Environmentally friendly methodologies of nanostructure synthesis

Environmentally friendly synthetic methodologies have gradually been implemented as viable techniques in the synthesis of a range of nanostructures. In this work, we focus on the application of green-chemistry principles to the synthesis of complex metal oxide and fluoride nanostructures. In particular, we describe advances in the use of the molten-salt synthetic methods, hydrothermal protocols, and template-directed techniques as environmentally sound, socially responsible, and cost-effective methodologies that allow us to generate nanomaterials without the need to sacrifice sample quality, purity, and crystallinity, while allowing control over size, shape, and morphology.     

Environmentally friendly antibacterial cotton textiles finished with siloxane sulfopropylbetaine

This paper reports a novel environmentally friendly antibacterial cotton textile finished with reactive siloxane sulfopropylbetaine(SSPB). The results show that SSPB can be covalently bound onto the cotton textile surface, imparting perdurable antibacterial activity. The textiles finished with SSPB have been investigated systematically from the mechanical properties, thermal stability, hydrophilic properties and antibacterial properties. It is found that the hydrophilicity and breaking strength are improved greatly after the cotton textiles are finished with SSPB. Additionally, the cotton textiles finished with SSPB exhibit good antibacterial activities against gram-positive bacteria Staphylococcus aureus (S.aureus, ATCC 6538), gram-negative bacteria Escherichia coli (E.coli, 8099) and fungi Candida albicans (C.albicans, ATCC 10231). Moreover, SSPB is nonleachable from the textiles, and it does not induce skin stimulation and is nontoxic to animals. Thus, SSPB is ideal candidate for environmentally friendly antibacterial textile applications.     

Phase transformation of zirconia in sulfated zirconia–LiCl system

The phase transformation from tetragonal to monoclinic of zirconia for a series of sulfated zirconia–LiCl samples was characterized by ultraviolet Raman spectroscopy (UVRS) and X-ray diffraction (XRD). Results show that such phase transformation increases with increasing LiCl content and the monoclinic phase is first detected by XRD than that by UVRS for the sample with Li content of 0.5 wt.%. The comparison between XRD and UVRS characterizations indicates that the phase transition takes place initially at the core.     

Environmentally friendly catalytic combustion of gaseous fuel to heat greenhouses

Data on the study of thermally stable manganese oxide catalysts for deep oxidation of lean CH₄ and propane–butane mixtures in air into CO₂ are presented in the paper. New approaches to the synthesis of polyoxide catalysts based on Mn, modified with rare earth elements (La, Ce) and alkaline earth elements (Ba, Sr) when its supporting from nitrate solutions onto the alumina granules stabilized with 2 % Ce were used in the preparation of catalysts. Polyoxide thermally stable (up to 1473 K) high-performance Mn-containing catalyst for deep oxidation of CH₄ and propane–butane in gas-air mixture was developed. Prototype of the catalytic heat generator for environmentally friendly burning of methane and propane–butane mixture was created. Experienced tests of the catalytic heat generator for heating of greenhouses were performed and carbon dioxide fertilizing of plants by combustion products of propane–butane mixture was carried out.     

Synthesis of sulfated zirconia nanopowders via polyacrylamide gel method

In the present study, polyacrylamide gel method was applied for synthesis nanosized sulfated zirconia powders, first time. An assessment of the influence of calcination temperature and sulfate ion loading on the properties of synthesized powders was performed and the samples were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy and thermal analysis. The results revealed that tetragonal phase was obtained on calcination at 500 °C and was stable towards higher temperatures (650 °C). The increase of crystallite size with increasing calcination temperature was observed. Calcination for long duration time led to evolution of some sulfur species, furthermore results in higher particle size (∼100–200 nm) as compared to calcination for short duration time resulting in lower particle size (<50 nm). The presence of sulfate had no significant effect on thermal stability of polyacrylamide gel network whereas structure and the nature of the sulfur species bound with the zirconia surface are affected by the sulfur content.     

一步法合成SO4^2-／TiO2酸位结构及酯化机理研究

利用高酸值麻疯树油中游离脂肪酸与甲醇酯化反应作为目标反应，通过直接煅烧工业原料偏钛酸，制得高酯化活性的ST（SO4^2-／TiO2）固体酸．FTLR研究表明：ST固体酸具有焦硫酸结构酸位，含有高键级高共价特性S=O．S=O强烈的诱导效应提高了与之相连的配位不饱和钛原子的路易斯酸性，吸水后产生质子酸。随着硫含量增加，质子酸性增加．ST固体酸制备过程中，硫酸根与二氧化钛发生固相反应，硫酸根强键舍在二氧化钛表面，同时部分硫酸根分解产生三氧化硫并原位吸附，从而形成固体酸位。ST固体酸通过质子化羧酸、甲醇亲核加成、脱水脱质子机理催化酯化反应。     

