Recycled PET Nanofibers for Water Filtration Applications.
Ontology highlight
ABSTRACT: Water shortage is an immediate and serious threat to our world population. Inexpensive and scalable methods to clean freshwater and wastewater are in high demand. Nanofiber filtration membranes represent a next generation nonwoven filter media due to their unique properties. Polyethlyene terephthalate (PET) is often used in the packaging of water and other commonly used materials, leading to a large amount of plastic waste often with limited incentive for recycling (few value-added uses). Here, we present work in the generation of nanofiber liquid filtration membranes from PET plastic bottles and demonstrate their use in microfiltration. PET nanofiber membranes were formed via solution electrospinning with fiber diameters as low as ca. 100 nm. Filtration efficiency was tested with latex beads with sizes ranging from 30 to 2000 nm. Greater than 99% of the beads as small as 500 nm were removed using gravity filtration. To reduce biofouling, the mats were functionalized with quaternary ammonium and biguanide biocides. The biguanide functionalized mats achieved 6 log reduction for both gram negative and gram positive bacteria.
Project description:The disposal of single-use personal protective equipment has brought a notable environmental impact in the context of the COVID-19 pandemic. During these last two years, part of the global research efforts has been focused on preventing contagion using nanotechnology. This work explores the production of filter materials with electrohydrodynamic techniques using recycled polyethylene terephthalate (PET). PET was chosen because it is one of the materials most commonly present in everyday waste (such as in food packaging, bags, or bottles), being the most frequently used thermoplastic polymer in the world. The influence of the electrospinning parameters on the filtering capacity of the resulting fabric was analyzed against both aerosolized submicron particles and microparticulated matter. Finally, we present a new scalable and straightforward method for manufacturing surgical masks by electrospinning and we validate their performance by simulating the standard conditions to which they are subjected to during use. The masks were successfully reprocessed to ensure that the proposed method is able to reduce the environmental impact of disposable face masks.
Project description:Steel slag is a secondary product from steelmaking process through alkaline oxygen furnace or electric arc furnace (EAF). The disposal of steel slag has become a thorny environmental protection issue, and it is mainly used as unbound aggregates, e.g., as a secondary component of asphalt concrete used for road paving. In this study, the characteristics of compacted porous steel slag disc (SSD) and its application in phosphorous (P)-rich water filtration are discussed. The SSD with an optimal porosity of 10 wt% and annealing temperature of 900 °C, denoted as SSD-P (10, 900) meets a compressive strength required by ASTM C159-06, which has the capability of much higher than 90% P removal (with the effluent standard < 4 mg P/L) within 3 h, even after eight filtration times. No harmful substances from SSD have been detected in the filtered water, which complies with the effluent standard ISO 14001. The reaction mechanism for P-rich water filtration is mediated by water, followed by two reaction steps-CaO in SSD hydrolyzed from the matrix of SSD to Ca2+ and reacting with PO43-. However, the microenvironment of water is influenced by the pH value of the P-rich water at different filtration times and the kind of P-rich water with different free positive ion that interferes the reactions of the release of Ca2+. This study demonstrates the application of circular economy in reducing steel slag deposits, filtering P-rich water, and collecting Ca3(PO4)2 precipitate into fertilizers.
Project description:Centrifugal spinning, which is a high-productivity fiber fabrication technique, was used to produce a value-added product from recycled poly(ethylene terephthalate) (rPET). In the present study, rPET fibers, with fiber diameters ranging from submicron to micrometer in scale, were fabricated by spinning a solution of rPET in a mixture of dichloromethane and trifluoroacetic acid. The influence of the polymer solution concentration (the viscosity), the rotational speed of the spinneret, and the inner diameter of the needles on the formation and morphology and mechanical properties of the fibers were examined through scanning electron microscopy and using a tensile testing machine. The thermal behaviors of fibrous mats with various average diameters were also investigated through differential scanning calorimetry. The smoothest and smallest fibers, with an average diameter of 619 nm, were generated using an rPET solution of 10 wt % under a rotation speed of 15,000 rpm using needles having an inner diameter of 160 μm. The fibrous mats have an average tensile strength and modulus of 4.3 MPa and 34.4 MPa, respectively. The productivity and the mechanical properties indicate that centrifugal spinning is an effective technique to fabricate high-value product from rPET.
Project description:Electrospun nanofibers have been successfully applied to remove toxic and carcinogenic contaminants such as heavy metals from polluted water. In this study, an efficient adsorbent based on poly(ethylene terephthalate) (PET) nanofibers was developed following a cheap, versatile and scalable process. PET nanofibers were first produced by electrospinning, and their surface was chemically functionalized using a simple aminolysis process. The capacity of the resulting material to adsorb Pb(II) from synthetic solutions was evaluated as a function of the contact time, pH, and initial metal ion concentration. The adsorbent system presented a quick kinetic adsorption, reaching an extremely high maximum adsorption capacity of about 50 millimol (mmol) of Pb(II) per gram of adsorbent system after just 30 min. Moreover, the effect of competing metal ions, such as Ni(II), Cd(II) and Cu(II), was studied at different molar ratios. Finally, when tested in continuous flow mode, aminated PET (APET) nanofibers were able to remove 97% of Pb(II) ions in solution, demonstrating their potential for the remediation of heavy metal-contaminated water.
Project description:Recycled water, the secondary water source of a city, is vital to alleviate regional water resource shortage and promote environmental conservation. The attitude and acceptance toward recycled water of the public, its direct user, hold the key to the implementation of a recycled water project. Currently, the public's low intention of using recycled water constitutes the biggest obstacle to its popularization. To identify the factors of public acceptance of recycled water and their influence path, this study analyzes the effect mechanism of information disclosure of recycled water on the public's acceptance of it based on the consciousness-context-behavior theory and by adopting a structural equation model. The results are as follows: (1) The public's consciousness of water saving, risk perception of recycled water, and consciousness of environmental responsibility can effectively promote public acceptance of recycled water; (2) The consciousness of water saving and that of environmental responsibility have a significant effect on public acceptance of recycled water, and so do the consciousness of water saving and the risk perception of recycled water; and (3) Recycled water information disclosure has the most significant regulatory effect on consciousness and public acceptance.
Project description:The recyclability of opaque PET, which contains TiO2 nanoparticles, has not been as well-studied as that of transparent PET. The objective of this work is to recycle post-consumer opaque PET through reactive extrusion with Joncryl. The effect of the reactive extrusion process on the molecular structure and on the thermal/mechanical/rheological properties of recycling post-consumer opaque PET (r-PET) has been analyzed. A 1% w/w Joncryl addition caused a moderate increase in the molecular weight. A moderate increase in chain length could not explain a decrease in the overall crystallization rate. This result is probably due to the presence of branches interrupting the crystallizable sequences in reactive extruded r-PET (REX-r-PET). A rheological investigation performed by SAOS/LAOS/elongational studies detected important structural modifications in REX-r-PET with respect to linear r-PET or a reference virgin PET. REX-r-PET is characterized by a slow relaxation process with enlarged elastic behaviors that are characteristic of a long-chain branched material. The mechanical properties of REX-r-PET increased because of the addition of the chain extender without a significant loss of elongation at the break. The reactive extrusion process is a suitable way to recycle opaque PET into a material with enhanced rheological properties (thanks to the production of a chain extension and long-chain branches) with mechanical properties that are comparable to those of a typical virgin PET sample.