Photooxidation of thiosaccharides mediated by sensitizers in aerobic and environmentally friendly conditions

A series of β-d-glucopyranosyl derivates have been synthesized and evaluated in photooxidation reactions promoted by visible light and mediated by organic dyes under aerobic conditions. Among the different photocatalysts employed, tetra-O-acetyl riboflavin afforded chemoselectively the respective sulfoxides, without over-oxidation to sulfones, in good to excellent yields and short reaction times. This new methodology for the preparation of synthetically useful glycosyl sulfoxides constitutes a catalytic, efficient, economical, and environmentally friendly oxidation process not reported so far for carbohydrates.

An environmentally friendly and simple sensitized photooxidation methodology to obtain glycosyl sulfoxides with outstanding chemoselectivity in aerobic conditions is described.     

Fabrication of PP hollow fiber membrane via TIPS using environmentally friendly diluents and its CO2 degassing performance

CO₂ removal is an essential water purification process in many fields, such as petrochemical production and thermal power generation. It is challenging to remove low concentrations of CO₂ from RO effluent water. The core component of the membrane degassing technique is a high-performance hydrophobic microporous membrane. Polypropylene (PP) membranes were prepared with environmentally friendly binary diluents via thermally induced phase separation. Firstly, the effects of PP concentration on the phase diagram, flat sheet membrane structure and mechanical properties were studied to optimize the PP content for a hollow fiber membrane (HFM). The PP HFM showed a sponge-like cross-sectional structure without any dense skin layer, a large loading force and breaking elongation, and a narrow pore size distribution with a mean pore size of 0.16 μm. The as-fabricated PP HFM module was applied for CO₂ removal from RO effluent water from a petrochemical plant. A higher water temperature and vacuum degree facilitated CO₂ removal. Increasing the effective membrane length enhanced degassing efficiency. Increasing the water flow rate increased CO₂ degassing flux, but simultaneously decreased degassing efficiency. When the water flow rate increased from 20 mL min⁻¹ to 63 mL min⁻¹, although the effective membrane length increased from 3 m to 4.8 m for the best degassing efficiency of 88%, the amount of treated water increased by 3.15 times. The declined CO₂ concentration in the outlet water was 1.6 mg L⁻¹.

A PP membrane prepared via TIPS using CO/SO as environmentally friendly binary diluents to remove low-concentration CO₂ from RO effluent water.     

Fully-biobased UV-absorbing nanoparticles from ethyl cellulose and zein for environmentally friendly photoprotection

Effective photoprotection is a vital consumer issue. However, there are many concerns regarding the adverse environmental and health impacts associated with current organic and inorganic UV filters. Here, we prepare fully-biobased UV-absorbing nanoparticles from ethyl cellulose (ECNPs) and zein (ZNPs) with encapsulated biobased photoprotectants obtainable from plants and foods (quercetin, retinol, and p-coumaric acid), which have the potential to satisfy both environmental and health issues in photoprotection. We show the ability of ECNPs and ZNPs to be easily tuned compositionally to obtain uniform, broadband UV spectrum absorbance profiles, and prepare transparent UV-absorbing coatings from the ECNPs. We find that the maximum loadings for retinol, quercetin, and p-coumaric acid into the ECNPs are 31 wt%, 14 wt%, and 13 wt% respectively. The ECNP size remains constant (except for the largest loading of retinol, 31 wt%) and the absolute zeta potential increases upon increasing the loading of quercetin and retinol, whereas increasing the loading of p-coumaric acid results in increasing the particle size and a lower absolute zeta potential. We find that quercetin and retinol are effectively retained inside the ECNPs at 64–70% after 72 hours. These results have significant implications for the development of novel photoprotection technologies and functional nanoparticles.

UV-absorbing nanoparticles are prepared with an entirely biobased composition, as a novel environmentally-friendly photoprotection technology.     

Well-confined polyoxometalate-ionic liquid in silicic framework for environmentally friendly asymmetric di-hydroxylation of olefins

Chiral 1,2-diols with a high yield could be directly prepared from asymmetric di-hydroxylation of olefins via an eco-friendly and enduring catalyst, in which abundant “chiral pools” of polyoxometalate-ionic liquid were target-designed into the silicic framework (POM-ILS) and well stabilized in aqueous media.

Abundant POMs double-locked by silicic frameworks and chiral ILs drive efficient and environmentally friendly asymmetric di-hydroxylation of olefins in water.     

