BET Analysis Research Articles

Methylene blue dye removal by adsorption with coconut coir and acid-treated forms: adsorption-desorption study, MPR and modeling using artificial intelligence

A batch study is conducted to remove methylene blue (MB) dye from an aqueous solution using coconut coir and its acid-treated forms. The sulfuric acid-treated coconut coir (SCC), phosphoric acid-treated coconut coir (PCC) and untreated coconut coir (UCC) were prepared. Adsorbents were characterized via BET, SEM, pHPZC, FTIR, and FT-Raman analysis. Adsorbent’s total organic carbon (TOC) and the number of oxygen-containing functional groups like carboxylic, lactonic and phenolic, total acidic, and basic groups were also estimated. FTIR and FT-Raman studies establish functional groups responsible for dye removal. The operating parameters were optimized through experiments. Dye was removed maximally at the lowest temperature, 303K. Langmuir and Temkin isotherm models use linear equations, and the Pseudo-second-order kinetic model uses a nonlinear equation, which fits well. The adsorption capacity of SCC, PCC and UCC adsorbents was 88.18 ± 0.63 mg/g, 92.68 ± 2.74 mg/g and 76.39 ± 0.36 mg/g, respectively, for 303K. Intraparticle diffusion dominated more than film diffusion. Physisorption was estimated by applying the Dubinin-Radushkevich (D-R) isotherm model. Thermodynamic study indicates a spontaneous, favorable, exothermic process. 75% glacial acetic acid and 100% methanol are the best solvents for desorbing dye-loaded adsorbents. Porous coir and non-covalent interactions like hydrogen bonding, van der Waals force and π-π interaction between dye and coir are vital in the dye removal process. The regression equation has been successfully formulated, and the application of a genetic algorithm has predicted the percentage removal of methylene blue dye.

Investigation of the efficacy of Zn/Ce-CuO nanoparticles for enhanced photocatalytic, antibacterial, and antioxidant activities.

The world is dealing with unprecedented environmental challenges, leading to a growing urgency to limit environmental damage. So, this study focuses on the synthesis of pure CuO, Zn, Ce, and Zn/Ce dual-doped CuO nanoparticles (NPs)using extract of Citrus limon leaves as reductant via simple co-precipitation method. The X-ray diffraction (XRD) characterization was employed to analyze structural characteristics of synthesized samples which confirm influence of Zn or Ce doping on crystallite size, dislocation density, and strain. The role of functional groups, changes in force constant, and bond length on addition of dopants was indicated by FTIR results. The SEM and TEM results showed variation in morphology from irregular to spherical. The zeta-potential and BET analysis confirmed surface potential as well as surface area characteristics. The change in energy gap values from 1.81 to 1.45eV of Zn/Ce-doped CuO NPscomputed from UV-vis analysis elevated its photocatalytic performance and reduced the chances of recombination of electron-hole pair due to presence of trapping levels between valence and conduction bands. The enhanced photo-degradation of Congo red (CR) and rhodamine B (RhB) with 91 and 94%, respectively, for Zn/Ce-doped CuO NPswas observed. The so-obtained samples have also exhibited good antibacterial and antioxidant activities.

Biogenically synthesized porous TiO2 nanostructures for advanced anti-bacterial, electrochemical, and photocatalytic applications

This study develops environmentally benign capping technique to synthesize nanoparticles of Curcuma longa-coated titanium dioxide (CR-TiO2) from titanium isopropoxide by utilizing the extract of Rosa rubiginosa flowers as reducing and chelating agent. The biogenically synthesized nanoparticles revealed excellent anti-bacterial, electrochemical, and photocatalytic properties due to the presence of porous TiO2 nanostructures. The sharp peaks by XRD pattern showed the crystallinity and phase purity of TiO2 nanoparticles. BET analysis proved mesoporous nature of the materials with specific surface area of 134 m2 g −1. The vibrational spectra suggest hydroxyl groups from flavonoids of Curcuma longa acting as functionalizing agent for TiO2 nanoporous structures with visible luminescence, which is proven in fluorescence spectra and is applicable for photocatalytic studies. The anti-bacterial studies showed good inference on TiO2 nanoparticles against Pseudomonas auruginosa and proved it to be an excellent antipseudomonal agent with the oxidative potential. The maximum degradation of phenol red dye in the presence of TiO2 under visible light conditions was observed. The supercapacitor fabricated using the biogenic TiO2 three-electrode system exhibited a specific capacitance of 128 Fg-1 (10 mV s−1), suggesting it as an excellent electrode material. The LSV curve at 50 mV s−1 scan rate showed that oxygen reduction potential (ORR) of CR-TiO2 electrodes was 121 mV. The present study is a new application of nanoparticles in sustainability consideration of the environment as well as a solution to the power crisis with fewer limitations. The well-distinguished antidiabetic and BSA denaturation potential suggests that these porous TiO2 nanostructures can be useful for drug delivery as glucose inhibitors and oral anti-inflammatory drugs with the restriction of adverse side effects.

