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The aim of this paper is the study of the magnetic separation of pollutants from water by means of a magnetic filter. A magnetic activated carbons nanometric powder that combines the well-known pollutants absorbent capacity of activated carbons with the magnetic properties of magnetite (Fe₃O₄) is used.

The considered magnetic filter is made of stainless steel spheres, magnetized by an external flux density field provided by permanent magnets. Flux density and fluid velocity fields are evaluated using volume integral equation method. The modelling of the particles trajectories inside the filter allows calculating its capture efficiency.

The results of the model are tested on the experimental data obtained using two different setups. A removal of the powder larger than 90 percent is achieved in both cases. The pollutant removal efficiency is checked on surfactants (water diluted). Their adsorption on magnetic activated carbons leads to residual concentration below the limit for the reuse in agriculture (according to the Italian legislation) for all the tested surfactants.

The proposed process combines efficiently a physico-chemical phase of adsorption and a magnetic phase of filtration due to the particular properties of magnetic activated carbons.

This study aims to explore the possibility of using magnetic biochar composite (MBCC) derived from Heglig tree bark (HTB) powder (agricultural solid waste) and cobalt ferrite (CoFe₂O₄, CFO) for oil spill removal from seawater surface.

One-pot co-precipitation route was used to synthesize MBCC. The prepared materials were characterized by X-ray diffraction, scanning electron microscopy-energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy. The densities of the prepared materials were also estimated. Crude, diesel engine and gasoline engine oils were used as seawater pollutant models. The gravimetric oil removal (GOR) method was used for removing oil spills from seawater using MBCC as a sorbent material.

The obtained results revealed that the prepared materials (CFO and MBCC) were able to remove the crude oil and its derivatives from the seawater surface. Besides, when the absorbent amount was 0.01 g, the highest GOR values for crude oil (31.96 ± 1.02 g/g) and diesel engine oil (14.83 ± 0.83 g/g) were obtained using MBCC as an absorbent. For gasoline engine oil, the highest GOR (27.84 ± 0.46 g/g) was attained when CFO was used as an absorbent.

Oil spill removal using MBCC derived from cobalt ferrite and HTB. Using tree bark as biomass (eco-friendly, readily available and low-cost) for magnetic biochar preparation also is a promising method for minimizing agricultural solid wastes (e.g. HTB) and obtaining value-added-products.

The purpose of this paper is to focus on the removal of Congo red dye from aqueous solution using magnetically separable novel adsorbent prepared by coating activated charcoal on magnetic nanoparticles.

The synthesized magnetic nanocomposite of activated charcoal was characterized using Fourier transform infra-red (FTIR), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analysis. The removal of Congo red from aqueous solution using magnetic nanocomposite of activated charcoal was optimized. The equilibrium and kinetics modeling of adsorption of Congo red was analyzed.

The presence of activated charcoal on magnetic nanocomposite was confirmed by FTIR analysis. The average size of the nanocomposite was found to be 12.77 nm using SEM characterization. The elemental composition by EDS analysis confirmed the increase in concentration of carbon due the adsorption of Congo red dye. The optimum conditions for batch adsorption was found to be 1 g/L of adsorbent, dye concentration 50 mg/L, pH 3 and temperature 70°C. The adsorption of Congo red dye on magnetic nanocomposite of activated charcoal was found to follow Temkin adsorption isotherm.

The experimental data were found to fit well with the pseudo second-order kinetics and the rate of adsorption was found to be controlled by intra-particle diffusion.

A review on additive manufacturing (AM) of shape memory polymer composites (SMPCs) is put forward to highlight the progress made up to date, conduct a critical review and show the limitations and possible improvements in the different research areas within the different AM techniques. The purpose of this study is to identify academic and industrial opportunities.

This paper introduces the reader to three-dimensional (3 D) and four-dimensional printing of shape memory polymers (SMPs). Specifically, this review centres on manufacturing technologies based on material extrusion, photopolymerization, powder-based and lamination manufacturing processes. AM of SMPC was classified according to the nature of the filler material: particle dispersed, i.e. carbon, metallic and ceramic and long fibre reinforced materials, i.e. carbon fibres. This paper makes a distinction for multi-material printing with SMPs, as multi-functionality and exciting applications can be proposed through this method. Manufacturing strategies and technologies for SMPC are addressed in this review and opportunities in the research are highlighted.

