Investigation Of Ramie Oxidation Degumming Using Fenton Reagent

Ramie is a special local product in our country.It has the characteristics of high linear density,longer length,tough and lightweight appearance,high moisture absorption and favorable air permeability.It is one kind of excellent textile materials and acknowledged as “the king of natural fibers”.The main component in raw ramie is cellulose,in addition,there are some non-cellulosic components,also called gums.It is a key stage to remove these gummy compositions from raw ramie and thus extract the high quality separated cellulose fibers prior to spinning process or wide-scale industrial use.At present,the main degumming methods of raw ramie are microbial degumming and chemical degumming.In general,the practical application in industry is mainly the chemical degumming and microbial-chemical degumming.From a practical point of view,the disadvantage of chemical degumming lies in the large number of chemicals usage,large discharge of degumming wastewater and heavy environmental pollution.This paper investigated the possibility of oxidation degumming using Fenton reagent as a new oxidizing agent to extract the cellulose fibers from raw ramie.Hydrogen peroxide,which could generate hydroxyl radicals under the catalysis of Fe SO4·7H2O,could cut the non-cellulosic molecules such as hemicellulose,pectin,lignin and finally oxidize to degradate them into small molecules.It can not only achieve the purpose of degumming,but also can be able to deal with degumming wastewater,reduce the chroma,p H value and COD value in degumming wastewater.Therefore,it can achieve the VI purpose of energy conservation and efficient environmental protection.The mechanism ofoxidation degumming was analyzed,and the degumming process was monitored and controlled using ORP.The main study of this paper are summarized as follow:The method of single factor experiment was used to investigate the operating parameters of p H value,scouring temperature,catalyst(Fe SO4·7H2O)dosage and hydrogen peroxide dosage on the effect of degumming.The experimental results indicated that when the p H value of degumming solution was either less than 3.0 or greater than 5.0,the degummed fibers using Fenton showed relatively smaller breaking tenacity and breaking elongation,but the linear density was comparatively higher.The breaking tenacity showed a trend of decrease after the first increase with the increase of Fe SO4·7H2O dosage,when the Fe SO4·7H2O dosage is either too high or too small.Meanwhile,the linear density of degummed fibers is larger,and the breaking elongation is comparatively smaller.The breaking tenacity showed a trend of decrease after the first increase with the increase of H2O2 dosage,and then achieve a trend of plateau.With the temperature increased,both breaking tenacity and breaking elongation of degummed fibers showed the trend of firstly increase and then decrease.And the linear density is decreased at the same time.By designing the orthogonal experiment,it was determined the optimal operation conditions as follows: p H = 4.0,Fe SO4·7H2O dosage 0.25%,H2O2 dosage 6%,temperature 50?.Based on the single factor experiment,an orthogonal experiment was designed to optimize the process of ramie degumming using Fenton reagent.The experimental results supported the optimal operation conditions as follows: p H = 4.0,Fe SO4·7H2O dosage 0.25%,H2O2 dosage 6%,temperature 50 ?.The degummed fiber properties using Fenton are improved significantly compared to the oxidation degumming under alkaline condition.Under these conditions,the linear density,string content,residual gum of degummed fibers using Fenton and COD value of degumming wastewater was reduced by 2.93%,87.63%,27.98% and 21.43% respectively.The breaking tenacity,breaking elongation,softness,degree of polymerization were increased by4.38%,16.88%,75.14% and 3.16% respectively.The results showed that,compared with the traditional degumming,the linear density,breaking elongation,residual gum and softness was increased by 1.48%,2.04%,3.49% and 31.91% respectively.While the breaking tenacity,string content,degree of polymerization and COD value of degumming wastewater was decreased by1.53%,86.2%,44.93% and 33.79% respectively.On the whole,the chosen Fenton reagent could serve as new and effective oxidizing agent to extract the cellulose fibers from raw ramie oxidation degumming.This novel oxidation reaction proceeded mildly,the degummed fiber experienced less damage,thus the physical and mechanical properties,especially softness,elongation and fineness were found to be remarkably improved.At the same time,the process of Fenton oxidation degumming were shown to save energy consumption and chemicals,time-saving,cost-effectiveand environment-friendly.SEM examination micrographs results indicated that the treated fibers using Fenton reagent had been completely separated,the effect of degumming was better,the fibers exhibited cleaner and smoother surface and the contour characteristics of individual fibers,namely regular horizontal grooves and vertical stripes,could be observed clearly on fibers' surface.XRD showed that the degummed fibers using Fenton had a relatively lower crystalline cellulose than both oxidation degumming under alkaline condition and traditional degumming.Therefore,it exhibited an improved properties of softness,elongation.From FTIR spectroscopy analysis,we can safely draw conclusion that most gummy substances were successfully removed from ramie under the oxidation degumming using Fenton.ORP(Oxidation-reduction potential)values throughout the Fenton oxidation degumming process were monitored.Variations in ORP were attributed to the operation conditions such as original p H level of solution,oxidation temperature,hydrogen peroxide dosage,and Fe SO4·7H2O dosage.The experimental results suggested that a trend of decrease after the first increase with the increase of p H level in solution,oxidation temperature,hydrogen peroxide dosage,and Fe SO4·7H2O dosage.In consideration of desired and reasonable degumming result,it determined the optimal operation conditions as follows: p H = 4.0,Fe SO4·7H2O dosage 0.75%,H2O2 dosage6%,temperature 60?.Monitoring ORP values throughout the Fenton oxidation degumming process could allow a better continuous and moderate process.The results showed that when the ORP value in the solution was set from +335m V to +430 m V,the mechanical property of treated fibers was better and the effect of degumming was comparatively better.