Superior Electrochemical Performance and Cyclic Stability of WS2@CoMgS//AC Composite on the Nickel-Foam for Asymmetric Supercapacitor Devices

Two-dimensional (2D) sulfide-based transition metal dichalcogenides (TMDs) have shown their crucial importance in energy storage devices. In this study, the tungsten disulfide (WS2) nanosheets were combined with hydrothermally synthesized cobalt magnesium sulfide (CoMgS) nanocomposite for use as efficient electrodes in supercapattery energy storage devices. The characteristics of the WS2@CoMgS nanocomposite were better than those of the WS2 and CoMgS electrodes. XRD, SEM, and BET analyses were performed on the nanocomposite to examine its structure, morphology, and surface area in depth. In three-electrode assemblies, the composite (WS2@CoMgS) electrode showed a high specific capacity of 874.39 C g−1 or 1457.31 F g−1 at 1.5 A g−1. The supercapattery device (WS2@CoMgS//AC) electrode demonstrated a specific capacity of 325 C g−1 with an exceptional rate capability retention of 91% and columbic efficiency of 92% over 7000 cycles, according to electrochemical studies. Additionally, the high energy storage capacity of the WS2@CoMgS composite electrode was proved by structural and morphological investigations.

Appraising the structural and magnetic properties in template assisted neodymium based metal organic frameworks

This study demonstrates synthesis of two novel lanthanide-based metal-organic frameworks, namely [{NdIII(5 N3-H2isa)2(H2O)2}(H2O)2}]∞ (1) and [{NdIII(5 N3-H2isa)2(H2O)2}(H2O)(1,2-PE)}]∞ (2), synthesized via solvothermal methods using 5-azidoisophthalic acid (5 N3-H2isa) and NdCl3. Both compounds were extensively characterized using single crystal X-ray diffraction, as well as other physicochemical techniques such as IR, TGA, PXRD, and elemental analysis. Structural differences were observed in both compounds depending on the nature of the template molecule used. Compound 1 exhibits an infinite 2D architecture with lattice-occluded water molecules within the 2D layers. In contrast, compound 2, where 1-(-2-pyridyl)-2-(4-pyridyl)ethylene (1,2-PE) was used as the template, shows replacement of interstitial water molecules by the template molecule, resulting in significant changes in overall pore topology which is further corroborated by BET analysis. These structural variations were further supported by magnetic behaviour analyses, indicating an antiferromagnetic behaviour for both compounds.

Understanding the column and batch adsorption mechanism of pesticide 2,4,5-T utilizing alginate-biomass hydrogel capsule: A computational and economic investigation

Water pollution has remained a pressing concern in recent years, presenting multifaceted challenges in search of effective mitigation strategies. Our study, which targets mitigating pollution caused by 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), a significant aquatic pollutant, is innovative in its approach. We have identified adsorption as a promising, cost-effective method for its removal. Our research strategy involves dynamic adsorption utilizing a peristaltic pump and composite beads containing activated carbon and sodium alginate (CA/Alg), a novel combination that mimics industrial processes. To optimize column adsorption, we examine bead stability under varied pH conditions and optimize parameters such as concentration, adsorption time, and pH through batch adsorption experiments, employing experimental design techniques. Additionally, we optimize column adsorption factors, including bead height, circulation time, and flow rate, crucial for process efficiency, and under these optimum conditions (C2,4,5-T = 80 ppm. pH = 2, t = 27h30min, H = 30 cm and D = 0.5 mL/min) the capacity of adsorption equal to 748.25 mg/g. Characterization techniques like SEM, EDX, BET analysis, XRD, and FTIR provide insights into the morphology, composition, surface area (331 m2/g), pore volume (0.11 cm3/g), crystal structure, and functional groups of the CA-P/Alg adsorbent. Theoretical analysis elucidates the adsorption mechanism and interaction with pollutants. Economic analysis, encompassing CAPEX and OPEX estimation, evaluates the feasibility of implementing this cleanup method at an industrial scale, considering initial investment and ongoing operational costs, indicating potential savings of 64 % compared with the activated carbon normally used on the Moroccan market. This comprehensive and innovative approach addresses water pollution challenges effectively while ensuring economic viability for industry-scale implementation.