This paper denotes the existing limitations in the current AM technologies and proposes several directions that will contribute to better use and improvements in the production of additive manufactured SMPC. With advances in AM technologies, gradient changes in material properties can open diverse applications of SMPC. Because of multi-material printing, co-manufacturing sensors to 3D printed smart structures can bring this technology a step closer to obtain full control of the shape memory effect and its characteristics. This paper discusses the novel developments in device and functional part design using SMPC, which should be aided with simple first stage design models followed by complex simulations for iterative and optimized design. A change in paradigm for designing complex structures is still to be made from engineers to exploit the full potential of additive manufactured SMPC structures.

Advances in AM have opened the gateway to the potential design and fabrication of functional parts with SMPs and their composites. There have been many publications and reviews conducted in this area; yet, many mainly focus on SMPs and reserve a small section to SMPC. This paper presents a comprehensive review directed solely on the AM of SMPC while highlighting the research opportunities.

A study to determine the effectiveness of PAC on the removal of COD and colour from dye wastewater. Factors affecting treatment efficiency were investigated and included PAC particle sizes, initial dye concentration and contact time. The adsorption parameters for Langmuir, Freundlich and Dziubek′s isotherms were determined. Results indicated that a very short contact time of one hour was needed to reach equilibrium of adsorption. A COD (chemical oxygen demand) removal efficiency of 90 per cent for disperse‐red‐60 dye wastewater was obtained with PAC (powdered activated carbon). With PAC dosage of less than 15g/l the adsorption followed both Freundlich′s and Langmuir′s isotherms. The ultimate capacity of the adsorption increased with decreasing PAC particle sizes or the initial dye concentration. The mass transfer coefficient was determined in this study.

The purpose of this study is to design carbon electrode materials for high performance electric double-layer capacitors (EDLCs) with pores that are large enough and have suitable pore size distribution for the electrolyte to access completely to improve EDLCs’ electrochemical performance.

This study develop an improved traditional KOH activation method, and a series of micro-meso hierarchical porous carbons have been successfully prepared from phenol formaldehyde resin by combining polyethylene glycol (PEG) and conventional KOH activation.

As evidenced by N₂ adsorption/desorption tests, the obtained samples present Types IV and I-IV hybrid shape isotherms compared with KOH-activated resin (typical of Type I). The sample AC2-7-1, which the addition quantity of PEG is 25 per cent PF (weight ration) activated at 700? For 1 h is considered as the optimum preparation condition. It exhibits the highest specific capacitance value of 240 F/g in 30 wt% KOH aqueous electrolytes because of its higher specific surface area (2085 m2/g), greater pore volume (1.08 cm3/g) and the maximum mesoporosity (43 per cent). In addition, the capacity decay of this material is only 3.1 per cent after 1000 cycles.

The materials that are rich in micropores and mesopores show great potential in EDLC capacitors, particularly for applications where high power output and good high-frequency capacitive performances are required.

The purpose of this paper is to introduce new implementations for parallel processing applications using bijective systolic networks and the corresponding carbon-based field emission controlled switching. The developed implementations are performed in the reversible domain to perform the required bijective parallel computing, where the implementations for parallel computations that utilize the presented field-emission controlled switching and their corresponding m-ary (many-valued) extensions for the use in nano systolic networks are introduced. The first part of the paper presents important fundamentals with regards to systolic computing and carbon-based field emission that will be utilized in the implementations within the second part of the paper.

The introduced systolic systems utilize recent findings in field emission and nano applications to implement the functionality of the basic bijective systolic network. This includes many-valued systolic computing via field emission techniques using carbon-based nanotubes and nanotips. The realization of bijective logic circuits in current and emerging technologies can be very important for various reasons. The reduction of power consumption is a major requirement for the circuit design in future technologies, and thus, the new nano systolic circuits can play an important role in the design of circuits that consume minimal power for future applications such as in low-power signal processing. In addition, the implemented bijective systems can be utilized to implement massive parallel processing and thus obtaining very high processing performance, where the implementation will also utilize the significant size reduction within the nano domain. The extensions of implementations to field emission-based many-valued systolic networks using the introduced bijective nano systolic architectures are also presented.

Novel bijective systolic architectures using nano-based field emission implementations are introduced in this paper, and the implementation using the general scheme of many-valued computing is presented. The carbon-based field emission implementation of nano systolic networks is also introduced. This is accomplished using the introduced field emission carbon-based devices, where field emission from carbon nanotubes and nano-apex carbon fibers is utilized. The implementations of the many-valued bijective systolic networks utilizing the introduced nano-based architectures are also presented.

