In recent decades, human activities have caused many adverse environmental issues that continue to pose a threat to the earth's ecosystems. Global warming and the widespread detection of microplastics are examples of these activities, both of which are largely associated with the use of fossil fuels. Farming and utilization of seaweeds for commercial and industrial applications presents a potential solution to alleviate these problems. Seaweed farming can sequester CO2 from the atmosphere without competing with human activities that rely on agricultural land and water resources and will therefore not contribute to deforestation. Polysaccharides extracted from seaweeds are raw materials for some biodegradable bioplastics and their use may limit the generation of microplastics in the environment. Under the right conditions, the degradation of seaweed bioplastics also produces fewer greenhouse gas emissions compared to the degradation of conventional plastics. However, the commercial acceptance of seaweed polymers is currently hindered by the relatively high manufacturing cost and quality of the final products. Therefore, further research is essential to advance the development of seaweed farming and the use of seaweed polymers as potential replacements for fossil-fuel based polymers.

Ensuring discrete dispersion of pigment particles is crucial to maintain their separation during processing and storage, and to achieve the desired properties in coatings. To facilitate dispersion and prevent aggregation, the stability of the dispersant along with the chemical interaction between pigment particles and dispersants is critical. This study was conducted to investigate the interaction between robust dispersants containing thermally stable carboxylate and phosphonate functional groups and the titania pigment surface at pH values experienced in pigment manufacturing as well as in application. The study found that the interaction depends on the type of group, the distribution density of the group, and the solution pH. Dispersant adsorption can occur under both alkaline and acidic solution conditions, with the adsorption density increasing when the pH is reduced or the carboxylate group density is increased. At pH 9.5, dispersant adsorption affinity and density is low, and hydrogen bonding occurs in addition to phosphate group chemisorption. At pH 5.5, both the adsorption affinity and density significantly increase due to electrostatic interactions between carboxylate and/or phosphonate groups and the pigment surface, combined with phosphate group driven chemisorption. Linear carboxylate-phosphonate copolymers and carboxylate dispersants present at the pigment surface provide electrostatic stabilisation while branched copolymers provide both electrostatic and steric stabilisation. The synergistic physical and chemical interaction combined with dispersion stability may lead to improved titania pigment suspensions using branched copolymer dispersants.

For the high content of carrageenan in some seaweed and the low cost and easy availability of semi refined carrageenan (SRC), SRC resin powder was selected as our research object. Due to its water solubility, a solution casting method was adopted to form film, hoping to prepare food packaging materials that partially replace petroleum based resin. The pure SRC resin casting film is very brittle and cannot be formed. Therefore, 40wt% glycerol was added to the formula to plasticize and improve the flexibility and demoulding ability of SRC. The plasticized SRC film still has limitations. Soluble petroleum based polymer poly(vinyl alcohol) (PVA) resin was used as a blending modifier, cinnamaldehyde (CIN) as a crosslinking agent for acetal reaction with hydroxyl groups, boric acid (BA) as a provider of acidic environment and an auxiliary agent for generating partial hydrogen bonds with hydroxyl groups. Eight experimental research formulas were designed and FTIR, XRD, thermodynamic properties and mechanical properties of the modified films were analyzed. Both microscopic and macroscopic analyses have shown that under the acidic conditions of BA, CIN undergoes an acetal reaction with SRC and PVA, therefore mass ratio of the formula that SRC/glycerol/PVA/CIN/BA is 100/40/33.3/10/10, the film has the best tensile strength of 34.85Mpa, higher than that of other films. It has been proven that CIN does indeed act as a crosslinking agent in the formula, forming a network structure that enhances it.

A novel and easy to fabricate graphene doped alginate thin film (Alg/GO) capable of binding with perfluorooctanoic acid (PFOA) and working on the principle of a Fabry-Perot interferometry (FPI) type optical fiber sensor (OFS) is presented here. Utilizing a simple dip coating technique, the Alg/GO coating was deposited on the freshly cleaved fiber end-face followed by cross-linking in calcium chloride. The experimental results from two independent data analysis techniques, including Fourier-transform infrared (FTIR) spectroscopy and analytical adsorption tests were used to confirm that the developed graphene-doped alginates can adsorb PFOA. It was also found that GO-doped alginate coating adsorbs twice as much PFOA compared to alginate alone. Similarly, experimental results of the developed FPI sensor demonstrate the sensitivity to PFOA in aqueous solutions with a limit of detection (LOD) of 0.4 ppb and a non-linear correlation between 0 and 2 ppb with increasing concentrations of PFOA in water. The response time at this concentration was estimated to be 17 s, considering a thin film coating thickness of approximately 30 $\mu \text{m}$ as determined via imaging with the aid of differential interference contrast (DIC) microscopy. The relatively high sensitivity and ease of formation of the coating offer the potential for the future development of portable optical sensors for emerging environmental contaminants.

