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The thermal degradation characteristics ofPosidonia Oceanica(PO), a marine biomass abundantly available on the coastal zone of the Mediterranean Basin, were investigated using thermogravimetric analysis under inert and oxidative atmospheres. The kinetic parameters of the both thermal degradations conditions were determined usingn-reaction order model. Coats–Redfern and Phadnis–Deshpande methods were used to discuss the probable degradation mechanisms. Results showed that PO is an attractive alternative for energy production owing to its elevated heating value. Moreover, PO thermal degradation follows the usual shape of biomass decomposition. Hence, under inert atmosphere, its thermal degradation had two different stages after moisture release. The first stage corresponded to the volatiles release while the second stage corresponded to the char formation. The solid-state decomposition mechanisms followed by the devolatilization step of PO were two or three dimensional diffusion controlled reaction. However, the decomposition mechanism during PO char formation corresponded to a nucleation and growth mechanism. Under oxidative atmosphere, two stages were also observed corresponding to volatiles release and char combustion, respectively. The solid-state mechanism of volatiles release followed three dimensional diffusion controlled reaction while the char combustion mechanism corresponded to a contracting area phase boundary controlled reaction. [ABSTRACT FROM AUTHOR]

The kinetics and mechanism of the oxidation of carbon by NO2 in absence and presence of water vapor were studied in a fixed bed reactor. The rate of carbon oxidation by NO2 is enhanced in the presence of water vapor in the range of temperature 300–400°C. The benefit effect of water is attributed to the intermediate formation of traces of nitric and nitrous acids, which enhance the rate of the carbon oxidation without modifying the global mechanism reaction. Therefore, water acts as a catalyst for the carbon oxidation by NO2. A kinetic mechanism derived from this parametric study shows a decrease in the activation energy of carbon oxidation by NO2 in the presence of water vapor. This result is in agreement with the experimental observation. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 236–244, 2009 [ABSTRACT FROM AUTHOR]

Abstract: The effect of a commercial Pt/Al2O3 catalyst on the oxidation by NO2 and O2 of a model soot (carbon black) in conditions close to automotive exhaust gas aftertreatment is investigated. Isothermal oxidations of a physical mixture of carbon black and catalyst in a fixed bed reactor were performed in the temperature range 300–450°C. The experimental results indicate that no significant effect of the Pt catalyst on the direct oxidation of carbon by O2 and NO2 is observed. However, in presence of NO2–O2 mixture, it is found that besides the well established catalytic reoxidation of NO into NO2, Pt also exerts a catalytic effect on the cooperative carbon–NO2–O2 oxidation reaction. An overall mechanism involving the formation of atomic oxygen over Pt sites followed by its transfer to the carbon surface is established. Thus, the presence of Pt catalyst increases the surface concentration of –C(O) complexes which then react with NO2 leading to an enhanced carbon consumption. The resulting kinetic equation allows to model more precisely the catalytic regeneration of soot traps for automotive applications. [Copyright &y& Elsevier]

Abstract: The oxidation mechanism of carbon by automotive exhaust gasses (O2, H2O and NO2) was investigated in the range of temperature (300–400°C) corresponding to the operation conditions of the continuous regeneration regime of the soot trap. No carbon gasification occurs when O2 is injected in absence of NO2 below 450°C. However, when O2 (10vol.%) and NO2 (100–600ppmv) are both present in the gas mixture, two distinct carbon oxidation reactions take place. A direct reaction occurs between NO2 and the carbon surface along with a co-operative one involving simultaneously O2 and NO2. In the latter case, NO2 promotes the decomposition of the intermediate C(O) complex. Injection of water vapour increases the overall oxidation rate but does not modify the global mechanism. The promoting effect of water is attributed to the intermediate formation of traces of nitric and nitrous acids which enhance the direct reaction C–NO2 rate. In contrast, water has no measurable effect on the co-operative C–NO2–O2 reaction. A relationship between the water promoting effect on the direct oxidation rate and the amount of theoretical formation of HNO2 and HNO3 was established. [Copyright &y& Elsevier]

