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Potato is a widely available feedstock with biocompatibility and biodegradability properties, making it a strong candidate for producing thermoplastic starch. The application of thermoplastic starch to replace petroleum-based plastic as a sustainable and environmentally friendly approach led to its further improvement through various techniques such as modification and filler reinforcement. Numerous studies have been done addressing the properties enhancement of potato thermoplastic starch through filler reinforcement including nanocellulose. This review focus on the recent and future potential of potato-based starch as one of the feedstocks for producing potato thermoplastic starch composites reinforced with nanocellulose.

Despite being one of the starch producers, barley has yet to be widely studied for thermoplastic starch applications, including nanocellulose thermoplastic composites, due to its uses in the food and beverage industries. However, only 20% of barley is used in the malting industry to produce both alcoholic and non-alcoholic beverages, and 5% is used as an ingredient in a wide variety of foods. As the fourth most important cereal in the world after wheat, corn, and rice, barley can be considered an interesting biomass source to produce biodegradable thermoplastics, stemming from its starch constitution. Therefore, this review attempts to highlight the barley starch properties and its potential utilization for nanocellulose thermoplastic starch composites. Several studies involving barley-based starch in thermoplastic production and nanocellulose reinforcement for properties enhancement are also reviewed, particularly in the attempt to provide various options to reduce and replace the uses of harmful petroleum-based plastic.

Biochar is conventionally and widely used for soil amendment or as an adsorbent for water treatment. Nevertheless, the need for transition to renewable materials has resulted in an expansion of biochar for use as a filler for polymer composites. The aim is to enhance the physical, chemical, mechanical and rheological properties of the polymer composite. The reinforcement of biochar into a polymer matrix however is still new, and limited reports are focusing on the effects of biochar towards polymer composite properties. Hence, this review highlights the unique properties of biochar and its effect on the crystallization, thermal, flammability, electrical conductivity, and mechanical properties of polymer composites. This review does not solely summarize recent studies on biochar-polymer-based composites, but also offers insights into a new direction of biochar as a renewable and superior polymer filler in the future.

Pretreatment routes of oil palm biomass.

The prolonged survival of microbes on surfaces in high-traffic/high-contact environments drives the need for a more consistent and passive form of surface sterilization to minimize the risk of infection. Due to increasing tolerance to antibiotics among microorganisms, research focusing on the discovery of naturally-occurring biocides with low-risk cytotoxicity properties has become more pressing. The latest research has centred on nanocellulosic antimicrobial materials due to their low-cost and unique features, which are potentially useful as wound dressings, drug carriers, packaging materials, filtration/adsorbents, textiles, and paint. This review discusses the latest literature on the fabrication of nanocellulose-based antimicrobial materials against viruses, bacteria, fungi, algae, and protozoa by employing variable functional groups, including aldehyde groups, quaternary ammonium, metal, metal oxide nanoparticles as well as chitosan. The problems associated with industrial manufacturing and the prospects for the advancement of nanocellulose-based antimicrobial materials are also addressed.

The utilization of lignocellulosic biomass in various applications has a promising potential as advanced technology progresses due to its renowned advantages as cheap and abundant feedstock. The main drawback in the utilization of this type of biomass is the essential requirement for the pretreatment process. The most common pretreatment process applied is chemical pretreatment. However, it is a non-eco-friendly process. Therefore, this review aims to bring into light several greener pretreatment processes as an alternative approach for the current chemical pretreatment. The main processes for each physical and biological pretreatment process are reviewed and highlighted. Additionally, recent advances in the effect of different non-chemical pretreatment approaches for the natural fibres are also critically discussed with a focus on bioproducts conversion.