Biopolymer nanoparticles (NPs) produced from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) are typically formed by first dissolving the polymer in organic solvents. In order to eliminate the use of toxic solvents, an alternative "green" solvent system using glacial acetic acid was used in this study for the preparation of NPs via nanoprecipitation. The influence of various factors on the resulting particle size was investigated including the use of an emulsifying agent, temperatures of stock and receiving solutions, and concentration of stock solution. The addition of emulsifier significantly reduced the NP size, whereas temperature had minimal influence on the particle size over the tested range. By varying the concentration of the stock solution, the size of the NPs can be adequately controlled. The minimum size of NPs prepared using a stock solution of 0.5 ml at 80 degrees C into a 100 ml receiving solution was 70 nm with a narrow size distribution. Imaging by scanning electron microscopy revealed smooth spherical NPs and thermal and structural analysis showed only minor changes in properties in comparison with the source PHBV powder. Overall, the results show that glacial acetic acid is an appropriate alternative solvent for the dissolution of PHBV and the subsequent formation of biopolymer NPs.

A supercritical solvent impregnation (SSI) technique was employed to incorporate, by batch- and semicontinuous-modes, bioactive olive leaf extract (OLE) into a food-grade multilayer polyethylene terephthalate/polypropylene (PET/PP) film for active food packaging applications. The inclusion of OLE in the polymer surfaces significantly modified the colour properties of the film. A correlation of 87.06% between the CIELAB colour parameters and the amount of the OLE impregnated in the film was obtained which suggests that colour determination can be used as a rapid, non-destructive technique to estimate the OLE loading in the impregnated matrices. The UV barrier and water permeability properties of the films were not significantly modified by the incorporation of OLE. The migration of OLE into a 50% (v/v) ethanol food simulant demonstrated faster release of OLE from the PP surface than from the PET surface which may be due to the different interactions between OLE and each polymer.

Ultrafiltration (UF) membranes can be used as a standalone process for the removal of enteric virus and are often combined with reverse osmosis (RO) processes for use as the pre-treatment to manage microbial risks. In this study, a water utility experienced multiple validation failures in one of its UF plants with virus log reduction values (LRV) as low as 0.79 reported. This resulted in the suspension of recycled water supply to customers and initiated a comprehensive root cause analysis to identify the reason for the unusually rapid membrane degradation and virus removal validation failure. Polyethersulfone (PES) membrane fibres were sampled from the used modules and a systematic autopsy was undertaken. The FTIR spectroscopic structural analysis revealed oxidative changes in the PES polymer structure. Thermal analysis by differential scanning calorimetry showed changes in the melting point of the PES and suggested a loss of the pore-forming polymer polyvinylpyrrolidone (PVP). Streaming potential analysis showed a decrease in the negativity of the surface charge from-50 mV to-30 mV at pH 7. Tensile testing revealed a 9% and 47% decrease in the breaking force and elongation at break of the used fibres respectively. The pore size evaluation challenge testing of the used fibres showed no rejection of nano particles with 150 nm diameter and smaller. The autopsy investigation suggested that the unusually rapid membrane degradation was due to chemical oxidation resulting in changes in the PES structure and physical properties. Detailed on-site investigation was then undertaken and it was suggested that the failure to operate appropriate chemical enhance backwash (CEB) was the main cause for the unusually rapid virus LRV reduction. Finally, CEB water sampling and analysis were undertaken, which confirmed the recommendations from membrane autopsy and site investigation. A range of system improvements (system control, new inline static mixer, CEB water quality monitoring, etc.) were implemented. Based on the root cause analysis and system improvements, the maximum virus LRV of 4 has been maintained since then.

