Kapok Fiber Research Articles

Ultralight, hydrophobic, sustainable, cost-effective and floating kapok/microfibrillated cellulose aerogels as speedy and recyclable oil superabsorbents

Cellulose aerogels achieve excellent absorption of waste oil and organic pollutant, which has received lots of attention recently. It is still a big challenge to obtain aerogels with both high cost-effectiveness and advanced oil absorption performance, since it is a time-consuming, and environmentally unfriendly process to obtain cellulose, compared with direct usage of natural fibers. In this manuscript, we develop highly porous and hydrophobic kapok/microfibrillated cellulose (MFC) aerogels with a dual-scale hierarchically porous structure at micro-level as cost-effective, sustainable, and floating superabsorbents via simple vacuum freeze-drying and surface modification. Kapok, a natural hollow fiber, has been recently considered as a new sustainable resource for oil cleanup. By partially replacing MFC with chopped kapok fibers in MFC aerogels (MMAs), the resultant kapok/MFC aerogels (KCAs) exhibit ultralow density (5.1 mg/cm−3), ultrahigh porosity (99.58%) and hydrophobicity (140.1°) leading to advanced oil sorption (130.1 g/g) that is 25.3% higher than that of MMAs. In addition, these KCAs can rapidly and selectively absorb waste oil from oil-water mixture with ultrahigh absorption ability of 104–190.1 g/g, which is comparable to other environmentally unfriendly and high-cost aerogels. Furthermore, the KCAs own excellent reusability and sustainability. These benefits enable the KCAs a suitable alternative to clean oil spills.

Low tortuosity thick cathode design in high loading lithium sulfur batteries enabled by magnetic hollow carbon fibers

The sluggish kinetic is the key factor to restrain electrochemical performance of high sulfur loading thick electrode. With thickness increase, the high tortuosity and long ion-path way lead to the sluggish kinetic in the electrode. Low tortuosity structure design can facilitate lithium ion (Li+) diffusion and electrolyte percolation into the electrode, which is an appropriate method to improve electrochemical performance. This paper focuses on the construction of low tortuosity electrode design. The hollow carbon micro-fibers of carbonized kapok fibers (CKFs) are decorated by superparamagnetic Co3O4 derived from ZIF-67, which are utilized to provide the vertical channel in the thick electrode. The orientation of CKFs@Co3O4 in the magnetic field provides the directional pathway to improve the kinetics of mass transport in the thick electrode. Compared with the conventional electrode, the low tortuosity electrode shows better electrochemical performance. With sulfur loading of 6 mg cm−2 and around 300 μm thickness, it exhibits the excellent reversible capacity of 866.2 mAh g-1at 0.2C after 100 cycles and delivers a high initial capacity of 479.1 mAh g−1 at 2C. The low tortuosity structure design reported from this paper is effective to relieve the sluggish kinetic of the thick electrode and is potential for practical application.

Mussel inspired durable pH-responsive mesh for high-efficient oil/water separation

The application of pH-responsive superwetting materials receives increasing attention in oil/water separation. In this work, a mussel inspired robust surface coating fabricated with dopamine, copolymer PDMAEMA-co-PHEMA-co-PHFBMA (PDHH) and SiO2 nanoparticles (DPS) was formed on stainless steel mesh to perform multiple repeatable oil/water separation. Herein, dopamine was chosen to provide strong adhesion strength and durability, endowing the mesh excellent stability in harsh environments, such as mechanical abrasion, acid/alkali immersion and UV irradiation. In virtue of pH stimulation, the as-prepared mesh can be reversibly switched between superhydrophobicity and superhydrophilicity. Moreover, the mesh possesses remarkable oil/water separation efficiency (SE) (≥98%) and desirable recyclability. An oil collector prepared by the mesh and kapok fiber showed good oil absorption capability in the range of 39.67–79.56 g/g. The facile and inexpensive preparation of the durable separation device enables it promising in actual oil/water separation.

Facile synthesis of porous organic polymers (POPs) membrane via click chemistry for efficient PM2.5 capture

Global environmental problems are facing serious challenges, especially the harm of air pollution to human health. It is meaningful to capture harmful particulate matter (PM) in the air. In this work, we report for the first time the facile synthesis of porous organic polymers (POPs) with macroporous structure, which were synthesized using 1,4-benzenedithiol, 1,4-diethynylbenzene and 1,3-benzenedithiol via click chemistry, for efficient PM capture. PM filtration measurement was simulated by the release of particulate pollutants from cigarette smoke. The test results of porous composite membranes (PCMs) show a high PM removal efficiency for PM2.5 (≥99.80 ± 1.58%) and PM10 (≥99.89 ± 0.89%) in 30 h. The PCMs based on kapok fiber not only has good mechanical properties, but also can be made into membranes of different sizes depending on the size of the substrate. Taking advantage of their simple one-step synthesis via click chemistry with great potentials for scale-up under mild conditions, such PCMs may find useful applications in PM capture.