Experimental and theoretical investigation on corrosion inhibitive properties of steel rebar by a newly designed environmentally friendly inhibitor formula

In order to mitigate the corrosion of steel rebar in concrete, a new environmentally friendly corrosion inhibitor formula (WKI) was designed and the corrosion inhibitive effects of WKI on steel rebar were studied by gravimetric method, electrochemical impendence spectroscopy (EIS), potentiodynamic polarization and Mott–Schottky scanning in simulated concrete pore solution. Furthermore, surface analysis and quantum chemical calculations were conducted in order to illustrate the corrosion inhibitive mechanism. The results indicate that WKI exhibits excellent corrosion inhibitive activities on steel rebar in simulated concrete pore solution. By the presence of WKI, local corrosion was significantly suppressed and no pitting could be detected during the whole experimental period. The total corrosion resistance was increased from 5469 Ω cm² to 64 440 Ω cm² and the corrosion current density was reduced from 3.23 μA cm⁻² to 0.21 μA cm⁻² for the sample immersed in the corrosion medium for 7 d with WKI. The corrosion potential of the steel rebar electrode moved to a higher level and the charge transfer resistance increased, indicating that the anti-corrosion properties of the steel rebar were enhanced. The corrosion inhibitive mechanism of WKI can be attributed to the fact that it can promote the formation of a passive film and reduce its defect concentration via its adsorption and interaction with the metal surface, consequently inhibiting the corrosion of steel rebar caused by chloride ions.

A new corrosion inhibitor formula was designed and the inhibitive mechanism was analyzed based on HSAB theory and the PDM model.     

Drug permeability of modified silicone polymers. III. Hydrophilic pressure-sensitive adhesives for transdermal controlled drug release applications

A new class of hydrophilic silicone/organic pressure-sensitive adhesives (PSAs) was formulated from polydimethylsiloxane-poly(ethylene oxide) graft copolymers and silicone resins. The following effects of the structure of the graft copolymers and silicone resins on the adhesion and the drug permeability were investigated: (a) the size and the degree of the grafting, (b) the degree of polymerization of the polysiloxane and (c) the loading level and molecular weight of the silicone resin. It was demonstrated that a number of therapeutic agents could be incorporated into the PSAs without compromising their functional adhesive tape properties. The PSAs not only had excellent drug permeabilities but also retained their adhesion upon aging, thus permitting their use in transdermal controlled drug release applications. This family of PSAs has a distinct advantage over other PSAs because it also enhanced the release rates of hydrophilic drugs.     

Kinetics study of dyeing bicomponent polyester textiles (PET/PTT) using environmentally friendly carriers

The biobased carriers o-vanillin, p-vanillin, and coumarin, can be used to dye poly(ethylene terephthalate)/poly(trimethylene terephthalate) (PET/PTT) bicomponent filaments at low temperature without affecting their excellent elasticity and elastic recovery. These ecological carriers, which are free from any toxic product, present an effective solution for obtaining an ecological and economical dyeing process. This paper presents a study of the effects of the kinetics when dyeing bicomponent (PET/PTT) filaments with three disperse dyes having different molecular weights at 100 °C (upon adding ecological carriers) and at a high temperature (130 °C). The physicochemical characterization of bicomponent filaments was done using several techniques, such as SEM, BET and DSC, before carrying out a modelling study. Different models (pseudo first-order, pseudo second-order, Elovich, and intra-particle diffusion models) were used to identify an acceptable dyeing mechanism. The dyeing rate constants, the half dyeing times, and the rise time coefficients were then determined and analyzed. The results of this work explain the adsorption mechanism during the dyeing process of bicomponent (PET/PTT) filaments using ecological carriers and provide an experimental foundation for future research.

The biobased carriers o-vanillin, p-vanillin, and coumarin, can be used to dye poly(ethylene terephthalate)/poly(trimethylene terephthalate) bicomponent filaments at low temperature without affecting their excellent elasticity and elastic recovery.     

Regression,kinetics and isotherm models for biosorption of organic pollutants,suspended and dissolved solids by environmentally friendly and economical dried Phragmites australis

Low cost adsorbents such as P. australis have received considerable interest owing to their low cost and easy availability. The aim of the present study was the evaluation of the removal of chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended and dissolved solids (TSS and TDS) using dried P. australis in influent wastewater to a wastewater treatment plant. The results of the COD and BOD concentration reduction with P. australis at optimum operating conditions were determined for maximum reduction and adsorption isotherms. The maximum reduction of COD, BOD, TSS and TDS concentrations under the optimum operating conditions was 92.27%, 93.89%, 94.38% and 91.61%, respectively. The results demonstrate that the new dried biosorbent is able to adsorb all the aforementioned contamination. It achieved an adsorption capacity for COD of 72.5 mg g⁻¹ and an adsorption capacity for BOD of 43.93 mg g⁻¹. The results were well fitted by the pseudo-second order model with R² = 0.984.