This study investigated a gas fractionation enhanced soil washing method for poly-and perfluoroalkyl substances (PFAS) removal from contaminated soil. With the assistance of gas fractionation, PFAS removal was increased by a factor of 9, compared to the conventional soil washing method. Pre-extraction (pre-treatment) of the soil with water before gas fractionation enhanced PFAS removal from soil. The optimum extraction time varied based on the soil particle size, since it will change the swelling time of the soil. The influence of various operational conditions such as water to soil mass ratio (W:S ratio), gas type in fractionation, gas flowrate, fractionation time and soil pre-treatment condition have been studied to identify the critical influencing factors. Among various W:S ratios (2, 4, 5, 6, 8, and 10) studied, higher W:S ratio resulted in better PFAS removals, but PFAS removal began to plateau as the W:S ratio increased. PFAS removal could be improved by repeated treatment with low water consumption. Air, oxygen, and ozone generated by air and oxygen were used, in which ozone generated by oxygen achieved the highest PFAS removals of 55.9%. Among different fractionation times (10 min, 20 min and 30 min), a fractionation time of 20 min achieved better total PFAS removal for studied soil, because PFOS was the dominant species in the total PFAS. However, the removal of some PFAS species, such as PFHxS, would be increased with extended fractionation time. With constant fractionation time (10 min), PFAS removal performance improved with the increasing gas flowrate.

The surface of semi-refined carrageenan (SRC) film samples were photocrosslinked with UV light using a solution of sodium benzoate as a photosensitizer. The surfaces were coated with a 6% (w/v) solution of the photosensitizer and exposed to the light source for 5,10,20 and 40 min. The effects of the surface crosslinking on the overall properties of the SRC films were investigated and related to the possible changes in the morphology of the substrate. The UV exposure and subsequent crosslinking were found to cause little color change in the films and increased the crystallinity as well as the thermal stability of the films. The mechanical properties were improved relative to the control sample with a ca. 36-55% increase in the tensile strength, ca. 140-144% increase in the modulus but with a concomitant ca. 50-52% decrease in the elongation at break. The crosslinking decreased the inherent water content in the films by ca. 48-55% and decreased the water vapor transmission rate by ca. 10-21% relative to the control. The water sensitivity of the films, however, increased by ca. 18-44% and 9-23% for the water solubility and water uptake respectively, with decreases of ca. 18-22% in water contact angle. These changes were attributed to possible photodegradation products and the presence of residual photosensitizer that rendered the samples more hydrophilic. Under the conditions of the experiments, a UV exposure time of ca. 20 min was found to be optimal in enhancing the mechanical and water barrier properties. The results suggest photocrosslinking provides a promising step towards the production of a low-cost food packaging material from SRC raw materials.

A comprehensive study has been conducted on some charring materials frequently found in buildings to characterise pyrolysis and combustion parameters concerning the variations in heating rate, temperature and heat flux. Since these parameters are input for computational fluid dynamics (CFD)-based fire models, incorporation of the effects of heating rate and heat flux when simulating building fires may lead to better predictions of tenability conditions. Three common construction and building materials were selected, namely pine, cotton and wool, to characterise via experimental protocols which can serve as examples of future novel charring materials. Parameter values related to pyrolysis reactions were determined using thermogravimetric analysis and differential scanning calorimetry. The values of the combustion parameters were obtained using cone calorimetry. It was found that the variation in heating rate has a significant effect on the values of the pyrolysis parameters of the studied materials. The kinetic parameter and heat of reaction (HoR) values of pine increased with the increment in heating rate. Conversely, the kinetic parameter values of cotton and wool decreased as the heating rate increased, whereas the HoR values followed a similar incremental trend with the increasing heating rate. The variation in combustion parameter values varied concerning heat flux due to the presence of high moisture contents and possible variations in char development in all materials. As CFD-based fire models are currently widely used to design and assess performance-based building fire safety designs, to obtain better predictions of tenability conditions, a proposal for the optimised use of parameters is presented.

New antioxidant films based on ethylene vinyl alcohol (EVOH) copolymer containing betalain-rich red beet were successfully manufactured and characterized to develop bioactive packaging for food products. Two types of red beet (powder and extract) at different proportions (0.1, 0.5, 1.0, 1.5, 2.0 and 2.5 % (w/w)) were incorporated into EVOH films, with attention focused on the optical, chemical, thermal, structural, and mechanical and antioxidant properties. The incorporation of any red beet type into EVOH resulted in purple-colored and semi-crystalline thin films, without modifying their thermal stability and mechanical properties. The addition of the beet extract led to a film with higher color intensity, antioxidant activity and lower water loss rate, whereas the addition of powdered beet resulted in an improved UV barrier compared to the extract. The results showed that new antioxidant food packaging films based on EVOH could be realized by utilizing beetroot extract or powder obtained from natural resources.