SYNTHESIS OF CELLULOSE AEROGEL FROM KAPOK FIBER FOR CLEANING THE WASTE OF LUBRICANT OIL

Cellulose aerogel is known to be superior in removal of oil pollutants and organic solvent. This research developed the synthesis of cellulose aerogel from kapok fiber, application as an adsorbent for lubricating oil waste and its reusability. Chemical delignification was carried out by immersing the kapok fibers in NaOH 6% solution at 100oC for 1h to obtained a cellulose of 65.5% (SNI-2009). The effect of urea concentration on adsorbent products was studied in the range of 8-16w%. Whereas the effect of cellulose was studied at a concentration range of 0.5-1.5w%. The gelation stage was carried out by adding cellulose in a NaOH/urea solution accompanied by stirring (1000rpm) for 15minutes. The mixture was cooled at 0 oC for 48h to form a gel. The formed gel is dried by the freeze drying method at -45°C. The cellulose aerogel from kapok fiber with a density of 0.11g/cm3 and porosity of 92.46% had an absorption capacity of up to 11.987g/g in the first cycle. The use of each aerogel cellulose sample to absorb lubricant oil waste reached a maximum of three cycles. DOI : https://doi.org/10.33005/jurnal_tekkim.v15i1.2305

Sound Absorption Properties of Natural Fibers: A Review

In recent years, in an attempt to substitute the conventional synthetic sound absorption material, natural fibers and their sound absorption properties have been increasingly studied. This is due to the fact that conventional synthetic fiber has potential health risks for human beings and significant environmental impact. In this review, existing and newly emerging natural fiber sound absorbers are summarized and highlighted in three categories: raw material, fiber assembly and composite. The sound absorption mechanism, several widely used prediction models and the popular acoustic characterization methods are presented. The comparison of sound absorption properties between some natural sound absorbers and glass fiber is conducted in two groups, i.e., thin material and thick material. It is found that many natural fibers have comparable sound absorption performance, some of them can be the ideal alternatives to glass fiber, such as kapok fiber, pineapple-leaf fiber and hemp fiber. Last, the conclusion part of this review gives an outlook regarding the promotion of the commercial use of natural fiber by means of theoretical study, efficient and environmentally friendly pretreatment and Life Cycle Assessment.

A phase change material embedded composite consisting of kapok and hollow PET fibers for dynamic thermal comfort regulation

Kapok fiber, an agricultural product, is a typical cellulosic fiber with the features of thin cell wall and large lumen. Herein, a microtubule-based composite with high porosity of 98.03 % was prepared using kapok fibers and hollow PET. The kapok fiber-based composite successfully encapsulated a phase change material (PCM), that is a fatty acid ester of myristic acid and tetradecyl alcohol (MA-TD), in the microtubules by vacuum impregnation. The SEM showed that the PCM was encapsulated in the lumens of the fibers with a calculated percentage of 40.5 %. This condition provided the composite a basic thermal insulation from air pockets in the composite and a dynamic thermal insulation from the PCM. The kapok/PET/MA-TD could absorb 76.8 J/g latent heat in the comfort temperature range of 24 °C – 42.3 °C or release 77.4 J/g latent heat in the comfort temperature range of 29.7 °C – 10.5 °C. It withstood repeated laundry and exhibited robust leakage resistance to continuous heating/cooling under pressure. In addition, the composite was successfully used to dynamically regulate the temperature with obvious thermal regulating capacity in the simulated cooling/hot environments. Such material will be a robust candidate for dynamic heat regulating and thermal insulating applications.

Acoustic isolation of Jute and Kapok fiber reinforced Polypropylene composites

For the requirements of human health initiative especially when emerging of advanced composite material technology, manufactures of high efficient acoustical materials are necessary to regulate the noise pollution. The objective of this study is to fabricate the jute and kapok fiber reinforced polypropylene composites and to analyze the comparison of acoustic isolation effect of jute and kapok fiber reinforced polypropylene composites. To produce these two types of composites material, the raw materials went through a different stage of procedure such as, blending, mixing and heat compression molding process. Polypropylene was filled with jute and kapok fiber at various loading at 0, 10, 20, 30 and 40% each. The composites were prepared by using Brabender Torque Rheometer Plastograph machine and the hot press at temperature 180°C with 50 rpm. The acoustic test was conducted by using insertion loss method in sine wave tube device to measure the different sound level, loss in these two composites material. Based on the result observed, the higher of weight percentage of jute and kapok fiber in each composition, the better of the performance for each material and the optimum result for each composite are determined to be 30% filler loading. It also can be conclude that the used of jute fiber reinforced polypropylene composites give an outstanding result in term of sound absorption and transmission loss compared to kapok reinforced polypropylene composites.

