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Nanocellulose is a promising nanomaterial that can be used in various applications such as reinforcements for composite films. Agricultural lignocellulosic wastes, such as coconut husks, offer great advantages as raw materials for nanocellulose extraction due to their abundance and economic viability. The aim of this study is to extract nanocellulose from matured coconut husk. Nanocellulose was extracted using sulfuric acid hydrolysis and characterized using Atomic Force Microscopy (AFM). Results showed that nanocellulose extracted from matured coconut husk has 2.26% yield with agglomerated, rod-shaped structures. An average aspect ratio of 3.16 ± 1.82 nm was also obtained.

Materials made from renewable resources offer a promising strategy for reducing environmental problems. Starch is a well-known alternative among several biodegradable materials due to its availability, cheap cost, and degradability. This research aims to develop a degradable film from cassava starch and use citric acid as the crosslinker. Light transmittance measurement reveals that the films produced have high UV barrier capacity in the UV region and above 80% transmittance values in the visible region. Additionally, it was found that the film with 10% citric acid had a favorable balance of tensile strength, elongation, and fracture stress.

Kapok fiber has been known for its hydrophobic-oleophilic characteristics and exhibits a great potential as oil sorbent. Methods in enhancing its hydrophobicity have been explored to improve its sorption performance in oil-in-water applications. This study investigates the oil sorption performance and hydrophobicity of kapok fibers coated with calcium stearate, a known waterproofing agent. The calcium stearate solution was prepared by mixing known amounts of stearic acid and calcium chloride in an ethanol solution. This was followed by hydrolysis using 0.12 M sodium hydroxide solution. The calcium stearate-coated kapok fibers exhibited higher hydrophobicity compared to raw kapok fibers with a water contact angle of ~137°. It achieved the highest oil sorption capacity and reusability of 50 g/g and 65% for viscous motor oil, respectively.

Kapok fibers were used as a filtering medium in a column-type filtration set-up to separate diesel from water molecules in dynamic conditions. The amount of diesel flowing out the filtration system with respect to time was monitored. The times wherein the diesel first came out the filtering system (breakthrough time) were shorter at higher influent concentration and faster flow rate. Meanwhile, the total sorbed diesel molecules in the filtering system were increasing with the influent concentration while invariant with flow rate. The shorter breakthrough time was associated with the higher amount of diesel molecules that could be sorbed at a shorter time and the rate at which the overall processes of sorption-desorption-resorption proceeded. On the other hand, the sorption capacity of the system was viewed to be affected by the amount of moving diesel molecules that would interact with the kapok fibers and/or surface-sorbed diesel molecules but not by the contact time.

We employed a microwave-assisted two-pot in-situ deposition technique to incorporate zinc oxide particulates in the structure of filter paper to produce antimicrobial paper. The process involved successive immersion of filter paper samples in ZnSO4 (precursor solution) and NaOH (precipitating agent) to form Zn(OH)2, which transformed into ZnO during microwave treatment. Successful deposition of ZnO particles on the filter paper was confirmed via X-ray diffraction and the corresponding morphologies were observed using field emission scanning electron microscopy. The ZnO-deposited papers were tested for antimicrobial activity and were found to be more effective against Staphylococcus aureus (gram-positive) than Escherichia coli (gram-negative). Bacterial populations were reduced by up to 92 ± 2% and 57 ± 4% for S. aureus and E. coli, respectively. Also, it was found that the samples prepared using higher concentrations of ZnSO4 and NaOH exhibited better antimicrobial properties.

Copper-based precipitates were synthesized using a straightforward wet chemical reduction method with copper sulfate salts as precursor and L-ascorbic acid as reducing agent. Scanning electron micrographs of the precipitates reveal particle-like structures with edges. The percent age yield was observed to increase with the reaction temperature and the reductant-to-precursor concentration ratio. Comparison of samples prepared at different times showed that the bulk of the precipitates was formed during the first 24 hours. New yield added to the bulk decreased over time. Here, the ascorbic acid served as a capping agent, which impeded the oxidation. This capping was not visible in the electron micrographs but may be inferred from the infrared spectra. Faster capping reduced the amount of oxides in the precipitates. This was seen in samples prepared at a higher temperature and with a lower reductant-to-precursor concentration ratio. Antimicrobial testing under dynamic contact conditions showed that the copper-based precipitates were more effective against Staphylococcus aureus (a gram-positive bacteria) than Escherichia coli (a gram-negative bacteria). Copper-based precipitates collected after the first 24 hours were more potent than those collected after eight days. Furthermore, samples prepared at room temperature and lower reductant-to-precursor concentration ratios were found to be more effective in reducing the number of S. aureus after one hour of contact. The synthesized copper-based precipitates was observed to reduce the population of S. aureus (CFU/mL) by up to 98% after one hour of contact. Keywords: Wet-chemical method, Capping, Antimicrobial, Staphylococcus aureus, Escherichia coli

