Volume 92, Issue 4

A novel approach of titanium nitride (TiN) incorporated into SBA-15 framework was developed using one-step hydrothermal synthesis method. TiN contents up to ~18 wt% were directly dispersed in a synthetic gel under a typical strong acidic condition. The physico-chemical characteristics and the surface properties were investigated by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), N 2 adsorption-desorption, field emission scanning electron microscope (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS), wavelength dispersive X-ray fluorescence (WDXRF) and CO 2 -temperature programmed desorption (CO 2 -TPD). The results indicated that the highly ordered mesostructured was effectively maintained with high specific surface area of 532–685 m 2 g −1 . The basicity of the modified SBA-15 increased with rising TiN loading. These modified materials were applied as a support of Ni catalyst in dry reforming of methane (DRM). Their catalytic behavior possessed superior conversions for both CO 2 and CH 4 with the highest H 2 /CO ratio (0.83) as well as 50 % lower carbon formation, compared to bare SBA-15 support.

This paper is devoted to the use of the principles of green chemistry in the search for technologies to reduce the chemical footprints of areas. The chemical footprint for mercury and its compounds was taken as an example to study. These chemicals belong to priority pollutants and their ever-increasing amounts in the environment have caused concern around the world, which is reflected in the adoption of the Minamata Convention. The Minamata Convention aims to protect human health and the environment from anthropogenic releases of mercury and mercury compounds. This Convention is an important component of efforts to achieve sustainable, inclusive and resilient human development through SDGs, which were adopted in September 2015 and especially SDG Goal 12: Ensure sustainable consumption and production patterns. Relevancy of this work is due to the need for the adopting of a series of measures to withdraw some mercury-containing goods from the production cycle. Also, one of the most important statements of the Convention is in reference to the issue of mercury contamination when recycling mercury. An important aspect of the work described in this paper is the reduction of mercury pollution from mercury-containing waste products by the development of technology in accordance with the principles of green chemistry. These are energy-efficient and without waste -water discharge technology. The main result of this work is the fundamental research for a transformation of elemental mercury and its compounds into less dangerous forms for the human body and the environment, providing a guaranteed absence of mercury-containing waste in the atmosphere and water systems. Various conditions for reaction of the immobilization of metallic mercury in mercury-containing wastes were investigated and it was established that it proceeded best under the following conditions: Reaction of metallic mercury with elementary sulfur; A ball mill is used as a reactor, which ensures constant updating of the contact area of the phases; For a good dispersion of mercury and for a relatively quick and complete reaction a large excess of sulfur up to 6500 % by stoichiometry (e.g. ratio of mercury:sulfur = 1:1.5 by weight) is necessary; The addition of a very small amount of water also has a positive effect (hydromodulus of Solid:Liquid = 3:1 by weight).

Plant metabolites being renewable in nature have tremendous significance for the development of a sustainable society. In this manuscript we show that, terpenoids having nanometric lengths, commonly having several functional groups and several centers of chirality, can be utilized as renewable Molecular Functional Nanos (MFNs). The terpenoids spontaneously self-assembled in liquids yielding different morphologies such as vesicles, tubes, flowers, petals and fibers of nano- to micro-meter dimensions and supramolecular gels. The self-assemblies were utilized for the entrapment and release of fluorophores including anticancer drug, pollutant capture, generation of hybrid materials and catalysis.

Bio-based solvents were investigated for the biocatalysed amidation reactions of various ester-amine combinations by Pseudomonas stutzeri lipase (PSL). Reactions were undertaken in a range of green and potentially bio-based solvents including terpinolene, p-cymene, limonene, 2-methyl THF, ɣ-valerolactone, propylene carbonate, dimethyl isosorbide, glycerol triacetate and water. Solvent screenings demonstrated the importance and potential of using non-polar bio-based solvents for favouring aminolysis over hydrolysis; whilst substrate screenings highlighted the unfavourable impact of reactants bearing bulky para- or 4-substituents. Renewable terpene-based solvents (terpinolene, p-cymene, D-limonene) were demonstrated to be suitable bio-based media for PSL amidation reactions. Such solvents could provide a greener and more sustainable alternative to traditional petrochemical derived non-polar solvents. Importantly, once the enzyme (either PSL or CALB) binds with a bulky para-substituted substrate, only small reagents are able to access the active site. This therefore limits the possibility for aminolysis to take place, thereby promoting the hydrolysis. This mechanism of binding supports the widely accepted ‘Ping Pong – Bi Bi’ mechanism used to describe enzyme kinetics. The work highlights the need to further investigate enzyme activity in relation to para- or 4-substituted substrates. A priority in PSL chemistry remains a methodology to tackle the competing hydrolysis reaction.

