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The development of a bimetallic Fenton-type catalyst with desirable activity and reusability remains a major challenge for the practical degradation of organic pollutants. Herein, we focused on modifying almond shell hydrochar with a Fe/Cu bimetal (Fe/Cu-HC) to develop a catalyst capable of activating H2O2 for degrading MO. The bimetallic Fe/Cu-HC catalyst was synthesized through hydrothermal carbonization and pyrolysis and characterized using SEM, FTIR, BET analysis, and XRD to confirm the presence and uniform dispersion of Cu and Fe co-doped species on HC. The impact of various factors, such as the solution pH (X1), organic pollutant concentration (X2) and catalyst mass (X3), on dye degradation efficiency via heterogeneous Fenton oxidation, was examined using the BBD model coupled with Surface response methodology (RSM). The Fe/Cu-HC catalyst showed superior performance in degrading MO dye compared to single-metal catalysts (Cu-HC, Fe-HC), due to the synergistic interaction between Fe and Cu species. To demonstrate the heterogeneous Fenton catalytic performance of the synthesized FeCu/HC, the results showed that 98.97 % of methyl orange was eliminated under optimal conditions: 100 mg. l-1 of methyl orange, a duration of 1 h, a catalyst mass of 1.65 g. l-1, a pH of 6, and a concentration of 4 mM H2O2. In addition, the Fe/Cu-HC catalyst showed excellent stability over multiple cycles, with minimal metal leaching. These results indicate that Fe/Cu-HC is a promising catalyst for the degradation of methyl orange and pave the way for the development of other cost-effective and efficient bimetallic catalysts for environmental remediation.

The valorization of biogenic waste by hydrothermal carbonization is widely discussed in research. However, to our knowledge, no study has combined almond shells and olive pomace to synthesize a solid carbon material. The purpose of this study is to enhance the hydrochar process from AS and OP using RSM methodology and machine learning models: ANN, SVM and XG-Boost. Subsequently, a study was carried out on the removal of organic pollutants by the synthesized material. The optimum Co-HTC operating conditions obtained at 180 C, 90 min with acid catalyst corresponding to 71.51 % and 87.13 % for mass yield and carbon retention rate respectively according to RSM-CCD. The comparison between RSM-CCD and ML in terms of prediction concludes that RSM remains more efficient in terms of planning and optimization. However, ANN is more suitable for modeling and predicting mass yields and carbon retention rates. Hydrochar’s physicochemical properties were evaluated by the use of spectroscopic methods like FTIR, SEM, XRD, and CHNO. To conclude, we studied the performance of HCop in methylene blue adsorption, varying the following parameters: pH, contact time, initial dye concentration, adsorbent dose and temperature. In addition, kinetic and isothermal models were studied to describe the dominant mechanisms in the MB adsorption process. The MB maximal adsorption using HCop obtained at pH 9, with an initial dye concentration of 100 mg. L−1, 40-min contact time, 0.1 g/L adsorbent dose, and a temperature between 25 and 30 °C. In conclusion, these results provide important information on the use of Co-HTC to convert biogenic wastes into high-performance carbon materials for the appropriate removal of organic pollutants. More studies are needed to use the material in other fields of application.