Conventional cellulose-based nanocomposites production requires two separate unit operations for the processing: (i) cellulose nanofibrillation unit, and (ii) polymer nanocomposites compounding unit. This two-unit process could be less efficient in terms of energy usage and material handling compared to a one-unit process. Moreover, the present of downtime in between the two steps may affect the overall productivity of the product. In this study, a one-pot process was adapted for nanofibrillation of oil palm mesocarp fiber (OPMF) cellulose and subsequently compounding of the cellulose nanofiber (CNF) with polyethylene (PE) for composites making. Both of these steps were conducted in an extruder with specially-designed twin screw, to allow nanofibrillation and compounding to occur in the same unit. It was interesting to note that CNF produced had diameter range of 80–100 nm, with an aspect ratio of 260. These superior physical properties have led to the excellent mechanical properties of the PE/OPMF-CNF nanocomposites, whereby PE/OPMF-CNF (3 wt%) recorded an increment of 57 and 198% for tensile strength and flexural strength, respectively, compared to the neat PE. Homogeneous dispersion of CNF in the PE matrix was also observed, suggesting the suitability of the one-pot processing method for cellulose-based nanocomposites production. Overall performance of the nanocomposites was similar to that prepared in a two-pot process; with the one-pot process was almost doubled in the productivity compared to two-pot process. A two-step in one unit operation (2-in-1) would be an ideal process for nanocomposites making as this method may improve productivity, reduce downtime in between the two steps, could contribute to a lower capital and processing costs, and may have lower energy consumption. The one-pot process meets most of the green chemistry principles; suggesting the method as a sustainable and greener method for polymer nanocomposites production.

Polylactic acid (PLA), a potential alternative material for single use plastics, generally portrays a slow crystallization rate during melt-processing. The use of a nanomaterial such as cellulose nanofibers (CNF) may affect the crystallization rate by acting as a nucleating agent. CNF at a certain wt.% has been evidenced as a good reinforcement material for PLA, nevertheless, there is a lack of information on the correlation between the amount of CNF in PLA that promotes its functionality as reinforcement material, and its effect on PLA nucleation for improving the crystallization rate. This work investigated the nucleation effect of PLA incorporated with CNF at different fiber loading (1&ndash, 6 wt.%) through an isothermal and non-isothermal crystallization kinetics study using differential scanning calorimetry (DSC) analysis. Mechanical properties of the PLA/CNF nanocomposites were also investigated. PLA/CNF3 exhibited the highest crystallization onset temperature and enthalpy among all the PLA/CNF nanocomposites. PLA/CNF3 also had the highest crystallinity of 44.2% with an almost 95% increment compared to neat PLA. The highest crystallization rate of 0.716 min&ndash, 1 was achieved when PLA/CNF3 was isothermally melt crystallized at 100 &deg, C. The crystallization rate was 65-fold higher as compared to the neat PLA (0.011 min&ndash, 1). At CNF content higher than 3 wt.%, the crystallization rate decreased, suggesting the occurrence of agglomeration at higher CNF loading as evidenced by the FESEM micrographs. In contrast to the tensile properties, the highest tensile strength and Young&rsquo, s modulus were recorded by PLA/CNF4 at 76.1 MPa and 3.3 GPa, respectively. These values were, however, not much different compared to PLA/CNF3 (74.1 MPa and 3.3 GPa), suggesting that CNF at 3 wt.% can be used to improve both the crystallization rate and the mechanical properties. Results obtained from this study revealed the dual function of CNF in PLA nanocomposite, namely as nucleating agent and reinforcement material. Being an organic and biodegradable material, CNF has an increased advantage for use in PLA as compared to non-biodegradable material and is foreseen to enhance the potential use of PLA in single use plastics applications.

Polypropylene (PP) is the most frequently used plastic in automotive manufacturing. Being a thermoplastic polymer, it can easily be molded into several shapes. Besides that, it has excellent heat and chemical resistance. The current research interest is to improve the PP properties to meet the automotive market demand. Cellulose nanofiber (CNF) has been widely studied as a reinforcement material in biocomposites. Recently, CNF has emerged as a subject of tremendous scientific interest and has attracted a great deal of attention across disciplines. In this study, biocomposites were prepared by the addition of 1–5 wt% CNF into PP using an internal blending technique. There are many factors that influence the properties of biocomposites such as concentration and the effect of drying on CNF. A homogenous dispersion of CNF in the PP matrix was obtained from biocomposites containing 1%–3% of CNF, which increased their tensile and flexural properties. Meanwhile, aggregations of CNF in the PP matrix occurred at a high amount of CNF loading, and freeze-dried prepared biocomposites resulted in the decrease of their mechanical properties. All in all, it is shown that the drying process of CNF can be eliminated in the production of biocomposites. Therefore, this proved that the biocomposites of PP/CNF are useful as automotive compartments with improved mechanical properties over neat PP.

