Kapok Fiber Research Articles

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.

Synthesis of kappa fiber modified graphite carbon nitride with outstanding photocatalytic phenol degradation ability

In this work, kapok fiber (KF) modified graphite carbon nitride (g-C3N4) was prepared by pyrolysis method and the photocatalytic degradation ability of phenol was investigated. XRD, UV–Vis DRS, FT-IR, TEM, XPS, N2 adsorption and PL were used to characterize the as-prepared catalysts. The results showed that KF, as a dual-function modifier, not only provided carbon source for carbon doping, but transformed into activated carbon substrate during calcination, making g-C3N4 grow on it. The KF modified g-C3N4 displays larger specific surface area, thinner layers, stronger visible light absorption capacity, higher separation efficiency and photocatalytic degradation performance. The KF modified g-C3N4 shows the phenol degradation rate constant of 0.258 h−1, which is 4.2 times higher than that of the neat g-C3N4, as well as excellent catalytic stability and structural stability. The excessive calcination temperature results in the low content of g-C3N4 in the catalyst, leading to the decline of photocatalytic performance.

Sound absorption properties for multi-layer of composite materials using nonwoven fabrics with kapok

Kapok fiber with high degree of hollow and small fiber diameter has excellent sound absorption. To optimize the sound absorption characters at the low frequency, sound absorption coefficients and specific surface impedance of two-layer, three-layer, and four-layer materials as polyethylene film-reinforced kapok fiber nonwoven fabrics have been studied by using the impedance tube method in the frequency range of 100–2500 Hz. The layering sequence, the polyethylene films thickness, and the gradient thickness structure of nonwoven fabrics affected the sound absorption properties at the low frequency for multi-layer materials that have been analyzed. The results show that the multi-layer composite materials have better sound absorption than a single-layer nonwoven fabrics at the low frequency. The elastic vibration of polyethylene film contributes to sound absorption improvement at the low frequency. The sound absorption at the low frequency of multi-layer materials can be further improved by changing polyethylene film position or increasing polyethylene film thickness. In addition, the gradient thickness structure of nonwoven fabrics can effectively improve sound absorption at the low frequency, and the gradient change direction also exhibits remarkable effects on the sound absorption of multi-layer materials.

Mussel‐Inspired Dual‐Superlyophobic Biomass Membranes for Selective Oil/Water Separation

AbstractDual‐superlyophobic membranes that exhibit underwater superoleophobicity and underoil superhydrophobicity concurrently have gained considerable attention for oil/water separation. To effectively treat oily wastewater, consistent efforts have been made to develop fast and simple methodologies with low cost, environmentally friendly materials. Here, the dual‐superlyophobic membranes are obtained based on one‐step tailored growth of mussel‐inspired polydopamine (PDA) nanoparticles on the surfaces of biomass membranes. The results demonstrate that the universal adhesion of PDA allows the modification of biomass fibers of different surface hydrophobicity. The oxidation polymerization of dopamine leads to the rapid growth of PDA nanostructures, which form stable coatings of high roughness instead of homogeneous conformal coatings generated in the conventional synthesis of PDA. The amphiphilic nature of PDA and the rough surfaces imparted by the PDA nanostructures collectively lead to dual‐superlyophobic properties. Membranes of the coated biomass fibers prewetted by either water or oil become impermeable to the counterpart liquids, giving rise to efficient oil–water separation in a broad spectrum of mixtures. In particular, the membranes derived from cotton or kapok fibers show oil/water separation efficiencies of above 99.98%, fluxes ranging from 4000 to 22 200 L m−2 h−1, and robust performance for regeneration and repeated uses.

