Transforming a volcanic rock powder waste into an efficient adsorbent to remove dyes (acid green 16 and acid red 97) and metals (Ag+, Co2+, and Cu2+) from water.

This study searched for the best synthesis route for producing an adsorbent from the alkaline fusion of volcanic rock powder waste. The samples synthesized under different conditions of temperature and alkalizing ratio/precursor material, nine in total (NP.F, NP.F1, NP.F2, ...NP.F8 ), were used in the adsorption of acid green 16 (AG 16) and acid red 97 (AR 97) dyes and Ag+, Co2+, and Cu2+ ions. Subsequently, the 22 central composite rotational design (CCRD) was applied, and the effects of the alkalizing ratio (NaOH)/volcanic rock (VR) and temperature (T) on the synthesis process were analyzed in terms of their influence on the physical properties of the materials and in the process of adsorption of contaminants. From the experimental design, it can be seen that the independent variables alkalizing ratio/volcanic rock and temperature greatly influence the characteristic and synthesis of adsorbent materials by alkaline fusion, which in turn reflects on the results achieved in the adsorption of contaminants. Therefore, the temperature of 550 °C and NaOH/VR ratio equal to 1 was the most satisfactory synthesis route to obtain high values of adsorption capacity (q, mg g-1) and removal (R, %) for all studied contaminants, as well as the optimization of the physical characteristics of the material. For example, the adsorption capacity of dye AG 16 was 49.1 mg g-1, and for Ag+ was 66.2 mg g-1, while the removal percentages were 97.6% and 93.4%, respectively. This approach made it possible to transform volcanic rock powder wastes into an efficient adsorbent to treat contaminated waters with dyes and metals.

Correlation between cocoa shell modifications by CTAB and its dye adsorption properties.

Cocoa shell was modified whit sodium hydroxide (NaOH) and cationic surfactant cetyltrimethylammonium bromide (CTAB) to increase surface functionality, surface area, and positive charge density. The prepared adsorbent CC-OH-CTAB was used to remove indigo carmine (IC) and bromocresol green (BCG) dyes from water. The optimal pH for IC and BCG adsorption were 2 and 4, respectively. The equilibrium was attained after a contact time of 30 min for IC and 120 min for BCG. The maximum adsorption capacity (Qmax) of IC and BCG obtained was 85.1 mg g-1 and 192.7 mg g-1, respectively. The Liu isotherm model best described the equilibrium results. The adsorption kinetics model showed that IC and BCG adsorption onto CC-OH-CTAB followed the pseudo-first-order and pseudo-second-order model, respectively. The regeneration and reusability experiments indicated that CC-OH-CTAB had much stability and excellent performance meanwhile repeatedly used. Finally, the insertion of CTAB on the CC-OH surface proved to be an excellent way to improve the adsorption performance of this material concerning dyes.

Herbs carbonization and activation for fast sorption of nitrate ions: a new challenge for a full treatment of groundwater pollution.

The evolution of low-cost ecotechnologies in water treatment and purification is highly increased. Face to the growing global demand for eco-friendly water treatment materials, the non-valorized herb-based biomass covering a large area could be a promising alternative. Herbs (HB) are currently one of the cheapest biomasses. Therefore, the utilization of HB for environmental applications is relevant. HB was treated and activated in this work to produce an eco-friendly adsorbent for nitrate removal from groundwater. HB was treated with modified carbonization at 220 °C to produce highly reactive biochar (BCH). Ammonium groups (AM) are immobilized covalently over the BCH surface, and then, the resulting materials BCH-AM are fully characterized. Results showed that ammonium is successfully grafted at the BCH surface, producing a highly stable material. Measurements on nitrate ion adsorption revealed that BCH-AM are of great interest as 80% of nitrate ions (NO3-) were removed. Importantly, the eco-friendly BCH-AM demonstrated the ability to easily desorb the nitrate ions using Na2CO3 as a green eluent. Parametric studies confirmed the effectiveness of the prepared adsorbent and approved that the adsorption occurred by electrostatic interactions. To demonstrate the performance of the adsorbent, BCH-AM was evaluated to remove NO3- from groundwater upstream in a water treatment plant. This work opens an immense perspective for herb biomass to be the actual challenge to resolve environmental problems.