Development of Kapok/Recycled-PET Blended Needle-Punched Thermal Waddings

ABSTRACT Kapok fiber is emerging as a cheaper natural fiber having excellent thermal insulation properties. Recycled polyester/kapok blended needle punched nonwoven waddings are prepared where the effect of kapok fiber %, sheet areal density, and needle punch density on thermal resistance and air permeability is measured and analyzed with the help of MINITAB®18.1. Three percentages of kapok fiber (20, 40, 60%), four levels of fabric areal density (150, 300, 450, 600 g.m-2) and two levels of punch density (15, 20 punches.cm-2) were chosen. The statistical analysis revealed that kapok fiber % and areal density had a significant effect on both thermal resistance and air permeability of nonwovens. The thermal resistance was decreased significantly with the increase in kapok fiber %, especially at higher punch density. A significant interaction between kapok fiber % and areal density was observed for air permeability. It may be concluded that, in the selected range of input variables, recycled PET/kapok nonwovens with less % of kapok fibers and punch density display better thermal insulation performance, especially at higher areal density. The prepared nonwovens may find applications in winter coats and wadding layers for quilts, etc., and will also help to reduce the pollution from the environment.

Thermal behavior of bi-layered needle-punched nonwovens produced from 100% raw kapok fibers

In the production of functional nonwovens with sustainable fibers, kapok, with unique qualities, becomes an excellent candidate for the production of thermal insulation textiles. However, the development of 100% raw kapok fiber structures is a challenge, since their mechanical resistance and inter-fiber cohesion is very low. In this work, the thermal behavior of new needle punched bi-layered nonwovens produced from 100% raw kapok fibers is studied. These innovative structures were obtained through dry heat-pressing of needle punched nonwovens, developed according to a novel method designed. The results obtained have shown that the heat-pressing conditions (temperature and number of cycles) affected the thermal properties of the nonwovens and the thermal performance profile of an insulating arrangement. The bi-layered nonwoven structures reinforced in one heat-pressing cycle at 100 °C showed the higher thermal resistance and the lower thermal conductivity and heat flux and led to the highest delay (decrement delay) of the heat transfer from the outside to the inside of the insulating assembly and vice-versa, acting as an effective thermal insulator.

Study of Water Absorption Properties of Water Absorption Core Made of Pulp Mold

The water absorption properties of the water absorption core made of pulp mold were investigated in this study. The pulp mold samples were modified using various natural non-wood fibers such as cotton linter, kapok, abaca, Tencel and through the high bulk-forming process with the low polarity solvent in order to find main factors for improving the water absorption properties. The application of the kapok fibers resulted in the higher water absorption amount following the bulkier structure. The alkali treated kapok showed the higher water retention value and the improvement in the water absorption properties. The bulk of the pulp mold samples was greatly increased by the high bulk-forming process with low polarity solvent, which led to a significant improvement in the water absorption amount. The addition of natural water absorption additives such as glucomannan and carboxyl methyl cellulose (CMC) also increased the water absorption amount. The double-layered pulp mold samples were prepared as a water absorption core made of the kapok fiber, utilizing the high bulk-forming process with the addition of the glucomannan, which resulted in a significant increase in the water absorption properties.

Flame-Retardant and Sound-Absorption Properties of Composites Based on Kapok Fiber.

In order to improve the utilization rate of kapok fiber, flame-retardant and sound-absorption composites were prepared by the hot pressing method with kapok fiber as the reinforced material, polyε-caprolactone as the matrix material, and magnesium hydroxide as the flame retardant. Then, the effects of hot pressing temperature, hot pressing time, density of composites, mass fraction of kapok fiber, thickness of composites, and air layer thickness on the sound-absorption properties of composites were analyzed, with the average sound absorption coefficient as the index. Under the optimal process parameters, the maximum sound absorption coefficient reached 0.830, the average sound absorption coefficient was 0.520, and the sound-absorption band was wide. Thus, the composites belonged to high-efficiency sound-absorbing material. The flame-retardant effect of magnesium hydroxide on the composites was investigated, and the limiting oxygen index could reach 31.5%. Finally, multifunctional composites based on kapok fiber with flame retardant properties, and sound-absorption properties were obtained.

