Improvised Centrifugal Spinning for the Production of Polystyrene Microfibers From Waste Expanded Polystyrene Foam and Its Potential Application for Oil Adsorption

A straightforward approach to recycle waste expanded polystyrene (EPS) foam to produce polystyrene (PS) microfibers using the improvised centrifugal spinning technique is demonstrated in this work. A typical benchtop centrifuge was improvised and used as a centrifugal spinning device. The obtained PS microfibers were characterized for their potential application for oil adsorption. Fourier transform infrared spectroscopy results revealed similarity on the transmission bands of EPS foam and PS microfibers suggesting the preservation of the EPS foam’s chemical composition after the centrifugal spinning process. Scanning electron microscopy displayed well-defined fibers with an average diameter of 3.14 ± 0.59 μm. At the same time, energy dispersive X-ray spectroscopy revealed the presence of carbon and oxygen as the primary components of the fibers. Contact angle (θCA) measurements showed the more enhanced hydrophobicity of the PS microfiber (θCA = 100.2 ± 1.3°) compared to the untreated EPS foam (θCA = 92.9 ± 3.5°). The PS microfiber also displayed better oleophilicity compared to EPS foam. Finally, the fabricated PS microfibers demonstrated promising potential for oil removal in water with a calculated sorption capacity value of about 15.5 g/g even at a very short contact time. The fabricated PS fiber from the waste EPS foam may provide valuable insights into the valorization of polymeric waste materials for environmental and other related applications

Salt-Induced Aggregation of Polyallylamine-Coated Gold Nanoparticles (PAH-AuNP) for Rapid Detection of Methyl Parathion

Several approaches for the detection of methyl parathion (MPT) have been reported. However, concern about the complexity and complicated instrumentation hampers its application for rapid analysis. Hence, colorimetric mode of detection for rapid analysis of MPT utilizing the unique property of an aggregated gold nanoparticles is reported herein. Polyallylamine-coated gold nanoparticles (PAH-AuNP) were prepared, and recombinant methyl parathion hydrolase (MPH) was used to specifically hydrolyze MPT into paranitrophoneol (PNP). Different experimental conditions, such as the pH of the salt-induced aggregation of AuNP, condition for the immobilization of MPH, the concentration of the MPH enzyme, the duration of incubation, among others were evaluated. Results showed that the prepared AuNP readily recognized the product (PNP) upon salt-induced aggregation when PNP is all converted to its ionic form. Rapid detection was obtained within 5 minutes at a pH greater than 7 at concentrations ranging from 0.1-14 ppm of MPT. The minimum MPT concentration that can be detected using this technique is 0.1 ppm. An ongoing experiment is currently being undertaken to demonstrate the applicability of the method for the detection of similar structure pesticides. Likewise, mechanistic study to further explain the obtained results is also being considered and will be incorporated in the subsequent report

Speciation and Bioavailability of Trace Metals (Cd, Cu and Pb) in Marine Sediment Samples from Placer Bay near Manila Mining Corporation, Surigao City, Philippines

Chemical speciation by sequential extraction method of Cd, Cu and Pb of sediment samples from Manila Mining Corporation is described in this study. Different extractants was employed during the extraction process to each of the defined host fractions; exchangeable, carbonate-bound, organic bound, Fe-Mn bound and residual metal fractions. Moreover, excellent metal recoveries for sequential extraction protocol as compared to the total digestion method were observed for Pb and Cd, while low metal recovery for Cu. Results on the speciation and bioavailability of the studied trace metals in the sediment samples showed that the extractability (potentially available metal fraction) follows the order as Pb > Cu >> Cd. Likewise, the average residual fraction (nonavailable metal fraction) in all sampling stations was found to be equal to 29 %, 38 % and 88 % for Pb, Cu and Cd, respectively. Importantly, Pb was found to be widely distributed in all of the host fractions across all sampling stations, while Cu was more associated in the following fractions: Fe-Mn oxide bound metal fraction (33 %), organic-bound metal fraction (28 %) and in the residual fraction (38 %). Similarly, Cd metal was found to be significantly adsorbed in the residual fraction which suggests that Cd metal is less available in all of the sediment samples being studied. Results of this study may serve as a basis to the administrators in conceptualizing an effective framework for proper remediation and rehabilitation program in the area