Wood waste-based functionalized natural hydrochar for the effective removal of Ce(III) ions from aqueous solution.

In this study, a sustainable and easily prepared hydrochar from wood waste was studied to adsorb and recover the rare earth element cerium (Ce(III)) from an aqueous solution. The results revealed that the hydrochar contains several surface functional groups (e.g., C-O, C = O, OH, COOH), which largely influenced its adsorption capacity. The effect of pH strongly influenced the Ce(III) removal, achieving its maximum removal efficiency at pH 6.0 and very low adsorption capacity under an acidic solution. The hydrochar proved to be highly efficient in Ce(III) adsorption reaching a maximum adsorption capacity of 327.9 mg g-1 at 298 K. The kinetic and equilibrium process were better fitted by the general order and Liu isotherm model, respectively. Possible mechanisms of Ce(III) adsorption on the hydrochar structure could be explained by electrostatic interactions and chelation between surface functional groups and the Ce(III). Furthermore, the hydrochar exhibited an excellent regeneration capacity upon using 1 mol L-1 of sulfuric acid (H2SO4) as eluent, and it was reused for three cycles without losing its adsorption performance. This research proposes a sustainable approach for developing an efficient adsorbent with excellent physicochemical and adsorption properties for Ce(III) removal.

Assessing Alternative Pre-Treatment Methods to Promote Essential Oil Fixation into Cotton and Polyethylene Terephthalate Fiber: A Comparative Study.

This study aims to develop a new refreshing feeling, ecological, and antimicrobial fabrics for medicinal applications. The geranium essential oils (GEO) are incorporated into polyester and cotton fabrics by different methods, such as ultrasound, diffusion, and padding. The effect of solvent, nature of fibers, and treatment processes were evaluated via the thermal properties, the color strength, the odor intensity, the wash fastness, and the antibacterial activities of the fabrics. It was found that the ultrasound method was the most efficient process for incorporation of GEO. Ultrasound produced a great effect on the color strength of the treated fabrics, suggesting the absorption of geranium oil in fiber surface. The color strength (K/S) increased from 0.22 for the original fabric to 0.91 for the modified counterpart. In addition, the treated fibers showed appreciable antibacterial capacity against Gram-positive (Staphylococcus epidermidis) and Gram-negative (Escherichia coli) bacteria strains. Moreover, the ultrasound process can effectively guarantee the stability of geranium oil in fabrics without decreasing the significant odor intensity and antibacterial character. Based on the interesting properties like ecofriendliness, reusability, antibacterial, and a refreshing feeling, it was suggested that textile impregnated with geranium essential oil might be used as a potential material in cosmetic applications.

An Electrolyte-Gated Graphene Field-Effect Transistor for Detection of Gadolinium(III) in Aqueous Media.

In this work, an electrolyte-gated graphene field-effect transistor is developed for Gd3+ ion detection in water. The source and drain electrodes of the transistor are fabricated by photolithography on polyimide, while the graphene channel is obtained by inkjet-printing a graphene oxide ink subsequently electro-reduced to give reduced graphene oxide. The Gd3+-selective ligand DOTA is functionalized by an alkyne linker to be grafted by click chemistry on a gold electrode without losing its affinity for Gd3+. The synthesis route is fully described, and the ligand, the linker and the functionalized surface are characterized by electrochemical analysis and spectroscopy. The as functionalized electrode is used as gate in the graphene transistor so to modulate the source-drain current as a function of its potential, which is itself modulated by the concentration of Gd3+captured on the gate surface. The obtained sensor is able to quantify Gd3+ even in a sample containing several other potentially interfering ions such as Ni2+, Ca2+, Na+ and In3+. The quantification range is from 1 pM to 10 mM, with a sensitivity of 20 mV dec-1 expected for a trivalent ion. This paves the way for Gd3+ quantification in hospital or industrial wastewater.

Adsorptive Features of Magnetic Activated Carbons Prepared by a One-Step Process towards Brilliant Blue Dye.