Separation of Water in Diesel Using Filter Media Containing Kapok Fibers.

Traditional water-repellent filter media for water separation in diesel fail to meet requirements due to the high content of surfactants in low sulfur diesel and ULSD (ultra low sulfur diesel). To improve the water separation performance of filter media, a novel dual-layer filter medium was prepared by hydrophilic fibers (glass microfibers) and hydrophobic fibers (kapok fibers and bi-component PET fibers). The results showed that the separation efficiency of a filter medium (sample #2) with the upstream layer containing 20 wt% kapok fibers was 89.5%, which was higher than that of filter samples with the upstream layer containing 0 wt%, 40 wt%, 60 wt% and 80 wt% kapok fibers. When the interfacial tension (IFT) of water in diesel was 21 mN/m, 17 mN/m and 13 mN/m, the separation efficiency of filter sample #2 was 99.5%, 89.5% and 30.5%, respectively, which was 23.9%, 57.4% and 17.8% higher than that of the commercial water-repellent filter samples composed of a polybutylene terephthalate (PBT) fiber layer and cellulose fiber layer.

Mechanical Design and Evaluation of Kapok Fibre Seeds Separator

The demand on Kapok fibre-based products has currently shown an increase particularly those from small business traders in comparison to massive market sellers due to lower cost offered. However, the small business traders commonly use manual technique to separate the Kapok fibre from its seed before continuing to the next stages, thus, leading to labour-intensive work, longer processing time, and low output. The aim of the study was to design and develop a Kapok fibre seeds separator to efficiently perform the work. A number of idea generation and concept development phases were undertaken. The finalised concept was the transformed into a three-dimensional (3-D) model using a computer-aided design (CAD) software. A computational 3-D finite element analysis (FEA) was conducted to evaluate the structural performance under simulated loadings. Also, the product prototype was built and its usability has been tested. The outcomes of 3-D FEA showed that the highest mechanical stress recorded within the structure was favourable with low tendency towards failure. Whilst, the results of usability testing demonstrated that the proposed product reported an increase of 52.8% in the amount of separated seeds. Thus, the new design of Kapok fibre seeds separator is found to be superior in solving the problems issued by the manual processing technique.

Synthesis, characterization, and mercury removal application of surface modified kapok fibers with dopamine (DA): investigation of bidentate adsorption

The present work evaluated a mercury adsorption from its aqueous solution through chemically enhanced kapok fiber with the self-polymerization of the dopamine (DA) on the surface of the kapok fiber. The adsorption capacity of mercury ions was greatly improved with the DA coated kapok fiber (235.7 mg/g), compared with the raw kapok fiber (39.9 mg/g). The kinetic and isotherm studies were established, and the most fitting pseudo-first-order reaction and the Langmuir model indicated that the homogenous chemisorption occurred on the surface of the chemically modified kapok fiber with the equilibrium time of 80 min. According to the FTIR and XPS spectra analyses, the bidentate adsorption of mercury ions was illustrated with hydroxyl groups induced by three-dimensional (3-D) polymerization of DA. The optimum pH was at 8 for the adsorption with the dopamine-coated kapok fiber and the high adsorption efficiency was still maintained after three recycle times, extending its application to treating a number of industrial wastewater streams.

The effect of lerak foam and kapok as a silencer on lightweight concrete

Lerak Foam is Foam produced by Lerak fruit mixed with water. This Foam is very suitable as an air cavity enhancer in lightweight concrete. Kapok is a natural material commonly used as pillows, mattresses and stuffed toys. Kapok with fine fibers and easily formed in a concrete mixture is expected to reduce noise. The purpose of this study is to reduce the noise of concrete materials by adding Lerak Foam and Kapok. This research was conducted in the Concrete Laboratory University of Jember, by making a sample of 40 cm x 40 cm x 40 cm concrete box with a thickness variation of 3 cm and 7 cm. This study intend to compare the value of noise reduction and transmission loss from the concrete specimen model with the addition of 100cc Lerak Foam and Kapok with 0%, 1.5%, 2.5%, 3.5% and 5% from the weight of concrete. The different values can be found by giving a noise gauge inside from the concrete box. The level of noise reduction is affected by the thickness of concrete. The level of noise reduction will increase as much as the addition of Kapok Fibers in concrete mixtures.