Electrochemical treatment of textile wastewater using electrodes from pyrolyzed rice husk

Rice husk char (RHC) electrodes were used for the first time in electrochemical treatment of textile wastewater. SEM analysis revealed RHC's porous structure, while TGA showed it decomposes in four stages and is stable up to 189 °C. BET analysis indicated a high surface area of 734 m2/g and a microporous structure with 11.7 Å pore diameter and 0.213 mL/g pore volume. RHC electrodes pyrolyzed at 700 °C for 2 h and placed 15 cm apart worked best in a 2 L batch reactor with methylene blue (MB) as the model pollutant and 6 g/L NaCl as the electrolyte. The process followed first-order kinetics, with fastest reaction at 100 mg/L initial MB. Reduced TOC and changed FTIR spectra confirmed MB breakdown. The batch system removed 85.8 % of dye from real textile wastewater in 150 min. In continuous flow, lower rates achieved higher efficiencies, up to 90 % at 0.45 L/h after 210 min. Although RHC electrodes had lower conductivity and strength than metal, they represent a sustainable, cost-effective alternative for electrochemical wastewater treatment.

Conversion of sugars into methyl lactate over poly (ionic liquid)s functionalized Sn/beta zeolites

Methyl lactate (MLA) is a versatile high value platform chemical prepared from biomass carbohydrates, with widely application in the pharmaceutical, food, pesticide, and cosmetics. The current study presented a one-pot catalytic conversion of sugars to MLA over poly (ionic liquid)s functionalized Sn/Beta zeolites under mild conditions. The Sn/Beta zeolites were prepared by an impregnation method, followed by modification with poly (vinyl imidazole) ([PVIM]) via an in-situ free radical polymerization method. Dosages of polymer and Sn, calcination temperature, reaction temperature, catalyst amount, substrate concentration, and reaction times were optimized. Results showed that an MLA yield of 61.4 % was obtained over 3[PVIM]-Sn/Beta with complete conversion of fructose at 140 °C for 8 h. The physicochemical properties were characterized by XRD, BET, FTIR, CO-DRIFTS, NH3-TPD and pyridine-FTIR analysis, indicating the coexistence of Lewis and Brønsted acid sites. Finally, a possible reaction mechanism was proposed that the weak Lewis acidity of imidazole rings of [PVIM] effectively regulated the local microenvironment of active sites, thus promoting the interaction of the active sites with electronegative oxygens of sugars. This study can provide as a reference for the development of solid acid catalysts for the catalytic conversion of biomass to platform chemicals.

3D simulation in a fixed bed coupled pervaporation reactor for biodiesel production

In this study, a solid acid catalyst SO42−/TiO2/ZSM-5 (STZ) was prepared. Biodiesel was synthesized from tall oil fatty acid (TOFA) by the ethanol esterification. The fixed bed and pervaporation (PV) coupling increased the esterification conversion of TOFA and ethanol by about 16 %. The spherical STZ catalyst’s appearance, composition, and catalytic activity were assessed through TGA, XRD, SEM, BET, FTIR, NH3-TPD and XPS analyses. The reaction parameters of ethanol/TOFA molar ratio (10:1–20:1), reaction temperature (75–85 ℃), catalyst dosage (6–12 g) and flow rate (0.3–0.9 mL/min) were optimized by the response surface method (RSM). Under RSM optimization, the TOFA esterification reaction achieved a conversion rate of 99.56 ± 0.23 %. After five cycles of esterification, TOFA conversion remained above 87 %. A computational fluid dynamics (CFD) model was established to predict the esterification reaction behavior in the reactor, and the TOFA conversion rate was found to be close to the experimental results through systematic simulation, by reaction kinetics equation, continuity equation, Navier-Stokes equation, and Brinkman equation. In addition, the TOFA biodiesel prepared by this study complies with EN 14214 and ASTM D6751 standards.

