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In this study, we conducted a comprehensive investigation on the influence of waste perlite powder (WPP) on the various properties of mortar and paste, including slurry performance, mechanical strength, hydration products, and microstructure. Additionally, we also aimed to uncover the underlying mechanism behind these effects. It was found that WPP reduced the workability and facilitated the setting process of cement-WPP pastes. WPP decreased the mechanical strength of mortar, but it exhibited significant strength enhancement during the subsequent stages. The incorporation of WPP worsened the water absorption behavior; however, this negative effect was mitigated as the curing age of the mortar was prolonged. The drying shrinkage cement-WPP binary system was significantly improved, with the prolongation of curing age. Moreover, WPP reduced the early heat release of the binary system, which may be beneficial for reducing the temperature gradient in mass concrete. It was confirmed that WPP accelerated the transformation from AFt to AFm, promoted the formation of C-A-S-H and optimized the pore structure of the system. It was confirmed that WPP was involved in the hydration reaction, which accelerated the transformation from AFt to AFm and promoted the formation of C-A-S-H. Such results suggested that the reuse of WPP in concrete production was technically feasible owing to its high pozzolanic reactivity.

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In the process of research and development of self-healing concrete, it is observed that there are three main factors controlling the self-healing effect of concrete: first, the bacteria with repair ability and strong vitality; Second, the carrying capacity of the carrier and the matching degree with concrete; The third is the concentration of bacteria. This paper focuses on the mechanical properties of Bacillus subtilis self-healing concrete with sisal fiber, PVA, and expanded perlite as the carrier. To better study the mechanical properties of self-healing concrete caused by the carrier, the experiment adopts the design parameters of C30 concrete and conducts experiments on compressive resistance, flexural resistance, freeze-thaw cycle, and sulfate corrosion resistance to analyze the influence of different carriers on the mechanical properties of self-healing concrete, and obtains the best carrier. The concentration gradients of three groups of bacterial solution were set as 2od, 2.5od, and 3od, respectively, for comparison to avoid the influence of bacterial concentration. It compared the impact of bacterial solution concentrations on the specimen's mechanical properties, and the effect of carriers was also analyzed. The experimental results show that the mechanical properties of the specimen using 2.5od bacterial liquid concentration with PVA as the carrier have peaked. With the increase in bacterial solution concentration, the specimens' comprehensive mechanical properties increased first and then decreased. The compression resistance of the specimen with PVA is higher than that of the specimen with sisal fiber and expanded perlite. At the same time, the frost resistance and corrosion resistance of the PVA carrier specimen is also higher than that of the specimen with sisal fiber and expanded perlite carrier.

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The present work analyzes the effect of releasing physically bound water from hydrogel, cork, perlite, and ceramsite on materials exposed to microwave radiation and subsequently investigates possible changes in the physical properties of these materials (water absorption and thermal conductivity coefficient). The release of physically bound water from individual materials has potential practical applications in materials engineering, for example, in the internal curing of concrete, where individual aggregates could, under the influence of microwave radiation, release water into the structure of the concrete and thus further cure it. Experimental analysis was carried out with samples of the above-mentioned materials, which were first weighed and then immersed in water for 24 h. Then, they were weighed again and exposed to microwave radiation. After exposure, the samples were weighed again, left immersed in water for 24 h, and weighed again. The focus of the study was on the ability of the aggregates to release water due to microwave radiation and on the changes in the properties (water absorption, thermal conductivity coefficient) of these materials when exposed to microwave radiation. The samples were further monitored by digital microscopy for possible changes in the surface layer of the materials. The hydrogels show the highest water absorption (1000%) and the fastest water release (45 min to complete desiccation). After the release of water due to microwave radiation, their ability to absorb water is maintained. Of interest, however, is that in the case of almost complete removal of water from the soaked hydrogel, the original powdered state of the hydrogel is not obtained, but the outcome has rather a solid structure. In the case of cork, the water absorption depends on the fraction of the material.