Abstract Iron-doped hydrochar can effectively remove the methyl orange dye (MO). In this study, iron-doped hydrochar (5% Fe@BC) was successfully synthesized through a two-step hydrothermal carbonization (HTC) process, using FeSO4.7H2O and sawdust. It was subsequently employed for MO removal. The characterization of the synthesized Fenton-like catalyst (5% Fe@BC) was conducted, using scanning electron microscopy, Fourier-transform infrared and X-ray diffraction techniques to confirm the presence of iron species. The effects of different operating parameters such as catalyst mass, H2O2 concentration, solution pH, organic pollutant concentration, and reaction temperature have been examined. The Box-Behnken design combined with three factors: catalyst mass X1, temperature X2, organic pollutant concentration X3. The response surface methodology coupled with Box-Behnken Design was used to optimize the key variables and response. With this approach, an exhaustive assessment of the variables influencing the optimization process was performed. A significant quadratic model was generated through analysis of variance with a P-value of 0.0001 and an R2 of 0.99. This confirms a strong relationship between the variables and the response, as well as a high level of model predictability. The optimum conditions were achieved with a catalyst mass of 0.5 g/L, a temperature of 35.5 °C, and an MO concentration of 50 mg/L. The result indicates that 93% of the discoloration efficiency was achieved within 60 min under the optimal conditions. Iron doping in the (5% Fe@BC) plays a crucial role in the degradation and removal of MO. Therefore, the 5% Fe@BC prepared from sawdust and iron salts (FeSO4·7H2O) through a two-step HTC process is an inexpensive and effective catalyst for removing organic pollutant from aqueous solutions, using heterogeneous Fenton-like process.

The textile industry’s waste often contains excessive amounts of crystal violet (CV), leading to environmental concerns. Graphene oxide has been studied as a promising adsorbent for removing crystal violet, a cationic dye, from aqueous solutions. The study involved a comprehensive analysis of various experimental parameters, including initial concentration, pH, adsorbent mass, contact time, and temperature. Graphene oxide underwent thorough analysis using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and specific surface area determination via the Brunauer–Emmett–Teller (BET) method. Energy-dispersive X-ray spectroscopy (EDS) was also employed. This study aimed to optimize the synthesis yield of graphene oxide from graphite using the Hummers method and response surface methodology (RSM), achieving a yield of 106.14% with 5 g of KMnO4 and 1 g of NaNO3 for 8 hours. The graphene oxide was analyzed via FTIR, XRD, SEM, BET, pHpzc, and EDS. Optimal conditions for maximal adsorption included 0.016 g of graphene oxide, 18 minutes of contact time, pH 10, and a temperature of 25°C, resulting in a 97.38% reduction in crystal violet with a monolayer adsorption capacity of 470.78 mg/g. Kinetic data were best fitted by the pseudosecond-order model, and the Langmuir isotherm accurately depicted adsorption. Thermodynamic analysis indicated spontaneous (ΔG°

Solid waste (SW) generated from extracting of essential oils from medicinal and aromatic plants (MAPs) is an abundant and renewable resource, but proper recycling is necessary to prevent negative environmental impacts from improper disposal. This study focused on converting SW from essential oil (EO) extraction industry by citric acid-catalyzed hydrothermal carbonization (c-HTC) coupled with chemical activation into a carbonaceous material to remove organic pollutants. For this purpose, an I-optimal design coupled with response surface methodology (RSM) was developed to investigate the relationship between the severity factor (SF) of the c-HTC process and citric acid dose (HTCcat) on carbon retention rate (CRR) and hydrochar mass yield (MY). Under optimal conditions (5.32 and 2 g for SF and HTCcat, respectively), an optimized hydrochar (HCop) was characterized by a CRR and MY of 71.02% and 56.14%, respectively. HCop was chemically activated by KOH solution (AHCop) and characterized by a specific surface area of 989.81 m2.g−1, a pore volume of 0.583 cm3.g−1, a higher heating value (HHV) of 37.3 MJ/Kg, oxygenated surface functions such as –OH, –COOH, C-O and a methylene blue (MB) removal rate of 90.71%. In addition, modelling of the adsorption isotherms found that the Freundlich isotherm better describes the experimental data, and the second-order model regulates the adsorption kinetics well. Furthermore, The maximum adsorption capacity of AHCop was 588.24 mg.g−1, with a separation factor of 0.625 under the operating conditions (t = 6 h, T = 25 °C, m(AHCop) = 0.2 g, [MB]0 = 300 mg.L-1, and pH = 7), indicating its potential for effectively removing organic pollutants. Together, these results provide crucial information on using c-HTC to convert waste biomass into functional carbon materials to remove organic pollutants efficiently. Therefore, several studies must be conducted out to discover other application fields of this material.