Adsorption of anionic methyl orange dye and lead(II) heavy metal ion by polyaniline-kapok fiber nanocomposite

Low value natural hollow kapok fibers (KpF) were utilized as support for the synthesis of highly efficient polyaniline (PANI)-based adsorbents for heavy metal and ionic dye pollutants. The PANI-kapok (PANI-KpF) nanocomposite was prepared via in situ polymerization of aniline monomer in acidic condition using ammonium persulfate (APS) as the oxidizing agent. The morphology, wetting property and adsorption capacity of the PANI-KpF nanocomposites were tailored by performing NaClO2 pre-treatment and varying the APS to aniline ratio during coating. NaClO2 pre-treatment was found to promote the adhesion of aniline monomer on the surface of kapok, leading to high quality coating. On the other hand, the nanocomposite with [APS]/[aniline] = 1.4 exhibited the highest adsorption capacity. The effects of adsorbent dosage, initial solution pH, contact time, initial dye and heavy metal concentrations, and temperature were investigated through batch adsorption experiments. Kinetic studies indicate that the adsorption of MO and Pb(II) onto the PANI-KpF nanocomposite agrees well with the pseudo-second order kinetic model. Equilibrium isotherm studies show that the adsorption of both model pollutants follows the Langmuir isotherm model, and the calculated monolayer adsorption capacities are 136.75 and 63.60 mg/g for MO and Pb(II), respectively. Thermodynamic studies reveal that the adsorption of MO and Pb(II) are both endothermic and spontaneous.

A reinforced-concrete-like ultrathick cathode supported by carbonization kapok fibers for high loading lithium sulfur batteries

It’s a focus on high sulfur loading electrode for lithium sulfur batteries (LSBs) to improve the practical energy density. Blade casting method is an ideal method due to its efficiency and convenience that means thick electrode was utilized to increase sulfur loading. However, the weak strength and sluggish kinetics hinder to improve the practical energy density. To overcome issues, carbonization kapok fibers (CKFs) were overlapped to form the percolation network like rebar in the reinforced concrete. The cathode (sulfur loading: 8.22 mg cm−2) exhibits the superior initial capacity (1090mAhg−1 at 0.1C) and cycling performance (728mAhg−1 after 80 cycles).

Surface modification of kapok fibers by cold plasma surface treatment

This work evaluated the effects of cold plasma treatment on kapok fibers (Ceiba pentandra L.). Fourier-transform infrared (FTIR) spectra showed changes in characteristic absorption bands, indicating modification of the chemical composition of the fiber. Surface roughness, observed by field-emission gun scanning electron microscope (FEG-SEM), increased. Furthermore, the water uptake was significantly affected, the ability to uptake oil increased and a mechanism of reaction was suggested. The thermal behavior, analyzed by thermogravimetric analysis (TGA), was slightly altered and it was also shown that fiber surface was activated by the plasma treatment. Ultimately, cold plasma may prove as a feasible approach to improve fiber-matrix adhesion for the production of biodegradable polymer composites.

Hard carbon micro-nano tubes derived from kapok fiber as anode materials for sodium-ion batteries and the sodium-ion storage mechanism.

Hard carbon materials are considered as the most promising anode for sodium-ion batteries (SIBs). However, the high cost and poor rate performance hinder their application in SIBs. Moreover, the controversial mechanism of Na-ion storage restricts the improvement of hard carbon anodes. Herein, hard carbon micro-nano tubes (HCMNTs) from low-cost biomass kapok fibers are prepared as a promising anode for SIBs. Benefitting from the micro-nano structure, which offers low surface area and short Na+ diffusion path, 1400HCMNT possesses a good initial Coulombic efficiency of 80%, a high reversible capacity of 290 mA h g-1, and an excellent rate capacity. Furthermore, electron paramagnetic resonance and thermogravimetric analysis were applied to investigate the Na-ion storage mechanism in the HCMNTs. Sodium is stored in the hard carbon in an ionic state in the slope region and as quasi-liquid metallic sodium clusters in the low-voltage plateau.