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This study aimed to obtain and characterize a mortar with perlite aggregate and thermal-treated materials that could substitute for Portland cement. First, the thermally treated materials were obtained by calcinating old Portland cement (OC-tt) and concrete demolition waste (CC-tt) at 550 °C, for 3 h. Second, plastic mortars with a perlite: cement volume ratio of 3:1 were prepared and tested for water absorption, mechanical strength, and thermal conductivity. The microstructure was also analyzed. Portland cement (R) was partially substituted with 10%, 30%, and 50% OC-tt. Thermal-treated materials negatively influenced the compressive and flexural strengths at 7 and 28 days. With an increase in the substitution percentage to 50%, the decrease in the compressive strength was 40% for OC-tt and 62.5% for CC-tt. The presence of 10% OC-tt/CC-tt positively influenced the water absorption. The thermal conductivity of the tested mortars was in the range of 0.37-0.48 W/m·K. SEM analysis shows the expanded perlite pores remained unbroken.

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This study compares the workability, mechanical, and thermal characteristics of structural self-compacting lightweight concrete (SCLWC) formulations using pumice aggregate (PA), expanded perlite aggregate (EPA), fly ash (FA), and silica fume (SF). FA and SF were used as partial substitutes for cement at a 10% ratio in various mixes, impacting different aspects: According to the obtained results, FA enhanced the workability but SF reduced it, while SF improved the compressive and splitting tensile strengths more than FA. EPA, used as a fine aggregate alongside PA, decreased the workability, compressive strength, and splitting tensile strength compared to the control mix (K0). The thermal properties were altered by FA and SF similarly, while EPA notably reduced the thermal conductivity coefficients. The thermal conductivity coefficients (TCCs) of the K0-K4 SCLWC mixtures ranged from 0.275 to 0.364 W/mK. K0 had a TCC of 0.364 W/mK. With 10% FA, K1 achieved 0.305 W/mK; K2 with 10% SF reached 0.325 W/mK. K3 and K4, using EPA instead of PA, showed significantly lower TCC values: 0.275 W/mK and 0.289 W/mK, respectively. FA and SF improved the thermal conductivity compared to K0, while EPA further reduced the TCC values in K3 and K4 compared to K1 and K2. The compressive strength (CS) values of the K0-K4 SCLWC mixtures at 7 and 28 days reveal notable trends. Using 10% FA in K1 decreased the CS at both 7 days (12.16 MPa) and 28 days (22.36 MPa), attributed to FA's gradual pozzolanic activity. Conversely, K2 with SF showed increased CS at 7 days (17.88 MPa) and 28 days (29.89 MPa) due to SF's rapid pozzolanic activity. Incorporating EPA into K3 and K4 reduced the CS values compared to PA, indicating EPA's lower strength contribution due to its porous structure.

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The application of microwave de-icing technology in road engineering is constrained by its low energy utilization rate, which can be attributed to low heat production rates and ineffective heat dissipation to the underlying pavement. In this work, asphalt mixtures are designed as an upper layer (heating layer) and a lower layer (thermal-resistance layer). Magnetite slag was selected as a microwave-sensitive source for generating heat, and expanded perlite powder was incorporated into the lower layer as a thermal resistance material. Structural layer optimization and thermal-resistance layer design of the asphalt mixture were carried out by changing the thickness of the upper and lower layers to further improve the heat production rates. The design effectiveness is comprehensively evaluated by factors such as the changing law of the average surface temperature of mixtures, ice-melting time, and cost-effectiveness analyses. The results show that EP possesses better thermal stability, lower microwave energy conversion ability and more excellent heat-resistance potential compared with mineral powder. The heat-resistance layer with EP can prevent heat from being conducted to the lower layer and promote it to concentrate on the specimen surface, which can endow the microwave heating efficiency of specimens to be further improved by up to 26.97% and the de-icing time reduced by 10%, ascribed to the heat-resistance design. Furthermore, the collaborative design of the structural layer optimization and heat-resistance layer can increase energy utilization efficiency and save microwave-absorbing materials while ensuring excellent microwave de-icing efficiency.

