| Hemp fiber must go through degumming process before becoming textile raw material.Degumming was an important link to determine the spinning quality of hemp fiber.Compared with ramie and flax,hemp had a higher proportion of non cellulose content and was more difficult to degumming,which put forward higher requirements for degumming methods.Anaerobic continuous flow biological degumming device for hemp fiber solved some problems of current degumming methods such as chemical degumming and biological degumming to some extent.It had the advantages of low operation cost,little fiber damage and less energy consumption and pollution,which was an innovative degumming method worthy of promotion.However,the existing anaerobic continuous flow biological degumming device for hemp fiber had some problems,such as uneven function of heat preservation system and obvious temperature observation error,which needed to be improved accordingly.The research adjusted the original common four-way water bath into independent water bath.Considering the heat loss caused by the heat transfer medium,the thermostat water bath was replaced by electrified heating belt,so as to achieve the uniformity of heat preservation.Change the position of the thermometer and use the tee joint to place it 20?30cm below the degumming solution level to improve the accuracy of the temperature measurement.In order to further improve the effect of anaerobic continuous flow biological degumming and provide parameter basis for the efficient operation of the device,the research focused on the analysis of the influence factors of the continuous flow biological degumming effect of hemp,explored the main influence factors affecting the continuous flow biological degumming effect,and made use of the evaluation and analysis of degumming effect of Qingshui raw hemp to judge the influence degree of some main influence factors,which provided reference and direction for the optimization of process parameters of the device.The research summarized and combed various factors affecting the continuous flow biological degumming effect of hemp,mainly including the comprehensive performance of Qingshui raw hemp,the process factors of the degumming device,the structure of degumming flora,etc.The main influence factors included different varieties and parts of Qingshui raw hemp,degumming time,degumming temperature,p H of degumming solution,the structure of degumming flora,etc,Several main factors were selected for key exploration,which were different varieties and parts of Qingshui raw hemp,degumming temperature,and dosage of p H additives.The experiment adopted the single factor design method.Under the condition of keeping other parameters stable,and according to several main influence factors selected the anaerobic continuous flow degumming experiment was carried out for nearly half a year with Qingshui raw hemp produced in Tianshui area,Gansu province.Combined with the corresponding detection and analysis experiment,a large number of detailed data were obtained.The results of analysis and discussion showed that:1)After continuous flow biological degumming treatment,the residual gum content of different varieties and parts of Qingshui raw hemp was little difference,which was about 20%.According to the appearance observation before and after degumming,relatively clear bundle fibers structure appeared in the head,middle or root of Qingshui raw hemp treated by this degumming technology.It showed that under certain conditions,this degumming technology mainly removed the gum between bundle fibers inside raw hemp,but the gum inside bundle fibers was not affected much.The degumming selectivity laid a solid foundation for ensuring the quality of technical hemp fiber.In terms of fineness and strength,the head was the best,the middle was the second,and the root was the worst.There was little difference in elongation between different parts.The fiber quality of degummed seed hemp in Qingshui raw hemp was not lower than that of degummed flower hemp.2)In the range of 33??39?,raising degumming temperature had a positive effect on the degumming effect of Qingshui raw hemp.When degumming temperature was raised,the weight loss rate of Qingshui raw hemp increased in varying degrees,but the tensile properties of the fiber were not affected much.With the weight loss rate increased,the tensile properties of the fiber did not change significantly,which verifies degumming selectivity.Raising degumming temperature promoted the gum degradation of Qingshui raw hemp.The influent p H and effluent p H of the degumming solution decreased.The organism concentration in the degumming solution increased,and the effluent COD concentration increased.The difference of COD concentration between the influent and effluent of the reactor increased.The removal rate of organism in the degumming solution improved significantly,which was reflected in the obvious increase of weight loss rate.3)In the experimental range,the dosage of p H additives(sodium bicarbonate)had a certain stage effect on the p H of degumming solution.Adding p H additives could improve the p H of degumming solution.At the initial stage of adding,the p H of degumming solution improved significantly.With the increasing dosage of p H additives,the p H of degumming solution had not changed significantly.The p H of degumming solution was generally maintained at 6.7?7.1.The increase in the dosage of p H additives was beneficial to improve the weight loss rate of Qingshui raw hemp.And it brought a relatively stable p H environment,which provided suitable reaction conditions for the degumming process.The increase in the dosage of p H additives had an effect on the tensile properties of Qingshui raw hemp,but it was irregular,which may be related to the difference of raw hemp itself.Overall,the increase in the dosage of p H additives had no obvious damage to the strength of fiber,which again reflected the degumming selectivity of the degumming technology used.The increase of p H additives promoted the degradation of gum by microorganisms.Gum was decomposed to produce organic matter,which increase the difference of COD concentration between the influent and effluent.The improvement of ammonia nitrogen removal rate in the degumming environment reflected the improvement of the decomposition activity of anaerobic bacteria.It was conducive to the degumming process of Qingshui raw hemp. |
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