Water pollution by dyes has been a major environmental problem to be tackled, and magnetic adsorbents appear as promising alternatives to solve it. Herein, magnetic activated carbons were prepared by the single-step method from Sapelli wood sawdust, properly characterized, and applied as adsorbents for brilliant blue dye removal. In particular, two magnetic activated carbons, MAC1105 and MAC111, were prepared using the proportion of biomass KOH of 1:1 and varying the proportion of NiCl2 of 0.5 and 1. The characterization results demonstrated that the different proportions of NiCl2 mainly influenced the textural characteristics of the adsorbents. An increase in the surface area from 260.0 to 331.5 m2 g-1 and in the total pore volume from 0.075 to 0.095 cm3 g-1 was observed with the weight ratio of NiCl2. Both adsorbents exhibit ferromagnetic properties and the presence of nanostructured Ni particles. The different properties of the materials influenced the adsorption kinetics and equilibrium of brilliant blue dye. MAC111 showed faster kinetics, reaching the equilibrium in around 10 min, while for MAC1105, it took 60 min for the equilibrium to be reached. In addition, based on the Sips isotherm, the maximum adsorption capacity was 98.12 mg g-1 for MAC111, while for MAC1105, it was 60.73 mg g-1. Furthermore, MAC111 presented the potential to be reused in more adsorption cycles than MAC1105, and the use of the adsorbents in the treatment of a simulated effluent exhibited high effectiveness, with removal efficiencies of up to 90%.

A review of the main methods for composite adsorbents characterization.

Adsorption is a promising technology for removing several contaminants from aqueous matrices. In the last years, researchers worldwide have been working on developing composite adsorbents to overcome some limitations and drawbacks of conventional adsorbent materials, which depend on various factors, including the characteristics of the adsorbents. Therefore, it is essential to characterize the composite adsorbents to describe their properties and structure and elucidate the mechanisms, behavior, and phenomenons during the adsorption process. In this sense, this work aimed to review the main methods used for composite adsorbent characterization, providing valuable information on the importance of these techniques in developing new adsorbents. In this paper, we reviewed the following methods: X-Ray diffraction (XRD); spectroscopy; scanning electron microscopy (SEM); N2 adsorption/desorption isotherms (BET and BJH methods); thermogravimetry (TGA); point of zero charge (pHPZC); elemental analysis; proximate analysis; swelling and water retention capacities; desorption and reuse.

Functional activated carbon: from synthesis to groundwater fluoride removal.

Developing green and functional adsorbents for the removal of inorganic pollutants from industrial wastewater is still a great challenge. Activated carbons (ACs) are promising eco-friendly materials for adsorption applications. This study reports on the preparation and functionalization of AC and its application for fluoride removal from water. Activated carbon was prepared from date stems, and the material was employed as a support for different modifications such as incorporation of Al(OH)3, in situ dispersion of aluminum particles (Al0) and grafting of 3-(aminopropyl)triethoxysilane (APTES). The resulting functional adsorbents were fully characterized by Fourier transform infrared spectroscopy, scanning electronic microscopy, energy dispersive X-ray fluorescence, X-ray diffraction, differential scanning calorimetry and zeta potential analysis. The results evidenced successful surface modifications. All adsorbents had affinity for the removal of fluoride ions (F-). The highest F- removal rate was up to 20 mg g-1 for AC-Al(OH)3. Removal of fluoride ions obeyed Langmuir isotherms and a second-order kinetic model, and reached 99% uptake. The AC-Al(OH)3 adsorbent was successfully used to treat a groundwater solution contaminated by fluoride ions. These results open an interesting avenue for developing eco-friendly functionalized AC for adsorption applications.

Advances in Amine-Surface Functionalization of Inorganic Adsorbents for Water Treatment and Antimicrobial Activities: A Review.