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Dyes, considered as toxic and persistent pollutants, must be removed from organic wastes prior to their composting and application in sustainable agriculture. Azo dyes, capable of altering the physicochemical properties of soil, are difficult to expel by conventional wastewater treatments. C.I. Acid Black 1 (AB 1), a sulfonated azo dye, inhibits nitrification and ammonification in the soil, lessens the nitrogen use efficacy in crop production and passes substantially unaltered through an activated sludge process. The retention of C.I. Acid Black 1 by raw and expanded perlite was investigated in order to examine the potential effectiveness of this aluminosilicate material toward organic waste cleanup. Dye adsorption proved spontaneous and endothermic in nature, increasing with temperature for both perlites. Expanded perlite having a more open structure exhibited a better performance compared to the raw material. Several of the most widely recognized two-parameter theoretical models, i.e., Langmuir, Freundlich, Temkin, Brunauer-Emmett-Teller (BET), Harkins-Jura, Halsey, Henderson, and Smith, were applied to reveal physicochemical features characterizing the adsorption. The Langmuir, Freundlich, Temkin, BET, Henderson, and Smith equations best fitted experimental data indicating that the adsorption of anionic dye on perlites is controlled by their surface, i.e., non-uniformity in structure and charge. This heterogeneity of surface is considered responsible for promoting specific dye adsorption areas creating dye "islands" with local dye supersaturations.

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Rhizosphere pH determines nutrient bioavailability, but this pH is difficult to measure. Standard pH tests require adding water to growth media. This dilutes hydrogen ion activity and increases pH. We used a novel, in situ, pointed-tip electrode to estimate rhizosphere pH without dilution. Measurements from this electrode matched a research-grade pH meter in hydroponic nutrient solutions. We then compared measurements from this electrode to saturated paste and pour-through methods in peat moss, coconut coir, and pine bark. The pointed-tip electrode was unable to accurately measure pH in the highly-porous pine bark media. Adding deionized water to the other media at container capacity using the saturated paste method resulted in a pH that was 0.59 ± 0.30 units higher than the initial in situ measurement at the top of the container. This increase aligns with established solution chemistry principles. Measurements of pH using the pour-through method were 0.38 ± 0.24 pH units higher than in situ measurements at the bottom of the container. We conclude that in situ pH measurements are not subject to dilution and are thus more representative of the rhizosphere pH than the saturated paste and pour-through techniques.

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Portland cement (PC) is known for its environmental and technical concerns and massive energy consumption during manufacturing. Geopolymer cement is a promising technology to totally replace the use of PC in the oil and gas industry. Although geopolymers are widely used in the construction industry, it is yet to see a full-scale application in the petroleum industry. High-density geopolymer cement development is essential to substitute heavy-weight Portland cement slurries for high pressure well cementing applications. Sedimentation issue is associated with high-density cement slurries which use high specific gravity solids such as weighting materials. This problem causes heterogeneity and density variation along the cemented sections. The main target of this work is to evaluate the use of perlite powder to address the sedimentation issue in the heavy weight geopolymer systems. Hematite-based Class F fly ash (FFA) geopolymer cement slurries with perlite concentrations of 0, 1.5, and 3% by weight of binder (BWOB) were prepared. The sedimentation problem was investigated using three techniques: API method, nuclear magnetic resonance (NMR), and computed tomography (CT) scan. The perlite effects on different geopolymer properties such as unconfined compressive strength (UCS), porosity, elastic and rheological properties were assessed. The results proved that perlite incorporation in high-density hematite-based FFA geopolymer significantly reduced sedimentation issue by increasing yield point and gel strength. NMR and CT scan showed that perlite decreases porosity and density variation across the geopolymer samples. The UCS increased with increasing perlite percentage from 0 to 3%. The measured Young's moduli (YM) and Poisson's ratios (PR) showed that the developed perlite based geopolymer systems are considered more flexible than Class G cement systems. It was found that the optimum perlite concentration is 3% BWOB for tackling sedimentation and developing a slurry with acceptable mixability and rheological properties.

