Study on melt-blown processing,web structure of polypropylene nonwovens and its BTX adsorption

Petroleum hydrocarbons can have adverse impacts on the environment and human health especially when they exist in the form of emulsion and aqueous solution. Nonwovens prepared by melt-blown method are a potential candidate for the removal of petroleum hydrocarbons. In this study, the processing-structure-oil sorption relationships of the PP (polypropylene) melt-blown nonwovens were investigated. Besides, the kinetics and mechanism of toluene sorption in simulated fire-fighting wastewater on the optimized prepared PP melt-blown nonwovens were studied at the static and dynamic conditions. The results showed that the web structure can be effectively controlled by adjusting the hot air temperature, metering pump speed and distance of collector to die to obtain an average fiber diameter of 3.0-10.5 μm, surface area of 0.5-1.5 m²/g and porosity of 71.0-99.0 %. The sorption capacity for pure BTX medium increased with the decreasing fiber diameter and increasing porosity. The pseudo-second-order kinetic model better fitted the experimental data to describe the sorption of emulsified and dissolved form of toluene at static and dynamic conditions. The toluene sorption can be a combination of adsorption and capillarity, the contribution of which was about 1:14.     

响应面法制备枇杷核微孔炭及其选择性吸附研究

以新鲜枇杷核为原料制备了枇杷核微孔炭（LMC）,以 LMC 对盐酸四环素的吸附率为指标,通过响应面法优化制备工艺,进一步研究了 LMC 的孔结构和选择性吸附性能。结果表明：最优制备工艺为活化时间 192 min、活化温度 565 ℃、活化升温速率 21.5 ℃/min、炭化温度 632 ℃;该工艺所得枇杷核微孔炭对盐酸四环素的吸附率高达 95.25%,其 BET 比表面积为 1 275 m2/g,微孔表面积为 1 219 m2/g,总孔容为 0.535 4 cm3/g,微孔孔容为0.473 cm3/g;较高的比表面积和高比例的微孔含量赋予其优异的分子尺寸选择性吸附性能。     

Development of Activated carbon from Windmill palm sheath fiber by KOH activation

In this study, activated carbon was prepared from windmill palm sheath fiber (WPF) powder by KOH activation for full utilization of the bioresource. First, the optimal parameters of the activation technology, such as impregnation ratio, temperature, and time, were determined. The pyrolysis process and activation mechanism of KOH were investigated by thermogravimetric analysis (TGA). WPF powder-based activated carbons were then prepared under the optimized condition and characterized by SEM, FTIR, XRD, and nitrogen adsorption techniques. The reaction mechanisms were deduced in two phases. The reaction mechanisms in the first carbonization process were mainly related to substitution, scission, and oxidization reactions of methylene. In the second activation process, KOH and carbon began to react at 350 °C, producing potassium compounds, which further reacted with carbon. Results show that the optimal process for preparing an excellent adsorbent from WPF employs an impregnation ratio of 4:1 at 850 °C for 2.5 h, which can result in a good adsorption property for methylene blue, high BET surface area of 1734.34 m²/g, and total pore volume of 0.96 cm³/g. WPF-based activated carbon demonstrates a remarkable adsorption capacity, and thus WPF has great potential value as a new agricultural resource.     

Adsorption Kinetics of Acid Red on Activated Carbon Web Prepared from Acrylic Fibrous Waste

In this work, activated carbon (AC) web was prepared using physical activation under the layer of charcoal in high temperature furnace. The carbonization of acrylic fibrous waste was performed at different temperatures (800 °C, 1000 °C, and 1200 °C) with heating rate of 300 °C/h and at different holding time. At 1200 °C, the heating rate of 300 °C/h and no holding time provided better results of surface area as compared to carbonization at 800 °C and 1000 °C. The activated carbon web (AC) prepared at 1200 °C was used for removal of Acid Red 27 dye from aqueous media by varying different parameters like initial concentration of dye, stirring speed, adsorbent dosage, and pH. The results were evaluated using non-linear forms of Langmuir and Freundlich isotherms. The Freundlich isotherm was found to describe the results more effectively because of non-homogenous surface of activated carbon web. Further, the kinetics of adsorption was examined using linear and nonlinear forms of pseudo 1st order and pseudo 2nd order.     