Carbocatalysts doped with heteroatoms such as nitrogen or sulphur have been reported to be useful in persulfate-based advanced oxidation processes for organic pollutant removal. However, there is limited research on the effect of doping with phosphorus atoms on degradation performance. In this work, a new nitrogen and phosphorus-doped carbocatalyst (N, P-HC) was designed using hydrothermal carbonization followed by pyrolysis at 700 °C, with olive pomace as a carbon source, to degrade organic pollutants in the presence of peroxydisulfate (PDS). Experimental results showed that N, P-HC, with its large specific surface area (871.73 m2.g−1), high content of N-pyridinic and N-pyrrolic groups, and the presence of P-O-C and O-P-C bonds, exhibited high degradation performance (98% degradation of Rhodamine B (RhB) in 40 min, with an apparent rate constant (kapp) of 0.055 min−1 and an excellent turnover frequency (TOF) of 0.275 min−1). Quenching study and EPR analysis revealed that singlet oxygen generation (1O2) and direct electron transfer were the main reaction pathways for the non-radical pathway in the degradation of RhB. The improved catalytic efficiency in the N, P-HC/PDS/RhB system can be attributed to the synergistic effect between N and P atoms in the graphitic structure of the carbocatalyst, its high surface area, and the presence of oxygenated functional groups on the surface of the N, P-HC. The used N, P-HC carbocatalyst can also be efficiently recovered by heat treatment at 500 °C. Overall, this study presents a simple and environmentally friendly method for synthesizing a high-performance N, P co-doped olive pomace-based carbocatalyst for water decontamination through PS-AOPs processes.

A statistical Simplex Lattice Mixture design was applied to develop a new formulation based on a combination of three plants grown in northern Morocco: Apium graveolens L., Coriandrum sativum L., and Petroselinum crispum M. We examined the extraction yield, total polyphenol content (TPC), 2′2-diphenyl-l-picrylhydrazyl (DPPH) radical scavenging activity, and total antioxidant capacity (TAC). The results of this screening study showed that C. sativum L. had the highest content of DPPH (53.22%) and TAC (37.46 ± 0.29 mg Eq AA/g DW) compared to the other two plants, while P. crispum M. showed the highest TPC (18.52 ± 0.32 mg Eq GA/g DW). Furthermore, the ANOVA analysis of the mixture design showed that all three responses (DPPH, TAC, and TPC) were statistically significant, with determination coefficients of 97%, 93%, and 91%, respectively, and fit the cubic model. Moreover, the diagnostic plots showed good correlation between the experimental and predicted values. Therefore, the best combination obtained under optimal conditions (P1 = 0.611, P2 = 0.289, P3 = 0.100) was characterized by DPPH, TAC, and TPC of 56.21%, 72.74 mg Eq AA/g DW, and 21.98 mg Eq GA/g DW, respectively. The results of this study reinforce the view of stimulating the effect of plant combinations to achieve better antioxidant activities, thus providing a better formulation using designs of mixtures for the food industry and in cosmetic and pharmaceutical applications. Moreover, our findings support the traditional use of the Apiaceae plant species in managing many disorders cited in the Moroccan pharmacopeia.