Low cost adsorbents such as P. australis have received considerable interest owing to their low cost, large amount of functional groups and easy availability.     

High pressure extraction of bioactive diterpenes from the macroalgae Bifurcaria bifurcata: an efficient and environmentally friendly approach

The brown macroalgae Bifurcaria bifurcata have gained special attention due to their ability to biosynthesize linear diterpenes (rarely found in other species). However, the conventional extraction methods normally used to extract these compounds involve organic solvents and often high temperatures, leading to the degradation of thermo-labile compounds. In this context, the main objective of this work was to study and optimize for the first time the extraction of diterpenes from B. bifurcata through an environmentally friendly methodology, namely, high pressure extraction (HPE) using ethanol : water. This was compared with conventional Soxhlet extraction, using dichloromethane. Box–Behnken design was employed to evaluate the linear, quadratic, and interaction effects of 3 independent variables (pressure (X₁), ethanol percentage (X₂), and time of extraction (X₃)) on response variables (extraction yield and diterpenes content (mg g⁻¹ of extract and mg kg⁻¹ of dry weight)) and the optimal extraction conditions (X₁: 600 MPa; X₂: 80%; X₃: 5 min) were estimated by response surface methodology (RSM). B. bifurcata extract obtained under HPE optimal conditions showed a diterpenes content (612.2 mg g⁻¹ of extract) 12.2 fold higher than that obtained by conventional extraction (50.1 mg g⁻¹ of extract). The HPE extract, obtained under optimal conditions, showed antioxidant and antibacterial (against Staphylococcus aureus) activities considerably higher than the Soxhlet extract, and also presented a promising synergic effect with antibiotics, improving the antibiotic efficacy against S. aureus. In conclusion, these results indicate that HPE is a promising methodology, compared to conventional methodologies to obtain linear diterpene rich extracts from B. bifurcata with great potential to be exploited in pharmaceutical or biomedical applications.

Bioactive linear diterpenes were selectively extracted from the macroalga Bifurcaria bifurcata through optimized high-pressure extraction.     

A review on bio-electro-Fenton systems as environmentally friendly methods for degradation of environmental organic pollutants in wastewater

Bio-electro-Fenton (BEF) systems have been potentially studied as a promising technology to achieve environmental organic pollutants degradation and bioelectricity generation. The BEF systems are interesting and constantly expanding fields of science and technology. These emerging technologies, coupled with anodic microbial metabolisms and electrochemical Fenton''s reactions, are considered suitable alternatives. Recently, great attention has been paid to BEFs due to special features such as hydrogen peroxide generation, energy saving, high efficiency and energy production, that these features make BEFs outstanding compared with the existing technologies. Despite the advantages of this technology, there are still problems to consider including low production of current density, chemical requirement for pH adjustment, iron sludge formation due to the addition of iron catalysts and costly materials used. This review has described the general features of BEF system, and introduced some operational parameters affecting the performance of BEF system. In addition, the results of published researches about the degradation of persistent organic pollutants and real wastewaters treatment in BEF system are presented. Some challenges and possible future prospects such as suitable methods for improving current generation, selection of electrode materials, and methods for reducing iron residues and application over a wide pH range are also given. Thus, the present review mainly revealed that BEF system is an environmental friendly technology for integrated wastewater treatment and clean energy production.

Bio-electro-Fenton system is a promising technology for the environmental organic pollutants degradation and bioelectricity generation.     

Photoresponsive,switchable, pressure-sensitive adhesives: influence of UV intensity and hydrocarbon chain length of low molecular weight azobenzene compounds

Unlike traditional adhesives with a fixed adhesive force, switchable adhesives, which have an adhesive force that can be adjusted by external stimuli, are specifically designed to be released according to user demand, or to enable the transfer of fine electronic devices. Previously developed switchable adhesives have limitations such as a slow switching rate, narrow adhesion modulation range, or the lack of reusability. Thus, we fabricated switchable pressure-sensitive adhesives (PSAs) that can overcome these limitations. The adhesive force of each switchable PSA, which comprises an azobenzene-containing acrylic polymer and low molecular weight compounds, was designed to be activated/deactivated via ultraviolet (UV) and visible light irradiation. The adhesive force and UV intensity required for the switch were found to be dependent on the aliphatic chain length of the compound. The adhesive force of the SP-C10, i.e., a switchable PSA containing a azobenzene compound with an aliphatic chain of 10 hydrocarbons, increased to 3.5 N from nearly zero in response to only 30 s of low-level (25 mW cm⁻²) UV irradiation. Additionally, SP-C10 did not lose its adhesive force even after 30 cycles of repeated adhesion switching. The mechanism of adhesion switching influenced by UV intensity and the structure of low molecular weight azobenzene compounds are also reported.