PAN-based carbon nanofiber absorbents prepared using electrospinning

This study takes polyacrylonitrile (PAN) as a raw material for PAN-based nanofiber nonwoven prepared using electrospinning. First we construct a thermal-stable process for the fabrication of oxidized nanofiber nonwovens as the precursor. A semi-open high-temperature erect furnace is then used with steam as the activator, through carbonization and activation processes to prepare carbon nanofiber absorbents continuously. The experiment varies the production rate and activator flow rate to prepare carbon nanofiber absorbents. Experimental results show that carbon nanofiber adsorbents are primarily made up of micropores and mesopores, averaging under 20 Å. Given a production rate of 10–20 cm/min with a matching activator feed rate of 120 ml/min, the specific surface area can reach about 1000 m²/g, producing an adsorption ratio of carbon tetrachloride over 200 %.     

Optimum manufacturing conditions of activated carbon fiber absorbents. II. Effect of carbonization and activation conditions

In this paper, viscose rayon-based knitted fabrics were utilized as the precursor to produce activated carbon fiber absorbents (ACFA). The effects of carbonization and activation conditions on characteristics (ACFA) were examined. Experimental results revealed that increasing the flow rate of environmental gas N₂ and steam activator used in conjunction and decreasing the production rate of ACFA can obtain better pore properties. However, higher flow rate of steam activator and lower production rate of ACFA reduced the weight yield. According to our findings, to maintain good absorption property of ACFA, the optimum manufacturing conditions are flow rate of gas N₂ at 80 cc/min, flow rate of steam activator at 60 ml/min, and production rate of ACFA at 30 cm/min, with flame retardant reagent concentration maintained at 30%. Under these conditions, the weight yield can be up to 40.85% and the BET surface area can exceed 1500 g/m².     

Development of Maghemite Glass Fibre Nanocomposite for Adsorptive Removal of Methylene Blue

Maghemite glass fibre nanocomposite with excellent magnetic and adsorption properties was successfully developed from nontoxic and eco-friendly reagents by thermal decomposition approach. The developed nanocomposite was utilized in adsorption of methylene blue which follows Freundlich adsorption isotherm. The excellent value of adsorption capacity (51.31 mg g^-1) as compared to other adsorbents recommends its potential role for adsorption phenomenon in multiple applications. The developed nanocomposite can be recycled and reused easily. Surface and other functional characteristics of developed nanocomposite were determined through scanning electron microscopy, X-ray diffraction, raman spectroscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometer. The obtained results revealed that maghemite glass nanocomposite is a potential tool that can be utilized in waste water treatments.     

Functional porous carbons from waste cotton fabrics for dyeing wastewater purification

A new functional porous carbons (PC-WF) is prepared by activation-pyrolysis method use waste cotton fabrics (WF) as an abundant, cheap and available precursor for removal of Brilliant Crocein (BC-GR) and Cationic Red 2GL (CR-GL) from aqueous phase. The PC-WF was characterized by BET, FTIR, SEM, and XRD techniques, the surface area, total pore volume, average pore diameter was found as 1463.5 m² g^-1, 0.783 cm³ g^-1 and 2.14 nm, respectively. The influences on BC-GR and CR-GL adsorption of various experimental factors such as initial concentration and temperature were investigated. Adsorption kinetics was found to be best represented by the pseudo-second order model. The adsorption capacity was 319.8 mg g^-1 for BC-GR and 842.5 mg g^-1 for CR-GL at 30 °C, respectively. The results indicate that for waste cotton fabrics in particular, the practical application of this process to the production of porous carbon would be possible.     

