This study aims to reduce radon gas emanations in the indoor environment by incorporating kenaf and oil palm nanocellulose that act as nano-fillers into building materials. Fabrication of composite brick was carried out according to the MS and ASTM standards. In this research, 40, 80, 120, 160 and 200 ml of nanocellulose were used to replace the usage of sand, stone and cement materials, respectively. Kenaf and oil palm nanocellulose were utilised to reduce the internal and surface porosity as well as to replace the radon resources (stone), which indirectly reduced radon gas emanation. Radon gas emanated from each composite brick was measured within 10 consecutive days in an airtight prototype Perspex room using Radon Monitor Sentinel 1030. A compression test was also carried out to investigate the physical strength of the fabricated composite bricks. The results showed that 40 ml of kenaf and oil palm nanocellulose was the optimum amount in reducing the radon concentration, where the radon readings were 1.4 and 0.93 pCi per l, respectively. Meanwhile, the brick with no nanocellulose exhibited the highest radon reading of 3.77 pCi per l. Moreover, the Young modulus for the composite brick of both kenaf and oil palm nanocellulose was 28.92 and 27.8 N per mm2 compared to the control brick, which was 27 N per mm2. The results proved that radon gas emanations were reduced by 62.86% for kenaf and 75.3% for oil palm by incorporating the organic nanocellulose, which has high potential towards a healthy indoor environment.
Kenaf fiber has recently garnered exponential interest as reinforcement in composite materials across diverse industries owing to its superior mechanical attributes, ease of manufacture, and inherent biodegradability. In the discourse of this review, various methods of manufacturing kenaf/Polylactic acid (PLA) composites have been discussed meticulously, as delineated in recently published scientific literatures. This paper delves into the chemical modification of kenaf fiber, examining its consequential impact on tensile strength and thermal stability of the kenaf/PLA composites. Further, this review illuminates the role of innovative 3D printing techniques and fiber orientation in augmenting the mechanical robustness of the kenaf/PLA composites. Simultaneously, recent insightful explorations into the acoustic properties of the kenaf/PLA composites, underscoring their potential as sustainable alternative to conventional materials have been reviewed. Serving as a comprehensive repository of knowledge, this review paper holds immense value for researchers aiming to utilize the capabilities of kenaf fiber reinforced PLA composites.
Roselle fiber is a renewable and sustainable agricultural waste enriched with cellulose polysaccharides. The isolation of Nanocrystalline cellulose (NCC) from roselle-derived microcrystalline cellulose (MCC) is an alternative approach to recover the agricultural roselle plant residue. In the present study, acid hydrolysis with different reaction time was carried out to degrade the roselle-derived MCC to form NCC. The characterizations of isolated NCC were conducted through Fourier Transform Infrared Ray (FTIR), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). As evaluated from the performed morphological investigations, the needle-like shape NCC nanostructures were observed under TEM and AFM microscopy studies, while irregular rod-like shape of NCC was observed under FESEM analysis. With 60min hydrolysis time, XRD analysis demonstrated the highest NCC crystallinity degree with 79.5%. In thermal analysis by TGA and DSC, the shorter hydrolysis time tended to produce NCC with higher thermal stability. Thus, the isolated NCC from roselle-derived MCC has high potential to be used in application of pharmaceutical and biomedical fields for nanocomposite fabrication.
The versatility of a well-known fibrous crop, Hibiscus cannabinus (kenaf) is still relatively new to many. Kenaf's potential applications, which can be extended even into critical industries such as pharmaceutical and food industries, have always been overshadowed by its traditionally grown fiber. Therefore, this study aimed to venture into the biotechnological approach in reaping the benefits of kenaf through plant cell suspension culture to maximize the production of kenaf callus biomass (KCB) and exopolysaccharide (EPS), which is deemed to be more sustainable. A growth curve was established which indicates that cultivating kenaf callus in suspension culture for 22 days gives the highest KCB (9.09 ± 1.2 g/L) and EPS (1.1 ± 0.02 g/L). Using response surface methodology (RSM), it was found that sucrose concentration, agitation speed, and naphthalene acetic acid (NAA) concentration can affect the production of KCB and EPS significantly (p
The purpose of this work was to establish the best particle size for recovering high yields of total phenolic compounds (TPC), total anthocyanin compounds(TAC) and total flavonoid compounds (TFC) from roselle (Hibiscus sabdariffa) by applying supercritical carbon dioxide (ScCO2). The extraction rate, diffusivity and solubility of yield in ScCO2 were also studied and calculated utilizing models. Pressure (10 and 30 MPa), temperature (40 and 60 °C), and particle size (250 µm
This study presents an innovative method for synthesizing activated carbon with an exceptionally high surface area (3359 m2 g-1) using kenaf fiber-based biochar through chemical activation. The achieved specific surface area surpasses activated carbon derived from other reported fiber-based precursors. The resulting activated carbon was investigated as electrodes for supercapacitors, revealing a remarkable maximum capacitance of 312 F g-1 at a current density of 0.5 A g-1. An aqueous symmetric supercapacitor employing these high-surface-area electrodes exhibited an outstanding energy density of 18.9 Wh kg-1 at a power density of 250 W kg-1. Notably, the supercapacitor retained exceptional capacitance, maintaining 93% of its initial capacitance even after 5000 charge-discharge cycles.