In this research, a comparative analysis was carried out to characterize the content of phenolics and biological activities of the whole plant of Papaver rhoeas L. (P. rhoeas) from different geographical regions of Morocco, as well as to determine the synergistic antimicrobial and antioxidant effects of all parts of P. rhoeas. The determination of total polyphenol content (TPC), total flavonoid content (TFC), and total anthocyanin content (TA) in extracts of whole plants of P. rhoeas from three different geographical regions: Taounate (P1E), Fez (P2E), and Sefrou (P3E) were estimated by the Folin–Ciocalteu reaction, the aluminum trichloride method and the differential pH absorption technique, respectively. Two tests were used to evaluate the antioxidant power of our samples: the DPPH test and the TAC test. Using two methods, disk diffusion and microdilution, antimicrobial activity was studied against four pathogenic bacteria and one yeast. The results of TPC, TFC, and TA show that the P3E sample is the richest in polyphenols, flavonoids, and anthocyanins, with values 37.33 ± 1.307 mg GAE/g, 4.72 ± 0.346 QE/g, and 1.77 ± 0.026 CGE/g, respectively. In addition, P3E showed the best antioxidant activity with an IC50 = 0.27 ± 0.001 mg/mL and TAC = 9.99 ± 0.768 mg AAE/g, respectively. The results of antimicrobial activity showed significant activity on almost all the tested strains. The lowest MIC was recorded for P3E against E. coli ATCC 25922 and E. coli CIP 53126 strains at 0.78 and 0.78 mg/mL, respectively. These results show that the geographical region can influence the plant’s phytochemistry and then these biological activities.

Providing efficient and environmental friendly ways to recover lignocellulosic waste remains a challenge around the world. In this study, citric acid-catalyzed hydrothermal carbonization (CHTC) was coupled with pyrolysis to convert date seed (Ds) into adsorbent material. In this regard, a central composite design (CCD) using response surface methodology (RSM) was developed to examine the influence of temperature, reaction time, and catalyst dose on the mass yield (Ym(%)) and carbon retention rate (CRR(%)) in the produced hydrochars. The optimized hydrochar (OHC-Ds) was obtained under optimal conditions (200°C, 120 min, 20 mg) and characterized by a Ym(%) and CRR(%) of 59.71% and 75.84%, respectively. Chemical activation by KOH of OHC-Ds followed by pyrolysis at 600°C resulted in an active material (AOHC-Ds) rich in carbon and characterized by a high specific surface area of 1251.5 m2/g, with the dominance of mesopores, as well as an amorphous structure comparable to graphite shown by X-ray diffraction (XRD) analysis. Adsorption experiments of two dyes on AOHC-Ds showed a high maximum adsorption capacity (Qm) of 657.89 mg g−1 for methylene blue (MB) and 384.61 mg g−1 for methyl orange (MO) compared to other conventional adsorbents. This result is due to the low acidity (pHpzc) of the surface of AOHC-Ds, which equals 6.75, and its surface, which is also rich in oxygenated functional groups such as (-OH), (C=O), and (C-O) shown by FTIR analysis. These results suggest that the coupling of CHTC and KOH activation followed by pyrolysis is an encouraging way to prepare an efficient and inexpensive adsorbent to remove dyes in wastewater.

Purpose: This work was aimed to exploit the technique of design of experiments to evaluate the olive mill waste cake residue obtained after oil extraction while searching for an adequate composition of the initial substrate mixtures (RPM, DMOV, FV and EB for humidification), in addition to validate it experimentally. Method: To this end, a mixture design using an efficient experiment methodology was constructed, with the aim of optimizing three responses of interest: pH, humidity, and organic matter of the 25 formulations. Results: The optimal composition was comprised of organic and green household waste (56.7%), olive mill waste cake residues (21.7%) and poultry droppings (21.7%). These analyses were followed by the evolution of some physio-chemical parameters such as pH, temperature, organic matter, C/N ratio and polyphenols until they are stabilized. In addition, using spectroscopic analysis, maturation and phytotoxicity tests were carried out on the germinating cress. Conclusion: The results of this research indicated the achievement of an ideal composition of an adequate mixture that had the characteristics of an organic amendment, non-phytotoxic and in conformity with the NFU-44-051 that led to mature compost. Article Highlights Valorization of olive mill waste cake residue was achieved after oil extraction by co-composting. The experimental design method was used to optimize the composition of compost. The elaborated compost was considered as non-phytotoxic organic amendment.