A photoresponsive switchable pressure-sensitive adhesive (PSA) was fabricated with an azobenzene-containing polymer and low molecular weight compounds. Its adhesion force was activated/deactivated rapidly by UV/visible light irradiation.     

Simple,fast and environmentally friendly method to determine ciprofloxacin in wastewater samples based on an impedimetric immunosensor

In this study an impedimetric immunosensor was developed in order to determine ciprofloxacin (CIP) in wastewater samples, an emergent contaminant widely found in wastewater. To achieve this, an anti-ciprofloxacin antibody was immobilized on the surface of a printed carbon electrode. Then, the developed immunosensor was applied in wastewater samples from Université Laval residences (Québec, Canada) through the load transfer resistance (R_ct) using [Fe(CN)₆]^3−/4− as a redox probe, and the average CIP concentration was found to be 2.90 × 10⁻⁴ μg mL⁻¹. The observed R_ct changes presented a linear relationship from CIP concentrations of 10⁻⁵ to 1.0 μg mL⁻¹, with detection and quantification limits of 2.50 × 10⁻⁶ and 7.90 × 10⁻⁶ μg mL⁻¹, respectively. The immunosensor presented high selectivity and repeatability, as well as a good recovery rate in wastewater samples (97%). Significant interference with other compounds was not observed. The proposed method requires only 30 μL of sample without the use of organic solvents or preceding sample preparation and/or extraction techniques. Moreover, the method is fast: only 20 min of incubation followed by 2 min of analysis time was sufficient to obtain the CIP concentration. The method''s estimated cost is U$ 2.00 per sample.

In this study an impedimetric immunosensor was developed in order to determine ciprofloxacin (CIP) in wastewater samples, an emergent contaminant widely found in wastewater samples.     

Novel nicotinoid structures for covalent modification of wood: an environmentally friendly way for its protection against insects

Timber is constantly exposed to environmental influences under outdoor conditions which limits its lifetime and usability. In order to counteract the damaging processes caused by insects, we have developed a novel and more environmentally friendly method to protect wood materials via covalent modification by organic insecticides. Starting with an important class of synthetic insecticides which are derived from the natural insecticide nicotine, various new carboxylic acid derivatives of imidacloprid were made accessible. These activated neonicotinoids were utilized for the chemical modification of wood hydroxy groups. In contrast to conventional wood preservation methods in which biocides are only physically bound to the surface for a limited time, the covalent fixation of the preservative guarantees a permanent effect against wood pests, demonstrated in standardized biological tests. Additionally, the environmental interaction caused by non-bound neonicotinoids is significantly reduced, since both, a smaller application rate is required and leaching of the active ingredient is prevented. By minimizing the pest infestation, the lifetime of the material increases while preserving the natural appearance of the material.

A novel and eco-friendly procedure for durable wood protection applying covalently bound organic insecticides is presented. Biological tests confirmed the effectiveness of the method, which also reduces the environmental impact.     

Preparation and properties of water-based acrylic emulsion-assisted flexible building tiles

The heavy and rigid appearance of conventional burnt building tiles is not suitable for a global sustainable development strategy. Flexible facing tiles with lightweight and environmental materials are highly desirable for the construction industry today. In this work, water-based polymer emulsion-assisted flexible building tiles were prepared. Based on the method of achieving post crosslinking and improving adhesion with inorganic matrix–based materials, WPAs modified with GMA and KH570 display good chemical resistance and low solvent absorption (0.132 in water and 0.289 in ethanol respectively). The optimum mechanical performance of flexible building materials prepared with WPAs can strain 1.406% and stress 1.8658 MPa. The TGA, XRD, SEM and AFM results further indicate the excellent thermal stability and compatibility of flexible building tiles. Hence, flexible building tiles prepared with WPAs can be promising building materials for construction.

Water-based acrylic emulsion-assisted flexible building tiles were prepared and applied to a kind of building facing material for construction.     