Carbon Microtube Aerogel Derived from Kapok Fiber: An Efficient and Recyclable Sorbent for Oils and Organic Solvents

Carbon microtube aerogel (CMA) with hydrophobicity, strong adsorption capacity, and superb recyclability was obtained by a feasible approach with economical raw material, such as kapok fiber. The CMA possesses a great adsorption capacity of 78-348 times of its weight. Attributed to their outstanding thermal stability and excellent mechanical properties, the CMA can be used for many cycles of distillation, squeezing and combustion without degration, which suggests a extremely potential pratical application in oil-water separation. In addition, the adsorption capacity still retained 98% by distillation, 97% by squeezing, and 90% by combustion after 10 cycles. Therefore, the obtained CMA has a broad prospect as an economical, efficient and environment-friendly adsorbent.

Composites from recycled polyethylene and plasma treated kapok fibers

In this study, composites from recycled polyethylene and kapok fibers were prepared with fiber contents of 1, 5 and 10 wt%. Cold plasma treatment was applied to the fibers in an attempt to improve fiber/matrix adhesion. The characterization of plasma treated fibers indicated modification in chemical composition and water and oil uptake, as compared to untreated fibers. The addition of plasma treated fibers to the polymer promoted a reduction in the steady-state torque during mixing. In addition, the thermal conductivity of composites was reduced as the amount of fibers increased. Dynamic mechanical thermal analyses of composites with plasma-treated fibers indicated an increase in storage moduli, as well as an increase in glass transition temperature as compared to the pure polymer. Images of fractured surfaces show fibers well connected to the matrix suggesting good fiber/matrix adhesion. Thus, cold plasma is demonstrated as a viable non-polluting alternative to activate cellulosic fibers and improve fiber/matrix interface in polymer composites.

MoS2-roughened hollow-lumen plant fibers with enhanced oil absorption capacity

A facile dipping strategy was performed for roughening the surface of two plant fibers (CGF, Calotropis gigantea fiber; KF, kapok fiber) via nano-sized MoS2 to obtain eco-friendly oil-absorbing materials, MoS2-CGF and MoS2-KF. The results indicated that in addition to the roughened surface topography, MoS2-CGF and MoS2-KF possessed also hydrophobic–oleophilic properties and highly hydrophobic stability to corrosive environments. For twelve selected model oils (including organic solvents), MoS2-roughened fibers had excellent absorption capacity, with the value of 25–100 g/g for MoS2-CGF and 65–135 g/g for MoS2-KF within a few seconds. Furthermore, MoS2-CGF and MoS2-KF exhibited outstanding oil–water selectivity by using trichloromethane and cyclohexane as the model oils. After ten absorption–desorption cycles, a limited reduction in the re-sorption percentage was observed, demonstrating that MoS2-CGF and MoS2-KF had good reusability. By combining the advantages of abundant resource, low cost, high efficiency and environmental friendliness, MoS2-roughened fibers may be promising as efficient oil sorbents for the removal of oil spills in water.

Preparation and oil–water separation of 3D kapok fiber‐reduced graphene oxide aerogel

AbstractBACKGROUNDOil spills from oil tankers and ships or industrial accidents have serious impacts on the ecological environment. There is an urgent need for finding effective ways to resolve these problems. The use of low‐cost and efficient adsorbents is considered to be one of the most effective ways.RESULTSIn this study, an ultra‐light 3D kapok fiber‐reduced graphene oxide (TKF‐rGO) aerogel was prepared by a simple and green one‐step hydrothermal method. The kapok fiber used as skeleton was embedded in a graphene network to successfully form a 3D aerogel structure. The as‐prepared TKF‐rGO aerogel featured low density, excellent mechanical strength, high thermal stability, and high hydrophobic lipophilicity. Furthermore, continuous oil–water separation could be achieved by the aerogel when connected to a vacuum system. The adsorption capacity of TKF‐rGO aerogel for various common oil products and organic solvents was 1.5‐fold greater than that of pure rGO aerogel and six‐fold greater than that of polypropylene melt spray, respectively. In addition, the initial adsorption capacity of the as‐prepared TKF‐rGO aerogel was maintained at 94% after eight cycles.CONCLUSIONThe TKF‐rGO aerogel could be synthesized by a low‐cost and green method, which was suitable for commercial production, and showed competitive adsorption capacities for oil removal. Thus, the TKF‐rGO aerogel is expected to be employed as a promising adsorbent in the removal of oil spill or hazardous organic solvents from water. © 2019 Society of Chemical Industry