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Recently, the usage of a cold-bonded method in the production of artificial green geopolymer coarse aggregates (GCA) has been crucial from an economic and environmental perspective because the sintering method consumes an enormous quantity of energy and generates a significant quantity of pollutants. This research investigated the manufacture of GCA via cold-bonded pelletization using two distinct industrial byproducts (GGBFS and FA) via a new and simpler pelletization technology. Three different binders were used to produce three distinct types of GCAs as partial replacements for natural coarse aggregate (NCA) at varying replacement rates (0%, 25%, 50%, and 75%). The first group used ground-granulated blast furnace slag, while the second used GGBFS with perlite, and the third used FA with perlite. An alkaline activator was commonly used with all three groups. The physical and mechanical properties of three distinct varieties of GCA were recorded. The results indicated that the mechanical and chemical properties of three different types of GCAs were nearly identical to those of natural aggregate, with the exception of their increased water absorption. According to the findings, the recommended mixtures were suitable for usage in the construction industry. The results indicated that the ratio of all investigated attributes declined as the number of GCAs increased. In contrast, lightweight concrete can be obtained at a ratio of GCA (FA with perlite) equal to 75%, where unit weight, compressive, splitting tensile, flexural, and water absorption strengths were 1.87 gm/cm3, 20.2 MPa, 1.8 MPa, 8 MPa, and 6.0%, respectively (FA with perlite).

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Mitigating methane (CH4) emissions using methanotrophs (methane-oxidizing bacteria, MOB), is a simple, energy efficient and cheap technology. The abundance and distribution of MOB in the environmental samples is critical for efficient removal of emitted CH4 from any source. This study evaluated the performance of farm soils without and with cheap, easily accessible bulking materials as sustainable hybrid biofilter media. Soil-only biofilters removed up to 865 ± 19 g CH4 m-3 d-1 with well-drained organic carbon-rich soils compared with 264 ± 14 g CH4 m-3 d-1 for poorly drained soil. The removal efficiency decreased with increasing flow rate (0.16→0.24 L min-1) and subsequent priming could not return soil biofilters to their previous removal rate.Hybrid biofilters using organic, carbon-rich soils and compost removed up to 2698 g CH4 m-3 d-1 (flow rate 0.35 L min-1). Increasing CH4 flow rates also reduced their efficiency, but the hybrid biofilters with compost quickly regained most of their efficiency and removed up to 2262 g CH4 m-3 d-1 (flow rate 0.3 L min-1) after remixing of biofilter media. These results show that hybrid biofilters removed higher CH4 than soil-only biofilters and were also more resilient. The MOB gene abundance results complement the CH4 removal capacity of both soil-only and hybrid biofilter materials used. The more aerobic, carbon-rich soils had more abundant MOB than the poorly drained soil. The most porous hybrid biofilter with compost and more available nutrients to sustain bacterial growth and activity had the highest MOB abundance and removed the most CH4.

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OBJECTIVES: Enhance the androstadienedione (Androst-1,4-diene-3,17-dione, ADD) production of rough morphotype Mycolicibacterium neoaurum R by repeated-batch fermentation of immobilized cells. RESULTS: M. neoaurum R was a rough colony morphotype variant, obtained from the routine plating of smooth M. neoaurum strain CICC 21097. M. neoaurum R showed rougher cell surface and aggregated in broth. The ADD production of M. neoaurum R was notably lower than that of M. neoaurum CICC 21097 during the free cell fermentation, but the yield gap could be erased after proper cell immobilization. Subsequently, repeated-batch fermentation of immobilized M. neoaurum R was performed to shorten the production cycle and enhance the bio-production efficiency of ADD. Through the optimization of the immobilization carriers and the co-solvents for phytosterols, the ADD productivity of M. neoaurum R immobilized by semi-expanded perlite reached 0.075 g/L/h during the repeated-batch fermentation for 40 days. CONCLUSIONS: The ADD production of the rough-type M. neoaurum R was notably enhanced by the immobilization onto semi-expanded perlite. Moreover, the ADD batch yields of M. neoaurum R immobilized by semi-expanded perlite were maintained at high levels during the repeated-batch fermentation.

