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Anaerobic digestion is a highly effective and innovative method for treating organic waste while simultaneously generating energy. However, the treatment of the resulting digestate remains a challenging endeavor. To address this issue, poultry by-products digestate is used in this study to prepare biochars at two different pyrolysis temperatures (500/600 °C). Despite their potential, the utilization of untreated biochar is restricted due to its inadequate adsorption capacity. Therefore, each biochar was chemically activated using either HNO3 or KOH to synthesize four activated biochars (BC5@KOH, BC6@HNO3, BC5@HNO3, and BC6@HNO3). The aim is to investigate how the nature of chemical activation and pyrolysis temperature influence the adsorption of methylene blue dye. Characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), Raman analysis, and pHpzc determination, were exploited to comprehensively elucidate the structure and composition of both unprocessed and chemically activated biochars. Among the activated biochars, the adsorbent BC5@HNO3 exhibits the highest methylene blue (MB) adsorption capacity, reaching 101.72 mg.g-1 at 298 K under (pH = 2, ads dose = 0.6 g.L-1, shaking time of 20 min, as optimal conditions for MB adsorption. Adsorption data for each adsorbent strongly aligns with both the Langmuir isotherm model and the pseudo-second-order kinetic model. Moreover, the thermodynamic study reveals that the adsorption process was endothermic and spontaneous. The adsorption mechanism of MB dye was explored using various analytical techniques, including FTIR, SEM, PZC, and pH impact assessment. The findings suggest correlations with electrostatic interactions, hydrogen bonding, pore filling, as well as n-π and π-π interactions. Apparently, activated biochars play a crucial role in efficiently removing methylene blue dye, showcasing their potential as environmentally friendly and effective adsorbents.

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In the quest for sustainable waste management solutions, this study explores the integration of ultrasonic pretreatment as a preparatory step for the anaerobic digestion of landfill leachate. Employing response surface methodology (RSM) coupled with central composite design (CCD), we systematically optimize the process parameters, including pH, inoculum volume, and ultrasonic pretreatment duration, to maximize the yield of bio-methane potential (ml CH4/g VS). The results demonstrate the effective application of RSM-CCD for predicting and modelling methane generation, with a highly significant model (R2 = 0.899). The optimized conditions reveal a remarkable biomethane potential of 177 ml CH4/g VS. Additionally, this study contributes to the understanding of the positive effect of ultrasound pretreatment on the anaerobic digestion of landfill leachate, and the quality of the digestate obtained after anaerobic digestion was studied and different valorisations were proposed.

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In this study, quartz sand (QS) incorporated into a crosslinked chitosan-glutaraldehyde matrix (QS@Ch-Glu) was prepared and employed as an efficient adsorbent for the elimination of Orange G (OG) dye from water. The sorption process is adequately described by the pseudo-second order kinetic model and the Langmuir isotherm model with maximum adsorption capacities of 172.65, 188.18, and 206.65mg/g at 25, 35, and 45°C, respectively. A statistical physics model was adopted to elucidate the adsorption mechanism of OG on QS@Ch-Glu. Calculated thermodynamic factors revealed that the adsorption of OG is endothermic, spontaneous, and occurs via physical interactions. Overall, the proposed adsorption mechanism was based on electrostatic attractions, n-π stacking interaction, hydrogen bonding interaction, and Yoshida hydrogen bonding. The adsorption rate of QS@Ch-Glu was still above 95% even after 6 cycles of adsorption and desorption. Furthermore, QS@Ch-Glu demonstrated high efficiency in real water samples. All these findings demonstrate that QS@Ch-Glu is qualified for practical applications.

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The nontoxicity, worldwide availability and low production cost of cuttlefish bone products qualify them an excellent biocoagulant to treat food industry wastewater. In this study, cuttlefish bone liquid waste from the deproteinization step was used as a biocoagulant to treat food industry wastewater. This work concerns a waste that has never before been investigated. The objectives of this work were: the recovery of waste resulting from cuttlefish bone deproteinization, the replacementof chemical coagulants with natural ones to preserve the environment, and the enhancement ofthe value of fishery byproducts. A quantitative characterization of the industrial effluents of a Moroccan food processing plant was performed. The physicochemical properties of the raw cuttlefish bone powder and the deproteinization liquid extract were determined using specific analysis techniques: SEM/EDX, FTIR, XRD and 1H-NMR. The protein content of the deproteinization liquid was determined by OPA fluorescent assay. The zeta potential of the liquid extract was also determined. The obtained analytical results showed that the deproteinization liquid waste contained an adequate amount of soluble chitin fractions that could be used in food wastewater treatment. The effects of the coagulant dose and pH on the food industrial effluents were studied to confirm the effectiveness of the deproteinization liquid extract. Under optimal conditions, the coagulant showed satisfactory results. Process optimization was performed using the Box-Behnken design and response surface methodology. Thus, the optimal removal efficiencies predicted using this model for turbidity (99.68%), BOD5 (97.76%), and COD (82.92%) were obtained at a dosage of 8 mL biocoagulant in 0.5 L of food processing wastewater at an alkaline pH of 11.