Improved photocatalytic degradation of malachite green, crystal violet and antibacterial activity of mesoporous Zn1-xCoxO nanoflakes

ABSTRACT The photocatalytic ability of the Zinc Oxide nanoparticles can be significantly enhanced through transition metal doping. In this work, Zn1-xCoxO nanoparticles were synthesised by a chemical coprecipitation method at room temperature. XRD studies indicated non-monotonic decrease in the Scherrer’s crystalline size from 19.79 nm for the pristine ZnO NPs to 14.81 nm for 2.5% Co2+ doped ZnO nanocrystals. The morphology of the nanoparticles was revealed by FESEM to resemble nanoflakes, and the existence of Co, Zn and O elements was verified by EDS findings. Tauc plots demonstrated a shrinkage of the optical band gap from 3.15 eV to 2.98 eV. The mesoporous nature and noteworthy increase in specific surface area (from 22.198 m2/gm to 54.159 m2/gm) were revealed by BET analysis of the N2 adsorption of the nanoflakes. Further, the degradation experiments of cationic dyes Malachite Green (MG) and Crystal Violet (CV) were carried out in the presence of synthesised catalysts under a high-pressure mercury vapour (450W-UV) lamp. Among the doped ZnO nanocatalysts, 2.5% Co2+ doped ZnO nanoflakes showed the most efficient photocatalytic degradation against MG (97.87%) and CV (93.27%) in 20 minutes. Furthermore, antibacterial activity was investigated against pathogenic bacteria Staphylococcus aureus, Bacillus subtilis and Escherichia coli which revealed improved bactericidal effects of 2.5% Co2+ doped ZnO nanoflakes. Hence, the current finding explored 2.5% Co2+ doped ZnO nanoflakes can serve as dual role efficient and potential candidate for eradication of organic as well as microbial contaminants from wastewater.

Removal of acetaminophen from wastewater using a novel bimetallic La/Th metal-organic framework: Kinetics, thermodynamics, isotherms, and optimization through Box-Behnken design

Acetaminophen (ACT), a common drug pollutant, has been effectively removed from wastewater by a novel adsorbent called La/Th-MOF. This adsorbent is made of stacked nanorods of 2-methyl imidazole with lanthanum and thorium. La/Th-MOF, which is characterized by sophisticated techniques including SEM, XRD, and BET analysis, has a mesoporous assembly with a 1.23 nm pore size and a capacious surface area of 2226.93 m2/g, which facilitates effectual adsorption. The adsorption tests, which were impacted by factors such as pH levels, ACT concentration, and contact time, fit into a pseudo-second-order chemisorption kinetic model and with the Langmuir isotherm, suggesting homogenous monolayer adsorption. The material in question demonstrated a noteworthy maximum adsorption capability of 339.75 mg/g for ACT, indicating its probable as a feasible and economical adsorbent for the mitigation of pharmaceutical contamination in wastewater. Our results designate that pH levels have an important influence on the efficacy of ACT absorption by La/Th-MOF, with an acidic pH 5 environment being most favorable for maximal adsorption at a material dosage of 0.02 g. It was discovered that the adsorption procedure was endothermic. Using pseudo-second-order kinetic models and the Langmuir isotherm, which both fit the experimental data very well, to explain the adsorption kinetics. A chemisorption mechanism was found to be predominant throughout the process, as specified by the predicted adsorption energy of 22.62 kJ/mol. In addition, optimized the influencing parameters by using the Box-Behnken design (BBD) and response surface methodology (RSM), which improved process efficiency. La/Th-MOF, has a remarkable half-life, as demonstrated by six rounds of adsorption and desorption without a discernible decline in performance. Research endeavors aimed at elucidating the interplay between La/Th-MOF and ACT hint to several plausible points of contact that could contribute to the adsorption procedure, such as hydrogen bonding, π-π interactions, pore filling or electrostatic forces. This study, which is innovative in its use, reveals the exceptional efficacy of La/Th-MOF in wastewater purification using ACT extraction. An astounding 339.75 mg/g of optimal adsorption capability was attained at an acidic pH of 5. This highlights how the La/Th-MOF can be used in practice to treat pharmaceutical pollutants found in water sources.

