Hydrolysation and Characterization of Acrylic Fibers

Effect of the cationic surfactant on the hydrolysis of acrylic staple fiber dispersed in alkaline aqueous solution was studied.The cationic dyestuff uptake of the resultant hydrolysates was investigated as well.The results showed that the surfactant accelerated the hydrolysis of cyano-and ester-groups.The carboxyl content of the hydrolyzed fibers reached the maximum 6.85 mmol/g(i.e.,total molar conversion of the two groups 38.7%) while keeping fiber integrity.The scanning electron microscopy(SEM) images implied that hydrolysis happened both on fiber surface and in the inner part of the fiber in the presence of surfactant.The cationic dye removal due to adsorption onto the hydrolyzed fibers increased with increasing temperature,with the removal 97.4% at 60℃.The adsorption of the fibers followed the Freundlich's adsorption isotherm and the Lagergren's pseudo-second order dynamic equation with the activation energy 5.4 kJ/mol.Unexpectedly,the steric hindrance of access to the inside carboxyl groups of the hydrolyzed fibers caused a low dye sorption capacity,5-6 mg/g.

A Challenging Approach to Improve the Low Affinity of Acrylic Fibres to Be Successfully Dyed with a Bio-Colorant Extracted from Grape Marc

Acrylic fibres are highly crystalline and non-polar polymers,which makes their dyeing a very difficult step that poses real technical challenges.In order to overcome this concern,it is intended in this paper to modify acrylic fibers by different methods namely cationisation using the Crosscolor DRT then amidoximation using hydroxylamine hydrochloride and ammonium acetate.The resulted samples were dyed then with the bio-colorant extracted from grape marc.The effect of the pretreatment on fibers fine structure using X-ray diffraction and the scanning electron microscope(SEM)images and its correlation with the colour strength of the dyed fabrics was investigated.The dyeing parameters,such as dye bath pH and temperature on the performances of this dyeing process were studied.Good dyeing qualities and new shades varying from brown to grey and dark green have been obtained following process optimization,mordanting and modification of acrylic fibers by the technique of cationisation.

Biodegradation kinetic of organic compounds of acrylic fiber wastewater in biofilm

A group function relation curve between flux(J) and bulk phase concentration of substrate(S) was set up. The biodegradation kinetic of organic compounds of acrylic fiber wastewater in biofilm is studied(the treatment technology is coagulation/sedimentation-anoxic/aerobic biofilm process), and the results showed that the concentration of non-degradation pollutants in effluent is 77 mg/L. In aerobic zone, the half-rate constant is 72.84 mg/L, the maximum removal rate of organic compounds at unit area filler is very low, 0.089 g/(m 2·d), which corresponds to the fact that there are some biorefractory compounds in the wastewater.

Modification of waste polyacrylonitrile fiber and its application as a filtrate reducer for drilling

Cationic polymer fluid loss additive （CPFL） was prepared by using the reaction of 2,3-epoxypropy- ltrimethyl ammonium chloride （EPTMAC） （as cationic reagent） with the amide group in the molecular structure of the sodium salt of partially hydrolyzed polyacrylonitrile fibers （HPAN-Na）. The chemical reaction was determined by studying the infrared absorption peaks of the materials and the products. The results proved that the cationic groups of EPTMAC were successfully grafted onto the HPAN molecular chain. The composition of the molecular chain of the product CPFL was determined by investigation and calculation of the elemental analysis results of the grafted HPAN and the final reaction product CPFL. The drilling fluid performance was evaluated, and the result showed that when the cation content was more than 0.27 mmol/g, the drilling fluid would have good resistance to fluid loss and to pollution from calcium chloride.

Laboratory Evaluation of Fiber-Modified Asphalt Mixtures Incorporating Steel Slag Aggregates

Vigorous and continued efforts by researchers and engineers have contributed towards maintaining environmental sustainability through the utilization of waste materials in civil engineering applications as an alternative to natural sources.In this study,granite aggregates in asphaltic mixes were replaced by electric arc furnace(EAF)steel slag aggregates with different proportions to identify the best combination in terms of superior performance.Asphalt mixtures showing the best performance were further reinforced with polyvinyl alcohol(PVA),acrylic,and polyester fibers at the dosages of 0.05%,0.15%,and 0.3%by weight of the aggregates.The performance tests of this study were resilient modulus,moisture susceptibility,and indirect tensile fatigue cracking test.The findings of this study revealed that the asphalt mixtures containing coarse steel slag aggregate exhibited the best performance in comparison with the other substitutions.Moreover,the reinforced asphalt mixtures with synthetic fibers at the content of 0.05%exhibited an almost comparable performance to the unreinforced asphalt mixtures.Modifying the asphalt mixtures with PVA,acrylic,and polyester fibers at the proportion of 0.15%have improved the fatigue cracking resistance by 41.13%,29.87%,and 18.97%,respectively.Also,the fiber-modified asphalt mixtures with PVA,acrylic,and polyester have enhanced the fatigue cracking resistance by about 57%,44%,and 39%,respectively.The results of the resilient modulus demonstrated that as the fiber content increase,the resilient modulus of the reinforced asphalt mixtures decreases.Therefore,introducing synthetic fibers at the content of 0.3%has slightly decreased the resilient modulus in comparison with unreinforced mixtures.On the other hand,the results of the mechanisticempirical pavement design showed that the reinforced asphalt mixes with a high content of synthetic fibers have shown lower service life than the control mixes due to the low resilient modulus.On the contrary,based on the laboratory results,the asphalt mixes incorporating PVA,acrylic,and polyester fibers at the proportion of 0.15%have shown the potential to reduce the thickness of the asphalt layer by about 14.9%,11.80%,and 8.70%,respectively.