Semi-refined carrageenan (SRC) films are sensitive to moisture and generally have poor mechanical properties. These factors limit their use in applications where moisture levels are high and good mechanical strength is required. This work investigated the incorporation of nanoclay (NC) into SRC film in combination with surface lamination using a thin layer of poly(caprolactone) (PCL) to enhance the barrier properties and hydrophobicity of the SRC film and concurrently improved the mechanical properties. The water vapor permeability, moisture uptake, and water solubility decreased by 92, 24, and 11%, respectively, and the water contact angle increased from 72 degrees to 95 degrees. The tensile strength and elongation at break increased by 17.9 and 2.8%, respectively, and the thermal stability also increased slightly. The PCL lamination was the main contributor to the enhanced barrier and mechanical properties of the films, whereas the NC inclusion contributed more to the enhanced thermal properties.

Pervaporation (PV) has been an intriguing membrane technology for separating liquid mixtures since its commercialization in the 1980s. The design of highly permselective materials used in this respect has made significant improvements in separation properties, such as selectivity, permeability, and long-term stability. Mixed-matrix membranes (MMMs), featuring inorganic fillers dispersed in a polymer matrix to form an organic–inorganic hybrid, have opened up a new avenue to facilely obtain high-performance PV membranes. The combination of inorganic fillers in a polymer matrix endows high flexibility in designing the required separation properties of the membranes, in which various fillers provide specific functions correlated to the separation process. This review discusses recent advances in the use of nanofillers in PV MMMs categorized by dimensions including zero-, one-, two- and three-dimensional nanomaterials. Furthermore, the impact of the nanofillers on the polymer matrix is described to provide in-depth understanding of the structure–performance relationship. Finally, the applications of nanofillers in MMMs for PV separation are summarized.

This work reports the development of a Fabry-Perot Interferometry (FPI) based optical fibre to detect perfluorooctanoic acid (PFOA) and other perfluoroalkyl substances (PFAS) in aqueous solutions. A novel and simple sensor fabrication procedure utilizing an immersion precipitation-based phase inversion process to form a thin polyvinylidene fluoride (PVDF) coating at the end-faces of freshly cleaved optical fibres is presented. The PVDF coating was rich in the electroactive beta-phase, which enhances dipole-dipole and hydrophobic interaction with PFAS at binding sites. Sensor testing with model PFOA solutions showed that the PVDF coated FPI optical fibre can detect PFOA. The change in optical path difference (OPD) with change in PFOA concentration was considered as a measure of sensitivity and it corresponded to a value of 0.9-5 nm/ppm for PFOA. In real PFAS solutions obtained from fire-fighting foams, the OPD was found to be significantly more sensitive at 178 nm/ppb.

Facilitated transport membranes (FTMs) comprising fixed carrier agents hold considerable potential for obtaining selective and fast separation of mixed molecules in either gas or liquid state. However, diffusion through the membrane is inevitably affected by the resistance from the polymer matrix, where the carrier is absent. Herein, a poly(vinyl alcohol) (PVA)-based separating layer combining the merits of fixed-site transport agents and inorganic nanofillers was developed to reduce the transport resistance. Carbon nanotubes (CNTs) with different degrees of oxidation were prepared and incorporated into the sulfonic acid (-SO3H)-modified PVA matrix. The resultant composite membrane consisting of a microporous polytetrafluoroethylene substrate and a thin PVA-based separating layer (∼700 nm thick) was subject to pervaporation desalination of sodium chloride solution (35,000 ppm) at 30 °C. The effect of -SO3H as a fixed transport agent in the PVA matrix was first investigated experimentally, showing an increase of water flux by 21.8% compared with a control membrane without the transport agent. Subsequently, the CNT-incorporated FTM exhibited good stability (50 h) and improvement in water transport, which was ∼161% of the control FTM (PVA with -SO3H) without loss of selectivity. Such high and stable performance achieved in the CNT-incorporated FTM originated from the construction of low-resistance transport pathways by CNTs between -SO3H groups as well as their uniform dispersion in the polymer matrix.

Carrageenans obtained from seaweeds can be processed into films for a range of applications including food packaging. The level of carrageenan refinement during extraction can influence the key properties, with semi-refined carrageenan (SRC) containing more impurities than the more refined carrageenan (RC). Further refinement steps, however, result in higher costs associated with the production of RC. In order to obtain a lower cost and more ecofriendly, bio-based material for food packaging applications, SRC was used in this investigation to produce a thin film reinforced with nanocellulose fibrils (NCF). Films derived from RC containing NCF were also investigated with water sensitivity and physico-mechanical and thermal properties among the properties tested. Levels of NCF were varied from 1% to 7% (w/w), and in general, the NCF reinforcement improved the overall properties of both the SRC and RC films, including the water sensitivity and moisture barrier. However, NCF inclusion in SRC film was less effective with regard to the mechanical and thermal properties compared with NCF inclusion in RC film. The enhancement in properties was attributed to the greater cohesiveness of the reinforced polymer structure and the crystalline regions formed in the structures of SRC and RC films by NCF incorporation.

