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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.

Stable electronic configuration between the interface of an n-type oxide semiconductor core and a p-type polymer shell is necessary in order to guarantee a consistent functioning core-shell structure. This research aims to use silane-aniline to link between an n-type Titanium (IV) oxide (TiO2) core and p-type polyaniline emeraldine salt (PANI-ES) shell. Core-shell structure was created by functionalizing TiO2 powders with silane aniline molecules using simple soaking technique and then polymerizing the attached aniline molecules using an oxidative technique. Infrared spectroscopy reveals the presence of Si-O bonds signifying the presence of linkage between the inorganic core and polymeric shell. Polymerization of the attached aniline molecules may have led to coupling of aromatic rings to form long polymeric structures which caused widening and shifting of aromatic rings’ IR peak to lower wavenumber. In conclusion, silane-aniline was successfully utilized to connect the n-type TiO2 core and p-type PANI-ES shell.

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.

Superhydrophobic oil sorbent was prepared by coating raw kapok fibers with titanium dioxide (TiO2) nanoparticles, followed by surface modification with 1H, 1H, 2H, 2H-perfluorooctyl-triethoxysilane (PTES). The TiO2 nanoparticles exhibited an anatase structure as confirmed by X-ray diffraction. Clusters of TiO2 nanoparticles were observed on the surface of the kapok fibers after hydrothermal process. On the other hand, Fourier transform infrared (FTIR) spectroscopy confirmed the effective attachment of PTES onto the TiO2-based kapok nanocomposite after surface modification. Maximum oil sorption capacities of modified kapok fibers were investigated using diesel, gasoline, chloroform and vegetable oil. The maximum sorption capacities were 44.78, 39.48, 61.94, and 72.79 g/g, respectively. This shows that the PTES modified kapok-TiO2 nanocomposite is very promising oil sorbent.

Polyaniline-zinc oxide composite on Kapok paper were fabricated for methylene blue dye removal in aqueous solution. Kapok fibers were fabricated into papers. The fabricate paper served as substrate for the zinc oxide-polyaniline composite. Zinc oxide particles were deposited on the Kapok paper using an in-situ method while polyaniline molecules are deposited on paper using Successive Ionic Layer Adsorption and Reaction (SILAR) method. The polyaniline molecules were deprotonated using sodium hydroxide (NaOH) to be able adsorb cationic dyes in aqueous solution. The samples were characterized using scanning electron microscope (SEM), energy dispersive X-ray (EDX) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Results show that the deprotonated polyaniline nanocomposite was able to remove at about 75% more dye compared to the as-synthesized polyaniline nanocomposite.

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.

In this study, conducting polyaniline (PANI) Emeraldine salt molecules were coated on polyethylene (PE) board using successive ionic layer adsorption and reaction (SILAR) technique. The number of dipping cycles were varied and the surface conductivity of the samples were measured using four-point probe technique. Fourier Transform Infrared (FTIR) spectroscopy was also done to verify the identities of the coated samples. Results show that PANI Emeraldine salt was successfully coated on PE board as indicated by the peaks of FTIR spectra. Surface conductivity of the PANI Emeraldine salt coated PE board increases with increased number of dipping cycles due to increases interconnectivity of PANI molecules. The conductivity decreases after reaching an optimum point at 80 dipping cycles due to either hindrance of movement of charges or the breaking away of chunks of PANI molecules. These results opens up several applications such as memory devices and erasable circuit boards.

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.

In this study, polyaniline on silane-functionalized zinc oxide was fabricated. The zinc oxide particles were functionalized by soaking in silane aniline-ethanol solution. Afterwhich, the polyaniline was polymerized on the grafted silane aniline molecules using oxidative polymerization. The FTIR spectra showed vibrational peaks associated with the silane aniline molecules and grafted polyaniline. The sampled soaked in silane aniline coupling agent showed FTIR peaks associated with grafted silane aniline. The sample soaked for one minute showed FTIR peaks associated with ortho-coupled aniline units that is formed during the start of aniline polymerization. The sample soaked for three minutes showed FTIR peaks that is broader compared to others due to ring vibration in long polymeric chain.

Cotton fabric was coated with polyaniline molecules using Successive Ionic Layer Adsorption and Reaction (SILAR) technique. This method provides layer by layer deposition of polyaniline molecules. Infrared spectrum showed the vibrational peaks attributed with the presence of polyaniline molecules on the samples. Four-point probe measurements were done to obtain the surface conductivity of the samples. Upon increasing the dipping cycles, the conductivity of cotton fabric significantly increases. The optimum number of dipping cycle is found to be at 130. Beyond the optimum dipping cycle, the conductivity starts to decrease.