Adsorption of NO2 on carbon black has been examined for different NO2 concentrations (400 or 600 ppm) and temperatures (50 or 100 °C). The influence of chemisorption of oxygen on the carbon surface at 300 °C before exposure to NO2 has been reported. Temperature programmed desorption (TPD) was performed after NO2 adsorption to identify the adsorbed species by measuring the amounts of evolved gases NO, NO2, CO and CO2. During the exposure of the carbon black to NO2, both adsorption and reduction of NO2 to NO has been observed. From the oxygen and nitrogen balance data, it is shown that the NO2 adsorption step leads to the formation of both oxygen and nitrogen surface complexes such as &z.sbnd;C(O) and &z.sbnd;C(ONO2). Based on the TPD results, a desorption process has been proposed. Chemisorption of oxygen before exposure to NO2 leads to an increase, during the adsorption step, of both nitrogen adsorbed and NO evolved species. This behaviour has been attributed to already existing oxygen complexes resulting from O2 chemisorption. In fact, NO2 adsorbs mainly on preexisting oxygen complexes. A relationship between the additional adsorbed NO2 during the adsorption step and the excess of CO2 released during the TPD below 500 °C has been established. [Copyright &y& Elsevier]

Despite the huge literature on biomass char gasification with CO 2 or H 2 O, ambiguity still hovers over the issue of char gasification in complex atmospheres. Gas alternation gasification experiments, in which the reacting gas is changed during the reaction, were performed with CO 2 /H 2 O at 900 °C for small (200 μm) and large (13 mm) Low Heating Rate (LHR) beech wood char particles to assess the potential influences that CO 2 and H 2 O can have on each other during the char gasification reaction. The results showed no influence of a first gasification atmosphere on the char reactivity under the second one. The char reactivity to a specific gas at a certain conversion level was the same as if the gasification reaction was operated from the beginning with the same atmosphere composition. The purpose of this paper is to bring understanding keys to this lack of influence of previous gasification conditions on the char reactivity. Characterization of the chars throughout the conversion by measuring the total surface area and the active surface area was first performed. Then a transport limitation analysis based on the Thiele modulus was considered. It was concluded that the two gasses develop different porosities in the char, however, the Thiele modeling results and active surface area analysis indicate respectively that gasses diffuse preferentially in large macro-pores and that the concentration of active sites evolves similarly during both gasification reactions. This similarity in the diffusion mechanism as well as in the evolution of the concentration of active sites could be a plausible explanation for the only-dependent conversion reactivity observed in the gas alternation gasification experiments. [ABSTRACT FROM AUTHOR]

Abstract: Adsorption of NO from a gas stream containing oxygen and water and desorption and reduction using a rich gas mixture were investigated in the temperature range 230–315°C on Na–Y zeolite loaded with 3wt.% ruthenium. The NO x storage capacity was found little dependent on temperature and water content of the gas. The adsorption–desorption–reduction process was modeled using a one-dimensional fixed-bed model and assuming co-adsorption of NO and NO2 molecules on Na–Y zeolite, ruthenium catalyzed NO into NO2 oxidation by molecular oxygen during adsorption and ruthenium catalyzed NO x reduction by hydrogen during desorption. Kinetic constants were estimated through data fitting. An acceptable agreement between experimental and calculated values was obtained. NO x adsorption and desorption kinetics on Na–Y zeolite with and without ruthenium were substantially different revealing that ruthenium besides catalyzing NO x oxidation and reduction had a drastic influence on the NO x adsorption sites of Na–Y zeolite. [Copyright &y& Elsevier]