In the last decade, adsorption has exhibited promising and effective outcomes as a treatment technique for wastewater contaminated with many types of pollutants such as heavy metals, dyes, pharmaceuticals, and bacteria. To achieve such effectiveness, a number of potential adsorbents have been synthesized and applied for water remediation and antimicrobial activities. Among these inorganic adsorbents (INAD), activated carbon, silica, metal oxide, metal nanoparticles, metal-organic fibers, and graphene oxide have been evaluated. In recent years, significant efforts have been made in the development of highly efficient adsorbent materials for gas and liquid phases. For gas capture and water decontamination, the most popular and known functionalization strategy is the chemical grafting of amine, due to its low cost, ecofriendliness, and effectiveness. In this context, various amines such as 3-aminopropyltriethoxysilane (APTES), diethanolamine (DEA), dendrimer-based polyamidoamine (PAMAM), branched polyethyleneimine (PEI), and others are employed for the surface modification of INADs to constitute a large panel of resource and low-cost materials usable as an alternative to conventional treatments aimed at removing organic and inorganic pollutants and pathogenic bacteria. Amine-grafted INAD has long been considered as a promising approach for the adsorption of both inorganic and organic pollutants. The goal of this review is to provide an overview of surface modifications through amine grafting and their adsorption behavior under diverse conditions. Amine grafting strategies are investigated in terms of the effects of the solvent, temperature, and the concentration precursor. The literature survey presented in this work provides evidence of the significant potential of amine-grafted INAD to remove not only various contaminants separately from polluted water, but also to remove pollutant mixtures and bacteria.

Pseudomonas aeruginosa Biofilm Dispersion by the Human Atrial Natriuretic Peptide.

Pseudomonas aeruginosa biofilms cause chronic, antibiotic tolerant infections in wounds and lungs. Numerous recent studies demonstrate that bacteria can detect human communication compounds through specific sensor/receptor tools that modulate bacterial physiology. Consequently, interfering with these mechanisms offers an exciting opportunity to directly affect the infection process. It is shown that the human hormone Atrial Natriuretic Peptide (hANP) both prevents the formation of P. aeruginosa biofilms and strongly disperses established P. aeruginosa biofilms. This hANP action is dose-dependent with a strong effect at low nanomolar concentrations and takes effect in 30-120 min. Furthermore, although hANP has no antimicrobial effect, it acts as an antibiotic adjuvant. hANP enhances the antibiofilm action of antibiotics with diverse modes of action, allowing almost full biofilm eradication. The hANP effect requires the presence of the P. aeruginosa sensor AmiC and the AmiR antiterminator regulator, indicating a specific mode of action. These data establish the activation of the ami pathway as a potential mechanism for P. aeruginosa biofilm dispersion. hANP appears to be devoid of toxicity, does not enhance bacterial pathogenicity, and acts synergistically with antibiotics. These data show that hANP is a promising powerful antibiofilm weapon against established P. aeruginosa biofilms in chronic infections.

Piezo-Resistive Properties of Bio-Based Sensor Yarn Made with Sisal Fibre.

In this work, a sensor yarn based on a natural sisal yarn containing a non-electro-conductive core impregnated with PVA polymer and coated by PEDOT:PSS polymer as an electro-conductive sheath was investigated. The main objectives include the development of this new sensor yarn as a first step. Then, we look towards the insertion of this sensor yarn into different woven structures followed by the monitoring of the mechanical behaviour of composite materials made with these fibrous reinforcements. The combined effect of the structural geometry and the number of PEDOT:PSS coating layers on the properties of the sensor yarns was investigated. It was found that the number of PEDOT:PSS coating layers could strongly influence the electromechanical behaviours of the sensor yarns. Different methods of characterization were employed on strain-sensor yarns with two and four coating layers of PEDOT:PSS. The piezo-resistive strain-sensor properties of these selected coating layers were evaluated. Cyclic stretching-releasing tests were also performed to investigate the dynamic strain-sensing behavior. The obtained results indicated that gauge factor values can be extracted in three strain regions for two and four coating layers, respectively. Moreover, these strain-sensor yarns showed accurate and stable sensor responses under cyclic conditions. Furthers works are in progress to investigate the mechanism behind these first results of these sisal fibre-based sensors.

New antibacterial cadiolide analogues active against antibiotic-resistant strains.

The synthesis of new cadiolide analogues was carried out using a one-pot multi component synthesis. The antibacterial activity of these molecules was evaluated on standard and antibiotic resistant bacterial strains chosen for their involvement in human health or in food-born poisoning. Four molecules have shown good activities with MICs of 2 µg/mL-1. The introduction of an indole group or the conversion of the lactone into lactam have highlighted two new families of molecules with promising antibacterial activity. In addition, most of these active molecules are devoid of cytotoxic activity against keratinocyte cells.

