Synthesis of 4-chlorophenoxyacetate-zinc-aluminium-layered double hydroxide nanocomposite: physico-chemical and controlled release properties

Layered organic-inorganic hybrid nanocomposite material was synthesised using 4-chlorophenoxyacetate (4CPA) as guest anion intercalated into the Zn-Al layered double hydroxide inorganic host by direct co-precipitation method at pH = 7.5 and Zn to Al molar ratio of 4. Both PXRD and FTIR results confirmed that the 4CPA was successfully intercalated into the Zn-AI-LDH interlayer. As a result, a well-ordered nanolayered organic-inorganic hybrid nanocomposite, with the expansion of the basal spacing from 8.9 angstroms in the layered double hydroxide to 20.1 angstroms in the resulting nanocomposite was observed. The FTIR spectrum of the nanocomposite (ZAC) showed that it composed spectral features of Zn-AI-LDH (ZAL) and 4CPA. The nanocomposites synthesized in this work are of mesoporous-type containing 39.8% (w/w) of 4CPA with mole fraction of Al3+ in the inorganic brucite-like layers (xAI) of 0.224. The release studies showed a rapid release of the 4CPA for the first 600 min, and more sustained thereafter. The total amount of 4CPA released from the nanocomposite interlayer into the aqueous solution were 21%, 66%, and 72% in 0.0001, 0.00025, and 0.0005 M sodium carbonate, respectively. In distilled water, about 75, 35, and 57% of 4CPA could be released in 1000 min, when the pH of the release media was set at 3, 6.25, and 12, respectively. In comparison with a structurally similar organic moiety with one more chlorine atom at the 2-position of the aromatic ring, namely 2,4-dichlorophenoxyacetate (24D), the 4CPA showed a slower release rate. The slightly bulkier organic moiety of 24D together with the presence of chlorine atom at the 2-position presumably had contributed to its higher release rate, and it seems that these factors may be exploited for tuning the release rate of intercalated guest anions with similar properties. This study suggests that layered double hydroxide can be used as a carrier for an active agent and the chemical structure of the intercalated moiety can be used to tune the desired release kinetics of the beneficial agent.     

Electrochemical-assisted photodegradation of mixed dye and textile effluents using TiO2 thin films

Mixed dye consists of six commercial dyes and textile effluents from cotton dyeing process were treated by electrochemical-assisted photodegradation under halogen lamp illumination. Two types of effluents were collected which are samples before and after undergone pre-treatment at the factory wastewater treatment plant. The photodegradation process was studied by evaluating the changes in concentration employing UV-vis spectrophotometer (UV-vis) and total organic carbon (TOC) analysis. The photoelectrochemical degradation of mixed dye was found to follow the Langmuir Hinshelwood pseudo-first order kinetic while pseudo-second order kinetic model for effluents by using TOC analyses. The chemical oxygen demand (COD) and biochemical oxygen demand (BOD) values of mixed dye and raw effluents were reported. Photoelectrochemical characteristic of pollutants was studied using the cyclic voltammetry technique. Raw effluent was found to exhibit stronger reduction behaviour at cathodic bias potential but slightly less photoresponse at anodic bias than mixed dye.     

Characterization of TiO(2)-chitosan/glass photocatalyst for the removal of a monoazo dye via photodegradation-adsorption process

In this paper, the newly explored TiO(2)-Chitosan/Glass was suggested as a promising alternative material to conventional means of wastewater treatment. Characterization of TiO(2)-Chitosan/Glass photocatalyst was studied with SEM-EDX, XRD, and Fourier transform infrared spectroscopy (FTIR) analysis. The combination effect of photodegradation-adsorption process for the removal of methyl orange (MO), an acid dye of the monoazo series occur promisingly when four layers of TiO(2)-Chitosan/Glass photocatalyst was used for MO removal. Approximately, 87.0% of total MO removal was achieved. The reactive -NH(2), -OH, and metal oxide contents in the prepared photocatalyst responsible for the photodegradation-adsorption effect were confirmed by FTIR study. Similarly, MO removal behavior was well supported by SEM-EDX and XRD analysis. Significant dependence of MO removal on the TiO(2)-Chitosan loading can be explained in terms of relationship between quantum yield of photocatalytic reactions and photocatalyst structure/activity. Hence, the research work done thus far suggests a new method, having both the advantages of photodegradation-adsorption process in the abatement of various wastewater pollutants.     