Basic concepts, advances and emerging applications of nanophotonics

Nanophotonics includes a diverse set of nontrivial physical processes, such as radiation-matter interaction, near-field optical microscopy, and the fabrication of nanophotonic materials, which extend far beyond diffraction limits. These effects have created new opportunities for a number of applications in nonlinear optics, light harvesting, media transmission, optical and biosensing, luminescence, and display technology. Emerging technologies in numerous optical systems, involving photon interaction with nanostructured materials at extremely small scales play a crucial role in improving our daily lives. The goal along this line is to develop nanometer-sized devices and equipment for efficient control and influence of photonic processes, in addition to slowing down the speed of photons. The industrial revolution has greatly impacted this multidisciplinary discipline, allowing researchers to discover new avenues in design, applied science, chemistry, physical science, and biological technology. This review familiarizes readers with the basic concepts of photonic nanostructures, including photonic nanoscale interactions, nanoconfinement, characteristics of nonlinear optical phenomena, and the use of photonic nanostructures in innovative domains such as light harvesting, theragnostic, metasurfaces, photovoltaics and plasmonics applications

Single-Dip Colorimetric Detection of Cyanide Using Paper-Based Analytic Device Based on Immobilized Silver Nanoparticles

The need to monitor the presence of cyanide (CN−) in water is necessary to minimize the risks to aquatic ecosystems and human health. In this paper; a paper-based analytical device (PAD) was fabricated by immobilizing silver nanoparticles (AgNPs) on filter paper (FP) for the semi-quantitative colorimetric detection of CN− in water. The average diameter of the synthesized AgNPs was estimated to be around 26.23 ± 8.37 nm; with a characteristic optical absorption peak around 420 nm. Scanning electron microscopy and energy-dispersive X-ray spectroscopy results confirmed the successful immobilization of AgNPs on the filter paper via direct immersion technique. The potential of the fabricated FP-AgNPs PAD as a colorimetric sensor for CN− was evaluated using water samples contaminated with various ions and CN− concentration. Here; a color change from yellow to colorless was instantly observed as the FP-AgNPs PAD was exposed to water samples containing CN−. Interestingly; no color change was observed for samples exposed to other analytes suggesting the good selectivity of the FP-AgNPs PAD. Ultraviolet–Visible spectroscopy results and digital image analysis revealed that the fabricated sensor can detect CN− with concentration down to 1.0 ppm. The colorimetric response was also obtained for real water samples spiked with CN−. The results stipulated in this work offer baseline information that can be used in developing highly selective and sensitive digital sensing devices for affordable; accessible; and fast water contaminant monitoring and other related applications

Unraveling Microplastic Pollution in Mangrove Sediments of Butuan Bay, Philippines

The mass production and consumption of plastics have serious effects on the environment, human health, and livelihood. Hence, global efforts to reduce plastic generation must be realized. This study aimed to determine the prevalence of microplastics in mangrove sediments of Cabadbaran, Buenavista, and Nasipit in Butuan Bay, Philippines. Seventy-two (72) microplastic particles were extracted from mangrove sediments dominated by fibrous type (71%) and blue (35%) as the most common color. Attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy was used to assess the polymer type of microplastics. Results reveal a total of six polymer types including high-density polyethylene, low-density polyethylene, polyethylene terephthalate, ethylene-vinyl acetate, polyamide, and polypropylene, with the latter comprising 39% of samples, the highest among the extracted particles. Overall, Nasipit (71.1/kg) obtained the highest microplastic density followed by Buenavista (48.9/kg) and Cabadbaran (40.0/kg). These data will serve as a piece of baseline information in crafting important environmental policies to address plastic pollution issues in the area. Long-term studies are recommended to better understand, monitor, and prevent further microplastic pollution in Butuan Bay

Unraveling Microplastic Pollution in Mangrove Sediments of Butuan Bay, Philippines

The mass production and consumption of plastics have serious effects on the environment, human health, and livelihood. Hence, global efforts to reduce plastic generation must be realized. This study aimed to determine the prevalence of microplastics in mangrove sediments of Cabadbaran, Buenavista, and Nasipit in Butuan Bay, Philippines. Seventy-two (72) microplastic particles were extracted from mangrove sediments dominated by fibrous type (71%) and blue (35%) as the most common color. Attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy was used to assess the polymer type of microplastics. Results reveal a total of six polymer types including high-density polyethylene, low-density polyethylene, polyethylene terephthalate, ethylene-vinyl acetate, polyamide, and polypropylene, with the latter comprising 39% of samples, the highest among the extracted particles. Overall, Nasipit (71.1/kg) obtained the highest microplastic density followed by Buenavista (48.9/kg) and Cabadbaran (40.0/kg). These data will serve as a piece of baseline information in crafting important environmental policies to address plastic pollution issues in the area. Long-term studies are recommended to better understand, monitor, and prevent further microplastic pollution in Butuan Bay