This study constitutes a comprehensive investigation centred on comprehending the behaviour and characteristics of recycled polyvinyl chloride (PVC) powders. The overarching objective is to successfully conclude the initial research phase, during which PVC-coated fabric offcuts undergo a transformation into PVC powder while achieving complete separation from polyethylene terephthalate fibres. The study entails a qualitative description of the morphology of PVC powder particles, employing an optical microscope to distinguish the diverse shapes exhibited by these particles. The optical microscope observations of PVC powder reveal a distinct array of non-spherical particles characterized by flat, elongated shapes. These high-magnification images unveil the intricate morphological features of the particles, highlighting their irregular shapes. Subsequently, a quantitative analysis of PVC particle size distribution is performed, comparing results from optical microscopy with those obtained through mechanical sieving. The qualitative and quantitative findings obtained provide robust evidence supporting the correlation and confirm that most particles are smaller than 600 µm (93.6%) using an optical microscope and the sieving process (96.39%). The greatest fraction (83.44%) is in the size range between 200 and 600 µm. Assessing flowability, another significant aspect in the evaluation of powders, provides insights into its behaviour and interparticle interactions. The flowability results indicate a Compressibility Index of approximately 26.84%, which suggests poor flowability. This means that the powder is likely to encounter difficulties in flowing freely. This finding is in line with the Hausner ratio, which measures 1.37. This investigation of recycled PVC powder will offer insights into the potential applications and processing considerations of this powder. More concretely, the use of recycled PVC powder shows promise as a viable alternative to conventional PVC resin in plastisol formulations, offering the potential to maintain the properties of the final PVC product without adverse effects., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Hydrogels based on natural polysaccharides have received special attention in the last decade due to their interesting features, such as availability, biocompatibility, biodegradability and safety. Such characteristics may make them sustainable and eco-friendly materials for water and wastewater treatment, meeting the concept of circular economy. In this study, a novel double-cross-linked alginate-based hydrogel has been successfully synthesized using epichlorhydrin and sodium trimetaphosphate (STMP) as cross-linker agents and then used for the removal of methylene blue (MB) dye under different operating conditions. The obtained hydrogel was deeply characterized by using various analytical techniques, namely Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. Experimental results showed that the synthesized double cross-linked hydrogel with relatively high STMP concentration (0.26 M) has promising structural and textural properties. This material exhibited excellent removal ability towards MB with a maximum adsorption capacity of about 992 mg/g for an initial pH of 10. The kinetic and isotherm modeling study revealed that the pseudo-second-order and Freundlich models fitted well the measured adsorption experimental data. The MB adsorption process onto the synthesized hydrogel is exothermic, feasible and spontaneous. It mainly includes electrostatic interaction and hydrogen bonds. These findings suggest that double-cross-linked alginate-based hydrogel can be considered as an attractive and potential adsorbent for an effective cationic dye removal from aqueous environments. The use of such a green adsorbent for the treatment of organic-pollutants-rich industrial wastewaters promotes sustainability and circular economy concepts., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