Synthesis,structure and thermal protective behavior of silica aerogel/PET nonwoven fiber composite

In recent years, flexible, mechanically strong and environmental friendly thermal insulation materials have attracted considerable attention. In this work, silica aerogel/polyethylene terephthalate (PET) nonwoven fiber composite with desirable characteristics was prepared via a two-step sol-gel process followed by an ambient drying method through immersing the PET nonwoven fiber into silica sol. The silica aerogel particles were characterized by FTIR, FE-SEM, TGA and nitrogen adsorption analysis. The morphology and hydrophobic properties of neat PET nonwoven fiber and its silica aerogel composite were also investigated. For studying thermal protective properties, the thermal diffusivity was calculated from temperature distribution curves. The mean pore size of 11 nm, the surface area of 606 m²/g and the total pore volume of 1.77 cm³/g for the silica aerogel particles in the composite are obtained from nitrogen adsorption analysis, indicating the aerogel can maintain its high porosity in the nonwoven composite structure. Silica aerogel particles were efficiently covered the surface of the PET fibers and completely filled the micron size pores of the nonwoven fiber leading to a stronger hydrophobicity and higher thermal insulation performance in the aerogel composite samples compared to the neat PET nonwoven. In this regard, an almost 64 % decrease in the thermal diffusivity was achieved with 66 wt% silica aerogel.     

剑麻渣果胶提取与测定

从剑麻的麻渣、纤维中提取果胶，测定果胶的含量、纯度和酯化度。将湿麻渣在密封与敞开空气中自然发酵后提取果胶，探讨湿麻渣在发酵后对果胶品质的影响。结果表明，果胶得率最高的是湿麻渣（13．342％），最低的是直纤维（0．450％），干麻渣的果胶得率（1．662％）略高于湿纤维（1．326％）与乱纤维（1．264％）的；果胶纯度最高的是直纤维（73．360％），最低的是干麻渣（32．567％）。直纤维果胶的酯化度（45．452％）略大于麻渣和乱纤维的（32％～35％）；湿麻渣经过自然发酵后，果胶得率与纯度均降低，但湿麻渣完全发酵后的果胶酯化度（33．432％）接近于干麻渣的（33．156％）。     

Evaluation of activated carbon fiber applied in supercapacitor electrodes

This study uses rayon woven fabrics as the raw material for activated carbon fabrics (ACFs), which were manufactured by oxidation, carbonization and activation engineering in a continuous semi-open high-temperature furnace. First, the activated carbon fabrics are prepared under two specific manufacturing conditions with different production rates and flow rates of steam activation at 1000 °C. Then the electrochemical prosperities of the ACFs are evaluated by a three-electrode device. The experimental results show that the BET specific surface area and electrical capacitance are higher with a lower production rate. Moreover, the steam activator higher flow rate under the proposed approach. ACFs with a 2332.1 m²/g specific surface area and 78.7 % mesopore ratio result in a higher electronic conductivity of 430.4 F/g at the low rate charge (5 mV/s) and with 60 % capacitance retention during the high-speed charging-discharging process (100 mV/s).     

Effects of carbonization temperatures on characteristics of porosity in coconut shell chars and activated carbons derived from carbonized coconut shell chars

A series of experiments have been conducted to study the effects of different carbonization temperatures (400, 600, 800 and 1000 °C) on characteristics of porosity in carbonized coconut shell char and activated carbon derived from carbonized coconut shell char with different activation times (30, 60, 90 and 120 min) at activation temperature of 900 °C. The results showed that high temperature carbonized coconut shell char and activated carbon samples derived from high temperature carbonized coconut shell chars had higher BET surface area, total volume, micropore volume and yield as compared to those of low temperature carbonized coconut shell char and activated carbon derived from low temperature carbonized coconut shell char. The BET surface area, total volume and micropore volume of activated carbon prepared from char obtained at 1000 °C with activation time of 120 min were 1926 m²/g, 1.26 cm³/g and 0.931 cm³/g, respectively. From the results, it was concluded that we could produce high surface area activated carbons from coconut shells using physical activation (steam activation) by proper selections of carbonization temperature and activation time.     