Effects of La_2O_3 addition on microstructure development and physical properties of harder ZTA-CeO_2 composites with sustainable high fracture toughness

The influence of La_2 O_3 inclusion(0-3 wt%) on the micro structure,phase formation and mechanical properties of zirconia toughed alumina(ZTA) added with 5.0 wt% CeO_2 was investigated.ZTA CeO_2 composites were sintered at 1600℃ for 4 h.The microstructure,phase formation,density,fracture toughness and hardness properties were characterised through FESEM,Microscopy Image Analysis Software and XRD diffractometer,Archimedes principle and Vickers indentation technique,respectively.The XRD,image processing and FESEM reveal the existence of LaAl_(11)O_(18).The addition of La_2 O_3 incites the sintering,microstructure refinement,densification of ZTA-CeO_2 matrix and phase transformation.Hence,the hardness of ZTA-CeO_2 ceramics is increased rapidly based on refinement of Al_2 O_3 grains,densification of ZTA-CeO_2 composites and porosity reduction.It is observed that the fracture toughness is enhanced through in situ formation of elongated LaAl_(11)O_(18) grains.The addition of 0.7 wt% La_2 O_3 culminated in the achievement of the optimum findings for density(4.41 g/cm3),porosity(0.46%),hardness(1792 HV) and fracture toughness(8.8 MPa·m~(1/2)).Nevertheless,excess La_2 O_3 is proven to be detrimental as it displays poor mechanical properties due to the poor compactness of numerous LaAl_(11)O_(18) grains,coarsening of Al_2 O_3 grains and decline in density.     

Optimal centralized integrated energy station site approach based on energy transmission loss analysis

Centralized integrated energy station, which combines electrical power, gas, and heat supplying source together, is emerging with the development of an integrated energy system. In the previous works, the site optimization approaches of energy stations were developed for electrical power and gas sources. In these approaches, the candidate sites only include user nodes. However, with the development of the integrated energy system, the previous approach cannot be applied effectively for the system containing heating networks with high energy transmission loss. The energy transmission loss must be calculated accurately in the optimization approach rather than valued by the simple linear model. This paper aims to propose an optimal site approach of a centralized integrated energy station, in which all possible candidates of energy station sites are considered. The candidates can be any point in the whole energy supplying area. The analysis of energy transmission losses, based on nodal energy flow models, in pipelines and feeders, are incorporated. The simultaneous optimization of the station site and energy distribution networks is conducted. It is found that the energy transmission loss is significant in heating networks; therefore, network optimization should be carried out considering exact energy transmission loss. The optimal station site obtained in the present work has reduced 2.3% of the life cycle cost much more than that obtained from the previous method selecting a site from the user node. A noticeable reduction in life cycle cost, 2.6%, can also be achieved when using the proposed approach for a single energy source station. Moreover, for integrated energy systems, it is found that the adoption of the centralized integrated energy stations is more competitive comparing with the adoption of the single energy source station.     

Patent-based trend analysis for advanced thermal energy storage technologies and their applications

Today, the world is moving towards sustainable and renewable energy resources. In order to ensure sustainable and steady power supply, thermal energy storage (TES) is playing a vital role. Most parts of the literature focus on different techniques and new energy storage materials. There is a scarcity of data on technological inventions in the form of patents to provide information to new researchers and investors before starting their new projects on TES. So this research work seeks to address this gap by concentrating on the patent analysis of various technologies with respect to their global publication trend in TES research field. The proposed research work also elaborates the technological evolution in domestic and industrial applications of TES. This analysis is carried out using patent database search tools IncoPat and Espacenet. Patent documents are retrieved between the time span ranging from 2006 to 2018. According to research findings, the number of published patents related to different TES technologies increase every year. China, the United States, Japan, and South Korea are categorized as main depositor countries. Moreover, technology-based applications and their inventing organizations from different countries are also ranked in current research work.     