Kinetics and Thermodynamics of Dispersed Oil Sorption by Kapok Fiber

Abstract This work was aimed at evaluating the sorption of dispersed oil by kapok fiber. The physicochemical characteristics of kapok fiber were investigated using BET, SEM, FTIR, XRD, contact angle and elemental analysis. The oil droplet size distribution at different temperatures was analysed using a Coulter counter, and its relationship with sorption was investigated. The effects of dosage, hydraulic retention time and temperature, on the sorption performance were studied. The result indicates that the sorption of dispersed oil by kapok fiber is spontaneous, endothermic and agreed with the pseudo-first-order reaction kinetics. The amount of oil that could be removed is about 28.5 %, while that of water is less than 1 % of the original amount (0.5 dm3). Kapok is a promising natural hydrophobic fiber for dispersed oil removal from oily wastewater.

Hematite microcube decorated TiO2 nanorods as heterojunction photocatalyst with in-situ carbon doping derived from polysaccharides bio-templates hydrothermal carbonization

The novel in-situ formation of a heterojunction photocatalyst consisting of C-doped TiO2 nanorods decorated on the surface of C-doped α-Fe2O3 microcubes was successfully achieved using a one-pot hydrothermal carbonization synthesis. In this work, the treated kapok fibers (t-KF) used as a polysaccharide bio-template provided a dual function for crystal growth control and in-situ carbon doping of the heterojunction photocatalyst. It was found that the α-Fe2O3 precursor concentration plays an essential role in the unique and well-developed C-doped TiO2/α-Fe2O3 heterojunction formation. Assessment of photocatalytic activity of all samples indicated that the sample prepared with 0.25 M of α-Fe2O3 precursor concentration (BT-TF-0.25) exhibited the most efficient bisphenol A photodegradation in aqueous solution. The highest photocatalytic activity of BT-TF-0.25 under simulated solar irradiation was mainly associated with C-doping and favorable heterojunction formation between C-doped TiO2 and C-doped α-Fe2O3. Excellent charge carrier and separation were confirmed from the photocurrent response and photoluminescence spectroscopy analysis. Overall, this study is expected to contribute to the development of more efficient visible light active heterojunction photocatalyst systems, as well as demonstrating the versatility of polysaccharide materials as a green and low-cost bio-templates.

Comparative study of acid-treated and alkali-treated carbonised Kapok–fibres for oil/water absorption system

Kapok predominantly utilized as an adsorbent in removing wastewater such as dye, oil and heavy metals. However, a comparative study between acid-treated and alkali-treated carbonized Kapok fibers has not been carried out in detail. In this study, as-made Kapok fibers were carbonized and subsequently undergo acid (HCL) and alkali (NaOH) treatment. The resultant treated Kapok fibers were characterized using Fourier transform infrared (FTIR) spectroscopy, Elemental Analyzer (EA) and Thermogravimetric Analysis (TGA). As-made carbonized Kapok fibers were tested with oil/water absorption model system. A reduction of band intensity at 1740 cm−1 and 1245 cm−1 occurred for NaOH treated sample compared with HCL. The composition of carbon in Kapok fiber increased after carbonization treatment using NaOH (62.42%) and HCL (66.15%) compared with untreated (0.17%). For oil/water absorption system, the result indicated that HCL-treated Kapok fibre was the highest absorption on 28.10 gg−1 diesel, 27.28 gg−1 petrol and 39.84 gg−1 for used vegetable oil respectively in comparison with NaoH-treated and as-made carbonized Kapor fibers. In conclusion, modification of the surface of carbonized Kapok fibers could significantly alter its textural properties which could enhance its oil absorptive behavior.

