In green chemistry, filamentous fungi are regarded as a kind of robust microorganism for the biotransformation of natural products. Nonetheless, the screening of microorganisms is crucial for the effective biotransformation of natural products such as phenazine compounds. The precursor metabolite of most phenazine derivatives in Pseudomonas spp. is phenazine-1-carboxylic acid (PCA), the key constituent of shenqinmycin, widely used to control rice sheath blight in southern China. In this study, a new fungus strain Aspergillus sclerotiorum was isolated, which can efficiently convert PCA into 3-hydroxy-phenazine 1-carboxylic acid (3-OH-PCA). Moreover, an effective whole cells biotransformation system was constructed by screening optimal reaction conditions and carbon sources. Hence, Aspergillus sclerotiorum exhibited desirable adaptation by consumption of different carbon sources and maximum whole cell biomass (10.6 g/L DCW) was obtained as a biocatalyst from glucose. Optimal conditions for whole-cell biocatalysis of PCA were evaluated, including PCA concentration of 1120 mg/L, pH 7.0, temperature of 25°C, rotation rate 200 rpm and dry cell weight 15 g/L for 60 h, thus 1060 mg/L of 3-OH-PCA was obtained and the conversion efficiency of PCA was 94%. Hence, the results of repeated batch mood revealed that the biotransformation efficiency of fungus pellets reduced with each subsequent cycle but remained stable in all five cycles with the provision of glucose supplement. These findings open the prospective of using filamentous fungi for the whole cell biocatalysis of phenazine in enormous amount and efficient production of 3-OH-PCA. Moreover, these results laid the foundation for further research to disclose the genetic based mechanism of the strain responsible for PCA biotransformation.

There is considerable interest in cellulose solubilisation in deep eutectic solvents (DESs) as a new emerging class of green solvents. However, the experimental data have indicated that cellulose is almost insoluble in most of DESs. Carboxylic acid-based DESs are a category of DESs that exhibit a modest ability to solubilise cellulose. However, the molecular-level reasons why carboxylic acid-based DESs can dissolve cellulose are unknown. Such information is crucial in developing DESs with enhanced cellulose solubilising ability. Here, we use molecular dynamics simulations to explore the molecular mechanism of cellulose solubility in oxaline (choline chloride/oxalic acid) as a typical carboxylic acid-based DES and cellulose insolubility in reline (choline chloride/urea) as the most famous DES. It was revealed that oxalic acid possesses a greater ability to weaken the interaction between the chloride anion and the choline cation when compared to other urea in reline. Self-interactions of hydrogen bond donors are also highly attenuated in oxaline than in reline. These results explain the observed more significant melting point depression of oxaline in comparison to reline. We depict a molecular mechanism indicating how oxalic acid synergically works with chloride ion to dissolve cellulose and why urea cannot play such a role in reline.

This study explored the adsorption of carboxylic acids, especially free fatty acids (FFA), present in biofuel (distilled fractions of bio-oil such as gasoline-like hydrocarbons, kerosene-like hydro-carbons and diesel-like hydrocarbons) using red mud-based adsorbents. The red mud was ther-mally activated (at 40 °C and 600 °C) and chemically activated with HCl (0.25M, 1M, and 2M). Analytical techniques were used to characterize the adsorbents' properties. At the same time, the study examined factors like feed type, adsorbents, FFA content, adsorbent percentage, activation temperature, acid solution concentration and contact time to assess adsorption efficiency. The characterization results indicated that chemical activation with 0.25M HCl significantly in-creased the surface area to 84.3290 m²/g, surpassing thermally activated samples (35.2450 m²/g at 400 °C). Adsorption experiments demonstrated that all chemically activated samples, with 5% adsorbent, adsorbed over 2000 mg FFA per gram of adsorbent, with CARM – 1M HCl achieving 100% removal of acids from gasoline-like hydrocarbons. Kinetic modeling showed that the pseudo-second-order model best represented the adsorption data, as evidenced by high R² values and close agreement between experimental and calculated qe values. Therefore, adsorption with chemically activated red mud efficiently deacidifies biofuels, providing a cost-effective and promising approach for their upgrading.

The objective of this work was to investigate the deacidification of bio-oils (BOs) from triglyceride-based biomass through the application of liquid-liquid extraction (LLE) in a simple stage, using methanol and water as a binary solvent and feed/solvent ratio of 1/1. For this, the effects of process parameters such as the water content present in the solvent, the content of carboxylic acids present in the bio-oil, and the extraction temperature on the deacidification process through the efficiency and distribution coefficient were evaluated, as well as the effects of such parameters on the quality of deacidified bio-oils through physical-chemical analyzes and GC-MS analysis. The results show that such process parameters significantly affect the quality of deacidified bio-oils. The ideal condition to have the highest acid removal, i.e., the highest deacidification efficiency (72.65%), is the one in which the deacidification process is performed with aqueous methanol (5% water) at 35 °C and for BOs that have a total acid number (TAN) equal to 24.38 mg KOH/g. Therefore, the process of deacidification by LLE using aqueous methanol is a promising alternative for removing carboxylic acids and other oxygenated compounds, contributing significantly to the upgrading or improving biofuels produced by catalytic thermal cracking.