Environmentally friendly aqueous solution synthesis of hierarchical CaWO4 microspheres at room temperature

An environmentally friendly route for the synthesis of hierarchical CaWO4 microspheres with novel morphology at room temperature has been successfully developed. CaCl2 and Na2WO4 were used as reaction regents, and distilled water was used as an environmentally friendly solvent. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence spectroscopy. This green wet-chemical route provides a simple, one-step, low-cost approach for the large-scale synthesis of hierarchical CaWO4 microspheres with relatively uniform diameters of 3-6 microm. The hierarchical microspheres are built up with numerous nanorods with an average diameter of 50 nm, which are radially oriented to the microsphere center. SEM observations of different intermediates indicate the possible growth process, in which the hierarchical structure growth is from nuclei through kayak-like, rod-like, peanut-like, dumbbell-like, and peach-like structures to final microspheres, via "self-assembled preferential end growth" of kayak-like particles in aqueous solution. The hierarchical CaWO4 microspheres exhibit a strong, broad blue emission peak of 412 nm.     

Environmentally friendly growth of single-crystalline K2Ti6O13 nanoribbons from KCl flux

Single-crystalline K₂Ti₆O₁₃ nanoribbons with typical width ranging from one hundred nanometers to a few hundred nanometers and length up to tens of microns were prepared from KCl flux. The nanoribbons were characterized by a range of methods including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, selected area electron diffraction and high-resolution transmission electron microscopy. Ultraviolet–visible experiments showed that the K₂Ti₆O₁₃ nanoribbons were wide-band semiconductors with a band width E_g = 3.4 eV. The mechanism of one-dimensional growth of the nanoribbons was attributed to the oriented attachment mechanism.     

Preparation of continuous zirconia fibres from polyzirconoxane synthesized by the facile one-pot reaction

A one-pot reaction of zirconium oxychloride octahydrate (ZOC) with ethyl acetoacetate (Hetac) in the presence of triethylamine was investigated. The reaction was carried out in molar ratios of Hetac/ZOC=1.0, 1.5, 2.0 to give highly viscous solutions with good spinnability and stability to self-condensation. Polyzirconoxanes (PZOs) were isolated as white powders by reprecipitation of the solutions with tetrahydrofuron (THF)-hexane that were soluble in acetone, methanol and THF. The molecular weight of PZO was Mn=1000–2000, and was dependent on the molar ratio and the reaction time. Dry spinning of the solution (Hetac/ZOC=1.5) containing 3mol% tris(acetylacetonato)yttrium [Y(acac)3] gave continuous precursor fibres (3.0Y–PZO). Yttria stabilized zirconia fibres of 12–18 m diameter with a tensile strength of 1.4GPa were obtained by heat treatment of the 3.0Y–PZO at 1100 or 1200 °C. The fibre consisted of submicrometre-sized particles of tetragonal crystallites. © 1998 Chapman & Hall     

Analysis of energy efficient and environmentally friendly technologies in professional laundry service

Professional laundry service (i.e., doing laundry for hospitals, hotels, production plants, dormitories, and students cafeterias) is an industrial, energy intensive process. Electrical energy and natural gas are commonly used to heat water and drying air. However, much of the energy leaves the process in waste flows completely without any profit. Professional laundry service has also direct impact upon environment. Waste water is often contaminated with laundry detergents and natural gas flue gas is used as drying medium. Therefore, it is an energy intensive process and its energy consumption and related environmental impact are worth researching. This article presents the concept of professional laundry service and main energy efficiency measures that may be relevant for the process. Impacts of laundry process on environment along with financial aspects are assessed in this article, too. Financial parameters of any measure are crucial for laundry operators. However, every assessment of profitability of particular measure has to be substantiated by source operational data. These may significantly vary depending on local prices of energy, water, and human labor. This fact is presented using case study where the difference between real operational costs in three European countries is evaluated (Germany, France, and the Czech Republic). Successful research and development of energy efficient and environmentally friendly technologies must encompass three aspects of every technology, i.e., energy intensity, environmental impact, and financial aspects. This three-component approach and its application in laundry service are unique and since they have not subject to any academic research yet, they are discussed in the conclusion of this article. Article is basically an overview of energy efficient and environmentally friendly technologies in professional laundry service and it must be asserted that it is a first of a kind in this area.     