花生壳残渣制备活性炭及吸附性能测定

用提取黄酮后废弃的花生壳做原料,选择不同的活化剂在一定温度下制备活性炭,并且测定其吸附性能。结果表明：磷酸作为活化剂时活性炭产率最高,达39.5%;当炭化温度为500℃、活化剂为氢氧化钾或磷酸、活化剂浓度为10%时,碘吸附值最高,为966.7mg/g;当炭化温度为500℃、活化剂浓度为10%时,几种活化剂制备出来的活性炭亚甲基蓝脱色力均达到40mL/g左右;与几种市售活性炭比较,花生壳活性炭碘吸附值能够满足市场需要,但是亚甲基蓝脱色力偏低;相同条件下,盐作为活化剂所制备出的活性炭对镍离子的吸附能力比较稳定。     

Transport properties of layered fabric systems based on electrospun nanofibers

Layered fabric systems with electrospun polyurethane fiber web layered on spunbonded nonwoven were developed to examine the feasibility of developing protective textile materials as barriers to liquid penetration using electrospinning. Barrier performance was evaluated for layered fabric systems, using pesticide mixtures that represent a range of surface tension and viscosity. Air permeability and water vapor transmission were assessed as indications of thermal comfort performance. Protection performance and air/moisture vapor transport properties were compared for layered fabric systems and existing materials for personal protective equipment (PPE). Layered fabric systems with electrospun nanofiber web showed barrier performance in the range between microporous materials and nonwovens used for protective clothing. Layered fabric structures with the web area density of 1.0 and 2.0 g/m² exhibited air permeability higher than most PPE materials currently in use; moisture vapor transport was in a range comparable to nonwovens and typical woven work clothing fabrics. Comparisons of layered fabric systems and currently available PPE materials indicate that barrier/transport properties that may not be attainable with existing PPE materials could be achieved from layered fabric systems with electrospun nanofibrous web.     

水肥运筹对剑麻幼苗生长的影响

采用盆栽试验的方法，探索不同水肥组合对剑麻生长的影响。研究结果表明不同的水肥组合会对剑麻的生长产生不同程度的影响，当含水量和施肥量均达到适宜水平时，会对剑麻生长产生叠加效应；剑麻的质膜透性随着土壤干旱程度的增加而升高；当施肥过量，不利于剑麻生长时，剑麻的质膜透性也明显增大。在一定施肥量范围内，剑麻体内过氧化物酶活性随着施肥量的增加而增加，同时也随着干旱胁迫的严重而增加；当施肥过量，过氧化物酶的活性反而降低。在一定的施肥量范围内，丙二醛随着干旱胁迫的加重而提高。施肥量上升会提高剑麻体内N、P、K的含量，同时土壤含水量的上升也会促进剑麻对这些元素的吸收。在本试验条件下，综合不同处理下对剑麻各项指标的影响，得出剑麻生长最适宜的水肥条件为土壤含水量占田间持水量的60％~70％，施肥量为每千克干土N 0.6、P2O5 0.4、K2O 0.6 g。     

Mechanical and thermal degradation behavior of sisal fiber (SF) reinforced recycled polypropylene (RPP) composites

The present investigation focuses on the effect of fiber surface treatment on the mechanical, thermal and morphological properties of sisal fiber (SF) reinforced recycled polypropylene (RPP) composites. The surface of sisal fiber was modified using different chemicals such as silane, glycidyl methacrylate (GMA) and O-hydroxybenzene diazonium chloride (OBDC) to improve the compatibility between fiber surface and polymer matrix. The experimental results revealed an improvement in the tensile strength to 11 %, 20 % and 31.36 % and impact strength to 78.72 %, 77 % and 81 % for silane, GMA and OBDC treated sisal fiber reinforced recycled polypropylene (RPP/SF) composites respectively as compared to RPP. The thermo gravimetric analysis (TGA), Differential scanning calorimeter (DSC) and heat deflection temperature (HDT) results revealed improved thermal stability as compared with RPP. The morphological analysis through scanning electron micrograph (SEM) supports improves surface interaction between fiber surface and polymer matrix.     

