Dissolution of superheated steam-treated oil palm biomass fiber in ionic liquid for the production of electrospun nanofiber

The use of ionic liquid has been considered as the emerging method for cellulose processing. In the production of electrospun nanocellulose fiber, dissolution of cellulose in solvent is important in order to ensure the formation of good nanofiber. In this study, oil palm biomass fiber was used for the production of nanofiber. Superheated steam (SHS) treatment was conducted at 260°C for 30 minutes followed by delignification using NaClO3 in order to remove hemicellulose and lignin. Control cellulose sample was prepared by treating the oil palm biomass with KOH and NaClO3. Cellulose obtained was dissolved in combined ionic liquids (IL): 1-ethyl-3-methylimidazolium acetate and 1-decyl-3-methylimidazolium chloride. Effects of cellulose dissolution in different concentrations were also evaluated. Electrospun nanocellulose fiber was successfully obtained by dissolution of SHS-treated oil palm biomass cellulose in the combined ILs. It was found that fiber diameter, morphological structure and spinnability of the nanofiber obtained were greatly influenced by lignin and hemicellulose content. This study revealed the possibility of utilizing lignocellulose from oil palm biomass treated with non-toxic chemicals for nanofiber production. Moreover, it represents a step forward into the search for environmentally friendly methodas an alternative to hazardous chemical pretreatment approach

Factors affecting spinnability of oil palm mesocarp fiber cellulose solution for the production of microfiber

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

Functionality of cellulose nanofiber as bio-based nucleating agent and nano-reinforcement material to enhance crystallization and mechanical properties of polylactic acid nanocomposite

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 (1–6 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–1 was achieved when PLA/CNF3 was isothermally melt crystallized at 100 °C. The crystallization rate was 65-fold higher as compared to the neat PLA (0.011 min–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’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

Static mechanical, thermal stability, and interfacial properties of superheated steam treated oil palm biomass reinforced polypropylene biocomposite

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 SHStreated 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

Characterization of polyethylene nanocomposite prepared by one-pot extrusion method

This study attempts to produce polyethylene (PE) nanocomposites reinforced with cellulose nanofiber (CNF) derived from oil palm mesocarp fibers (OPMF). Unlike other polymers, PE has always been underestimated and it was extensively been used as packaging products. Therefore, instead of being continuously used for the manufacturing of low-value products, the prospect of PE for the manufacturing of high-end products should be identified. In order to do so, the properties of PE needs to be improved and one of the possible method to improve the properties of PE is by reinforcing CNF during composite processing stage. Most conventional methods however required two separated processing; nanofibrillation and composite fabrication. In this study, cellulose extracted from OPMF was nanofibrillated and subsequently fabricated into PE matrix by one-pot extrusion method. Results obtained from this study showed that nanocomposites prepared by one-pot extrusion recorded 57, 93, 198, and 25% higher for tensile strength, Young’s modulus, flexural strength and flexural modulus, respectively compared to the neat PE. This study hence proved that one-pot extrusion method is able to produce nanocomposite with better mechanical properties compared to the neat PE

Melt-vs. Non-melt blending of complexly processable ultra-high molecular weight polyethylene/cellulose nanofiber bionanocomposite

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 °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’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’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 ± 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

Superheated steam pretreatment of cellulose affects its electrospinnability for microfibrillated cellulose production

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

Production of biochar from oil palm frond by steam pyrolysis for removal of residual contaminants in palm oil mill effluent final discharge

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

Emerging development of nanocellulose as an antimicrobial material: An overview

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

Cellulose nanofibers from oil palm mesocarp fiber and their utilization as reinforcement material in low density polyethylene composites

Oil palm mesocarp fiber (OPMF) is made up of mainly cellulose, making it a potentially raw material for microfibrillated cellulose (MFC) and cellulose nanofiber (CNF) production. MFC and CNF properties may be influenced by their production method; it is therefore in this study three different methods were used for the production of MFC and CNF from OPMF: electrospinning, ultrasonication and high pressure homogenization. In electrospinning, cellulose concentration and ionic liquid formulation affected the cellulose solubility, and viscosity; which influenced the properties of the MFC produced. The best MFC was formed when 6% (w/v) OPMF-cellulose was dissolved in ([EMIM]Cl:([C10MIM][Cl]):DMF; whereby MFC with average diameter of 200 to 500 nm, crystallinity of 57% and Td50% at 348 °C was obtained. By using electrospinning, nano-sized fiber (< 100nm) was not obtained, hence, ultrasonication and high pressure homogenization were conducted. Ultrasonication at 125 W and 36 kHz for 9 hours produced mixture of MFC and CNF with non-homogeneous diameter size between 40 – 200 nm, having crystallinity index and Td50% of 41% and 338 C, respectively. Meanwhile, high pressure homogenizationconducted at 50 MPa for 30 passes with cellulose concentration of 0.2% (w/v) resulted in CNF with diameter of 80 – 100 nm, crystallinity index of 62% and Td50% at 353 C. The CNF obtained from high pressure homogenization method was then used as reinforcement material for low density polyethylene (LDPE) composites production. Effect of melt compounding methods on the mechanical properties of nano-sized fiber composites was determined. Composites consisted of low density polyethylene (LDPE), maleic anhydride-grafted PE (PEgMA) and CNF at formulations of 97/3/0.5–5 (wt/wt/wt), respectively, were prepared by twin screw extrusion and internal melt blending processes. Morphology of the composites as revealed by SEM-EDS and X-CT scan showed that the twin screw extrusion process permitted homogeneous dispersion of CNF, thus led to an increment of up to 195% in flexural strength compared to neat LDPE. In contrast, the composites prepared by internal meltblending method showed an agglomeration and heterogeneous dispersion of CNF within LDPE matrix, caused the composites to have lower tensile strength and flexural strength compared to those prepared by twin screw extrusion. CNF-based composites preparation method can be shortened by introducing simultaneous nanofibrillation and melt compounding using one unit operation. Herewith, a onepot process was conducted by using an extruder with specially designed twin screw. FE-SEM micrograph exhibited that the resultant LDPE/CNF composites had CNF with average diameter of 80 – 100 nm. These composites prepared by one-pot process had similar properties with those prepared in conventional twopot process, with the advantage of having higher productivity – by almost doubled. A two-step in one unit operation (2-in-1) would be an ideal process for composites 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 also meets most of the Green Chemistry Principles; suggesting the method as a sustainable and greener method for polymer composites production