Kajian ini menilai potensi ekstrak pewarna kaliks Hibiscus Sabdariffa L. (rosel) sebagai bahan sensor. Dalam kajian ini, sensor pH dibangunkan menggunakan ekstrak warna kemerahan semulajadi dalam kelopak rosel, delfinidin-3-sambubiosida yang dipegunkan dalam kertas turas gentian kaca. Dalam larutan bebas, ekstrak rosel dicirikan menggunakan spektrofotometer UL-nampak untuk mengkaji kesan pH, kepekatan ekstrak, masa ransangan keadaan mantap, analisis kebolehulangan dan analisis kestabilan foto. Ekstrak rosel terpegun dicirikan dengan menggunakan spektrofotometer pantulan untuk mengkaji kesan pH, masa ransangan keadaan mantap, analisis kebolehulangan, analisis kestabilan foto dan kajian histerisis. Hasil kajian menunjukkan bahawa ekstrak bahan semulajadi boleh digunakan sebagai bahan sensor dalam pembinaan sensor optik pH.
Kajian ini dijalankan bagi menentukan kesan penambahan kalsium karbonat (CaCO3) dan sukrosa ke atas ekstrak roselle dengan menggunakan Kaedah Respon Permukaan. Sebanyak 21 perlakuan digunakan berdasarkan reka bentuk eksperimen Central Composite Rotatable Design (CCRD). Penentuan nilai pH dan Briks telah dijalankan. Bagi nilai pH, model yang didapati adalah 4.03+0.39x1-8.20x2-0.05x1 2-4.16x2 2-0.02x1x2 dengan nilai x1 adalah kalsium karbonat dan nilai x2 adalah sukrosa. Nilai positif pada kepekatan kalsium menunjukkan penambahan kalsium meningkatkan nilai pH ekstrak roselle. Model untuk Briks adalah 8.91 + 0.23x1 + 2.20x2. Nilai positif pada kepekatan kalsium dan sukrosa menunjukkan penambahan kalsium dan sukrosa meningkatkan nilai Briks ekstrak roselle. Penilaian sensori dengan menggunakan panel terlatih (n=8) menunjukkan penambahan sukrosa meningkatkan penerimaan keseluruhan terhadap ekstrak Roselle. Manakala, kesan penambahan kalsium karbonat telah mengurangkan penerimaan keseluruhan kerana ia merendahkan rasa masam.
Membran selulosa terjana semula (MS) daripada pulpa teras kenaf telah berjaya dihasilkan menggunakan kaedah pra penyejukan dan digumpal menggunakan larutan asid sulfurik. MS disediakan daripada pelarutan selulosa kenaf dalam larutan akues NaOH/urea dan larutan selulosa seterusnya digumpal dengan H2SO4 pada kepekatan 5-12 peratus berat (% bt.) selama 1-10 min. Pengaruh kepekatan penggumpal H2SO4 dan masa penggumpalan ke atas struktur, saiz liang, sifat mekanik dan ketelusan cahaya MS telah dikaji menggunakan pembelauan sinar-X (XRD), imbasan mikroskop elektron tekanan boleh ubah (VPSEM), penguji regangan dan spektrofotometer ultra-violet sinar tampak (UV-vis). Keputusan VPSEM menunjukkan perubahan saiz liang membran bergantung kepada kepekatan larutan penggumpal H2SO4, manakala masa penggumpalan tidak mempengaruhi saiz liang membran. Membran yang direndam dengan larutan penggumpal pada kepekatan 10 % bt. dan masa pembekuan yang sederhana iaitu 5 min menunjukkan sifat mekanik yang lebih baik dengan nilai kekuatan regangan masing-masing 41.9 dan 43.5 MPa. Oleh itu, kajian ini dapat memberikan maklumat mengenai penyediaan MS dengan pelbagai saiz liang dan sifat mekanik dengan pengubahsuaian kepekatan dan masa penggumpalan.
