Enhancing The Adsorption Properties Of Waste Bio-based Materials Toward Dyes In Dyeing Wastewater By Steam Explosion Method

Waste ginger fiber,goat hair,and chicken feather come from a wide range of sources,large reserves,and low prices.A large amount of ginger fiber,goat hair and chicken feather have no use value and become waste,which is not environmentally friendly and causes economic burden.Its application needs further development and research to enhance its value.In the textile industry,a large number of dyes are used for dyeing,in which the amount of reactive dyes accounts for 40%to 60%,which generates a large amount of dyeing wastewater,which causes serious environmental pollution.Adsorption treatment of dyeing wastewater has proven to be effective Methods.The currently used adsorbents such as wheat straw and activated carbon have problems such as low adsorption amount and high preparation cost.In this paper,steam flash explosion and freeze and disintegration combined treatment methods were used to treat ginger fibers,goat hair and chicken feathers.Flash steam exploded ginger fibers,goat hair and chicken feathers were prepared and used in the treatment of dyeing wastewater.While effectively treating the dyeing wastewater,it can also expand the application scope of ginger fiber,goat hair and chicken feather.Steam explosion significantly increased the adsorption capacity of ginger fiber(GF)toward reactive blue 19(RB 19)in dyeing wastewater.Dyeing wastewater is one of the major contributors to environmental pollution.Natural waste as eco-friendly bioadsorbents for dye removal has become an important research field.Steam explosion technology is an efficient and environmentally friendly treatment method to bio-based materials.Ginger fiber cannot be used in textile industry due to its coarse diameter and high hardness and most of them has to be abandoned.In order to increase the utilization value of ginger fiber,the ginger fiber was steam exploded,frozen and disintegrated to prepare ginger fiber powder,and was further used for the adsorption of RB 19 in this paper.The effects of steam explosion,freezing and disintegration on the adsorption capacity of ginger fiber were studied.The effects of time,concentrations of NaCl,pH value and steam explosion conditions on the adsorption capacity of steam exploded ginger fiber powder(EGFP)were also studied.The surface morphologies and crystallization indexes of ginger fiber before and after steam explosion were analyzed to explain why the steam explosion significantly improved the adsorption capacity.It was shown that the steam explosion of 1.9 MPa and 150 s increased adsorption from 48.8 to 115.12 mg/g.It was reported that several RB19 molecules aggregated into an ellipsoid with three axes 33.4?×11.4?×8.8?.When surface of ginger fiber was broken,more RB19 dye molecules could enter the EGFP more easily.And all EGFP after the different steam explosion conditions show significantly lower CI than GF.Moreover,the CI of EGFP decreased from 35%to 20%with the increasing steam pressure from 1.3 to 1.9 MPa,it indicated that the amorphous region of ginger fiber expanded after the steam explosion.Therefore,more RB19 molecules could be adsorbed into the expanded amorphous region of EGFP and the adsorption capacity improved.The increased adsorption was mainly due to the broken surface and decreased CI from 39%to 20%of GF.In addition,EGFP became small particles which had a diameter of 80?m and the pores enlarged in EGFP.These structure changes resulted in more dye molecules could easily and fast entered into the amorphous region of EGFP thereby improving the adsorption rate and amount of EGFP.These results demonstrated that EGFP could be considered as suitable and promising bioadsorbent to treat the wastewater from dyeing industry.As same as,The time required to reach the equilibrium of adsorption decreased from 12 to 8 h.The adsorption of RB 19 was in accord with the second-order kinetic model and the Langmuir thermodynamic model for ginger fiber(GF),frozen and disintegrated ginger fiber(FDGF)and steam exploded ginger fiber powder(EGFP).The adsorption capacity still maintained 80%of the first adsorption capacity after 5 adsorption-desorption cycles.This paper believes that efficient green steam explosion can effectively improve the adsorption capacity of ginger fiber.Using EGFP as biomass adsorbent can not only reduce the environmental burden but also achieve the goal of“treating waste by waste”.In the future environmental governance,it will have broad space for development.Compared with ginger fiber,there were amino and carboxyl groups on the protein surface of goat hair,which was beneficial to the adsorption of RB19.The results showed that the steam pressure was 1.9 MPa,the maximum adsorption capacity(426.7 mg/g)was7.72 times and 3.42 times of that of the original goat hair(55.24 mg/g)and the comminuted goat hair(124.75mg/g),respectively.The adsorption kinetic process was in accordance with the quasi second-order dynamic model(R~2=0.99),and the adsorption isotherm was in accordance with Langmuir Model(R~2=0.98).After six cycles of adsorption desorption,the adsorption capacity of flash smashed cashmere can still reach 79%,which was good.SEM analysis showed that there were scales on the surface of goat hair.With the increase of steam explosion pressure,the damage of scales on the surface of goat hair was more serious.In the process of RB19 adsorption,the dye was easier to enter into the amorphous area of goat hair without the barrier of scale,so as to improve the adsorption performance.At the same time,more adsorption sites were exposed on the wool after the scale was destroyed.The results of X-ray diffraction showed that the crystallinity index decreased from 30.1%to2.6%compared with that of goat hair,and the amorphous area expanded,which improved the adsorption capacity.The analysis of specific surface area showed that the BET specific surface area of goat hair was 0.6777m~2/g,and the cumulative specific surface area of BJH adsorption pore was 0.269m~2/g.The pore volume was 0.000170 cm~3/g respectively.With the increase of flash pressure to 1.9 MPa,BET specific surface area and cumulative specific surface area of BJH adsorption pore of wool increased to 8.5829 m~2/g and 5.539 m~2/g respectively.The pore volume increased to 0.00541 cm~3/g.Therefore,more dye adsorption sites will be exposed and the adsorption capacity will increase accordingly.Compared with ginger fiber,waste goat hair can be used as adsorbent better.Based on the above research,this paper uses the same method to treat the protein chicken hair to obtain the flash explosion smashed chicken hair,and carries on the comparative study with the goat hair.The chicken hair had no scale hindrance,the crystallization index was lower than the goat hair,its specific surface area,BJH adsorption pore cumulative specific surface area,pore volume were 1.81,1.55,2.99 times of the goat hair respectively.Therefore,the adsorption capacity of chicken hair(175 mg/g)was higher than that of goat hair(55.24 mg/g).After steam explosion and freeze and disintegration,the crystallization index of 1.9 MPa in goat hair which was steam exploded and frozen and disintegrated decreased significantly,and its specific surface area,cumulative specific surface area and pore volume of BJH adsorption pore were 1.64,2.74 and 2.65 times of that in chicken feather which was steam exploded and frozen and disintegrated.Therefore,the adsorption capacity of goat hair which was steam exploded and frozen and disintegrated was enhanced significantly,so as to shorten the difference between the adsorption capacity of chicken feather and goat hair which was steam exploded and frozen and disintegrated.