Mo@GAA-Fe3O4 MNPs: a highly efficient and environmentally friendly heterogeneous magnetic nanocatalyst for the synthesis of polyhydroquinoline derivatives

Polyhydroquinolines were efficiently obtained from a sequential four-component reaction between dimedone or 1,3-cyclohexandione, ethyl acetoacetate, or methyl acetoacetate as a β-ketoester, aldehydes, and ammonium acetate, under the catalysis of Mo@GAA-Fe₃O₄ MNPs as a green, effective, recyclable, and environmentally friendly nanocatalyst. Due to its magnetic nature the prepared catalyst can be easily separated from the reaction mixture by an external magnet and reused several times without significant changes in catalytic activity and reaction efficiency. The catalyst was characterized using energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

Polyhydroquinolines were obtained from a sequential four-component reaction between dimedone or 1,3-cyclohexandione, ethyl acetoacetate, or methyl acetoacetate as a β-ketoester, aldehydes, and ammonium acetate, with Mo@GAA-Fe3O₄ MNPs as a green nanocatalyst.     

Enhancement performance of application mussel-biomimetic adhesive primer for dentin adhesives

In this study, we evaluated bioinspired adhesive primers for durable adhesion between dentin and composite resins. N-3,4-Dihydroxyphenethyl methacrylamide (DMA) primer monomer (small bifunctional group molecules containing catechol and acrylic groups at opposite ends) was prepared to mimic the interaction between the catechol group and the mineral interface of marine mussels. The shear bonding strength, microleakage, degree of conversion, contact angle, and compatibility were tested. The shear bond strength was significantly improved, and microleakage was diminished after the application of the DMA primer. However, the degree of conversion was decreased. The wettability of the dentin was enhanced, and the DMA primer showed no negative influence on cell proliferation. The results of this study showed the possibility of using DMA primers in clinical practice. This may provide a new strategy for improving adhesion durability.

In this study, a bioinspired adhesive primer monomer was prepared and evaluated for durable adhesion between dentin and composite resins.     

Preparation of sulfonated carbon-based catalysts from murumuru kernel shell and their performance in the esterification reaction

In the present study, heterogeneous acid catalysts for fatty acid esterification reactions were synthesized using agro-industrial waste from murumuru kernel shells. The waste was carbonized and functionalized with concentrated sulfuric acid under different sulfonation conditions, obtaining the sulfonated biochar. The results indicate that the best sulfonation conditions were obtained with a contact time of 4 h, the temperature of 200 °C, and a solid-acid ratio of 1 : 10 (w/v). The best catalyst was characterized by acid–base titration for the determination of total acid density, X-ray diffraction, scanning electron microscopy, X-ray energy dispersion spectroscopy, Fourier transform infrared spectroscopy and thermal analysis. Reaction conditions of oleic acid with methanol and the viability of catalyst reuse were also investigated. A conversion of 97.2% was achieved under optimum esterification reaction conditions, employing 5% catalyst, 10 : 1 molar ratio of methanol to oleic acid, during 1.5 h at a temperature of 90 °C. After 4 reaction cycles, the catalyst preserved its efficiency at 66.3% conversion. The catalyst activity was evaluated in reactions using palmitic acid, soybean fatty acid distillate, palm fatty acid distillate, and coconut fatty acid distillate. The results demonstrate that the catalyst is applicable and efficient in esterification reactions of raw materials, containing different fatty acid compositions since different carbonized materials have varying abilities to combine acid groups. This work reveals the promising feasibility of using biomass generated in large quantities by the agroindustry for the development of a new heterogeneous acid catalyst for biodiesel production.

In the present study, heterogeneous acid catalysts for fatty acid esterification reactions were synthesized using agro-industrial waste from murumuru kernel shells.     

Preparation of gemini surfactant/graphene oxide composites and their superior performance for Congo red adsorption

Gemini surfactant/GO composites (10-2-10/GO, 12-2-12/GO, and 14-2-14/GO) have been successfully prepared using three gemini surfactants with different tail chain lengths. The morphology and physicochemical properties of the as-synthesized composites were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform-infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The gemini surfactant/GO composites were applied to the adsorption of Congo red dye, and from the experimental data, optimum adsorption conditions, adsorption kinetics, and isotherms were obtained. The removal process was favorable at acidic pH and reached equilibrium in ∼60 min. The results showed that the pseudo-second-order model and the Langmuir adsorption isotherm were a good fit for the adsorption of Congo red onto gemini surfactant/GO composites. Compared with other adsorbents reported in the literature, these composites showed superior Congo red adsorption capabilities, with absorption capacities as high as 2116, 2193, and 2325 mg g⁻¹ for 10-2-10/GO, 12-2-12/GO, and 14-2-14/GO, respectively. Moreover, the adsorption capacities were more than 1000 mg g⁻¹ even for the fifth cycle. The results of the present study substantiate that the gemini surfactant/GO composites are promising adsorbents for the removal of organic dyes in wastewater treatment.

Gemini surfactant/GO composites were prepared for the removal of Congo red dye, and show excellent adsorption capacities and reusabilities.