Removal of Heavy Metal Ions from Aqueous Solutions Using Lignocellulosic Fibers

Abstract

Spruce, coconut coir, sugarcane bagasse, kenaf bast, kenaf core, and cotton were tested for their ability to remove copper, nickel and zinc ions from aqueous solutions as a function of their lignin content. The fibers were analyzed for sugar and lignin content and extracted with di-ethyl ether, ethyl alcohol, hot water, or 1% sodium hydroxide.

The order of lignin content in un-extracted fibers is coconut coir > spruce > kenaf core > bagasse > kenaf bast > cotton. The fiber with the highest level of heavy metal removal was kenaf bast that had a very low level of lignin, showing that removal of heavy metals does not correlate with lignin content. Cotton, with about 1% lignin, was very low in metal ion sorption while all of the fibers containing lignin did remove heavy metal ions showing that lignin does play a role in metal ion sorption. Extraction with the various solvents removed different cell wall components and did change heavy metal sorption that indicates that cell wall chemistry and architecture may also be important factors in the sorption of heavy metals from aqueous solutions using lignocellulosic fibers.     

Study on the Application of Kenaf Core as a Composite Reinforcement: Injection Molding of Kenaf Core/Poly(l-lactide) Compounds

Injection molding was performed using poly(l-lactide) (PLLA) as a matrix and by varying the reinforcements, i.e., dry-distilled kenaf core (D-core) or untreated kenaf bast fibers, and the physical properties for these composites were subsequently compared. The dry-distillation was able to reduce the moisture content of D-core by a maximum of 4.2% as compared with untreated control core. As a result, the hydrophobicity was increased, which contributed to favorable Charpy impact strength and tensile properties of the D-core/PLLA composite relative to the kenaf bast fiber/PLLA composite. Moreover, the puffing phenomenon, which arises when heating with a microwave oven due to the vaporization of water dispersed within the interfacial regions and associated softening of the PLLA matrix by the heated vapor, was completely suppressed for the D-core/PLLA composite, whereas a large puffing ratio was observed for the kenaf bast fiber/PLLA composite. Reducing the moisture content also effectively suppressed the occurrence of transesterification reactions, leading to a decrease in the molecular weight of PLLA. However, the apparent nucleation effect of the D-core remains slightly inferior to that for the hydrophilic bast fibers due to its stronger affinity for PLLA molecules.     

红麻纤维及其造纸基本特征（下）

红麻纤维及其造纸基本特征（下）邝仕均王菊华薛崇昀王锐林茹（中国制浆造纸工业研究所，北京，１０００２０）４红麻纤维的超微结构为进一步研究纤维形态对成纸物理性能的影响，笔者对红麻纤维的超微结构进行了研究。４１红麻木质部纤维超微结构图４红麻木质部纤维横切...     

Diversity and Characteristics of Kenaf Bast Degumming Microbial Resources

Kenaf is one of the most important natural fiber crops. Traditional degumming with water retting causes serious environmental pollution and reduces the quality of fiber products. The development of kenaf industry is hindered by high production cost. Microbial degumming is suitable for kenaf bast degumming because of its high efficiency, energy conservation, low pollution, and high quality, among others. Through enrichment and screening from water sample, soil sample, and humus sample, we concentrated and identified 92 bacterial strains that could degrade kenaf bast colloid. The strains belonged to 11 genera and 16 species. Five of these strains did not produce cellulase and the weight loss rate of the kenaf bast fiber raw material was more than 20%. These strains belonged to Bacillus subtilis, Paenibacillus polymyxa, Clostridium acetobutylicum, Bacillus alcalophilus, and Erwinia chrysanthemi and were assigned with serial numbers from K1–K5, respectively. This study is the first to report the function of Bacillus pumilus, B. alcalophilus, Clostridium tertium, Brevibacillus brevis, Pectobacterium carotovora, E. chrysanthemi, and Tyromyces subcaesius in kenaf bast degumming. Pectinase and mannanase were the key enzymes in the degumming of kenaf bast.     