The major hurdle in melt-processing of ultra-high molecular weight polyethylene (UHMWPE) nanocomposite lies on the high melt viscosity of the UHMWPE, which may contribute to poor dispersion and distribution of the nanofiller. In this study, UHMWPE/cellulose nanofiber (UHMWPE/CNF) bionanocomposites were prepared by two different blending methods: (i) melt blending at 150 &deg, C in a triple screw kneading extruder, and (ii) non-melt blending by ethanol mixing at room temperature. Results showed that melt-processing of UHMWPE without CNF (MB-UHMWPE/0) exhibited an increment in yield strength and Young&rsquo, s modulus by 15% and 25%, respectively, compared to the Neat-UHMWPE. Tensile strength was however reduced by almost half. Ethanol mixed sample without CNF (EM-UHMWPE/0) on the other hand showed slight decrement in all mechanical properties tested. At 0.5% CNF inclusion, the mechanical properties of melt-blended bionanocomposites (MB-UHMWPE/0.5) were improved as compared to Neat-UHMWPE. It was also found that the yield strength, elongation at break, Young&rsquo, s modulus, toughness and crystallinity of MB-UHMWPE/0.5 were higher by 28%, 61%, 47%, 45% and 11%, respectively, as compared to the ethanol mixing sample (EM-UHMWPE/0.5). Despite the reduction in tensile strength of MB-UHMWPE/0.5, the value i.e., 28.4 &plusmn, 1.0 MPa surpassed the minimum requirement of standard specification for fabricated UHMWPE in surgical implant application. Overall, melt-blending processing is more suitable for the preparation of UHMWPE/CNF bionanocomposites as exhibited by their characteristics presented herein. A better mechanical interlocking between UHMWPE and CNF at high temperature mixing with kneading was evident through FE-SEM observation, explains the higher mechanical properties of MB-UHMWPE/0.5 as compared to EM-UHMWPE/0.5.

In this study, three types of oil palm biomass (OPB) namely, oil palm mesocarp fiber (OPMF), oil palm empty fruit bunch (OPEFB) and oil palm frond (OPF), were studied and compared as the alternative fillers in the biocomposite reinforced polypropylene (PP). The fibers were treated using the optimal condition of superheated steam treatment obtained from previous study. The OPB/PP biocomposites at weight ratio of 30:70 were fabricated by melt blending technique and hot pressed moulding. Results showed that the tensile and flexural properties of optimized-SHS-treated OPB/PP biocomposites were improved by 9 – 30% and 9 – 12%, respectively compared to the untreated OPB/PP biocomposites. The same observation was recorded for thermal stability. Improved surface morphology as shown by the tensile fracture surface indicates better interfacial adhesion between SHS-treated OPB fibers with PP matrix during blending. Overall results showed that OPF/ PP biocomposites had better properties compared to biocomposites prepared from OPMF and OPEFB, suggesting that OPF is a better OPB fiber choice as a filler in PP reinforced biocomposite.

Waste paper is the second-highest municipal solid waste collected in Malaysia and as current practice, it is recycled for further use in the manufacturing of low-grade products. Instead of continuously utilizing waste paper for low-grade products manufacturing, it can be used as a feedstock to produce high bioproducts such as cellulose nanofiber (CNF). Hence, this study explored the potential of waste paper as a feedstock for CNF production. The waste paper was subjected to a different number of cycles of wet disk milling (WDM): 0, 5, 10, 15 and 20 cycles. The presence of nano-sized cellulose was confirmed by FE-SEM micrographs, where CNF with diameter size 20 – 40 nm was formed after 10 cycles of milling. It was also revealed that the obtained CNF possessed appropriate properties as a reinforcement material. The tensile strength and Young’s modulus of poly((R)-3-hydroxybutyrate-co- (R)-3-hydroxyhexanoate (PHBHHx) increased by 19 and 12%, respectively after the reinforcement of 1% CNF. Overall, this study portrays that waste paper could be utilized as a raw material for CNF production, without the need for chemical pretreatment.