Removal of Cu(II) from aqueous solution using a composite made from cocoa cortex and sodium alginate.

The aim of this work was to prepare a composite material based on cocoa cortex and sodium alginate and test it to remove Cu(II) ions in aqueous solution in batch conditions. The composite was characterized using elemental analysis, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTG), and point of zero charge. The highest amount of adsorbed Cu(II) for the composite was 19.54 mg/g, i.e., 95.32% of an initial concentration of 100 mg/L. Under the same conditions, the cocoa cortex untreated exhibited extremely low adsorption, while when it was treated with hot soda, it adsorbed 13.67 mg/g. Adsorption by the composite reached the equilibrium after 220 min. Kinetic data analysis suggested that the process was governed by adsorption (pseudo-second-order model) and diffusion through macropores and/or mesopores (intra-particle model). The adsorption isotherm that best described the system was Langmuir's. The maximum adsorption capacity of Cu(II) was 76.92 mg/g. The values of the thermodynamic parameters indicated that the process was spontaneous, with ΔG° values between (- 7.886 and - 9.458 kJ/mol) and endothermic, with ΔH° = 7.728 kJ/mol. Graphical abstract.

Modification of fibrous membrane for organic and pathogenic contaminants removal: from design to application.

In this study, a flexible multifunctional fibrous membrane for heterogeneous Fenton-like removal of organic and pathogenic contaminants from wastewater was developed by immobilizing zerovalent iron nanoparticles (Fe-NPs) on an amine/thiol grafted polyester membrane. Full characterization of the resulting polyester membranes allowed validation of successful grafting of amine/thiol (NH2 or SH) functional groups and immobilization of Fe-NPs (50-150 nm). The Fenton-like functionality of iron immobilized fibrous membranes (PET-Fe, PET-Si-NH2-Fe, PET-NH2-Fe, and PET-SH-Fe) in the presence of hydrogen peroxide (H2O2) was comparatively studied in the removal of crystal violet dye (50 mg L-1). The effect of pH, amount of iron and H2O2 concentration on dye removal was systematically investigated. The highest dye removal yield reached 98.87% in 22 min at a rate constant 0.1919 min-1 (R 2 = 95.36) for PET-SH-Fe providing 78% toxicity reduction assessed by COD analysis. These membranes could be reused for up to seven repeated cycles. Kinetics and postulated mechanism of colour removal were proposed by examining the above results. In addition, the resultant membranes showed substantial antibacterial activity against pathogenic bacteria (Staphylococcus epidermidis, Escherichia coli) strains studied through disc diffusion-zone inhibitory and optical density analysis. These findings are of great importance because they provide a prospect of textile-based flexible catalysts in heterogeneous Fenton-like systems for environmental and green chemistry applications.

Heterogeneous-phase Sonogashira cross-coupling reaction on COC surface for the grafting of biomolecules - Application to isatin.

The grafting of 5-iodoisatin heterocycle on a cyclic olefin copolymer (COC) and a gold surface was performed using a heterogeneous phase Sonogashira reaction consisting of coupling 5-iodoisatin with an arylalkyne previously introduced onto the surfaces. This optimized strategy takes advantage of the well-established methodology to functionalize COC or gold surfaces using aryldiazonium surface chemistry. Herein, we reported the first example of an isatin decorated polymeric or metallic surface. The surfaces were analyzed with a combination of techniques such as IR (Infrared spectroscopy), XPS (X-Ray photoelectron spectroscopy) and SPR (surface plasmon resonance). Docking studies showed that isatin and two derivatives interact with AmiC, a dimeric protein produced by Pseudomonas aeruginosa. Bacterial adhesion on isatin-COC platform was also observed. This general strategy for robust surface functionalization represents an easy approach for patterning surfaces with compounds of biological interest, allowing access to a large panel of original biosensors.

Iron-loaded amine/thiol functionalized polyester fibers with high catalytic activities: a comparative study.