This study investigates-for the first time-the synthesis of a novel Ca-rich biochar (N-Ca-B) and its potential use for phosphorus (P) recovery from both synthetic solutions (SS) and treated urban wastewater (TUW) in a continuous stirring tank reactor (CSTR) mode. The novel biochar was synthesized by pyrolysis at 900 °C of a mixture composed of three different materials: animal biomass (poultry manure; PM), lignocellulosic waste (date palm fronds; DPFs), and abundant mineral waste (waste marble powder; WMP). Characterization of N-Ca-B showed that it has good textural properties: well-developed porosity, and high specific surface area. Furthermore, high calcium hydroxide (Ca(OH) 2 ) and calcium oxides (CaO) nanoparticle loads were observed on the biochar surface. The dynamic CSTR assays indicated that the P recovery efficiency mainly depended on the biochar mass, P influent concentration, and, especially, the Ca content of the feeding solution. Owing to its richness in Ca cations, TUW exhibited the highest adsorbed P amount (109.2 mg g -1 ), i.e., about 14% larger than the SS. P recovery occurs through precipitation as hydroxyapatite, surface complexation, and electrostatic interactions with positively charged biochar particles. In real-world scenarios, CSTR systems can be applied as a tertiary treatment step in existing wastewater treatment plants (WWTPs). Decanted P-loaded biochar can be used in agriculture as a slow-release fertilizer instead of commercial products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Phosphorus (P) represents a major pollutant of water resources and at the same time a vital element for human and plants. P recovery from wastewaters and its reuse is a necessity in order to compensate the current important depletion of P natural reserves. The use of biochars for P recovery from wastewaters and their subsequent valorization in agriculture, instead of synthetic industrial fertilizers, promotes circular economy and sustainability concepts. However, P retention by pristine biochars is usually low and a modification step is always required to improve their P recovery efficiency. The pre- or post-treatment of biochars with metal salts seems to be one of the most efficient approaches. This review aims to summarize and discuss the most recent developments (from 2020- up to now) in: i) the role of the feedstock nature, the metal salt type, the pyrolysis conditions, and the experimental adsorption parameters on metallic-nanoparticles-loaded biochars properties and effectiveness in recovering P from aqueous solutions, as well as the dominant involved mechanisms, ii) the effect of the eluent solutions nature on the regeneration ability of P-loaded biochars, and iii) the practical challenges facing the upscaling of P-loaded biochars production and valorization in agriculture. This review shows that the synthesized biochars through slow pyrolysis at relatively high temperatures (up to 700-800 °C) of mixed biomasses with Ca- Mg-rich materials or impregnated biomasses with specific metals in order to from layered double hydroxides (LDHs) biochars composites exhibit interesting structural, textural and surface chemistry properties allowing high P recovery efficiency. Depending on the pyrolysis's and adsorption's experimental conditions, these modified biochars may recover P through combined mechanisms including mainly electrostatic attraction, ligand exchange, surface complexation, hydrogen bonding, and precipitation. Moreover, the P-loaded biochars can be used directly in agriculture or efficiently regenerated with alkaline solutions. Finally, this review emphasizes the challenges concerning the production and use of P-loaded biochars in a context of circular economy. They concern the optimization of P recovery process from wastewater in real-time scenarios, the reduction of energy-related biochars production costs and the intensification of communication/dissemination campaigns to all the concerned actors (i.e., farmers, consumers, stakeholders, and policymakers) on the benefits of P-loaded biochars reuse. We believe that this review is beneficial for new breakthroughs on the synthesis and green application of metallic-nanoparticles-loaded biochars., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Tomato pomace was slowly pyrolyzed at 350 and 550 °C (under an N 2 flow of 50 L/h) at a rate of 6 °C/min and a residence time of 1:30 h to produce two biochars named B350 and B550, respectively. In addition, the two biochars were chemically activated with ΚΟΗ (at a ratio of 1:10 w/v) at 800 °C to produce two new materials named BA350 and BA550. The four biochars produced were characterized physically and chemically (pH, yield, calorific value). They were also analyzed by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (B.E.T), elemental analysis (EA), and thermogravimetric analysis (TGA). The results showed that as the pyrolysis temperature increased (350 to 550 °C), the specific surface area (SSA) increased. The latter was also significantly increased by the activation process. EA showed a variation in the mineral content of the produced biochars, resulting in a different content of the biochars after activation. The parameters studied showed that biochars from tomato waste could be used as an organic amendment to improve soil fertility in agricultural. In addition, because of their ability to absorb water, they could be used as a water reservoir in soils in arid areas., Competing Interests: Declaration of competing interest The authors have no competing interests to declare that are relevant to the content of this article., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Humanity's three main components are energy, food and clothing. Each of us, individually and collectively, contributes to climate change and CO 2 emissions, natural resource consumption, and social attitudes and behaviour. Global fashion trends are expected to increase in value from 1.5 trillion dollars in 2020 to around 2.25 trillion dollars by 2025, indicating that the fashion demand is on the rise. Due to climate change, soil and water scarcity, and a variety of other diseases, new natural resources must be developed from plastic fibres, natural colours must replace synthetic ones, water consumption must be reduced and the 'buy-and-throw-away philosophy' must be replaced with 'buy-less-and-these-are-needed' and incorporate the 12 'R' strategies to aid the transition to a circular economy. In the context of waste management as well as on the development of new strategy approach, the fashion industry requires a new business circular model and furthermore a new mindset.