The use of nanocellulose composites in biomedical applications is highlighted in this chapter. Nanocellulose composites hold great promise in a wide variety of biomedical applications; these include pharmaceuticals, wound dressings and skin substitutes, cardiovascular applications, orthopedics, dental, as well as ophthalmologic applications. The versatility of nanocellulose and its excellent properties—biocompatibility, high mechanical strength, good flexibility and elasticity, low toxicity, shear-thinning properties, and ability to swell and hold water—enable it to be used in various biomedical applications. Despite its advantages, further studies should aim to investigate different effects of the three types of nanocellulose (bacterial nanocellulose [BNC], cellulose nanocrystals [CNC], and cellulose nanofibers [CNF]) on the respective biomedical applications. This will indirectly pave the way for greater acceptance of nanocellulose as a commercially available nanomaterial in biomedical applications.

Currently, the harmful gas emission, rapid climate change, air and water pollution, and deterioration of earth's land surface are mainly produced by the aggressive utilization of petroleum-based plastic and the unmanaged garbage disposal including dumping and burning of polymeric products and substances. Many experts from throughout the globe revealed that the dumping of petroleum-based plastic and undecomposed materials is the main principle problem of environmental pollution. Hence, in order to overcome these challenging issues, biopolymers, such as starch, cellulosic-based polymer, and other biodegradable materials, are considered the most promising materials and as alternatives to non-biodegradable petroleum-based materials. This is due to their long shelf life properties such as resistance to enzymatic or chemical reaction and as they are biodegradable in nature. Starch is an abundantly available, highly biodegradable, cheap, and renewable biopolymer. However, some studies have found that the properties of starch biopolymer such as mechanical and water barrier are comparatively low than petroleum-based plastic. Therefore, nanofillers such as nanocellulose are introduced in order to overcome this issue. Nanocellulose has attracted huge attention due to its good physical and mechanical behaviors. In recent years, nanocellulose has also attracted the interest among researchers, since the technology capable to cater the environmental issues. This chapter explains the outline of current development in this particular field, including the isolation, characterization, behaviors, and various applications of nanocellulose reinforced starch biopolymer nanocomposites. Followed by explaining the distinctive properties of nanocellulose and its numerous preparation methods, an arranged introduction of various sources of nanocellulose reinforced biodegradable starch polymers is provided. Herein, nanocellulose reinforced starch biopolymer for engineering and interdisciplinary applications, comprising approaches for the transformation of various sources of cellulose to nanocellulose, and the technique of fabrication for their composites have been studied. Furthermore, the results of nanocellulose on the behavior of starch biopolymers are presented. Finally, the chapter summarizes with a new finding and innovation researches on nanocellulose reinforced starch biopolymer composites. In certain circumstances, an evaluation study was conducted between cellulose nanofiber and cellulose nanocrystals reinforced starch biodegradable polymers. Considering the vast amount of research on nanocellulose reinforced starch biopolymer composites, special highlights on such composites are allowed at the end of the review.

In this study, oil palm mesocarp fiber (OPMF) was pretreated with (1) superheated steam (SHS) and (2) potassium hydroxide (KOH) to remove hemicellulose. Both SHS–OPMF and KOH–OPMF underwent delignification step to isolate the cellulose and dissolved in selected ionic liquid and its co-solvent before being electrospun to obtain microfibrillated cellulose (MFC). FE-SEM images showed that SHS–OPMF cellulose produced discontinuous MFC fiber with diameter ranging from 100 to 500 nm, of which 15.5% were in the range of 100–200 nm; while KOH–OPMF cellulose produced continuous MFC with sizes larger than 200 nm. The differences in fiber size and continuity of fiber produced were due to incomplete removal of hemicellulose from SHS–OPMF sample that inhibited fiber re-coalescence and resulted in interruption in fiber formation.