Effects of high hydrostatic pressure on swelling behavior of rice starch

In this study, we aimed to reveal the effects of high hydrostatic pressure (HHP) on the swelling behavior of starch. We investigated the changes in starch granule size, specific surface area and porosity, and swelling factors of HHP- (HHGS) and heat-gelatinized rice starch (HGS) at a similar degree of gelatinization (DG) by using scanning electron microscope, a laser diffraction particle size analyzer, low-temperature N adsorption/desorption and ultraviolet spectrophotometer. Results showed that the average diameter of HHGS increased from 6 μm to 572 μm, and that of HGS increased to 877 μm. The adsorption-desorption isotherms of HHGS and HGS in terms of shape were the type IV profile. Pore structure loosened and enlarged from mesopore to macropore. The specific surface area of HHGS decreased from 1.165 m²/g to 0.138 m²/g, and that of HGS decreased to 0.260 m²/g. Swelling of HHGS was not instantaneous. HHP gelatinization possesses simultaneous compression and swelling.     

Effect of high temperature treatment on electrochemical properties of activated carbon fabric in supercapacitor application

In this study, viscose rayon-based activated fabrics were used as the electrodes of supercapacitors. First, viscose rayon knitted fabrics underwent oxidation, carbonization and activation in a semi-open high-temperature erect furnace to produce activated carbon fabrics (ACFs). They were then treated at temperatures up to 1500 °C for one hour. Electrochemical properties of ACFs were investigated by cycle voltammetry and electrochemical impedance spectroscopy. The ACFs after high temperature treatment has improved conductivity and substantially increased mesopore ratio, yielding higher capacitor retention in rapid charging-discharging processes. It is shown that the ACFs treated at 1500 °C had the highest mesopore ratio of 83 %, specific surface area of 1254 m²/g and average pore diameter of 20.9 Å, resulting in lower resistance of 0.2 Ω-cm. In addition, this ACFs electrode showed the highest capacitance retention of 49 % at high charging speed of 250 mV/s.     

蒸汽爆破处理对剑麻纤维组分分离的影响

采用高温、高压水蒸汽瞬间爆破处理剑麻纤维。通过处理前后剑麻纤维的水溶物、碱溶物、木质素含量、纤维素含量的比较,分析研究了蒸汽爆破处理条件对剑麻纤维组分分离效果的影响。试验结果表明:爆破前预处理、处理温度(压力)、维压时间是影响组分分离的重要因素:随着处理强度的增大,纤维中木质素含量降低,纤维素含量增大;爆破前的不同试剂预浸泡处理中,质量分数为17.5％的NaOH和质量分数为0.1％的H2SO4预浸泡处理效果较优,水和质量分数为1％的NaOH浸泡处理效果较差。      

Incorporation of Buriti Endocarp Flour in Gluten-free Whole Cookies as Potential Source of Dietary Fiber

Cookies were prepared by replacing a mixture of brown rice flour (70 %) and corn starch (30 %) (BRFCS) by buriti endocarp flour (BEF) (0, 5, 10, 15 or 20 %). BEF figured as a potential source of dietary fiber (70.53 g 100 g^?1), especially of insoluble fiber (67.50 g 100 g^?1), and gluten-free whole cookies showed increased dietary fiber content by adding 5, 10, 15 and 20 % BEF (8.58 to 20.02 g 100 g^?1) when compared to control cookie (6.91 g 100 g^?1). The addition of BEF affected diameter, spread ratio, color and texture of cookies. All cookies added with BEF were darker, harder and presented smaller diameter and smaller spread ratio than the control cookie. These difference increased proportionally to level of substitution of BRFSC by BEF. Gluten-free whole cookies with up to 15 % BEF were well accepted by consumers. Therefore, the use of BEF in cookies may increase the availability of functional ingredients source of dietary fiber for celiac consumers, add economic value to buriti processing by-products and decrease environmental impacts due to the high amounts of waste generated by buriti processing industries.