Elucidation of synergism in Ce-Zr/SBA-15 mesoporous catalysts and the effects on the activity in selective glycerol to lactic acid reaction

The continued conversion of glycerol to value-added chemicals is essential in ensuring the sustainable development of the biodiesel industry. Selective catalytic oxidation of glycerol to lactic acid provides an alternative approach to valorizing glycerol. A mesoporous SBA-15 supported mixed-metallic oxide catalyst is deemed essential to selectively produce lactic acid in this mixed parallel and multi-step reaction. SBA-15-supported bimetallic Ce and Zr oxides were proved to be highly efficient catalysts for the selective glycerol oxidation into lactic acid in base-free media. The synergism between Ce and Zr in the bimetallic oxide compounds could enhance the creation of oxygen vacancies in the catalyst via the reduction of Ce4+ to Ce3+. The 2:1CeZr/SBA-15 catalyst exhibited prominent catalytic activity in selectively oxidizing glycerol to lactic acid, with a glycerol conversion of 91.8% and a lactic acid yield of 35.1%. This work achieved superior catalytic performance compared to previously conducted studies, primarily due to the significantly higher initial glycerol concentration employed in this study. To ascertain the intrinsic active sites of the catalyst, the physicochemical properties of the catalyst were thoroughly examined using BET, FTIR, XRD, FESEM, TEM, CO2-TPD, O2-TPD, and H2-TPR analysis. This work concluded that the synergistic interaction of the active sites, which led to the formation of active oxygen species, facilitated primary dehydrogenation of the terminal -OH bond in glycerol. Hence, in this work, a plausible glycerol conversion mechanism over the 2:1CeZr/SBA-15 catalyst was also proposed.

Effect of annealing temperature and precipitation agent on the structure, optical and magnetic characteristics of dysprosium orthoferrite nanoparticles

Powders consisting of DyFeO3 nanoparticles were obtained by the co-precipitation method using two different precipitating agents (NaOH (SH) and (NH4)2CO3 (AC) solutions) and followed by annealing for 1 h at 850, and 950 °C. Properties of the synthesized samples were characterized by FT-IR, PXRD, BET, TEM, UV-Vis DRS, and VSM analyses. The obtained data revealed that both calcination temperature and precipitation agent had notable influence on the structural parameters and properties of the synthesized DyFeO3 nanoparticles. Increasing the calcination temperature led to the increase of structural characteristics such as average crystallite size (DScher, DW-H, DRietveld, nm), lattice cell volume (V, Å), and crystallite phase content as well as in properties such as band gap energy value (Eg, eV), coercivity (Hc, Oe), remanent magnetization (Mr, emu∙g−1), and net magnetization (Mn, emu∙g−1). Additionally, when comparing samples calcined at the same temperature, DyFeO3-AC exhibited higher structural, optical, and magnetic properties compared to DyFeO3-SH. Moreover, the DyFeO3 nanoparticles synthesized in this study exhibited lower band gap energy (1.87–1.93 eV), coercivity (0.018–0.023 Oe), and remanent magnetization (2.82∙10−6–3.87∙10−6 emu∙g−1) values, but larger net magnetization (2.43–2.62 emu∙g−1) when compared to RFeO3 perovskites synthesized by different methods (R = La, Y, Ho, Dy, Eu, Tb).

Statistical modeling and optimization of heavy metals (Pb and Cd) adsorption from aqueous solution by synthesis of Fe3O4/SiO2/PAM: isotherm, kinetics, and thermodynamic

