NTU to 40.3 NTU,the CODcr decreases from 13013 mg/L to 4915 mg/L,and the contents of iron ions and sodium hydroxide remain unchanged.2.Continuous treatment of alkali liquor after coagulation with PES1000 ultrafiltration membrane.The experimental results show that the chroma decreases from 325.9 to 66.9,the turbidity decreases from 40.3 NTU to 13.9 NTU,the CODcr decreases from 4915 mg/L to 597 mg/L at the transmembrane pressure of 5.0 bar and the temperature of 25 C,and the iron ion and hydroxide ion are not intercepted.3.NF 270 was selected to treat the alkali liquor after ultrafiltration.The results showed that when the temperature was 25 C and the transmembrane pressure was 40 bar,the chroma decreased from 66.9 to 0.2,the turbidity from 13.9 NTU to 0.0 NTU,the CODcr from 597 mg/L to 257 mg/L,the iron ion content from 286.4 ug/mL to 36.9 ug/mL,and the hydroxide ion concentration decreased slightly,from 165.4 g/L to 15 8.9 g/L.4.order to verify the pretreatment effect of alkali liquor after removing impurities such as iron ions on cotton fabric,one bath desizing,scouring and bleaching experiments were carried out on cotton fabric.The results show that the whiteness,capillary effect and breaking strength of treated cotton fabrics are 77.7%,9.6 cm/30 min and 822.4 N respectively,which are superior to those of alkali solution.