Molecular separations using synthetic membranes have been widely recognized as energy-efficient processes relative to conventional separation technologies. Rational design of the membrane structures for attainment of exceptionally permselective materials is highly beneficial in this respect. Herein, an ultrathin organic-inorganic hybrid nanofilm is formed on a hydrophobic polytetrafluoroethylene porous substrate through a facile and scalable solution casting process, thereby realizing an intrusion-free composite structure. Nanosizing Ti3C2Tx MXene and sulfosuccinic acid are incorporated as nanofiller and crosslinker to manipulate the structural rigidity and free-volume property by polymer-nanofiller interaction and polymer chain crosslinking while simultaneously rendering outstanding membrane transport property, selectivity and stability. The synthesized nanofilm composite membrane with thickness down to approximate to 230 nm, comparable with the lateral dimension of small-sized MXene (approximate to 142 nm), exhibits outstanding pervaporative separation of water from various aqueous-ion or -alcohol mixtures with high throughput that is around 5-70 times of other reported polymer-based membranes. Transport modelling of this hybrid nanofilm suggests that ultralow-resistance permeation behavior induced by MXene nanosheets dominates as the nanofilm thickness approaches the filler size.

Hybrid membranes, featuring combinations of inorganic and organic materials at the nanometre or molecular level, have been widely reported as providing superior separation performance compared with the traditional polymeric membranes. However, for rational design of membranes, there remains a major doubt as to how each constituent functions in the separation process. Herein, carbon nanotube (CNT) incorporated poly (vinyl alcohol) (PVA) membranes were analysed using pervaporation (PV) process for aqueous mixture separation. The impacts of CNT on the functional properties, morphologies and microscale structures of the PVA/CNT hybrid membranes was investigated by ATR-FTIR, AFM, SEM and positron annihilation lifetime spectroscopy (PALS). Further, a comparison of the interactions between the membrane and solvents (water and ethanol) were identified by swelling test and XRD. The resultant PVA/CNT hybrid membranes were then subject to both desalination and dehydration of ethanol. The results showed that PVA exhibited preferential adsorption of water over ethanol. The addition of CNT enlarged the fractional free volume (FFV) and enhanced water diffusivity (up to 185%), which indicated a diffusion-dominated type of the PVA/CNT hybrid membranes with a synergistic effect of CNT on water transport. The transport of Na+ ions through the membrane was examined to be with larger activation energy than that of ethanol during the separation process. This work investigated the state of polymer as well as the effect of nanofillers in the separation of water vs. non-volatile or volatile component for the first time, which can provide in-depth understanding of the polymer-based hybrid membranes for practical applications.

The objective of this study is to investigate how the specific heat capacity ( c p ) value of a material changes with respect to temperature and heating rate of that material. In-depth knowledge in the variation of c p will provide a better knowledge of the thermo-physical properties of these materials and will increase the capabilities and fidelity of computational fluid dynamics (CFD)-based fire modelling. The models and simulations are reliant on input data gained through experimentation and this allows for the present study to provide such input data and trends, which are useful in understanding how fires respond in different situations. The value of c p in relation to the rate of temperature change has been measured using differential scanning calorimetry (DSC) and hot disk analysis (HDA). This study encapsulates the determination of c p values, trends and equations for poly(methyl methacrylate), pinewood, pinewood char, and two fabrics: cotton and wool. The c p values were found to increase with the sample temperature and for the two fabrics; they vary with the change in heating rate. The derived equations show that c p values from DSC and HDA are comparable. To include these relationships in CFD-based fire models, a set of suggestions have been made.

A novel polyvinylidene fluoride (PVDF) coated fiber-optic Fabry-Perot interferometric (FFPI) sensor for temperature measurement is proposed and experimentally validated. The sensor head consists of a PVDF thin film formed by the phase inversion process via immersion precipitation at the freshly cleaved endface of a single mode telecommunications optical fibre. The resin polyvinyl butryl (butvar) was used as a cross-linker to promote good adhesion between the optical fibre glass and PVDF in order to reduce operational coupling loss. Sensor operation is demonstrated by shifts of the FFPI reflection spectra and its performance was analysed through measurement of optical thickness or path difference with temperature variation. Experimental data shows that the thermal expansion effect of the PVDF coating is more dominant than its thermo-optic effect. The proposed sensor exhibits an exponential response over 21 to 160 degrees C inside a tube furnace with a sensitivity that spans between 1.6 nm/degrees C and 7.5 nm/degrees C.