Structural characteristics and sound absorption properties of poplar seed fibers

In order to make reasonable utilization of poplar seed fibers, their macromolecular structure, supramolecular structure and morphological structure were analyzed by means of a biological microscope, scanning electron microscope, Fourier transform infrared spectrometer and X-ray diffractometer, and the relationship between the structure of poplar seed fiber and its sound absorption performance was explored. The acoustic impedance transfer function method was used to test the sound absorption performance of poplar seed fiber, kapok fiber, cotton fiber, wool fiber and hemp fiber aggregates that could be used in the field of sound absorption. The results showed that the order of sound absorption properties of the five fiber aggregates was as follows: kapok fiber, poplar seed fiber, cotton fiber, wool fiber, hemp fiber. The special structure of poplar seed fiber meant it had excellent sound absorption performance in the entire tested frequency range. The poplar seed fiber aggregate had a wide sound absorption frequency band and the maximum sound absorption coefficient reached 0.84, which has high application value in the field of sound absorption.

Oil release behavior and kinetics of oil-impregnated kapok fiber powder

In this study, kapok fiber powder (KFP) was evaluated as a wicking material for the application of mechanical lubricants. KFP had lengths ranging from several microns to 2 mm, with part of the hollow lumen being compressed. Experiments showed that the oil sorption capacity of KFP for mineral oil and PAO4 was 21.9 g/g, and 19.9 g/g, respectively. The oil release behavior of oil-impregnated KFP was quantitatively evaluated by a device proposed in the present study to simulate the usage of lubricant in bearings. The results indicated a two-step oil release process including a rapid release phase and a slow release phase. The cumulative oil release increased with an increasing oil/fiber ratio and temperature. The release mechanism of oil-impregnated KFP was further investigated by release kinetics models which demonstrated that the oil release followed Fickian diffusion and could be described by the Rigter–Peppas model. These results are proposed to provide a reference for the evaluation of the oil release performance of oil-impregnated wicking materials when they are applied in mechanical bearing field.

KAPOK AS AN ADSORBENT FOR INDUSTRIAL WASTEWATER

The study focuses on investigating kapok fiber as an adsorbent for oily industrial wastewater. Kapok fiber, KF (Ceiba Pentandra) is a natural plant fiber that poses excellent hydrophobic-oleophilic characteristics, due to the presence of penetrable hollow lumen structure and waxy material on its surface. The objectives of this study are to investigate the morphology of raw and treated kapok fiber (KF) before and after adsorption of wastewater as well as to study the sorption capacity of KF (including raw KF, ethanol-treated KF and chloroform-treated KF) in wastewater. Hence, the morphology of raw KF and KF treated with oil are analysed using scanning electron microscopy (SEM). Besides, the sorption condition of different types of wastewater including emulsified wastewater, immiscible oil-and-liquid wastewater and non-oily wastewater on raw KF are studied in this experiment. From the study, the raw KF shows the best sorption capacity of oil (29.00g/g) compared to the ethanol-treated KF (18.22g/g) and Chloroform-treated KF (16.58g/g) as the treated KF has larger amount of cellulosic content (hydroxyl group) present on the wall of kapok, making it less oleophilic. On the other hand, raw KF has the lowest sorption capacity of water (0.59g/g) followed by ethanol-treated KF (3.05g/g) and chloroform-treated KF (3.20g/g) on non-oily wastewater. Kapok fiber shows great potential as oil sorbent on any type of oil owing to its excellent hydrophobicity-oleophilicity characteristic. In conclusion, the raw KF shows the best sorption capacity of oil compared to the ethanol-treated KF and chloroform-treated KF because the effectiveness is resulted from the hydrophobic waxy coating on the kapok surface. Besides that, the lower sorption capacity of water than oil is due to the incomplete removal of wax from the wall of kapok, making it a little hydrophilic (likes water) as compared to oleophilic (likes oil).

Kapok fibre as potential oil-absorbing material: Modification mechanism and performance evaluation

Kapok fibre has gained considerable attention as a potential oil-absorbing material due to its lipophilicity, hydrophobicity, and configuration of its central lumen which is the key component of its high oil absorption capacity. However, the weak structural integrity of the fibre greatly retards its application. This study aims to develop a reinforcement method for kapok (Ceiba pentandra) fibre to enhance its reusability and oil recovery. Oil-sorption capacities of several modified kapok fibres have been evaluated to resolve the oil-polluted water issues. Oxidation using sodium chlorite (NaClO2) followed by sol-gel coating with tetraethylorthosilicate (TEOS) and sponge formation via freeze-drying method successfully enhance the structural integrity of the fibre without significantly reduce its hydrophobicity. Further coating the sponge with dodecyltrimethoxysilane (DTMS) using the chemical vapor disposition method results in superhydrophobic fibre. The best performance achieves an oil-sorption capacity of 48.6 g-oil/g-fibre and can maintain 62.6% of its oil-sorption capacity even after ten reuse cycles.