Effects of hybrid fillers based on micro- and nano-sized silver particles on the electrical performance of epoxy composites

In the present study, electrically conductive adhesives produced from hybrid fillers based on micro- and nano-sized silver (Ag) was developed. The influence of the hybrid filler composition on the electrical properties of the hybrid system was studied. The electrical conductivity of the epoxy composites filled with micro- and nano-silver was correlated with their morphologies. A positive effect was observed in the electrical conductivity result when the composition of micro- and nano-sized Ag particles reached a 50:50 weight ratio. The nano-sized Ag particles became interconnecting particles in the interstitial spaces between micro-sized particles. Micrograph scanning shows that the particles were well distributed and dispersed, the separation between lumps of Ag filler by the insulating matrix was significantly reduced, leading to the formation of continuous linkages. The increased electrical conductivity resulted in a charge around the particle distribution, which led to the high capacity. Hence, these particles increased the conductivity of the system.     

Effects of annealing on the properties of SnSe films

Tin selenide thin films were deposited potentiostatically from an unstirred aqueous solution containing Sn-EDTA and Na₂SeO₃ onto indium-doped tin oxide glass substrates. The difference in the structural and compositional properties of the film before and after heat treatment in a nitrogen atmosphere were studied. The as-grown and treated films were characterised using various techniques such as X-ray diffractometry, scanning electron microscopy and energy-dispersive X-ray analysis. Photoactivity of the samples was studied using linear sweep voltammetry. An annealing temperature of 150°C was found to be the optimum temperature.     

The effect of substitution of zinc with aluminium in the brucite-like layers on the physicochemical properties of zinc-aluminium-layered double hydroxide-pamoate nanocomposite

Layered organic–inorganic hybrid materials of Zn-Al-layered double hydroxide (LDH)-pamoate nanocomposite (ZAPR) were prepared using various initial Zn/Al molar ratios (R_i) from 8:1 to 2:1 which gave initial values of A³⁺/(Zn²⁺ + Al³⁺) mole fractions, (x_i) from 0.11 to 0.33. The Al³⁺ mole fractions in the resulting nanocomposite material (x_f) were greater than x_i and the difference between x_i and x_f was found to be a constant value of 0.03. The increase in the x_f values will increase the Al³⁺ content in the interlayer spaces of layered double hydroxide and therefore increases the charge density of the inorganic brucite-like layers and give stronger electrostatic attraction between the excess positive charge of Al³⁺ and the negative charge of the interlayer pamoate anion and hence decreases the d value of the material. However, the BET surface area of the resulting materials will decreases when the x_f is increased. This shows that the mole fraction of Zn²⁺ replaced by Al³⁺ in the inorganic brucite-like layer plays an important role in controlling the physicochemical properties of the resulting material, which is particularly useful in determining tailor-made property required in the designed material.     

Characterization of CdTe Films Deposited at Various Bath Temperatures and Concentrations Using Electrophoretic Deposition

CdTe film was deposited using the electrophoretic deposition technique onto an ITO glass at various bath temperatures. Four batch film compositions were used by mixing 1 to 4 wt% concentration of CdTe powder with 10 mL of a solution of methanol and toluene. X-ray Diffraction analysis showed that the films exhibited polycrystalline nature of zinc-blende structure with the (111) orientation as the most prominent peak. From the Atomic Force Microscopy, the thickness and surface roughness of the CdTe film increased with the increase of CdTe concentration. The optical energy band gap of film decreased with the increase of CdTe concentration, and with the increase of isothermal bath temperature. The film thickness increased with respect to the increase of CdTe concentration and bath temperature, and following, the numerical expression for the film thickness with respect to these two variables has been established.