Conversion of carbon black recovered from waste tires into activated carbon via chemical/microwave methods for efficient removal of heavy metal ions from wastewater.

In this research study, recovered carbon black (rCB) was obtained via pyrolysis of waste tires. The obtained rCB was then converted into activated carbon species through both chemical treatment and microwave coupled with chemical treatment as a two-step activation process. The activated carbon obtained from chemical activation was denoted as C-AC, while that obtained from exposure to microwave followed by chemical activation was labeled as MC-AC. These two structures were consequently introduced as sorbents for the removal of cadmium ions from an aqueous solution. The structural characteristics of the introduced adsorbents were confirmed using various techniques, namely X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and energy-dispersive X-ray (EDX) spectroscopy. Additionally, textual features of these adsorbents were acquired via both scanning electron microscopy (SEM) and N2 adsorption-desorption BET surface area analyses. These two structures were then introduced for Cd ion adsorption under different operating conditions. Particularly, the effect of pH, contact time, adsorbent dose, and metal ion concentration on the efficiency of adsorption was investigated. The 1maximum adsorption capacity was detected at a pH value of 5.0, a contact time of 30 min, a sorbent dose of 0.4 g L-1, and an initial metal concentration of 50 mg L-1 using MC-AC, which exhibited nearly double the sorption capacity detected for C-AC. Kinetic studies indicated that the process of Cd(ii) adsorption is perfectly described and fitted by the pseudo-second-order model. However, adsorption isotherms for the two adsorbents were found to match the Langmuir model, referring to the occurrence of uniform monolayer adsorption for the metal ions. Thermodynamic analysis demonstrated that the adsorption process was spontaneous and endothermic.

Sonochemical synthesis of heterostructured ZnO/Bi2O3 for photocatalytic desulfurization.

In this study, metal oxides nanoparticles heterogeneous photocatalysts prepared by coprecipitation and ultrasonic techniques were used for diesel desulfurization. They were characterized by scanning electron microscope, powder X-ray diffraction, energy dispersive analysis, diffused reflectance spectra, photoluminescence analysis and BET surface area. The surface area of catalyst B is larger than catalyst A confirming its higher reactivity. X-ray reflectance spectroscopy was used to analyze the sulfur contents in feed. Thiophene was used as a model fuel to evaluate the photocatalytic activity of catalysts A and B. Using the Scherrer equation, sharp and intense signals suggesting their higher degrees of crystallinity, with average crystal sizes for ZnO, Bi2O3, catalysts A and B, respectively; of 18, 14.3, 29.7, and 23.8 nm. The operational parameters of the desulfurization process were optimized and have been studied and the maximum sulfur removal was achieved via a further solvent extraction step. A diesel fuel with a 24 and 19 ppm sulfur content and hence a total sulfur removal of 94.6% and 95.7% was acquired for catalysts A and B, respectively (sulfur compounds concentration in diesel fuel feedstock was 450 ppm). These findings demonstrated that photocatalysts A and B are good and effective catalysts for desulfurization of diesel fuel.

Synthesis of fungal chitosan-polystyrene modified by nanoparticles of binary metals for the removal of heavy metals from waste aqueous media.

The objective of this study was to assess the efficacy of fungal chitosan-polystyrene-Co-nanocomposites (FCPNC) as a material for the adsorptive removal of cadmium (Cd) ions from aqueous solutions. The synthesis and characterization of FCPNC were accomplished using various analytical techniques, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, and dynamic light scattering (DLS). The effectiveness of this adsorbent in removing Cd(ii) species from solution matrices was systematically investigated, resulting in the achievement of a maximum adsorption capacity of approximately 112.36 mg g-1. This high adsorption capacity was detected using the following operational parameters: solution pH equals 5.0, 60 min as a contact time between the adsorbent and Cd(ii) solution, Cd initial concentration of 50 ppm, adsorbent dosage of 0.5 g L-1 and room temperature. The process of cadmium adsorption by FCPNC was found to follow the Langmuir isotherm model, suggesting that a chemical reaction occurs on the biosorbent surface. Kinetic studies have demonstrated that the cadmium removal process aligns well with the pseudo-second-order model. The thermodynamic analysis revealed the following values: ΔH° = 25.89 kJ mol-1, ΔG° = -21.58 kJ mol-1, and ΔS° = 159.30 J mol-1 K-1. These values indicate that the sorption process is endothermic, spontaneous, and feasible. These findings suggest the potential of FCPNC as an exceptionally effective biosorbent for the removal of water contaminants.

Nickel-hydroxide-encapsulated polyacrylamide as a novel adsorptive composite for the capture of methylene blue from wastewater.