Composites from Bast Fibres-Prospects and Potential in the Changing Market Environment

Abstract

Composite materials reinforced with natural fibres, such as flax, hemp, kenaf and jute, are gaining increasing importance in automotive, aerospace, packaging and other industrial applications due to their lighter weight, competitive specific strength and stiffness, improved energy recovery, carbon dioxide sequestration, ease and flexibility of manufacturing and environmental friendliness besides the benefit of the renewable resources of bast fibres. The market scenario for composite applications is changing due to the introduction of newer biodegradable polymers, such as PLA synthesized from corn, development of composite making techniques and new stringent environmental laws requiring improved recyclability or biodegradability for industrial applications where stress bearing capacities and micro-mechanical failures dictate serviceability. Bast fibre reinforced composites, made from biodegradable polymers, will have to compete with conventional composites in terms of their mechanical behaviour. Biocomposites, in which natural fibres, such as kenaf, jute, flax, hemp, sisal, corn stalk, bagasse or even grass are embedded in a biodegradable matrix, made as bioplastics from soybean, corn and sugar, have openedup new possibilities for applications in automotive and building products. Obviously, new approaches to research and development will be required to improve their mechanical properties, such as tensile, bending and impact resistance to match their performance and commercial competitiveness against petroleum based products. The research community has to look at the various possibilities of combining natural fibres, such as sisal, flax, hemp and jute with polymer matrices from non-renewable and renewable resources to develop cost effective biocomposites. This paper will review the newer products and techniques that can improve the properties of bast fibre based composites as well as potential structural and non-structural applications which can increase their market share.     

Evaluation and Impact Factors of the Mechanical Properties of Phloem Bundle Fibers Obtained from Kenaf Germplasm

The mechanical properties of kenaf phloem bundle fibers are valuable for reinforced composites or boards, more so than similar materials also used in textile or papermaking applications. 55 kenaf germplasm studied here showed an average phloem bundle fiber tensile strength of 643.6 MPa and an average elastic modulus of 23.3 GPa after chemical retting treatment. 19 of these kenaf germplasm had fiber tensile strengths >700 MPa, which can be attributed to intensive breeding programs. The fiber tensile strength and elastic modulus of kenaf germplasm had a significant positive correlation, but there was no such correlation between a fiber’s mechanical properties and its diameter or agronomic characteristics. Among 56 hybridized combination F₁ generations, the highest tensile strength was 928.3 MPa from a combination of No.30 of Xinan Wuchi × Guatemala 4. Therefore, breeding and screening are both useful for improving the mechanical properties of kenaf phloem bundle fibers. However, the effects of the used bundle fiber preparation method or cultivation year on the fiber’s mechanical properties were more pronounced than those of the type of kenaf germplasm or breeding operation used. The mechanical properties of kenaf phloem bundle fibers treated by chemical retting were superior to those treated using natural retting.     

The Dimensional Distribution of Kenaf and Apocynum Fibers

ABSTRACT

In this research, single fiber cell separation method was studied and optimized. More than 200 fiber cell dimensional sizes of kenaf and apocynum were analyzed. Furthermore, the diameter changes of kenaf fiber cell before and after different degumming treatments were also explored. Results showed that the average length and diameter of kenaf fiber are 2.16 mm and 10.56 μm, while the average length and diameter of apocynum fiber are 9.04 mm and 7.41 μm. It was also found that the average diameter of kenaf and apocynum fibers decreased with the degumming process, and the diameter distribution became more even.     

The Hybrid Effect of Jute/Kenaf/E-Glass Woven Fabric Epoxy Composites for Medium Load Applications: Impact,Inter-Laminar Strength,and Failure Surface Characterization

This research has been carried out to find better hybrid natural/glass fiber-reinforced composites for engineering applications. This research work studied the impact and inter-laminar strength of E-glass with jute/kenaf woven fabric epoxy composites with the aim of evaluating the hybridization effects on different laminate stacking sequences made with jute, kenaf, and E-glass fabrics by the vacuum bagging method. All the laminates were prepared in 300 × 300 mm² with a total of five plies maintained at 3 mm thickness, by varying the number and position of jute, kenaf, glass layers so as to obtain nine different stacking sequences. Among them, one group of all pure jute, pure kenaf, and pure E-glass laminates were also fabricated for comparison purpose. The specimen preparation and testing were carried out as per ASTM standards. From the results, it is shown that the properties of jute/kenaf fabrics-reinforced epoxy composites can be enhanced by hybridization with the addition of glass fabrics. The hybridization of jute/kenaf fabrics with E-glass fabrics provides a method to improve the mechanical impact and inter-laminar strength over pure natural fiber-reinforced composites. The hybrid laminate having E-glass and kenaf fiber plies as skin layers and jute fiber plies as core layers showed better properties compared to other laminates.     