Cellulosic fibers from kenaf bast were isolated in three distinct stages. Initially raw kenaf bast fibers were subjected to an alkali pulping process. Then pulped fibers undergone a bleaching process and finally both pulped and bleached fibers were separated into their constituent nanoscale cellulosic fibers by mechanical shearing. The influence of each treatment on the chemical composition of fibers was investigated. Moreover morphology, functional groups, crystallinity, and thermal behavior of fiber hierarchy at different stages of purification were studied using scanning and transmission electron microscopies, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA), respectively. Microscopy studies revealed that applied procedures successfully isolated nanoscale cellulosic fibers from both unbleached and bleached pulps. Chemical composition analysis and FTIR spectroscopy showed that lignin and hemicellulose were almost entirely removed by the applied treatments. XRD and TGA analyses demonstrated progressive enhancement of properties in fibers, hierarchically, in going from micro to nano scale. Interestingly no significant evolution was observed between obtained data of characterized ubnleached and bleached nanofibers.
Extraction of lignin via green methods is a crucial step in promoting the bioconversion of lignocellulosic biomasses. In the present study, utilisation of natural deep eutectic solvent for the pretreatment of kenaf fibres biomass is performed. Furthermore, extracted lignin from natural deep eutectic solvent pretreated kenaf biomass was carried out and its comparative study with commercial lignin was studied. The extracted lignin was characterized and investigated through Infrared Fourier transform spectroscopy, X-ray Diffraction, thermogravimetric analysis, UV-Vis spectroscopy, and scanning electron microscopy. FTIR Spectra shows that all samples have almost same set of absorption bands with slight difference in frequencies. CHNS analysis of natural deep eutectic solvent pretreated kenaf fibre showed a slight increase in carbon % from 42.36 to 43.17% and an increase in nitrogen % from - 0.0939 to - 0.1377%. Morphological analysis of commercial lignin shows irregular/uneven surfaces whereas natural deep eutectic solvent extracted lignin shows smooth and wavy surface. EDX analysis indicated noticeable peaks for oxygen and carbon elements which are present in lignocellulosic biomass. Thermal properties showed that lignin is constant at higher temperatures due to more branching and production of extremely condensed aromatic structures. In UV-VIS spectroscopy, commercial lignin shows slightly broad peak between 300 and 400 nm due to presence of carbonyl bond whereas, natural deep eutectic solvent extracted lignin does not show up any peak in this range. XRD results showed that the crystallinity index percentage for kenaf and natural deep eutectic solvent treated kenaf was 70.33 and 69.5% respectively. Therefore, these innovative solvents will undoubtedly have significant impact on the development of clean, green, and sustainable products for biocatalysts, extraction, electrochemistry, adsorption applications.
In this study, microcrystalline cellulose (MCC) was extracted from roselle fiber through acid hydrolysis treatment and its properties were compared with those of commercially available MCC. The physicochemical and morphological characteristics, elemental composition, size distribution, crystallinity and thermal properties of the obtained MCC were analyzed in this work. Fourier transform infrared spectroscopy (FTIR) analysis provided clear evidence that the characteristic peak of lignin was absent in the spectrum of the MCC prepared from roselle fiber. Rough surface and slight aggregation of MCC were observed by scanning electron microscopy (SEM). Energy dispersive X-ray (EDX) analysis showed that pure MCC with small quantities of residues and impurities was obtained, with a similar elemental composition to that of commercial MCC. A mean diameter of approximately 44.28μm was measured for MCC by using a particle size analyzer (PSA). X-ray diffraction (XRD) showed the crystallinity increased from 63% in roselle pulp to 78% in roselle MCC, the latter having a slightly higher crystallinity than that of commercial MCC (74%). TGA and DSC results indicated that the roselle MCC had better thermal stability than the roselle pulp, whereas it had poorer thermal stability in comparison with commercial MCC. Thus, the isolated MCC from roselle fibers will be going to use as reinforcing element in green composites and may be a precursor for future roselle derived nanocellulose, and thus a promising subject in nanocomposite research.