In this study, hydrophilic kapok papers (KP) with grammage of 60 g m−2 were synthesized by treating naturally hydrophobic kapok fibers with chloroform and sodium chlorite. A hybrid nanocomposite consisting of zinc oxide (ZnO) and polyaniline (PANI) was successively deposited on the hand-made paper. SEM images show nano-size PANI and ZnO particles. XRD results revealed amorphous structure of the PANI with presence of peaks correlating to ZnO. FT-IR showed the change on kapok fibers upon chemical treatment and confirmed the presence of PANI on the synthesized paper. The KP-ZnO-PANI nanocomposite was further applied to test the photocatalytic removal of methyl orange (MO) from aqueous solution under UV irradiation. Results showed that the hybrid nanocomposite could be employed as an adsorbent of MO dye and was 10% more efficient when irradiated under UV light.

This study dealt with the synthesis and characterization of thin transparent conducting films (TCF) from cellulose acetate (CA) blend and polyaniline (PANI). CA was produced from the pulp of abaca hybrid 7. CA-PANI films with different PANI loadings (0, 0.125, 0.25, 0.50, 1.0 and 2.0%) were produced using solvent casting method. Chemical transformations were analyzed using Fourier Transform Infrared (FTIR) spectroscopy. The conductivity was measured using the Four-Point Probe Test. Morphological characterization was done using Scanning Electron Microscopy (SEM). The transparency of the films was determined using UV-Vis Spectroscopy. FTIR spectra proved the embedment of PANI in the CA matrix. It was found that increasing the PANI loading increases the conductivity of the films but up to a certain limit. The highest average conductivity at 2.0264 x 10-5 S/m was observed in CA-PANI films with 0.50% PANI loading. SEM images revealed that conductivity is a function of PANI loading by forming networks. Further addition of PANI (1.0 and 2.0%) resulted to decreased conductivity due to agglomeration. Transparency, on the other hand, is negatively affected by PANI loading.

Nanostructured zinc oxide (ZnO) particles were grown on paper substrate made from Abaca hybrid 7 pulp. Microwave irradiation technique was used at power levels (180 and 540W) and exposure times (5, 10, 20 and 25 minutes). Chemical transformations were observed using Fourier Transform Infrared (FTIR) Spectroscopy. The effects of the power levels and exposure times on the morphology of the nanostructures were determined using scanning electron microscopy. FTIR spectra proved the embedment of ZnO on the paper substrate. Power levels and exposure times affected the distribution, particle size and structure of the ZnO nanoparticles. Higher power level and longer exposure resulted to the formation of more ZnO with larger particles. Grainlike and flowerlike ZnO nanostructures were formed at lower and higher levels, respectively.

Carbonized natural fibers show great promise as sorbents because of their low fabrication costs, high surface area, high sorption capacity, and improved oil selectivity. Pyrolysis was performed on cotton and kapok fiber blends to produce carbon fiber sorbents. The carbon sponges showed improved mechanical properties with the addition of cotton. Pure carbonized kapok fibers were quite brittle, leading to challenges in recovery after use. The static water contact angle of carbonized kapok fibers, carbonized kapok-cotton blend (50K50C), and carbonized cotton fibers were determined to be 137.0°, 135.0°, and 135.9° respectively. This was an observed improvement from 127.9° for raw kapok and 0° for raw cotton. Sorption experiments revealed that the 50K50C fibers have sorption capacities about 25-27 times its original weight at 27.77 g/g, 25.72 g/g, and 26.01 g/g for motor oil, palm oil, and diesel, respectively.

Polyaniline-coated papers were fabricated using two-pot layer-by-layer technique. The process involved successive dipping in monomer-acid and oxidant solutions. The infrared spectra showed vibrational modes associated with the presence of polyaniline molecules and cellulose fibers. The polyaniline-coated papers were observed to have electrical and antimicrobial properties. SEM images showed an interconnected network where charges can flow. Measured AC conductivities varied with the amount and configuration of deposits. The values were higher for samples prepared using a larger acid-to-aniline molar ratio. The polyaniline-coated papers were more effective in reducing S. aureus (gram positive) than E. coli (gram negative) after 1 h of contact. The samples’ ability to reduce these bacterial populations decreased after deprotonation.