Experimental particleboards from Kenaf plantations grown in Greece

Hibiscus cannabinus L.) plantation grown in N.Greece during the period June–October 1996 provided the raw material for experimental particleboards. After harvesting, the kenaf stems were storaged under shelter for a week, the core of each stem was separated from bark and both were dried at about 20% and 10% moisture content, respectively, and chipped by a hammermill. Kenaf core, bast fibers and industrial wood chips were mixed in various proportions in order to produce three-layer E2 grade UF bonded particleboards. Kenaf core chips were characterized by a lower slenderness ratio than wood chips of the middle layer. Bulk density of both core chips and fibers was lower than that of wood chips. Substitution of wood chips with kenaf core chips in the middle layer up to 75% slightly affects static bending and internal bond of the boards, but reduces screw holding strength and increases water absorption and thickness swelling; a 100% substitution deteriorates all properties except static bending. In boards with surface layers from kenaf bast fibers or from fibers:wood chips (50:50), static bending and surface roughness are improved, while the other properties tested are deteriorated. Substitution of kenaf core chips in the middle layer with fibers in proportion 50% negatively affects the board properties except static bending. It can be concluded that core chips and bast fibers from kenaf stems may substitute industrial wood chips in the middle and surface layers of the boards, respectively, up to 50%.

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Versuchsspanplatten aus griechischen Kenaf Plantagen

Hibiscus cannabinus L.) in N. Griechenland. Nach der Ernte wurden die Kenafstengel für eine Woche unter Dach gelagert, dann wurde das Holzgewebe im Stengelinneren von der Rindenschicht getrennt, anschliessend auf ca. 20% bzw. 10% Feuchtigkeit getrocknet und beides in einer Hammermühle zerkleinert. Die Herstellung dreischichtiger harnstoffharzverleimter (E₂ Typ) Spanplatten erfolgte unter Verwendung verschiedener Beimischungen aus Kenafholzsp?nen, Kenaffasern und Industrieholzsp?nen. Kenafholzsp?ne und Kenaffasern zeichnen sich durch eine niedrigere Streudichte als Industrieholzsp?ne aus; darüberhinaus weisen Kenafholzsp?ne einen niedrigeren Schlankheitsgrad auf im Vergleich zu den Mittelschichtsp?nen der Industrie. Der Ersatz von Industrieholzsp?nen durch Kenafholzsp?ne in der Plattenmittelschicht bis zu einem Anteil von 75% beeinflusst unwesentlich die Biege-, und Querzugfestigkeit der Platten, hat aber eine negative Auswirkung auf das Schraubenhalteverm?gen, die Dickenquellung und die Wasseraufnahme; ein Zusatz von 100% Kenafholzsp?nen zur Mittelschicht bewirkt eine Verschlechterung aller Spanplatteneigenschaften mit Ausnahme der Biegefestigkeit. Spanplatten, deren Deckschichten aus reinen Kenaffasern oder aus einer Beimischung von Kenaffasern und Industrieholzsp?nen in einem Verh?ltnis von 50:50 bestehen, weisen h?here Qualit?t bezüglich Biegefestigkeit und Oberfl?chenrauhigkeit auf, aber niedrigere hinsichtlich der übrigen Eigenschaften. Der Ersatz von Kenafholzsp?nen durch Kenaffasern in der Plattenmittelschicht hat, abgesehen von der Biegefestigkeit, einen negativen Einfluss auf alle Platteneigenschaften. In ihrer Gesamtheit führte die Untersuchung zu dem Resultat, dass der Zusatz von Kenafholzsp?nen und Kenaffasern in der Mittelschicht bzw. der Deckschicht von Spanplatten bis zu einem Anteil von 50% m?glich ist.

     

Extraction and Characterization of Calotropis gigantea Bast Fibers as Novel Reinforcement for Composites Materials

The aim of this study is to scrutinize the use of Calotropis gigantea bast fibers as potential reinforcement in polymer composites. The bast fibers were extracted from the Calotropis gigantea plant bark and some of them were treated with alkali (5 wt.%) solution. The chemical composition, physico-chemical structural properties of the untreated and the alkali treated Calotropis bast fibers were studied. The results of chemical composition analysis indicated that alkali treatment removed most of the non-cellulose materials as confirmed by the FTIR analysis. The X-ray diffraction results exhibited that the crystallinity index of the alkali treated fibers increased in comparison with the untreated fibers, which agrees with the results obtained in the mechanical tests. The tensile strength and modulus of the alkali treated fibers were found to be higher whereas the elongation at break was lower than the untreated fibers. Thermal stability of alkali treated fibers was lower than that of the untreated fiber. Scanning electron micrographs showed roughening of the surface of the fiber due to the removal of the surface impurities and non-cellulosic components on alkali treatment.It can be concluded that alkali treatment is an effective method to improve the surface and mechanical properties of Calotropis bast fibers to be used in composite materials.     