The wastewater released from different industries is a major environmental issue that has grabbed significant attention lately. Thus, the implementation of suitable routes for the treatment of such water is strongly recommended to reach the level of possible reuse for either industrial or agricultural purposes. In line with such a concept, this research work introduces a new composite structure made via the coating of polyacrylamide by loading nickel hydroxide nanoparticles for use as an absorbent for the purification of wastewater from dye contaminants. High internal phase emulation (HIPE) polymerization was utilized to first prepare particles of polyacrylamide followed by their coating with particles of nickel hydroxide to ultimately obtain the designated adsorbent. The structural features and chemical composition of the synthesized composite were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and energetic dispersive X-ray (EDX) spectroscopy. Additionally, scanning electron microscopy (SEM) and N2 adsorption-desorption surface area analysis were employed to detect the textural characteristics of the composite. Subsequently, the efficiency of this structure, as an adsorbent for the disposal of methylene blue dye species from a wastewater sample, was studied. During the water purification process, several operating parameters, namely, retention time, solution pH, initial concentration, and absorbent dose, were investigated. The presented Ni-polyacrylamide composite achieved the promising removal of methylene blue dye. An increased adsorption capacity of 14.3 mg g-1 toward methylene blue was achieved by the composite, thanks to the presence of both organic and inorganic functional groups within its structure. Kinetic and isotherm studies for the adsorption of methylene blue species were found to fit pseudo-second-order and Langmuir models. Additionally, thermodynamic measurements indicated that the adsorption process of methylene blue is feasible, spontaneous, involves physisorption, and is endothermic.

Decoration of polystyrene with nanoparticles of cobalt hydroxide as new composites for the removal of Fe(iii) and methylene blue from industrial wastewater.

Effluent water from different industries is considered one of the most serious environmental pollutants due to its non-safe disposal. Therefore, proper treatment methods for such wastewater are strongly stimulated for its potential reuse in industries or agriculture. This study introduces a composite fabricated via doping of polystyrene with nanoparticles of cobalt hydroxide as a novel adsorbent for dye and heavy metal decontamination from wastewater. The adsorbent fabrication involves the preparation of polystyrene via high-internal phase emulation (HIPE) polymerization followed by its intercalation with particles of alkali cobalt. The chemical composition and structural properties of the synthesized composite were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). Moreover, scanning electron microscopy (SEM) and N2 adsorption-desorption surface area analysis were performed to identify the surface and morphological characteristics of the composite. Then, the ability of this structure toward the removal of methylene blue dye (MB) and heavy metal (iron iii) species from waste aqueous solutions was investigated. Successful elimination for both MB and Fe(iii) was achieved by the presented composite. Elevated adsorption capacities of 75.2 and 112.3 mg g-1, toward MB and Fe(iii) respectively, were detected for the presented polymer-metal hydroxide composite. The increased values of the composite are attributed to the presence of both organic and inorganic functional groups within its structure. Kinetic and isotherm studies for the removal of both cationic species revealed that adsorption processes fit the pseudo-second-order kinetic model and Langmuir isotherm model. Additionally, thermodynamics measurements indicated that the adsorption process of methylene blue and Fe ions is feasible, spontaneous, physisorption, and endothermic.

Elevated CO-free hydrogen productivity through ethanol steam reforming using cubic Co-Nanoparticles based MgO catalyst.

Hydrogen production through the processes of ethanol catalytic steam reforming (SR) is one of the promising routes due to its extensive yield that can be gained. However, catalyst deactivation (as a result of coke formation) is a major drawback in such a process. Therefore, this research work introduces efficient MgO supported Cubic cobalt oxide catalyst for the process of ethanol SR. This catalyst was successfully able to produce gases that have high contents of CO-free hydrogen was produced (above 78%) at 500°C and various flow rates of feed. This catalyst had also avoided coke formation at that temperature while attaining capture of the in-situ produced CO2 gas. The employment of an operating temperature beyond 500°C, during the SR process, could reduce the percentages of hydrogen (in products) to less than 55%. Such increases in the operational temperature could leave behind the detection of coke deposits onto the catalyst surface. The presence of these deposits was confirmed visually as well as via Raman spectroscopy.

Increased production of hydrogen with in situ CO2 capture through the process of water splitting using magnetic core/shell structures as novel photocatalysts.

One of the chief challenges in hydrogen production through the photocatalytic splitting of water is to employ an efficient photocatalyst that has an absorption edge at the range of long wavelengths. In this study, composite structures made of different Ag-based shells over the core of Fe2O3 nanoparticles were utilized as novel magnetic photocatalysts for hydrogen generation from water. Specifically, Ag nanoparticles, Ag/(3-aminopropyl) triethoxysilane (APTS), and Ag/polyethyleneimine (PEI) were capped on the surface of the hematite core to produce three visible light-effective photocatalysts. Structural and textural properties of the synthesized photocatalysts were confirmed by Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Additionally, their thermal stability and optical properties were respectively studied using thermogravimetric analysis (TGA) and UV reflectance. Photocatalytic activities of the presented core/shells were planned either as a function of the magnetic force or composition of the shell layer. It could be noted that the incorporation of organic or polymer layer could significantly increase the electronic density at the metal centers. Thus, the ability of iron oxide to catalyze the water-splitting process could be enhanced. Hence, the variation of shell structure could show a key-role in the photocatalytic potential of the presented structures in terms of manipulating the composition of produced gases. On the other hand, the magnetic nature of hematite could also positively affect the photocatalytic activity of these structures by minimizing the scattering of light irradiation during the splitting process. Particularly, shifting the way of photocatalysts dispersion from magnetic to mechanical (during water splitting) had in turn reduced hydrogen productivity from 540 to 485 mmol h-1 g-1. This obviously confirms the relationship between the level of hydrogen production by the presented photocatalysts and their magnetic nature which results in quenching of irradiation scattering.