Polyaniline emeraldine salt (PAni-ES) was successfully deposited on paper through layer-by-layer technique. In this method, a paper was alternately dipped in aniline monomer and an oxidizing agent for different dipping cycles. This process produced green PAni-ES on paper. The morphology of the samples showed polymeric networks with pores, fiber-like structures and aggregates. There is a transition from frequency-independent to frequency-dependent conductivities of the samples. The conductivity increased with increasing number of dipping cycles. The frequency-dependent conductivities follow the power-law behavior reflecting conducting network and hopping mechanisms. Lastly, the conductivities with frequency followed a scaling behavior reflecting a common physical mechanism in PAni-ES on paper.

CuSO4-deposited and CuO-deposited polyurethane foam (PUF) were fabricated in this study. Image analysis showed color transformation of the PUF from yellow to blue-green, which is indicative of the deposited CuSO4 particles on the substrate. Further color transformation of the material from blue-green to greenish-brown after soaking in NaOH suggest that the CuSO4 oxidized to form CuO, which was confirmed by the presence of CuO peaks during XRD analysis. SEM images also reveal the presence of CuO rods embedded in the PUF. The antibacterial activities of the CuSO4- and CuO-deposited samples against the gram-negative Escherichia coli bacteria were conducted.

In this study, copper sulfate was successfully embedded in filter paper through soaking and copper oxide was successfully embedded in filter paper via in situ technique using the copper sulfate-embedded paper as the starting material. Using color analysis, the filter paper soaked with copper sulfate solution was observed to change color from white to blue, indicating the presence of embedded copper sulfate salts. Furthermore, upon soaking this filter paper with sodium hydroxide solution, the color changed from blue to brown, indicating the presence of copper oxide. X-ray diffraction (XRD) spectroscopy confirms the observed results of the color analysis. Scanning electron microscopy (SEM) and electron dispersive x-ray (EDX) spectroscopy were used to determine the surface morphology and elemental composition of the samples, respectively. The antimicrobial property of the filter paper with copper-based particles was tested against Gram-negative bacterium (Escherichia coli) and Gram-positive bacterium (Staphylococcus aureus), and two species of fungi (Candida albicans and Aspergillus niger) using disc diffusion method. The reactivity of the copper sulfate-embedded filter paper against E. coli was found to be severe, whereas that against S. aureus was moderate. The reactivity of the samples against the two fungi was mild, having a relatively small zone of inhibition. For the copper oxide-embedded paper, the reactivity of the paper to both bacteria was moderate, whereas it shows no reactivity to C. albicans and only a mild reactivity to A. niger. After 60 min of contact with Escherichia coli, both the copper sulfate-embedded and copper oxide-embedded filter papers reduced the amount of colony forming unit to more than 99.9%.

In this study, acid-doped polyaniline-zinc oxide composites were prepared and used to investigate their effect on the removal of methyl orange dye under visible light exposure. The composites were prepared by mixing different volume fractions of polyaniline and ZnO powders. Their effect on the removal of methyl orange was determined through transmittance spectroscopy. Polyaniline-zinc oxide composites of 75% volume fractions showed the highest percent removal of methyl orange. This was attributed to the presence of p-n heterojunctions and adsorption capability of the polyaniline molecules.

Acetate films were coated with polyaniline molecules using the successive ionic layer adsorption and reaction (SILAR) method. In this method, polyaniline molecules are synthesized as they are being coated on the acetate film. Fourier transform infrared (FTIR) spectroscopy shows the existence of molecular vibrations attributed to the presence of polyaniline molecules. A model was created to explain the structures seen in the Scanning Electron Microscopy (SEM) micrographs. A four-point probe measures the surface conductivity of the samples. The surface conductivity was found to significantly increase with more cycles of dipping.

Polyacrylonitrile (PAN)-coated kapok hollow microtubes were synthesized using a facile surfactant-assisted method. Cetyltrimethylammonium bromide (CTAB) was employed to assist in polymer deposition and arrangement. The kapok fibers retained its hollow microtube structure after PAN coating. A drastic decrease in water contact angle from 133.43 to 0° was also determined. Generally, thicker and more uniform PAN coating was achieved at higher concentration of CTAB. On the other hand, addition of larger amount of AN resulted in thicker PAN coating. Batch experiments were utilized to investigate the effect of contact time and temperature on the adsorption efficiency of methyl orange dye and Cu(II) from aqueous solution. Isotherm studies revealed that removal of methyl orange and Cu(II) follow the Langmuir isotherm model, with maximum adsorption capacity of 34.72 and 90.09 mg/g, respectively. This suggests that Cu(II) is preferentially adsorbed on the PAN-kapok fibers over methyl orange. Kinetic studies show that the adsorption of methyl orange and Cu(II) on PAN-kapok follow a pseudo-second order kinetic model, indicating chemisorption as the rate-determining step. Based on thermodynamic data, both Cu(II) and methyl orange adsorption is spontaneous and endothermic.