The recent study focused on lignin-phenol-glyoxal (LPG) as an alternative way to replace toxic formaldehyde used in commercially available wood adhesives. The concern of the uses of carcinogenic formaldehyde in wood adhesive industry has become major problem over human health, environmental and economy issues. In this study, lignin isolated from Kenaf (Hibiscus cannabinus) via soda and Kraft pulping were modified into SLPG (soda lignin-phenol-glyoxal) and KLPG (Kraft lignin-phenol-glyoxal) adhesives and were compared to phenol-formaldehyde (PF). Complementary analyses such as Fourier Transform Infrared (FTIR) spectroscopy, 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy, thermal stability; Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) were utilized to characterize all isolated lignin samples. The physical properties of the resins were further characterized in term of viscosity, gel time and total solid content. It was found that soda lignin comprised higher phenolic OH content and greater molecular weight compared to Kraft lignin. Various molar ratio of adhesives were applied on plywood and were mechanically tested. The 30% (w/w) SLPG has shown to have higher tensile strength and internal bonding stress at 72.08 MPa and 53.83 N mm-2 respectively to that of PF.
Kenaf (Hibiscus cannabinus L.) seed is a non-conventional edible oilseed that can be valorized into various food products. There is a recent discovery of kenaf seed beverage (KSB) potential as a novel plant-based beverage. KSB had less crude protein than soybean (SB)but more carbohydrate, magnesium, and phosphorus contents.Levels of crude fat, phytates, oxalates, total saponins, and lipid peroxidability in KSB were lower than SB. Sugar content between KSB and SB were comparable, while antioxidant properties of KSB were superior. Ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) analysis detected gluconic acid, citric acid, palmitic acid, oleic acid, and 13-hydroxyoctadecadienoic acid in both KSB and SB. Considering its novelty, acute and subacute oral toxicity assessments in male Sprague Dawley rats were conducted. The acute toxicity assessment was performed at a single dose of 9.2 ml/kg body weight of KSB. In the following subacute toxicity assessment, different groups of rats consumed different doses of KSB (3.1, 6.1, and 9.2 ml/kg body weight) daily for 28 days. Rats presented normal behavioral and physiological states in both toxicity studies. Growth, food and water intakes, organ weight, and hematological parameters were unaffected. No mortality was reported. Several alterations in serum biochemical parameters were within the normal range, and unassociated with histopathological changes. The oral lethal dose (LD50) and the no-observed-adverse-effect-level (NOAEL) of KSB in rats was greater than 9.2 ml/kg (=1533 mg/kg) body weight. Interestingly, KSB exhibited comparable effects with soybean beverage (SB) on high-density lipoprotein cholesterol and triglycerides which worth further research Follow-up toxicity assessments in animals and human trials are also recommended to ascertain its long term safety.
Development of strategies for removing heavy metals from aquatic environments is in high demand. Cadmium is one of the most dangerous metals in the environment, even under extremely low quantities. In this study, kenaf and magnetic biochar composite were prepared for the adsorption of Cd2+. The synthesized biochar was characterized using (a vibrating-sample magnetometer VSM), Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption batch study was carried out to investigate the influence of pH, kinetics, isotherm, and thermodynamics on Cd2+ adsorption. The characterization results demonstrated that the biochar contained iron particles that help in improving the textural properties (i.e., surface area and pore volume), increasing the number of oxygen-containing groups, and forming inner-sphere complexes with oxygen-containing groups. The adsorption study results show that optimum adsorption was achieved under pH 5-6. An increase in initial ion concentration and solution temperature resulted in increased adsorption capacity. Surface modification of biochar using iron oxide for imposing magnetic property allowed for easy separation by external magnet and regeneration. The magnetic biochar composite also showed a higher affinity to Cd2+ than the pristine biochar. The adsorption data fit well with the pseudo-second-order and the Langmuir isotherm, with the maximum adsorption capacity of 47.90 mg/g.