Highly Efficient Visible-Light-Induced Photocatalytic Hydrogen Production via Water Splitting using FeCl3 -Based Ionic Liquids as Homogeneous Photocatalysts.

The ionic liquid (IL) 1-octyl-3-methylimidazolium bromide/FeCl3 [OMIM]Br/FeCl3 was prepared with three molar ratios of [OMIM]Br/FeCl3 (0.5 : 1, 1 : 1, and 2 : 1), and fully characterized through 1 H and 13 C NMR, Fourier-transform IR, and Raman spectroscopic techniques. The optical properties of the prepared [OMIM]Br/FeCl3 ILs were revealed via diffuse reflectance and photoluminescence spectra. The photocatalytic activity of [OMIM]Br/FeCl3 ILs as homogenous photocatalysts were investigated towards hydrogen generation from methanol/water mixtures under visible light irradiation. The FeCl3 -based IL with [OMIM]Br/FeCl3 molar ratio of 1 : 1 exhibited the highest visible light photocatalytic activity with a hydrogen productivity of 243.2 mmol h-1 g-1 and a hydrogen purity of 95.5 %; such a high hydrogen yield and purity was reported for the first time. It was proposed that [OMIM] Br acted as an electron acceptor, which delayed the electron-hole pair recombination of FeCl3 . Also, [OMIM] Br could capture the produced carbon dioxide that is released with hydrogen gas. Additionally, [OMIM] Br/FeCl3 could be reused six times with nearly the same photocatalytic activity. These outstanding credits in terms of hydrogen generation rate and purity plus the economic feasibility, through several cycles of reuse, could certify such an IL as a promising photocatalyst for employment in water splitting. This paper suggests ways forward for research to develop the use of ILs as efficient and effective photocatalysts for hydrogen generation via water splitting.

Water decontamination via the removal of Pb (II) using a new generation of highly energetic surface nano-material: Co(+2)Mo(+6) LDH.

CoMo(CO3(2-)) layered double hydroxide of a highly energetic surface, as a new LDH consisting of divalent and hexavalent cations (M(+2)/M(+6)-LDH), was prepared by a homogeneous co-precipitation method. The structure and morphology of the prepared material was confirmed by several analytical techniques namely; X-ray diffraction analysis (XRD), X-ray fluorescence (XRF), Fourier transform infra-red (FT-IR) spectroscopy, differential scanning calorimetry and thermal gravimetric analysis (DSC-TGA), N2 adsorption-desorption isotherm and scanning electron microscope (SEM). The highly energetic surface of the prepared LDH was demonstrated via the X-ray photoelectron spectroscopy (XPS). The surface energy is due to the formation of +4 surface charges in the brucite layer between Co(+2) and Mo(+6). The prepared LDH was applied as a novel adsorbent for the removal of Pb (II) from its aqueous solution at different experimental conditions of time, temperature and initial Pb (II) concentrations. The change of the Pb (II) concentrations; due to adsorption, was monitored by atomic absorption spectrophotometer (AAS). The maximum uptake of Pb (II) by the Co Mo LDH was (73.4 mg/g) at 298 K. The Pb (II) adsorption was found to follow Langmuir isotherm and pseudo second order model. The adsorption process was spontaneous and endothermic. The interference of other cations on the removal of the Pb (II) was studied. Na(+) and K(+) were found to increase the adsorption capacity of the Co Mo LDH toward Pb (II) while it was slightly decreased by the presence of Mn(+2) and Cu(+2). The synthesized LDH showed a great degree of recoverability (7 times) while completely conserving its parental morphology and adsorption capacity. The mechanism of the lead ions removal had exhibited more reliability through a surface adsorption by the coordination between the Mo(+6) of the brucite layers and the oxygen atoms of the nitrates counter ions.

Enhanced hydrogen production from water via a photo-catalyzed reaction using chalcogenide d-element nanoparticles induced by UV light.

Hydrogen has the potential to meet the requirements as a clean non-fossil fuel in the future. The photocatalytic production of H2 through water splitting has been demonstrated and enormous efforts have been published. The present work is an attempt to enhance the production of H2 during water splitting using synthesized nanoparticles based on chalcogenide d-element semiconductors via a photochemical reaction under UV-light in the presence of methanol as a hole-scavenger. In general, the enhanced activity of a semiconductor is most likely due to the effective charge separation of photo generated electrons and holes in the semiconductors. Hence, the utilization of different semiconductors in combination can consequently provide better hydrogen production. Accordingly in this research work, two different semiconductors, with different concentrations, either used individually or combined together were introduced. They in turn produced a high concentration of H2 as detected and measured using gas chromatography. Herein, data revealed that the nano-structured semiconductors prepared through this work are a promising candidate in the production of an enhanced H2 flux under visible UV radiation.