Polymer-oxide semiconductor exhibits a promising application on electronic devices. In this study, zinc oxide-polyaniline (ZnO-PAni) junctions were constructed which showed a photodiode-like behavior. The junctions were built through connecting the electrodeposited zinc oxide to electrodeposited HCl-doped polyaniline. Without illumination, the junctions exemplify a diode-like behavior (e.g., large amount current at forward-bias while small amount of current at reverse-bias). When illuminated, the junctions exhibit a photodiode-like behavior. In such, the reverse-bias current increases with light intensity.

Hydrophobic surfaces are eyed for their self-cleaning ability because water droplets can roll on them (instead of clinging), thus the surface have capability to remove dirt. Hydrophobic surfaces were created by coating functionalized Titanium Dioxide-based paint. The paint was fabricated by reacting fluorosilane molecules in ethanol with titanium dioxide nanoparticles. Ethanol also serves as the volatile suspension medium that evaporates when the paint is coated on surfaces. The paint was coated on different surfaces by simple dipping. Contact angle of coated aluminum sheet, soda-lime glass, filter paper and silicon carbide polishing paper showed hydrophobicity. Water droplets are made to roll on coated soda-lime glass at angle of 0.057°. The ability of water droplets to roll highlights the coated surface self-cleaning potential.

Many traditional photocatalytic materials such as ZnO and TiO2 are ultraviolet light-triggered due to their wide band gap, however indoor light and sunlight reaching the surface of the earth are in the visible light region. This research aims to fabricate a photocatalytic material that can be triggered using visible light. Ceramic composites with ZnO and CuO interfaces were constructed using heterogeneous mixing technique. The photocatalytic activities of the samples were determined through their ability to degrade methyl orange dye under visible light illumination. Results show that the existence of the ZnO-CuO interface improved the visible light photocatalytic activity of the material.

Hollow tubular structured kapok fibers (Ceiba pentandra) were coated with polyaniline (PANI) molecules using an in situ oxidative polymerization technique. The tubular morphology of the kapok fibers was retained after PANI coating. The Fourier transform infrared (FT-IR) spectrum of the PANI-coated kapok fibers illustrated the vibration modes associated with the presence of PANI molecules. The PANI-treated kapok fibers achieved complete wettability with water molecules (zero water contact angle) from initially being highly hydrophobic (contact angle = 120°). In the present work, the removal of contaminants such as methyl orange dye and Cu(II) from aqueous solution using polyaniline-coated kapok fibers was investigated. Isotherm studies show that the removal of methyl orange dye (R2 ≥ 0.959) and Cu(II) (R2 ≥ 0.972) using PANI-coated kapok fibers follow the Langmuir isotherm model with maximum sorption capacities determined to be 75.76 and 81.04 mg/g, respectively. Based from thermodynamic studies, the sorption of methyl orange dye and Cu(II) are endothermic, feasible and spontaneous. Furthermore, kinetic studies show that the both processes follow a pseudo-second-order model, implying that the rate-determining step is chemisorption.

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.

Copper-based particles were synthesized using an electroless deposition technique. The said synthesis was done in an aqueous solution by reducing copper oxide powders using hydrazine. In this technique, gelatin was used as protective agent. X-ray Diffraction (XRD) measurement shows that the synthesized sample is composed of cuprous oxide (Cu2O) and copper (Cu) particles. Scanning Electron Microscopy (SEM) shows the morphology of the synthesized copper-based particles. Antimicrobial test shows that the number of Escherichia coli organisms reduced to 62.06% after 2 minutes of contact with the sample. Likewise, SEM micrographs of the Escherichia coli organisms show that the said organism underwent morphological changes in the presence of the synthesized copper-based particles.

Hydrophobic surfaces were created by coating various substrates (aluminum sheet, soda-lime glass, silicon carbide polishing paper, glass with double-sided adhesive) with paint containing functionalized oxide particles. The paint was created by functionalizing oxide particles (ground ZnO, TiO2 nanoparticles, or TiO2 microparticles) with fluorosilane molecules in absolute ethanol. Water contact angle of samples shows that the coated substrate becomes hydrophobic (water contact angle ≥ 90°). Among the oxides that were used, ground ZnO yielded contact angle exemplifying superhydrophobicity (water contact angle ≥ 150°). Scanning electron micrograph of paint-containing TiO2 nanoparticles shows rough functionalized oxides structures which probably increase the hydrophobicity of the surface.