Environmentally friendly polymer hybrids Part I Mechanical, thermal, and barrier properties of thermoplastic starch/clay nanocomposites

As an attempt to develop environmentally friendly polymer hybrids, biodegradable thermoplastic starch (TPS)/clay nanocomposites were prepared through melt intercalation method. Natural montrorillonite (Na⁺ MMT; Cloisite Na⁺) and one organically modified MMT with methyl tallow bis-2-hydroxyethyl ammonium cations located in the silicate gallery (Cloisite 30B) were chosen in the nanocomposite preparation. TPS was prepared from natural potato starch by gelatinizing and plasticizing it with water and glycerol. The dispersion of the silicate layers in the TPS hybrids was characterized by using wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). It was observed that the TPS/Cloisite Na⁺ nanocomposites showed higher tensile strength and thermal stability, better barrier properties to water vapor than the TPS/Cloisite 30B nanocomposites as well as the pristine TPS, due to the formation of the intercalated nanostructure. The effect of clay contents on the tensile, dynamic mechanical, and thermal properties as well as the barrier properties of the nanocomposites were investigated.     

Synthesis of sulfated Y-doped zirconia particles and effect on properties of polysulfone membranes for treatment of wastewater containing oil

Polysulfone (PSF) membranes are broadly applied in many fields owing to good physicochemical stability, resistance to oxidation and chlorine. But when treated with wastewater containing oil, PSF membranes are easily contaminated due to their hydrophilicity, causing declining flux and lifespan of the membranes thereby limiting their large scale applications. In order to enhance the hydrophilic and anti-fouling capability of PSF membranes for treating wastewater containing oil, sulfated Y-doped zirconia particles (SO₄²⁻/ZrO₂-Y₂O₃ or SZY particles) were firstly synthesized and then doped into polysulfone to fabricate a novel hybrid membrane (SZY/PSF). The optimum preparation conditions of SZY particles were studied and determined. SZY particles were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), specific surface area and transmission electron microscopy (TEM). Wastewater containing oil (80 mg/L) was used to investigate the separation properties of SZY/PSF membranes. The results show that the oil concentration in the permeation is 0.67 mg/L, which meets the recycle standard of the Chinese oil-field (SY/T 5329-94, oil concentration <10 mg/L). It is concluded that doping SZY particles into polysulfone can reasonably resist membrane fouling and SZY/PSF membranes can be considered feasible in treating wastewater containing oil.     

Tungstophosphoric acid supported onto hydrous zirconia: Physicochemical characterization and esterification of 1ℴ and 2ℴ alcohol

The Keggin type heteropolyacid, 12-tungstophosphoric acid (PW), was supported onto hydrous zirconia (Z) by impregnation method and designated as ZH₃. The ZH₃ was calcinated at 300°C and 500°C and designated as ZH₃₃ and ZH₃₅, respectively. The resulting materials were characterized by FTIR, diffuse reflectance spectroscopy (DRS), XRD, surface area measurement (BET method) and particle size distribution. The surface morphology was studied by scanning electron microscopy. The acidity of all materials was evaluated by carrying out chemisorption of ammonia and esterification of 1ℴ alcohol (n-butanol) with different acids like formic acid, acetic acid and propionic acid and 2ℴ alcohol (cyclohexanol, iso-butanol) with acetic acid. Above studies show the high dispersion of HPA in a non-crystalline form on the support as well as uniform distribution of particles of ZH₃ which contains 30% 12-tungstophosphoric acid. It also shows that when ZH₃ was calcinated at 500°C, it possesses highest acidity for both chemisorption of NH₃ as well as esterification reactions.     

Copper nanoparticles catalysed an efficient one-pot multicomponents synthesis of chromenes derivatives and its antibacterial activity

In this study, copper nanoparticles (Cu NPs) were synthesised by using diethylenetriamine as a protective agent in chemical reduction method. The obtained nanoparticles were characterised by various spectroscopic techniques like powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR), UV–visible spectroscopy, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermal analysis (TG/DTA). The structure and composition were estimated by PXRD, FTIR, EDS, UV–visible and TG/DTA techniques, while particles size and morphology behaviours were investigated by SEM and TEM instrumentation. A noteworthy, average particle size of nanoparticles was found around 40 nm with spherical shapes. Furthermore, the applications part of NPs were studied as a catalyst for one-pot solvent-free green synthesis of 3,4-dihydropyrano[c]chromenes from different aromatic aldehydes, malonitrile and 4-hydroxycoumarin by stirring at 80 °C. Moreover, the antibacterial properties of NPs were assessed in vitro against human bacterial pathogen such as Staphylococcus aureus, Escherichia coli, Klebsiella sp. and Pseudomonas aruginosa using agar well diffusion method. Gram positive bacteria S. aureus (18 mm) exhibited a maximum zone of inhibition at 60 µg/ml of Cu NPs. Nonetheless, antibacterial activities of Cu NPs (10–100 µg) were compared with four well-known antibiotics likes amikacin (30 mcg), ciprofloxacin (5 mcg), gentamicin (5 mcg) and norfloxacin (10 mcg). This study indicates that Cu NPs exhibited a strong antibacterial activity against all the test pathogens even at lower concentration.