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This baseline study describes the microplastic (MPs) problem on seven beaches located on Agadir, central Atlantic coast of Morocco. Microplastics abundances (densities) ranged from 7680 MPs/kg to 34,200 MPs/kg above other world beaches. The following shapes were found: fibers, fragments, films, and pellets. Fibers were the dominant typology with a 73%. Polyethylene (PE) was the predominant polymer in all beaches with an average percentage of 59%, followed by Polypropylene (PP - 18%), Polystyrene (PS - 9%), Polyvinyl chloride (PVC - 8%), and Ethylene-vinyl acetate (EVA - 6%). Microplastics abundances presented in this work suggest continuous inputs of plastics of all sizes and types. Also, all observed shapes highlight a combination of sources (primary and secondary). Central Atlantic Moroccan beaches are currently affected by extreme values of MPs that demand urgent interventions to restore environmental quality.

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A novel liquid chitosan-based biocoagulant for treating wastewater from a Moroccan fish processing plant was successfully prepared from shrimp shells (Parapenaeus longirostris), the most abundant fish by-products in the country. The shells were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transforms infrared spectroscopy. Using chitosan without adding acetic acid helps to minimize its negative impact on the environment. At the same time, the recovery of marine shellfish represents a promising solution for the management of solid fish waste. In order to test the treatment efficiency of the biocoagulant developed, a qualitative characterization of these effluents was carried out beforehand. The optimization process was conducted in two steps: jar-test experiments and modeling of the experimental results. The first step covered the preliminary assessment to identify the most influential operational parameters (experimental conditions), whereas the second step concerned the study of the effects of three significant operational parameters and their interactions using a Box-Behnken experimental design. The variables involved were the concentration of coagulant (X1), the initial pH (X2), and the temperature (X3) of the wastewater samples, while the responses were the removal rates of turbidity (Y1) and BOD5 (Y2). The regression models and response surface contour plots revealed that chitosan as a liquid biocoagulant was effective in removing turbidity (98%) and BOD5 (53%) during the treatment. The optimal experimental conditions were found to be an alkaline media (pH = 10.5) and a biocoagulant dose of 5.5 mL in 0.5 L of fish processing wastewater maintained at 20 °C.

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Engineering of versatile binding chemistry on graphene oxide surface using nucleophilic substitution/amidation reactions for highly efficient adsorption of Cd (II), Cu (II) and Pb (II) is herein proposed. Graphene oxide (GO) was used as a precursor for covalent bonding of hexamethylenediamine (HMDA) molecules via the nucleophilic substitution/amidation reactions on epoxy (COC) and carboxyl (COOH) groups to yield hexamethylenediamine functionalized graphene oxide (GO-HMDA) with multiple binding chemistries such as oxygen and nitrogen. Afterwards, GO-HMDA was encapsulated in alginate hydrogel beads with different loadings 5, 10, 15 and 20 wt% to produce Alg/GO-HMDA hybrid adsorbents for the removal of trace heavy metal ions from aqueous solution. Batch adsorption studies showed remarkable adsorption rates reaching 100% for Pb (II), 98.18% for Cu (II) and 95.19 for Cd (II) (~1 mg L-1) with only 15 wt% of GO-HMDA incorporated into the alginate beads. Moreover, Alg/GO-HMDA showed high removal efficiencies of heavy metals from tap water with a removal order of (Pb > Cu > Cd) similar to that observed in single aqueous solution. In Addition, the Alg/GO-HMDA adsorbents displayed excellent regeneration ability for six consecutive adsorption-desorption cycles confirming the high performance and potential of these adsorbents, for real heavy metals remediation in environment and in drinking waters in both single and multiple systems. Finally, the adsorption mechanism of traces heavy metals resulted from several phenomena including the electrostatic interactions occurring between the COOH groups of Alginate and the GO-HMDA surface groups as well as, through chelation interactions occurring between the metal cations and amino-functionalized groups of Alg/GO-HMDA 15 hybrid adsorbent.

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[This corrects the article DOI: 10.1039/D0RA00617C.].