In order to meet the growing demand for adsorbents to treat wastewater effectively, there has been increased interest in using sustainable biomass feedstocks. In this present study, the dermal tissue of oil palm frond was pyrolyzed with superheated steam at 500 °C to produce nanoporous biochar as bioadsorbent. The effect of operating conditions was investigated to understand the adsorption mechanism and to enhance the adsorption of phenol and tannic acid. The biochar had a microporous structure with a Brunauer-Emmett-Teller surface area of 422 m2/g containing low polar groups. The adsorption capacity of 62.89 mg/g for phenol and 67.41 mg/g for tannic acid were obtained using 3 g/L biochar dosage after 8 h of treatment at solution pH of 6.5 and temperature of 45 °C. The Freundlich model had the best fit to the isotherm data of phenol (R2 of 0.9863), while the Langmuir model best elucidated the isotherm data of tannic acid (R2 of 0.9632). These indicated that the biochar-phenol interface was associated with a heterogeneous multilayer sorption mechanism, while the biochar-tannic acid interface had a nonspecific monolayer sorption mechanism. The residual concentration of 26.3 mg/L phenol and 23.1 mg/L tannic acid was achieved when treated from 260 mg/L three times consecutively with 1 g/L biochar dosage, compared to a reduction to 72.3 mg/L phenol and 69.9 mg/L tannic acid using 3 g/L biochar dosage in a single treatment. The biochar exhibited effective adsorption of phenol and tannic acid, making it possible to treat effluents that contain varieties of phenolic compounds.

Advances in biochar production and modification have extended the applications of biochar to wastewater treatment. However, not all feedstocks produced porous biochar at a moderate temperature suitable for wastewater treatment. In this study, biochar was produced from oil palm frond using steam pyrolysis at 500 °C and pulverized to granular and micro-fine particles. Both biochar particles were characterized and applied as adsorbents for treating final discharge of palm oil mill effluent. The effluent was also filtered and treated to examine the effect of suspended solids on adsorption capacity. The biochar had Brunauer-Emmett-Teller surface area of 406.6 m2 g−1. Pulverization eliminated the residual macropores in granular biochar, created new external surface area, and exposed constricted nanopores, which resulted in increasing the surface area to 457.7 m2 g−1. The adsorption capacity decreased from 24.6 to 6.1 mg g−1 for chemical oxygen demand and 49.0 to 10.9 Pt–Co g−1 for color by increasing the dosage of micro-fine biochar from 5 to 30 g L−1. The total suspended solids affected the adsorption capacity of granular biochar by blocking residual macropores that provide access to adsorption sites in micropores and mesopores. At 30 g L−1, the micro-fine biochar exhibited an effective reduction of chemical oxygen demand from 224 to 41.6 mg g−1 and color from 344 to 15 Pt–Co g−1 making the wastewater suitable for reuse in palm oil mills and safe for discharge into the aquatic environment.

Conventional aerobic treatment of facultatively treated palm oil mill effluent (POME) containing phenolic compounds such as phenol, encounters difficulty because of microbial inhibition. In this study, adsorption of phenol in facultatively treated POME was proposed as a solution for mitigating the inhibition. Low-cost biochars produced from oil palm frond using nitrogen or steam pyrolysis at 600 °C were characterized and investigated for efficient and effective removal of phenol. Nitrogen and steam pyrolysis yielded mesoporous biochars with Brunauer–Emmett–Teller surface area of 368.4 m2/g and 461.3 m2/g respectively. Within 8 h, steam-derived biochar attained equilibrium capacity of 59.6 mg/L in distilled water, which decreased to 18.5 mg/L in facultatively treated POME. Steam-derived biochar exhibited slightly higher adsorption capacity for phenol in facultatively treated POME due to higher surface area, wider nanopore size distribution, a larger volume of mesopores and a stronger affinity for phenol. More than 90% of phenol was removed using 16–20 g/L dosage, yielding a facultatively treated POME with 0% inhibition to aerobic microbial growth. Overall, low-cost biochar produced from oil palm frond can be used as an efficient and effective adsorbent for adsorbing phenol in facultatively treated POME to enhance the performance of aerobic treatment system.