Monitoring the Diameter Changes of Flax Fibre Elements during Twin Screw Extrusion Using X-Ray Computed Micro-Tomography

ABSTRACT

Fiber size aspect ratio is known to impact the mechanical and reinforcement properties of natural fiber-based composites. However, the representation of fiber diameter change occurring during the extrusion process is controversial compared to the length. Fiber elements undergo multidirectional stresses and complex interactions within the extruder, leading to their breakage, which consequently may modulate their reinforcing properties. To better understand these mechanisms, short fiber reinforced polymer composites were prepared from flax fibers and polypropylene matrix (PP) by melt mixing. Five sampling zones were selected along the screws, both in screw conveying elements and inside blocks of kneading discs. X-ray computed micro-tomography, and 3D images analysis were then used for monitoring sample diameter distributions along the screw profile, according to specific twin-screw compounding conditions. The effects of the considered processing condition on fiber bundle diameters decrease along the screw profile are quantified.     

Optimisation of the surface treatment of jute fibres for natural fibre reinforced polymer composites using Weibull analysis

Abstract

The natural bast fibres such as jute, flax, kenaf, hemp, ramie are chemically modified for improving the interfacial adhesion with the hydrophobic matrices. Alkali treatment is amongst the widely used chemical treatment for the surface modification of these natural fibres. In this study, jute fibres are treated with 0.5, 4 and 25?wt.% sodium hydroxide (NaOH) solution at room temperature for 24?hours, 30?min and 20?min respectively. A comparison has been made between the physical and mechanical properties of these untreated and alkali treated jute fibres. Subsequently, a comparison between the cross-sectional areas of jute fibres before and after alkali treatment by using SEM analysis and circular fibre assumption is also made. The aim of the work is to optimise the alkali treatment processes of jute fibres with different concentrations of NaOH at room temperature. Two-parameter Weibull distribution is also applied to analyse the tensile properties of untreated and different alkali treated jute fibres. It has been observed that probabilistic tensile strength is an effective technique rather than presenting the average tensile strength. The study clearly demonstrates the jute fibre treated with 0.5?wt.% NaOH is more feasible and effective way to improve the mechanical properties of natural fibre reinforced composites.     

Development of Unconventional Fabric from Banana (Musa Acuminata) Fibre for Industrial Uses

ABSTRACT

Banana fiber is a lingo-cellulosic under-exploited bast fiber, which obtained from the pseudo-stem of banana plant (Musa acuminata). In this study, an attempt has been made to explore the possibility of production of needle-punched nonwoven from fibrous material of biowaste for value addition and diversified uses. Mechanical processing for preparation of all banana, banana-jute (1:1), and banana-polypropylene (1:1) blended needle punched nonwoven has been optimized and processing parameters have been suggested. Softening treatment of banana fibre has been done successfully for better processing. Boiling in water with 1% nonionic detergent has been suggested as pre-processing for softening. Tenacity, elongation-at-break, initial modulus, breaking energy, stress relaxation, creep, compressibility, recovery-from-compression, bending load, electrical insulation, thermal insulation, sound insulation, air permeability, and frictional force have been evaluated and analyzed for all the above-mentioned samples. Based on those properties the probable use has been suggested as insulation (thermal and sound) and filter material.     

红麻皮,龙须草纸浆黑液的特性

本文对红麻皮、龙须草原料的化学组成和不同制浆条件蒸煮纸浆黑液的物化性能进行了分析，红麻皮纸浆黑液含硅量低，粘度低，纸浆黑液能满足碱回收要求，而龙须草纸浆黑液含硅量与粘度均较高，需进行适当处理。     

红麻粗纱酶解效果测定及其分析

对红麻韧皮纤维经生物酶一浴法脱胶改性处理后,运用咔唑比色法测定红麻粗纱果胶和木质素的残留量,定量测定果胶的去除率。分析了酶浓度、温度、pH值和作用时间对酶解后果胶及木质素去除率的影响。实验表明,复合酶对红麻粗纱中果胶和木质素去除效果较好,所得纤维质量明显改善。     