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Iron oxide/biochar (Fe2O3/biochar) was prepared by green synthesis via a microwave to evaluate ultrasound-assisted adsorption capacity of Nonsteroidal Anti-inflammatory Drugs (NSAIDs) (salicylic acid, naproxen, and ketoprofen) from the water. Several techniques of characterization, including, Fourier transform infrared spectrometry, scanning electron microscopy, EDS analysis, N2 adsorption-desorption, X-ray diffraction, and Raman spectrometry were applied. The adsorption of NSAIDs onto Fe2O3/biochar was performed using an ultrasonic bath. The effects of batch adsorption under various experimental parameters such as contact time (0-120 min), initial concentration (10-500 mg L-1) and pH (2-12) were tested. The obtained Fe2O3/biochar specific surface area, mesopore volume/micropore volume, and pores size were equal to 786 m2 g-1, 0.409 cm3 g-1, and 1.534 cm3 g-1, respectively. The pseudo-second-order model could describe better all NSAID adsorptions onto Fe2O3/biochar. The Langmuir model agreed well with the NSAID adsorptions and the maximum adsorption capacities reached 683 mg g-1, 533 mg g-1 and 444 mg g-1 for salicylic acid, naproxen, and ketoprofen, respectively. Fe2O3/biochar can be used as an excellent adsorbent for the treatment of NSAIDs in water.

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Herein, ethylenediamine functionalized porous carbon (PC-ED/1.5) was synthesized, then characterized by various methods and finally used as a functional material for Cu(ii) and Pb(ii) ion removal from water. XPS revealed the presence of numerous functionalities within the surface of PC including -NH and C-N-C groups. Furthermore, S BET, RS, XRD and FTIR analyses confirmed the changes implemented on the PC surface. Thereafter, a systematic study was implemented to analyze the interactions of the PC-ED/1.5 surface with Cu(ii) and Pb(ii) heavy metal ions. Hence, adsorption experiments showed that the PC-ED/1.5 exhibits maximum adsorption capacities of 123.45 mg g-1 and 140.84 mg g-1 for Cu(ii) and Pb(ii), respectively. Moreover, in situ electrostatic interactions occurring between the divalent cation and the PC-ED/1.5 functional groups was investigated. The mechanism involves chelation processes, electrostatic interactions and mechanical trapping of the metal ions in the adsorbent pores. Interestingly, a synergistic effect of the pores and surface active sites was observed. Finally, by using alginate bio-polymer we prepared membrane films of PC-ED/1.5 which showed long-term stability, regeneration capabilities and high mass recovery.

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This work goes inside the understanding of organic pollutants adsorption mechanism over network alginate hydrogel beads based on immobilized bio-sourced PC@Fe3O4-NPs (PC@Fe3O4-NPs@Alginate) and highlights its high extent mass recovery in aqueous media. The samples were successfully synthesized, we previously developed porous carbon (PC), which, was used to elaborate PC@Fe3O4-NPs via simple in situ coprecipitation (PC@ Fe3O4-NPs), which was encapsulated by alginate-Ca2+ via the blend crosslinking method. The structural, textural, chemical and morphological proprieties of as prepared materials were studied by XRD, FTIR, Raman spectroscopy, nitrogen adsorption-desorption, XPS, SEM and TEM. The adsorption kinetic and isotherm data were well fitted to the pseudo-second-order and Langmuir models. Magnetic particles exhibited an excellent ability to adsorb methylene blue (MB) from aqueous solutions with maximum MB adsorption capacity of 180.42 mg g-1 (PC@Fe3O4 NPs powder) and 49.66 mg g-1 (beads based PC@Fe3O4-NPs@Alginate). Response surface methodology was used to optimize the removal efficiency of MB from aqueous solution and optimum parameters were determined. Magnetic beads based PC showed good magnetic propriety, long-term stability, regeneration capabilities and high extent mass recovery.

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Valorization of agri-food organic waste in order to reach zero waste using cleaner methods is still a challenge. Therefore, both anaerobic co-digestion (ACD) (biological process) and adsorption (physicochemical process) were used in combination for this objective. ACD allows the activation of biodegradable organic matter by microbial action and produces a digestate (co-product). This coproduct was used as a raw material to produce porous carbon having a high specific surface area after chemical treatment using sulfuric acid and thermal activations at temperature T = 350 °C. The resulted material was used for the preparation of core-shell particles with a core made of porous carbon and a shell consisting mainly of alginate and a calcium ion layer. The final core-shell particles were then used for dye treating wastewater and solving the solid-liquid separation problem in the adsorption process. We show here that in the ACD process, significant bio-methane potential (BMP) was produced. Furthermore, the data indicate that 153 L CH4 kg·SV-1 of BMP was produced under optimum conditions of pH = 8 and inoculum/load ratio = 1.2. The overall results concerning the methylene blue (MB) adsorption from water onto the core-shell particles show the occurrence of a maximum adsorbed amount equal to 26.178 mg g-1, and good agreement was found between the experimental adsorption data with pseudo-second-order and Langmuir theoretical models. The response surface methodology coupled with the central composite design has allowed the identification of optimal conditions for MB removal and has led to the elucidation of adsorption mechanism and the regeneration of the adsorbent without the occurrence of the solid/liquid separation problem.