In this study, magnetic material was synthesized using iron salts, then silicon-specific material was used to gain porosity, straight-chain polyacrylamide (PAM) was modified to give the surface functional properties, and the final product synthesized Fe3O4/SiO2/PAM nanocomposite material. Heavy metal (Pb and Cd) removal studies were carried out with the synthesized composite material, considering the central composite design and response surface methodology (CCD-RSM) optimization model. The effects of various parameters, for example, the initial concentration, pH, adsorbent dose, temperature and contact time, were investigated as a part of this study. To optimize these parameters, the CCD-RSM model was applied to design the experiments. Analysis of variance (ANOVA) was applied to evaluate statistical parameters and investigate interactions of variables. In the designed experimental set, the amount of adsorbent (30 mg), pH 7.0 value, temperature (40 °C), initial concentration of Pb (80 mg/L) and Cd (20 mg/L) and 90 min contact time were determined as the optimum conditions. The high coefficient of determination of both metals showed good agreement between experimental results and predicted values (R2 0.99; 0.95). TEM, SEM, XRD, FTIR, BET and Zeta potential analyses were performed to characterize the structure and morphology of the adsorbent. In Pb2+ and Cd2+ heavy metal removal studies, maximum adsorption capacities were determined as 66.54 and 13.22 mg/g, respectively. Additionally, adsorption isotherms, adsorption kinetics and thermodynamic modeling studies were conducted. Features such as large surface area and high adsorption capacity of the synthesized nanoparticles were observed. In this study, Fe3O4/SiO2/PAM demonstrated its potential as an effective adsorbent for the removal of heavy metal ions present in simulated wastewater samples. In particular, we can say that the material has a strong selectivity, as well as a high affinity for Pb(II) ions.

Effective adsorptive removal of Pb2+ ions from aqueous solution using functionalized agri-waste biosorbent: New green mediation via Seidlitzia rosmarinus extract

Currently, the use of natural adsorbent for the elimination of pollutants, such as heavy metals, from water has been extensively investigated. However, the low adsorption capacity of these natural adsorbents has led researchers towards the use of synthetic surfactants, which themselves can become environmental pollutants. In this research, an investigation was conducted to examine the impact of a surfactant obtained from the Seidlitzia rosmarinus plant on the adsorption properties of Pumpkin seed shell (PSS), a natural adsorbent. As a result, a modified version of PSS, known as functionalized Pumpkin seed shell (FPSS), was developed, and the effect of these two adsorbents on the elimination of Pb2+ has been investigated. FESEM, EDS, FTIR, and BET analyses were conducted to get detailed information of the adsorbent. Additionally, the effects of contact time, dosage of the adsorbent, pH of the solution, and temperature on the adsorbent were studied. The experimental data was fitted using Langmuir, Freundlich, Temkin, and Jovanovic isotherms. The PSS adsorbent was fitted best with the Langmuir isotherm, showing an adsorption capacity of 160.80 mg g−1, while the FPSS adsorbent was fitted with the Jovanovic isotherm, exhibiting an adsorption capacity of 553.57 mg g−1. Furthermore, kinetic modeling results indicated that the data for these adsorbents follow pseudo-second-order kinetic. Finally, the impact of coexisting ions and reusability was examined, with the FPSS adsorbent outperforming PSS. Therefore, the investigation of all these aspects demonstrated that the use of this natural surfactant significantly improves the performance of the adsorbent.

Boosting photocatalytic performance of cubic Co2SnO4-MnO2@g-C3N5 ternary composites: Analysis of morphology, degradation ability of tetracycline hydrochloride and fragments pathway mechanism

The increasing prevalence of tetracycline contaminants poses a profound threat to biodiversity in both aquatic and terrestrial ecosystems worldwide. To address this issue, the current study presents an innovative degradation approach using a ternary composite photocatalyst of Co2SnO4/MnO2 encapsulated with g-C3N5 synthesized via a hydrothermal method. This research describes the first report on the use of Co2SnO4/MnO2@g-C3N5 heterostructures for the photodegradation of tetracycline hydrochloride. A comprehensive characterization of the nanocomposites was performed using XRD, FTIR, SEM (including EDX and mapping), TEM, BET, XPS, and DRS-UV analyses, which confirmed their crystalline structure and revealed a morphology of Co2SnO4 nanocubes and MnO2 nanorods on the g-C3N5 layers. Photocatalytic experiments under visible light illumination showed that with an optimum catalyst loading of 40 mg/L and an initial tetracycline concentration of 5 μM, the composite achieved a degradation efficiency of 93.22 % within 75 min, following pseudo-first order kinetics. The degradation process was predominantly driven by hydroxyl radicals, as confirmed by scavenger studies. The reusability tests was confirmed the stability of the catalyst, which maintained high efficiency over four cycles. A degradation pathway was proposed based on LC-MS analysis of the reaction intermediates. This study confirms that Co2SnO4/MnO2@g-C3N5 composites (ratio 50:30:20) outperform comparative photocatalysts under similar conditions, providing a viable and environmentally benign solution for tetracycline remediation in wastewater.