Dispersion of iron nanoparticles (Fe-NPs) was achieved on polyester fabrics (PET) before and after the incorporation of dendrimers (PAMAM), 3-(aminopropyl) triethoxysilane (APTES) or thioglycerol (SH). The catalytic activity of the resulting materials (PET-Fe, PET-PAMAM-Fe, PET-APTES-Fe and PET-SH-FE) was comparatively investigated in the degradation of 4-nitrophenol (4-NP) and methylene-blue (MB). Full characterization through diverse instrumental methods allowed correlating the type of the organic moiety incorporated with the Fe content, catalytic properties and stability. The highest 4-NP degradation yield reached 99.6% in 12 min for PET-SH-Fe. The catalytic activity was explained in terms of reactant interaction with Fe-NPs. The 1st order reaction kinetics and pseudo-1st order adsorption kinetics provide evidence of the key role of reactant adsorption. These findings allow envisaging the preparation of fiber-based catalysts for potential uses in environmental and green chemistry.

Development of a novel functional core-shell-shell nanoparticles: From design to anti-bacterial applications.

This article reports the synthesis and functionalization of a novel CuO@SiO2-APTES@Ag0 core-shell-shell material using a simple and low-cost process. The growth, design strategies and synthesis approach are the key factors for the development of CuO@SiO2-APTES@Ag0 as efficient material with enhanced antibacterial activity. We investigated the morphology, surface charge, structure and stability of our new core-shell-shell by atomic force microscopy, scanning electron microscopy, energy dispersive X-ray, Fourier transform infrared and UV-visible spectroscopies, zeta potential measurements, and differential scanning calorimetry. The covalent surface grafting of APTES (3-(aminopropyl)triethoxysilane) onto CuO@SiO2 involving electrostatic interactions was confirmed. Size measurements and Scanning electron images showed that both APTES grafting and SiO2/Ag shells dropped on the surface of CuO produced structural compaction. UV-Vis spectroscopy proved to be a fast and convenient way to optically detect SiO2 shell on the surface of colloids. Additionally, the Ag-decorated CuO@SiO2-APTES surfaces were found to possess antibacterial activity and thermally more stable than undecorated surfaces. CuO@SiO2-APTES@Ag0 core-shell had antibacterial properties against Gram-positive bacteria making it a promising candidate for antibacterial applications.

Chemical modification of the cocoa shell surface using diazonium salts.

The outer portion of the cocoa bean, also known as cocoa husk or cocoa shell (CS), is an agrowaste material from the cocoa industry. Even though raw CS is used as food additive, garden mulch, and soil conditioner or even burnt for fuel, this biomass material has hardly ever been investigated for further modification. This article proposes a strategy of chemical modification of cocoa shell to add value to this natural material. The study investigates the grafting of aryl diazonium salt on cocoa shell. Different diazonium salts were grafted on the shell surface and characterized by infrared spectroscopy and scanning electronic microscopy imaging. Strategies were developed to demonstrate the spontaneous grafting of aryl diazonium salt on cocoa shell and to elucidate that lignin is mainly involved in immobilizing the phenyl layer.

The aliphatic amidase AmiE is involved in regulation of Pseudomonas aeruginosa virulence.

We have previously shown that the eukaryotic C-type natriuretic peptide hormone (CNP) regulates Pseudomonas aeruginosa virulence and biofilm formation after binding on the AmiC sensor, triggering the amiE transcription. Herein, the involvement of the aliphatic amidase AmiE in P. aeruginosa virulence regulation has been investigated. The proteome analysis of an AmiE over-producing strain (AmiE+) revealed an expression change for 138 proteins, including some that are involved in motility, synthesis of quorum sensing compounds and virulence regulation. We observed that the AmiE+ strain produced less biofilm compared to the wild type, and over-produced rhamnolipids. In the same line, AmiE is involved in P. aeruginosa motilities (swarming and twitching) and production of the quorum sensing molecules N-acyl homoserine lactones and Pseudomonas Quinolone Signal (PQS). We observed that AmiE overproduction reduced levels of HCN and pyocyanin causing a decreased virulence in different hosts (i.e. Dictyostelium discoideum and Caenorhabditis elegans). This phenotype was further confirmed in a mouse model of acute lung infection, in which AmiE overproduction resulted in an almost fully virulence decrease. Taken together, our data suggest that, in addition to its role in bacterial secondary metabolism, AmiE is involved in P. aeruginosa virulence regulation by modulating pilus synthesis and cell-to-cell communication.