Deep Eutectic Solvents (DESs) show promising abilities for the delamination of multilayer packaging films that are used in food packaging and in pharmaceutical blister packs. Due to the complexity of their structure, the recycling of these materials is a challenging task, leading to the easiest or cheapest option, landfilling. Towards the development of ‘green’ solvents for the efficient waste management and recycling, the conducted research focuses on the preparation of a range of hydrophobic and hydrophilic DES based on carboxylic acids. Also, their chemical and physical characterization, such as DSC, rheometer and density measurements, was followed for the determination of their properties. The laminate packaging waste products that were tested were Al/PE, PE/Al/PET, Al/PE/paper and PVC/PE/Al. Different batches of solvent systems were tested based on various naturally derived aliphatic and aromatic organic compounds as well as amino acids. The separated films were collected and studied further for the examination of the delamination extend. Results showed full or partial delamination of some materials as well as challenges of solvent systems. Variables such as temperature, agitation rate, mixing time and solvents ratios were monitored and collected during the design of experimental process. The results showed that the used DESs can offer an efficient, low-energy, affordable and green option for the delamination tested packaging materials.

Various optically active 2-hydroxyamide derivatives are produced based on the kinetic resolution of racemic 2-hydroxyamides with a diphenylacetyl component and (R)-benzotetramisole [(R)-BTM], a chiral acyl-transfer catalyst, via asymmetric esterification and acylation. It was revealed that a tertiary amide can be used with this novel protocol to achieve high selectivity [22 examples; s-value reaching over 250]. The resulting chiral compounds could be transformed into other useful structures while maintaining their chirality.

The incorporation of polycarboxylate ether superplasticizer (PCE) type polymer and silica fume (SF) in high-performance concretes (HPC) leads to the achievement of remarkable rheological and mechanical improvements. In the fresh state, PCEs are adsorbed on cement particles and dispersants, in turn promoting the workability of the concrete. Silica fume enables a very well compacted concrete to be obtained, which is characterized by high mechanical parameters in its hardened state. Some PCEs are incompatible with silica fume, which can result in the loss of slump and in poor rheological behavior. The main objective of the research is the study of the influence of three types of PCEs, which all have a different molecular architecture, on the rheological and mechanical behavior of high-performance concretes containing 10% of SF as a partial replacement of cement. The results show that the carboxylic density of PCE has an influence on its compatibility with SF.

The pulp and paper industry is one of the biggest industry sectors worldwide, whose market growth is expected to reach 370.12 billion USD by 2028. However, as a water-intensive process, the pulp and paper production generate huge volumes of contaminated effluents, some of which contain dissolved high-value chemical compounds, such as lignin, hemicellulose, or carboxylic acids. These compounds can be recovered using membrane operations. Thus, membrane operations represent a method to valorize effluents and byproducts from this industry sector and narrow the gap between biorefinery models and the pulp and paper production as an integrated biorefinery. The present review reviews the state-of-the-art-research and the state-of-the-art applications of membrane operations in the pulp and paper industry.

β-cyclodextrin (CD) derivatives containing aromatic triazole ring were studied as potential carriers of drugs containing an anthraquinone moiety in the structure: anthraquinone-2-sulfonic acid (AQ2S), anthraquinone-2-carboxylic acid (AQ2CA) and a common anthracycline, daunorubicin (DNR). UV-Vis and voltammetry measurements were carried out to determine the solubilities and stability constants of the complexes formed and revealed the unique properties of the chosen CDs as effective pH dependent drug complexing agents. The stability constants of the drug complexes with the CDs containing triazole: βCDLip and βCDGAL were significantly larger than with the native βCD. The AQ2CA and AQ2S drugs are ill-soluble and their solubilities increased as the result of complex formation with βCDLip and βCDGAL ligands. AQ2CA, AQ2S were negatively charged at pH 7.4 and therefore they were less prone to form inclusion complex with the hydrophobic CD cavity than at pH 3 (characteristic of gastric juices) when they were protonated. βCDTriazole and βCDGAL ligands were found to form weaker inclusion complexes with the positively charged drug DNR at acidic pH (pH 5.5) than in the neutral medium (pH 7.4) when the drug dissociates to the neutral, uncharged form. This pH dependence is favorable for anti-tumor applications.

A Staudinger reaction on solid phase between an electronodeficit organic azide such as sulfonyl azide, and the phosphite triester formed upon phosphoramidite coupling is a convenient method for chemical modification of oligonucleotides at the internucleotidic phosphate position. In this work, 4-carboxybenzenesulfonyl azide either with a free carboxy group or in the form of an activated ester such as pentafluorophenyl, 4-nitrophenyl, or pentafluorobenzyl ester were used to introduce a carboxylic acid function to the terminal or internal internucleotidic phosphate of an oligonucleotide via Staudinger reaction. A subsequent treatment with excess primary alkyl amine followed by usual work-up, after prior activation with a suitable peptide coupling agent such as HBTU/HOBt in the case of a free carboxyl, afforded amide-linked oligonucleotide conjugates in good yields including multiple conjugations of up to the exhaustive modification at each phosphate position for a weakly activated pentafluorobenzyl ester, whereas more strongly activated and, thus, more reactive aryl esters provided only single conjugations at the 5′-end. The conjugates synthesized include those with di- and polyamines that introduce a positively charged side-chain to potentially assist intracellular delivery of the oligonucleotide.