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Herein, the selectivity/simultaneously adsorption associated with Congo Red (CR) and Methylene Blue (MB) has been efficiently undertaken via amorphous perlite. Under optimum conditions of 38 min, 96 mg/L and 312°K for the contact time, the dye concentration, and the temperature, respectively, the optimization study using central composite design (CCD) matrix gave rise to high adsorption yields of 82.22 and 96.65% for CR and MB, respectively. Importantly, kinetic and isotherm studies attested that the batch adsorption occurs as intra-diffusional mass transport onto porous material. The obtained thermodynamic parameters are indicative of an endothermic/spontaneous physisorption process. Whereas SEM-EDS characterization revealed the superficial adsorption process of both CR and MB onto perlite. In addition, the FTIR analysis suggests that the adsorption process disrupted the short-range compounds order of perlite samples, revealing the marked crystallinity decrease of the adsorbent after adsorption. Finally, application of these optimum conditions tests on real industrial wastewater show that the adsorption was simultaneous at neutral pH and at 312°K, whereas CR and MB can be selectively adsorbed at pH 4 and 9, respectively. Supplementary Information: The online version contains supplementary material available at 10.1007/s40201-023-00870-1.

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Fully stimulating the capacity of light-driven phase change materials (PCMs) for efficient capture, conversion, and storage solar energy requires an ingenious combination of PCMs, supporting structural materials, and photothermal materials, therefore motivating the synergistic effects between the components. Herein, this work thoroughly explores the interaction forces between PCMs and supporting structural materials and the synergy between PCMs and photothermal materials in photothermal conversion. Rejoicingly, when capitalizing on the prepared directional channel structure of hierarchically porous composite aerogel (PEPG) as a supporting structural material, a superior paraffin wax (PW) encapsulation rate of 85.11% is achieved, and the prepared PEPG2-PW has a high phase change enthalpy of 182.9 J/g. The van der Waals force and Lewis acid-base action between PEPG and PW molecules reveal the excellent stabilities of PEPG-PW. More importantly, the PEPG2-PW has an ultrahigh photothermal conversion efficiency of 95.2% under 1 sun irradiation and durability. Most importantly, the COMSOL Multiphysics software calculations demonstrate that transparent PW can anchor sunlight on the surface of graphite nanoplates, converting it into heat by enhancing the loss of graphite backbone lattice vibrations, and the accumulated heat is then stored in molten PW. This work provides some design principles for high-efficiency solar-thermal conversion materials.

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This study was aimed to coat a hybrid bioceramic composite onto Ti6Al4V by using hydrothermal method. The Hybrid bioceramic composite for coating was prepared by reinforcing different rations of expanded perlite (EP) and 5 wt.% chitosan into synthesized Hydroxyapatite (HA). Coating was performed at 1800°C for 12 hours. The coated specimens were gradually subjected to a sintering at 6000°C for 1 hour. For in vitro analysis, the specimens were kept in Ringer's solution for 1, 10, and 25 days. All specimens were examined by SEM, EDX, FTIR, and surface roughness analyses for characterizing. It was concluded that as the reinforcement ratio increased, there was an increase in coating thickness and surface roughness. The optimum reinforcement ratio for expanded perlite can be 10 wt.% (A3-B3). With increasing ratio of calcium (Ca) and phosphate (P) (Ca/P), the surface becomes more active in body fluid and then observed the formation of the hydroxycarbonate apatite (HCA) layer. As the waiting time increased, there was an increase in the formation of an apatite structure.

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This article presents an innovative approach to the flame retardancy of rigid polyurethane foams using natural waste in the form of buckwheat hulls in combination with an inorganic additive-perlite. A series of tests were presented in which various contents of flame-retardant additives were used. Based on the test results, it was found that the addition of the buckwheat hull/perlite system affected the physical and mechanical properties of the obtained foams, i.e., apparent density, impact strength, and compressive and flexural strength. The structure of the system had also changed, directly affecting the hydrophobic properties of the foams. In addition, it was observed that the addition of buckwheat hull/perlite modifiers improved the burning behavior of composite foams.