胡麻双螺杆法皮杆分离后的制浆性能研究

本文主要研究双螺杆法分离胡麻韧皮部和木质部纤维所得纤维的制浆性能,以及加入NaOH等药品对其制浆性能的促进作用。结果发现,双螺杆法可使胡麻韧皮部和木质部纤维得以很好的分离(总得率可达40.4%),加入药品后韧皮部纤维100g/m2定量纸张的抗张和撕裂指数以及耐折度可达56.36 N.m/g、42.84 mN.m2/g和168次,比不加药品是高出了25%、30%和60%左右。与此同时,木质部纤维在经过磨浆处理后也可成浆,其50g/m2定量纸张的抗张和撕裂指数以及耐折度可达42.47N.m/g、5.30 mN.m2/g和10次,与不加药品相比提高了约100%、70%和200%。因此,综合可知,双螺杆法可将胡麻韧皮部和木质部纤维得以较好的分离,加入一定量NaOH等化学药品可提高其制浆性能,最终可针对两种纤维的性质,将二者进行合理利用,提高胡麻作为制浆造纸原料的利用效率。     

红麻制浆造纸现状及发展方向（下）

对国内外开发红麻制浆造纸的主要成就及世界近年成功的红麻ＣＴＭＰ制新闻纸和高效皮秆分离技术作了评述，叙述了我国红麻全秆制浆造纸的最新发展并提出了建议。     

Mechanical,morphological, and thermogravimetric analysis of alkali-treated Cordia-Dichotoma natural fiber composites

ABSTRACT

Usage of composites with natural fiber reinforcement is drastically increasing in recent times because of their low density, biodegradable nature, and low cost. However, natural fibers have certain core problems such as poor adhesion between the fiber and matrix and a relatively high degree of moisture absorption. Alkaline treatment of natural fibers is aimed at improving the adhesive strength so that effective stress transferability takes place in the composite. In the present work, Cordia-Dichotoma fibers were treated with sodium hydroxide (NaOH) and composites were prepared with different weight ratios of these fibers reinforced with epoxy. The prepared composites were tested for their tensile and flexural strengths (mechanical properties). Besides, for a comprehensive material characterization, IR spectroscopy (FT-IR), scanning electron microscope, and thermogravimetric analysis were carried out. This work investigates the influence of aforementioned NaOH treatment on thermal, mechanical, and morphological properties of the composite material.     

Influence of various retting methods on properties of kenaf fiber

Gum, as the important noncellulosic tissue present in kenaf fiber, has a close relation with downstream processing and product properties, so the predominant task in pretreatment of kenaf fiber for textile application, retting, is to remove gum including pectin, hemicellulose, lignin, and other impurities without damage to cellulose fiber. The traditional retting method is water retting; that is, the harvested kenaf bast is soaked in natural water (rivers or tanks) in which indigenous bacteria attack the gum in an anaerobic process, yielding much water pollution. Currently, much interest has been focused on various retting methods in order to seek one environmentally-friendly method. Therefore, microbe, chemical, water, and microbe–chemical rettings are performed in this experiment. Retted kenaf fibers at optimal conditions of various retting methods are then characterized and compared by light microscopy and indices consisting of residual gum content, fineness, tenacity, elongation, and softness. In addition, chemical oxygen demand (COD) is also tested. The results indicate that microbe retting induces higher residual gum content and lower elongation but better tenacity and softness and finer fiber; chemical retting gives lower tenacity and thicker fiber; water retting produces weak, poor quality fiber; and microbe–chemical retting produces moderate indices.     

Extraction and Characterization of Lignocellulosic Fibers from Girardinia Bullosa (Steudel) Wedd. (Ethiopian Kusha Plant)

ABSTRACT

Currently, eco-friendly products have been given great attention as the world is being polluted severely by non-biodegradable products and by-products. Different textile products have their own share in affecting the environment. This research is focused on exploring alternative bast fiber products to support the supply chain and to assess the possibility of using this fiber as a substitute to already available bast fibers. Kusha fiber was extracted and optimized from Ethiopian kusha plant stem – Girardinia bullosa (Steudel) wedd. – using caustic soda solution by varying the concentration, temperature, and time using design expert 6.0.10, quadratic model software. Tensile property, chemical composition, X-ray diffractometer (XRD), Fourier-transform-infrared spectroscopy (FTIR), fiber morphology, and thermogravimetric analysis (TGA) of the fiber were determined. Fiber characterization showed its tensile strength, and the cellulose content was equivalent to or even better than other bast fibers. Morphology of the fiber was similar to that of typical cotton with visible lumen and a slightly flat surface. Therefore, this new extracted fiber has a great potential to be used for different applications such as fiber-reinforced composites, textile furnishing, apparel, and nanocellulose extraction.