In this study, the deoxygenation pathway was proposed to eliminate oxygen species from biomass-derived oil, thereby producing a high quality of hydrocarbon chains (green fuel). The catalytic deoxygenation reaction of bio-oil model compound (oleic acid) successfully produced green gasoline (C 8 –C 12 ) and diesel (C 13 –C 20 ) via activated hydrotalcite-derived catalysts (i.e. CMgAl, CFeAl, CZnAl and CNiAl). The reaction was performed under inert N 2 condition at 300 °C for 3 h, and the liquid products were analysed by GC–MS and GC–FID analyses to determine the hydrocarbon yield and product selectivity. The activity of the catalysts towards the deoxygenation reaction presented the following increasing order: CNiAl > CMgAl > CZnAl > CFeAl. CNiAl produced a hydrocarbon yield of up to 89 %. CNiAl demonstrated the highest selectivity with 83 % diesel production, whereas CMgAl showed the highest gasoline selectivity with 30 %. These results indicated that catalysts with a high acidic profile facilitate C–O cleavage via deoxygenation, producing hydrocarbons (mainly diesel-range hydrocarbons). Meanwhile, highly basic catalysts exhibit significant selectivity towards gasoline-range hydrocarbons via cracking and lead to the occurrence of C–C cleavage. The large surface area of CNiAl (117 m 2 g −1 ) offered high approachability of the reactant with the catalyst’s active sites, thereby promoting high hydrocarbon yield. Consequently, the hydrocarbon yield and selectivity of the deoxygenation products were predominantly influenced by the acid–base properties and structural behaviour (porosity and surface area) of the catalyst.

Glyphosate (GFT) is a widely used herbicide, considered toxic and a probable carcinogen. The main challenge is its detection, usually requiring expensive and laborious methodologies. Herein, we report a colorimetric detection of GFT, using a derivatization reaction with 2,4-dinitrofluorobenzene (DNFB) that leads to a yellow-colored product. This is undertaken under mild conditions (weakly basic aqueous medium and ambient conditions). A thorough kinetic study was carried out, showing that the derivatization reaction with GFT predominates over the hydrolysis of DNFB. Hence, the colorimetric product is the major product formed, which was fully characterized by nuclear magnetic resonance. Finally, a portable, handmade and cheap colorimeter was used to detect and quantify GFT, relying on the colorimetric reaction proposed. Simulating real contaminated samples, it was possible to analyze in just 10 min, with less than 7 % of error of the nominal concentration. Overall, a highly sustainable approach is shown for an herbicide monitoring, with a simple and mild derivatization reaction that does not require purification and leads to a colorimetric product. Moreover, a simple apparatus with low time analysis is proposed that uses a problematic electronic trash: cellphone chargers. This cheapens the process and allows field analysis that can be extended to other agrochemicals.

Food waste valorisation is currently at the core of discussions and development of future economic models which, allied to the application of green and sustainable technologies, offers a viable alternative to shift industrial practices towards a circular bioeconomy. The feasibility and technological possibilities based on an integrated mango waste biorefinery concept, focusing on the extraction of bioactive compounds, are discussed in this paper. Additionally, a statistically robust methodology is presented as a green approach to optimise the variables of a sustainable, low time and energy consumption extraction technique (homogenizer-assisted extraction). Maximum concentrations of the bioactive compounds were obtained in similar values of parameters ethanol/water concentration (67.73 and 70.11 %), sample/solvent ratio (29.33 and 28.17 %) and time (4.47 and 5.00 min) for mangiferin (354.4 mg/kg DW) and hyperoside (258.7 mg/kg DW), respectively. These results demonstrated the efficiency of the proposed green and sustainable method to obtain bioactive compounds from a very common and significant tropical fruit waste in Brazil, based on an integrated mango biorefinery concept.

Current pulping technologies only valorize the cellulosic fiber giving total yields from biomass below 50 %. Catalytic fractionation enables valorization of both cellulose, lignin, and, optionally, also the hemicellulose. The process consists of two operations occurring in one pot: (1) solvolysis to separate lignin and hemicellulose from cellulose, and (2) transition metal catalyzed reactions to depolymerize lignin and to stabilized monophenolic products. In this article, new insights into the roles of the solvolysis step as well as the operation of the transition metal catalyst are given. By separating the solvolysis and transition metal catalyzed hydrogen transfer reactions in space and time by applying a flow-through set-up, we have been able to study the solvolysis and transition metal catalyzed reactions separately. Interestingly, the solvolysis generates a high amount of monophenolic compounds by pealing off the end groups from the lignin polymer and the main role of the transition metal catalyst is to stabilize these monomers by transfer hydrogenation/hydrogenolysis reactions. The experimental data from the transition metal catalyzed transfer hydrogenation/hydrogenolysis reactions was supported by molecular dynamics simulations using ReaXFF.

Recommendations are given concerning the terminology of methods used in electroanalytical chemistry. Fundamental terms in electrochemistry are reproduced from previous PAC Recommendations, and new and updated material is added for terms in electroanalytical chemistry, classification of electrode systems, and electroanalytical techniques.