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The increasing amount of waste from the vulcanization industry has become a serious environmental challenge. Even the partial reuse of the steel contained in tires as dispersed reinforcement in the production of new building materials may contribute to reducing the environmental impact of this industry while supporting the principle of sustainable development. In this study, the concrete samples were made of Portland cement, tap water, lightweight perlite aggregates, and steel cord fibers. Two different addition of steel cord fibers (1.3% and 2.6% wt. of concrete, respectively) were used. The samples of lightweight concrete based on perlite aggregate with steel cord fiber addition showed a significant increase in compressive (18-48%), tensile (25-52%), and flexural strength (26-41%). Moreover, higher thermal conductivity and thermal diffusivity were reported after incorporating steel cord fibers into the concrete matrix; however, the specific heat values decreased after these modifications. The highest values of thermal conductivity and thermal diffusivity were obtained for samples modified with a 2.6% addition of steel cord fibers and were equal to 0.912 ± 0.002 W/mK and 0.562 ± 0.002 µm2/s, respectively. Maximum specific heat, on the other hand, was reported for plain concrete (R)-1.678 ± 0.001 MJ/m3 K.

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A single performance evaluation does not cover all the situations encountered in cement-based plastering mortar applications in walls. This paper proposes a comprehensive performance evaluation method for assessing the cement-based plastering mortar by comprehensively considering the physical characteristics, microstructures, thermal performances, mechanical properties and adsorbability of materials. The relative performances of each test item were compared with standards and previous studies, and the calculation equation of the comprehensive performance value was obtained. In this study, the common cement plastering mortar (CM) and lightweight mortar were mixed with expanded and vitrified beads as aggregates mortar (EVBM), wood fibres, sepiolite and expanded perlite-based plastering mortar (WM) and three types of homemade optimized mortars were moulded as testing specimens. The reference material was marked as CM, and the weights of each parameter in the equation were artificially set according to the applied conditions of the building and restricted by the comprehensive performance value of the ideal plastering mortar at the same time. Through the evaluation of the comprehensive performance and the calculation of these mortars from a case setting of weights, the combined mixing of diatomite, sepiolite with fly ash is better than each single material mixed in mortars, and the comprehensive performance value of mortars with a single function is functional, such as thermal insulation mortar. This paper provides an evaluation method for the comprehensive application of cement-based plastering mortar on the wall.

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To allow an amputee resume healthy walking, a well-designed lower limb prosthesis is required. However, in many developing countries, the cost of high-tech and often imported prosthesis is out of the financial reach of many amputees. The objective of this study was to design and implement a mechanical, body-powered transfemoral prosthetic device to help transfemoral amputees regain functional ambulation. The materials used include socket adapter, acetone hardener, plaster of Paris bandages, perlite lining, and polyester resin. Using anthropometric measurements of a volunteer amputee, a user-friendly and ergonomic transfemoral prosthetic device was designed using AutoCAD rendering and fabricated using engineering methods such as casting and welding. The prosthetic limb consists of a polypropylene socket, a galvanised iron knee joint with a hinge and spring suspension system, and a perlite foot. An evaluation of the prosthetic limb after fabrication showed that it restores the ambulatory function of the amputee.

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Herein, the catalytic activity of two types of iron-loaded perlite catalysts prepared by impregnation of raw and calcined perlite in terms of 8-hydroxyquinoline-5-sulfonic acid (8-HQS) degradation was investigated by the Fenton reaction. Different iron contents were used to optimize the Fenton catalytic reaction. The as-prepared catalysts were characterized using different spectrophotometry techniques. The effect of some operating parameters on the Fenton oxidation of 8-HQS was carried out. Iron content of 10% has led to the highest catalytic efficiency. Furthermore, the oxidation of 8-HQS is highly affected by the addition of H2O2, proposing that the heterogeneous Fenton reaction has been successfully activated. Whatever the type of the used catalyst, the heterogeneous catalytic oxidation process is extremely rapid, even instantaneous. The synthesized catalysts remained potentially active and retained their catalytic activity for successive Fenton reactions suggesting their economic benefit over the homogenous Fenton process. Accordingly, the newly prepared heterogeneous solid could be successfully used to treat wastewater effluents containing persistent organic compounds.

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