Roselle is an annual botanical plant that widely planted in different countries worldwide. Its different parts, including seeds, leaves, and calyces, can offer multi-purpose applications with economic importance. The present review discusses the detailed profile of bioactive compounds present in roselle seeds, leaves, and calyces, as well as their extraction and processing, to explore their potential application in pharmaceutical, cosmetic, nutraceutical, food and other industries. Roselle seeds with high phenolics, fiber, and protein contents, which are suitable to use in functional food product development. Besides, roselle seeds can yield 17-20% of roselle seed oil with high content of linoleic acid (35.0-45.3%) and oleic acid (27.1- 36.9%). This unique fatty acid composition of roselle seed oil makes it suitable to use as edible oil to offer the health benefits of essential fatty acid. Moreover, high contents of tocopherols, phenolics, and phytosterols were detected in roselle seed oil to provide nutritional, pharmaceutical, and therapeutic properties. On the other hand, roselle leaves with valuable contents of phenols, flavonoids, organic acid, and tocopherols can be applied in silver nanoparticles, food product development, and the pharmaceutical industry. Roselle calyces with high content of anthocyanins, protocatechuic acids, and organic acids are widely applied in food and colorant industries.
Roselle (Hibiscus sabdariffa L.) seed is a valuable food resource as it has an excellent source of dietary fibre. Therefore, this study examined the functional properties of roselle seeds. Replacement of cookie flour with roselle seed powder at levels of 0-30 % was investigated for its effect on functional and nutritional properties of cookies. Among the four formulations cookies, the most preferred by panelists was 20 % roselle seed powder cookie (F3), followed by 10 % roselle seed powder cookie (F2) and 30 % roselle seed powder cookie (F4). The least preferred formulation among all was control cookie (F1). Cookie with 20 % roselle seed powder added showed higher content of total dietary fibre (5.6 g/100 g) as compared with control cookie (0.90 g/100 g). Besides that, cookies incorporated with roselle seed powder exhibited improved antioxidant properties. Thus, roselle seed powder can be used as a dietary fibre source and developed as a functional ingredient in food products.
Fiber composites are known to have poor through-thickness mechanical properties due to the absence of a Z-direction binder. This issue is more critical with the use of natural fibers due to their low strength compared to synthetic fibers. Stitching is a through-thickness toughening method that is used to introduce fibers in the Z-direction, which will result in better through-thickness mechanical properties. This research was carried out to determine the mechanical properties of unstitched and silk fiber-stitched woven kenaf-reinforced epoxy composites. The woven kenaf mat was stitched with silk fiber using a commercial sewing machine. The specimens were fabricated using a hand lay-up method. Three specimens were fabricated, one unstitched and two silk-stitched with deferent stitching orientations. The results show that the stitched specimens have comparable in-plane mechanical properties to the unstitched specimens. For the tensile mechanical test, stitched specimens show similar and 17.1% higher tensile strength compared to the unstitched specimens. The flexural mechanical test results show around a 9% decrease in the flexural strength for the stitched specimens. On the other hand, the Izod impact mechanical test results show a significant improvement of 33% for the stitched specimens, which means that stitching has successfully improved the out-of-plane mechanical properties. The outcome of this research indicates that the stitched specimens have better mechanical performance compared to the unstitched specimens and that the decrease in the flexural strength is insignificant in contrast with the remarkable enhancement in the impact strength.
The aim of this study was to investigate the oxidative stability, antioxidant activity and fatty acid composition of 2 minutes microwave pre-treated kenaf seed oil (MKSO) in comparison with the untreated kenaf seed oil (KSO) under accelerated storage for 24 days. Results obtained on oxidative stability for both KSO and MKSO by the end of storage with PV were 9.83 meq O2 /kg and 8.97 meq O2 /kg, respectively; p-Anv were 17.28 and 13.48, respectively; TOTOX value of 36.94 and 31.42, respectively; IV value were measured 84.50 g of I2 / 100 g and 84.34 g of I2 / 100 g oil, respectively; FFA value of 5.67 mg KOH/100g oil and 5.14 mg KOH/100g oil, respectively. Aside from that, the antioxidant activity in MKSO was better than KSO. For the fatty acid composition, the oleic and linoleic acids were affected significantly throughout storage for both KSO and MKSO. MKSO presented a better overall oxidative stability, antioxidant activity and retained higher content of MUFA and PUFA significantly (p< 0.05) upon accelerated storage.
A hybrid composite consisting of untreated kenaf fibre and glass fibre was investigated by varying the fibre glass weight ratios and using interply fabrication method. The expected results were to have better composite performance in terms of its toughness and impact strength as a comparison between the hybrid (kenaf/E-glass fibre composites) and E-GF composites alone. For the purpose of this study, all the samples were prepared using typical sample preparation. Results show that the incorporation of E–glass fibre resulted in brittle failure and a higher amount of E-Glass fibre with low percentage of kenaf fibre causing high strength, low ductile, and low toughness behaviours.