The use of biodegradable polymers for food packaging material is favorable due to its ability to degrade after use. Nevertheless, the real application of the polymers is still limited due to its poor physical properties. Polylactic acid (PLA) is one of the biodegradable polymers commonly used for packaging. Recently, there have been reports on the use of nanocellulose as filler in polylactic acid (PLA) for improving the mechanical properties of PLA; however, it has limitation in which non-uniform dispersion of nanocellulose is formed within the polymer during melt-blending. Uniform dispersion can be obtained through solvent casting method; nevertheless, it is not industrially applicable. In this study, a one-pot process was developed where nanofibrillation of cellulose and subsequently melt-blending of the nanocellulose with PLA were conducted in a twin-screw extruder. Results showed that nanocomposite reinforced with 3 and 5 wt% cellulose nanofiber (CNF) exhibited higher tensile strength and Young’s modulus compared to neat PLA. Crystallinity of the polymer increased by 43% with the addition of 5 wt% CNF. Meanwhile, wettability of the polymer was also improved as seen by the reduction in contact angle value. Results obtained exhibited the potential of the composite films to be used in packaging material, especially for high respiration products.

Cellulose microfiber (MF) formation by electrospinning is affected by several factors. In this paper, fabrication of MF from oil palm mesocarp fiber (OPMF), a biomass residue abundantly available at the palm oil mill, was conducted by electrospinning. The effect of OPMF-cellulose solution properties on the spinnability of the solution was determined. Extracted cellulose from OPMF was dissolved in four different formulations of ionic liquids: (i) ([EMIM]Cl), (ii) ([EMIM][Cl):DMF, (iii) ([EMIM]Cl):([C10MIM][Cl]), and (iv) ([EMIM]Cl):([C10MIM][Cl]):DMF at cellulose concentrations of 1% to 9% (w/v). Scanning electron microscopy (SEM) analysis showed that MF formed had diameter sizes ranging from 200 to 500 nm. MF was formed only at 6% (w/v) cellulose concentration, when DMF was mixed in the solution. The results showed that cellulose concentration and viscosity played major roles in the spinnability of cellulose solution, in which too high viscosity of the cellulose solution caused failure of the electrospinning process and eventually affected the formation of MF. The characteristics of MF obtained herein suggest the potential of OPMF cellulose as a starting material for the production of MF.

Oil palm mesocarp fiber (OPMF) is rich in cellulose and suitable to be used as raw material for the production of cellulose nanofiber (CNF) and biocomposite. Recently, there have been reports on the use of CNF as filler in polypropylene (PP) for improving the mechanical properties of PP, however the process requires two steps: (i) nanofibrillation for CNF production and (ii) biocomposite compounding. In this study, a one-pot process was developed whereby nanofibrillation of cellulose and subsequently melt-blending of the CNF with PP were conducted at once, in a twin-screw extruder. Morphological analysis of the biocomposites by SEM showed that the cellulose was successfully fibrillated into CNF and compounded homogeneously with PP. The highest tensile strength, Young's modulus, flexural strength, and flexural modulus recorded were 34.9 ± 0.5 MPa, 12.1 ± 0.1 GPa, 59.3 ± 1.3 MPa, and 2.3 ± 0.05 GPa, respectively when 3 % CNF was used in the biocomposite. The reinforcement of CNF-OPMF in PP improved the mechanical properties of the biocomposite by 33.4 % compared to neat PP. It is interesting to note that the addition of CNF managed to improve the crystallinity of the biocomposite (54.6 %) compared to neat PP (50.1 %), despite of the lower crystallinity of CNF compared to PP. This observation can be attributed to the high density of covalent bonds per cross-sectional area and the large number of hydrogen bonding sites. Additionally, the observation can be explained by the role of CNF in composite which acted as nucleation agent, which eventually increased the crystallinity of the biocomposite.

Oil palm mesocarp fibre (OPMF) is one of the major biomass generated from palm oil industry and it is currently inefficiently burnt at palm oil mill for energy and as a mean of disposal. With the growing concern on environmental sustainability and finite supply of non-renewable resources, particular attention has been given to produce value-added materials from OPMF, such as biocomposite and biocompost. Since OPMF contains mainly cellulose, there is high potential for the production of cellulose nanofiber (CNF) from OPMF. In this study, cellulose was obtained from OPMF by chemical extraction. OPMF-cellulose obtained was then soaked in distilled water [0.2 - 1% (w/v)] prior to nanofibrillation using an ultrasonicator at 125 W and 36 kHz for 3 to 12 hours. Scanning electron microscopy (SEM) micrographs of fiber undergone ultrasonication confirmed the occurrence of CNF having diameter in the range of 40-200 nm. CNF produced had crystallinity value in the range of 31-43%, and was thermally stable up to 340 °C.