Optimization of Sulfuric Acid Concentration and Hydrolysis Time on Crystallinity of Nanocrystalline Cellulose : A Response Surface Methodology Study

Kapok is a source of natural fiber in addition to cotton, which availability is abundant and contain high cellulose but not been utilized optimally. This study aimed to determine the optimal conditions of sulfuric acid concentration and hydrolysis time in the production process of nanocrystalline cellulose (NCC) from kapok fiber. The research was conducted in several stages, namely the delignification with alkali hydrothermal, bleaching with alkaline hydrogen peroxide agents, isolation with sulfuric acid solutions, and NCC characterization. The optimization used Response Surface Methodology (RSM) with Central Composite Design (CCD), which consisted of two factors, namely H2SO4 concentration and hydrolysis time. The optimized parameter was the crystallinity degree of the NCC. NCC characterization included functional group analysis with Fourier Transform Infrared Spectroscopy (FTIR), surface profiles and dimensions by Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The results showed that the optimum condition of NCC isolation from kapok fiber was obtained at 54.46% (b/b) H2SO4 with hydrolysis time of 48.96 minutes, resulting in a maximum degree of crystallinity of 71.8%. The hydrolysis process with H2SO4 caused a change in the NCC functional group. NCC had a diameter of about 11.2 ± 2.63 nm and high thermal stability that potential for various composite materials

Acoustic absorptive properties of Kapok fiber, Kapok fiber layered tricot fabric and Kapok fiber layered double weave fabric

Kapok fiber was one of the natural cellulosic fiber that can be found widely in Asia’s forest especially in Indonesia. Kapok fiber was short and smooth surface causing poor inter-fiber cohesion that could not be processed in spinning. This fiber could be utilized to be accoustic sound proofing material. This research investigated about absorptive properties of non woven kapok fiber (SK) and its layered combination with tricot knitted fabric (TC) and double weave fabric (DWK). Combination of various kind of fabric’s type improved thickness and air cavity that impact absorptive properties of fabric. Impedance tube were used to characterization sound absorptive properties at low until normal frequency on 100 until 5000 Hz. The optimum sound absorptive were showed by combination of non woven kapok fiber with double weave fabric with thicknes 11,25 mm. It shows thickness impact to air cavity and gave significant effect to sound absorptive properties.

Comparative Study on the Effects of Laser Bleaching and Conventional Bleaching on the Physical Properties of Indigo Kapok/Cotton Denim Fabrics

Kapok is a hollow fiber with a 90% hollow degree. Compared with cotton fiber, kapok fiber has excellent performances, such as good hygroscopicity, and a good warmth retention property. In this work, desized indigo kapok/cotton denim fabrics were bleached in different ways: Laser, cellulose enzyme, sodium hypochlorite, potassium permanganate and hydrogen peroxide. After bleaching, the K/S values, tensile strength, air permeability, thickness, color fastness to rubbing and the crease recovery angle of denim fabrics were measured through the spectrophotometer, tensile strength tester, air permeability tester, thickness tester, rubbing fastness tester and fabric crease elasticity tester, respectively. The surfaces of fabrics and fibers were observed by scanning electron microscopy (SEM). Results show that the kapok/cotton fabrics were color-faded after five kinds of bleaching, the K/S values of denim with laser bleaching was declined dramatically, while there was a little change in the permeability. The tensile strength and the weight of the fabrics were decreased, and cloth which was bleached with potassium permanganate was most affected. The color fastness to rubbing and the crease recovery angle of denim fabrics with laser treatment is most suitable for industrial production. In general, laser bleaching is the better way to fade the kapok/cotton denim fabrics. Meanwhile, after five kinds of bleaching, the physical properties of kapok/cotton denim fabrics were similar to those of cotton denim fabric, which indicates that kapok/cotton denim fabric is suitable for the existing industrial bleaching technology.