Advanced treatment of wet-spun acrylic fiber manufacturing wastewater using three-dimensional electrochemical oxidation

A three-dimensional electrochemical oxidation （3D-EC） reactor with introduction of activated carbon （AC） as particle micro-electrodes was apphed for the advanced treatment of secondary wastewater effluent of a wet-spun acrylic fiber manufacturing plant. Under the optimized conditions （current density of 500 A/m2, circulation rate of 5 mL/min, AC dosage of 50 g, and chloride concentration of 1.0 g/L）, the average removal efficiencies of chemical oxygen demand （CODer）, NH3-N, total organic carbon （TOC）, and ultraviolet absorption at 254 nm （UV2s4） of the 3D-EC reactor were 64.5%, 60.8%, 46.4%, and 64.8%, respectively; while the corresponding effluent concentrations of CODcr, NH3-N, TOC, and UV2s4 were 76.6, 20.1, and 42.5 mg/L, and 0.08 Abs/cm, respectively. The effluent concentration of CODer was less than 100 mg/L, which showed that the treated wastewater satisfied the demand of the integrated wastewater discharge standard （GB 8978-1996）. The 3D-EC process remarkably improved the treatment efficiencies with synergistic effects for CODer, NH3-N, TOC, and UV2s4 during the stable stage of 44.5%, 38.8%, 27.2%, and 10.9%, respectively, as compared with the sum of the efficiencies of a two-dimensional electrochemical oxidation （2D-EC） reactor and an AC adsorption process, which was ascribed to the numerous micro-electrodes of AC in the 3D-EC reactor. Gas chromatography mass spectrometry （GC-MS） analysis revealed that electro- chemical treatment did not generate more toxic organics, and it was proved that the increase in acute biotoxicity was caused primarily by the production of free chlorine.

Superabsorbent Fibers for Comfortable Disposable Medical Protective Clothing

Disposable medical protective clothing for 2019-nCoV mainly consists of stacked layers with nanopore films,polymer coated nonwoven fabrics and melt-blown nonwoven fabrics against anti-microbial and anti-liquid penetration.However,such structures lack moisture permeability and breathability leading to an uncomfortable,stuffy wearing experience.Here,we propose a novel medical protective clothing material with a superabsorbent layer to enhance moisture absorption.Poly(acrylic acid-co-acrylamide)/polyvinyl alcohol superabsorbent fibers(PAAAM/PVA fibers)were prepared via wet spinning.And the superabsorbent composite layer was stacked from PAAAM/PVA fibers,bamboo pulp fibers(BPF)and ethylene-propyl-ene side by side fibers(ESF).The novel disposable medical protective composite fabric was obtained through gluing the superabsorbent layer to the inner surface of strong antistatic polypropylene nonwoven fabric.The resultant composite fabric possesses excellent absorption and retention capacity for sweat,up to 12.3 g/g and 63.8%,and a maximum hygroscopic rate of 1.04 g/h,higher than that of the conventional material(only 0.53 g/h).The moisture permeability of the novel material reached 12,638.5 g/(m^(2) d),which was 307.6%of the conventional material.The novel material can effectively reduce the humidity inside the protective clothing and significantly improve the comfort of medical staff.

Lead removal from water using organic acrylic amine fiber(AAF)and inorganic-organic P-AAF,fixed bed filtration and surface-induced precipitation

Granular porous sorbents were normally used for heavy metals removal from water.To search for the new commercial sorbent and treatment strategy,an organic acrylic amine fiber(AAF)and phosphorus loading inorganic-organic AAF(P-AAF)were prepared and used for lead(Pb)removal from water.A new strategy of inorganic-organic coupling technology was proposed for Pb removal,based on the hypothesis of surface-induced precipitation mechanism.The AAF showed a Pb adsorption capacity of 417 mg/g from the Langmuir fitting,while the column filtration technology was further applied to measure the adsorption edge and applications.Effects of different initial Pb concentrations,hydraulic retention time,and co-existing P were considered in the filtration experiments.The presence of 0.8 mg/L P in water significantly improved the Pb breakthrough point from 15,000 to 41,000 bed volumes of water spiked with 85μg/L Pb,while the P-AAF fixed bed showed better removal of Pb than AAF SEM/EDX and XRD spectra were employed for determining the surface functional groups and the formation of surface-induced precipitation of pyromorphite(Pb_5(PO_4)_3 OH)on AAF.This study verified the application of AAF sorbent for Pb removal and the enhanced effect of coating P on AAF,thus improved our fundamental understanding and application of the surface chemistry process of Pb with P.

Adsorption and recovery of phosphate from water by amine fiber,effects of co-existing ions and column filtration

A weak-base adsorption fiber,acrylic amine fiber(AAF),was prepared for removal and recovery of phosphate from water.The adsorption properties of the AAF for phosphate and effects of co-existing ions were investigated using batch and column filtration experiments,scanning electron microscope,and Fourier transform infrared techniques.Experimental results showed that AAF had a high phosphate adsorption capacity of 119 mg/g at pH 7.0.The effects of calcium,sulfate,carbonate,nitrate,and fluoride showed that sulfate and calcium inhibited phosphate adsorption.However,AAF showed higher binding affinity toward phosphate than sulfate.Column filtration results showed that AAF could filter 1420 bed volumes of tap water containing 1.0 mg-P/L of phosphate.The saturated AAF could be regenerated using 0.5 mol/L hydrochloric acid solution and reused.After desorption,phosphate was recovered through precipitation of hydroxyapatite(Ca5(PO4)3OH).The easy of regeneration,good adsorption performance,and the fiber morphology of AAF make it an attractive alternative for phosphate recovery from multiple water sources.