The introduced bijective systolic implementations form new important directions in the systolic realizations using the newly emerging nano-based technologies. The 2-to-1 multiplexer is a basic building block in “switch logic,” where in switch logic, a logic circuit is realized as a combination of switches rather than a combination of logic gates as in the gate logic, which proves to be less costly in synthesizing multiplexer-based wide variety of modern circuits and systems since nano implementations exist in very compact space where carbon-based devices switch reliably using much less power than silicon-based devices. The introduced implementations for nano systolic computation are new and interesting for the design in future nanotechnologies that require optimal design specifications of minimum power consumption and minimum size layout such as in low-power control of autonomous robots and in the adiabatic low-power very-large-scale-integration circuit design for signal processing applications.

This study has covered many types of solar-powered air-conditioning systems that may be used as an alternative to traditional electrically powered air-conditioning systems in order to reduce energy usage. Solar adsorption air cooling is a great alternative to traditional vapor compression air-conditioning. Solar adsorption has several advantages over traditional vapor-compression systems, including being a green cooling technology which uses solar energy to drive the cycle, using pure water as an eco-friendly HFC-free refrigerant, and being mechanically simple with only the magnetic valves as moving parts. Several advancements and breakthroughs have been developed in the area of solar adsorption air-conditioners during the previous decade. However, further study is required before this technology can be put into practise. As a result, this book chapter highlights current research that adds to the understanding of solar adsorption air-conditioning technologies, with a focus on practical research. These systems have the potential to become the next iteration of air-conditioning systems, with the benefit of lowering energy usage while using plentiful solar energy supplies to supply the cooling demand.

Water is a vital natural resource without which life on earth would be impossible. Properties of synthetic dyes like high stability and noxious nature make it difficult to remove them from the effluent. This review focuses on the removal of synthetic dyes using nanoparticles (NPs) based on the adsorption principle.

Adsorption technique is widely used to remove synthetic dyes from their aqueous solution for decades. Synthetic dye removal using NPs is promising, less energy-intensive and has become popular in recent years. NPs are in high demand for treating wastewater using the adsorption principle due to their tiny size and vast surface area. To maximise environmental sustainability, the utilisation of green-produced NPs as efficient catalysts for dye removal has sparked attention amongst scientists.

This review has prioritised research and development of optimal dye removal systems that can be used to efficiently remove a large quantity of dye in a short period while safeguarding the environment and producing fewer harmful by-products. The removal efficiency of synthetic dye using different NPs in wastewater treatment varies mostly between 75% to almost 100%. This review will aid in the scaling up of the wastewater treatment process.

There is a lack of research emphasis on the safe disposal of NPs once the reuse efficiency significantly drops. The relevance of cost analysis is equally critical, yet only a few papers discuss cost-related information.

Comprehensive and planned research in this area can aid in the development of long-term wastewater treatment technology to meet the growing need for safe and reliable water emphasising reuse and desorption efficiency of the NPs.

The purpose of this paper is to investigate the inhibitive effect of azathiones, namely cyclopentyl‐tetrahydro‐azathione, cyclohexyl‐tetrahydro‐azathione and isobutyl‐methyl‐tetrahydro‐azathione on the corrosion of carbon steel in formic and acetic acid solution. The effect of inhibitor concentration, immersion time, acid concentration, and solution temperature on the inhibition efficiencies of the selected azathiones were studied systematically.

The synthesis of inhibitor was confirmed by methods such as Fourier transform infrared and nuclear magnetic resonance studies. All inhibition experiments were conducted on carbon steel in 20 percent formic acid and 20 percent acetic acid solution. Weight loss experiments were carried out according to the American Society for Testing and Materials standard procedure. Polarization studies were carried out in a three electrode cell assembly connected to an EG&G Princeton Applied Research potentiostat/galvanostat (model 173). The electrochemical impedance technique was carried out using Zahner IM‐6 electrochemical workstation at a frequency range of 5‐100 Hz. The scanning electron microscopy (SEM) study was carried out using a VP LEO model no. 435 microscope for the surface characterization of inhibited and uninhibited metal surfaces.

Various thermodynamic parameters were calculated using weight loss data in order to elaborate the mechanism of corrosion inhibition. Polarization measurements revealed that the studied azathiones acted predominantly as mixed inhibitors. Electrochemical impedance measurements revealed that the compounds were adsorbed onto the carbon steel surface and the adsorption obeyed the Langmuir adsorption isotherm. The SEM study showed that the inhibited metal surfaces were smoother than were uninhibited metal surfaces.

The presence of high efficiency and low cost inhibitors is essential for protection of carbon steel. In comparison with conventional carbon steel corrosion inhibitors, these findings would be considered as a step forward in development of new corrosion inhibitor.

This paper reveals that azathiones can be used successfully for the protection of carbon steel surfaces exposed in acid solution.