Copper sulfate salts were embedded on multipurpose paper using simple soaking technique while copper oxide particles were embedded using in-situ technique. In simple soaking technique, the papers were simply soaked in copper sulfate solution in order for the copper salts to be incorporated in the paper. In the in-situ technique, the copper sulfate-embedded papers were soaked in sodium hydroxide solution for reactions to occur that will lead to the formation of copper oxide. Copper sulfate-embedded papers have blue green color while copper oxide-embedded papers have brown color. The copper sulfate-embedded paper shows excellent antimicrobial property against Staphylococcus aureus. Meanwhile, the copper oxide-embedded paper shows small zone of inhibition against Escherichia coli and Staphylococcus aureus.

The current-voltage characteristics of copper oxide (CuO) - zinc oxide (ZnO) heterojunctions under different illumination intensities were observed in this study. ZnO and CuO films were deposited on separate graphite electrodes via electrophoretic deposition (EPD). The films underwent heat treatment and were physically joined to form the p-n junction. The current-voltage characteristics of the junctions were obtained under forward and reverse bias under different illumination intensities. It was observed that the ZnO-CuO junctions exhibited diode-like behavior in the dark, indicated by the passing of current in forward bias and restricting in reverse bias. Under illumination, the junctions exhibited photodiode-like behavior, with increasing reverse current at greater illumination intensities.

Water-triggered release of antimicrobial solutions is advantageous in inhibiting the growth of bacteria and fungi in moist and wet environments. In this study, we fabricated a composite, by mixing polyvinyl acetate adhesive with copper sulfate solution, which exhibits antimicrobial activities against bacteria. Polyvinyl acetate adhesive serves as the binder and water soluble substance while copper sulfate serves as the antimicrobial agent. The composite was coated in an acetate film and air-dried. To monitor the rate of release of copper ions, the composite was submerged in water and the conductivity was measured. The conductivity saturation time was determined. The composite showed antimicrobial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive).

Polyaniline-coated kapok (Ceiba pentandra) fibers that were embedded with Cu-based particles were fabricated for antimicrobial application. Kapok fibers were coated with polyaniline molecules using oxidative polymerization. The coated fibers were embedded with copper-based particles using soaking method in prepared CuO suspension. X-ray diffraction (XRD) pattern shows presence of Cu and Cu2O particles on the modified fibers. Scanning electron microscopy (SEM) supports the presence of embedded particles on the modified fibers. The samples showed antimicrobial activity against Escherichia coli and Staphylococcus aureus.

Polyaniline molecules are embedded on adhesive tape using successive ionic layer adsorption and reaction (SILAR) technique. The infrared spectrum shows the existence of molecular vibrational modes associated with the presence of polyaniline molecules on the sample. With the addition of polyaniline molecules, the conductivity of adhesive tape increases. Surface conductivity increases with number of dipping cycle until it reaches a certain value. Beyond this value, surface conductivity begins to decrease. The surface conductivity of the sample is associated with the connectivity of the embedded polyaniline molecules. The connectivity increases as the number of dipping cycle progresses. Meanwhile, the decrease in surface conductivity is attributed to the eroding of existing embedded structure at higher number of dipping cycle.

Coupling of copper oxide (CuO) and zinc oxide (ZnO) was done by chemical precipitation method. In this method, copper sulfate pentahydrate and zinc sulfate heptahydrate salt precursors were separately dissolved in distilled water; then were mixed together. The copper sulfate-zinc sulfate solution was then combined with a sodium hydroxide solution. The precipitates were collected and washed in distilled water and ethanol several times, then filtered and dried. The dried sample was grounded, and then undergone heat treatment. After heating, the sample was grounded again. Zinc oxide powder and copper oxide powder were also fabricated using chemical precipitation method. X-Ray Diffraction measurements of the coupled CuO/ZnO powder showed the presence of CuO and ZnO in the fabricated sample. Furthermore, other peaks shown by XRD were also identified corresponding to copper, copper (II) oxide, copper sulfate and zinc sulfate. Results of the photocatalytic activity investigation show that the sample exhibited superior photocatalytic degradation of methyl orange under visible light illumination compared to copper oxide powder and zinc oxide powder. This may be attributed to the lower energy gap at the copper oxide-zinc oxide interface, compared to zinc oxide, allowing visible light to trigger its photocatalytic activity.