Impregnation of Silica Gel with Choline Chloride-MEA as an eco-friendly adsorbent for CO2 capture

Deep eutectic solvents (DES) are a generation of ionic liquids that benefit from low cost, good stability, and environmental-friendly features. In this research, a porous silica gel was impregnated with a eutectic Choline Chloride-Monoethanolamine solvent (ChCl-MEA) to greatly improve its CO2 capture performance. In the impregnation, the weight percentages of ChCl-MEA were used in the range of 10–60 wt% at a temperature of 25 °C. The effect of ChCl-MEA loading on the structural properties of the DES-modified silica samples was studied by BET, FTIR, and TGA analyses. Investigation of the CO2 adsorption performance at different operational conditions showed that the modified silica gel with 50 wt% ChCl-MEA (Silica-CM50) presents the highest CO2 capture capacity of 89.32 mg/g. In the kinetic modeling, the fractional order model with a correlation coefficient of 0.998 resulted in the best fit with the experimental data. In addition, the isotherm data for Silica-CM50 were well-fitted with the Dual site Langmuir isotherm model with a correlation coefficient of 0.999, representing two distinct sites for the adsorption process. Moreover, the thermodynamic parameters including Enthalpy, Entropy, and Gibbs free energy at 25 °C were obtained to be − 2.770, − 0.005 and − 1.162, respectively. The results showed the exothermic, spontaneous and feasibility of the adsorption process.

Development of a γ-Al2O3-Based Heterogeneous Fenton-like Catalyst and Its Application in the Advanced Treatment of Maotai-Flavored Baijiu Wastewater

Heterogeneous Fenton technology was employed for the advanced treatment of Maotai-flavored Baijiu wastewater. Novel catalysts were prepared by loading different active ingredients (Mn, Fe, and Cu) on γ-Al2O3 using an impregnation method. The effects of active ingredient, reaction time, initial pH, H2O2 dosage, catalyst dosage, and other factors on the reaction were examined. The properties of the new catalysts were analyzed using BET analysis, XPS, and SEM. Moreover, the mechanisms of Fenton-like oxidation and its reaction kinetics were explored through experiments and analyses including GC–MS and intermediate active species scavenging by tertiary butyl alcohol (TBA) and/or para-benzoquinone. The results revealed that the most effective removal of organic matter was achieved with a Mn-Fe/Al (2:1 wt%) catalyst dosage of 30 g/100 g water, pH of 5.0, H2O2 dosage of 0.3 g/L, and reaction time of 60 min; the effluent COD value was 12 ± 1 mg/L, and the degradation rate was 65.7 ± 3%, approximately 14% higher than that of the conventional Fenton catalyst under similar conditions; moreover, the catalytic efficacy remained high after seven cycles. Kinetic analysis indicated that the heterogeneous Fenton oxidation reaction followed a third-order kinetics model, with R2 = 0.9923 and K = 0.0006 min−1.

Study on the adsorption performance of fly ash loaded on nano-FeS for chromium-containing wastewater treatment

In view of the problems caused by chromium-containing wastewater, such as environmental pollution, biological toxicity, and human health risks. Based on fly ash adsorption and nano-FeS reduction characteristics, fly ash loaded nano-FeS composite (nFeS-FA) was synthesized using mineral supported modification technology and ultrasonic precipitation method. The effect of adsorbent dosage, initial pH, contact time, and initial concentration of the solution on the adsorption of Cr(VI) and total Cr by nFeS-FA was investigated. The characteristics of Cr(VI) and total Cr adsorption by nFeS-FA were studied using adsorption isotherms, adsorption kinetics principles, as well as XRD, TEM, SEM-EDS, and BET analysis. The results demonstrated that under the conditions of nFeS-FA of 8 g/L, initial pH of 4, contact time of 150 min, and initial concentration of the solution at 100 mg/L, nFeS-FA achieved removal efficiency of 87.85 % for Cr(VI) and 71.77 % for total Cr. The adsorption of Cr(VI) and total Cr by nFeS-FA followed the Langmuir model and pseudo-second-order kinetic model, indicating monolayer adsorption with chemical adsorption as the dominant mechanism. XRD, TEM, SEM-EDS, and BET revealed that the flaky nano-FeS was uniformly distributed on the surface of fly ash, exhibiting good dispersion and thereby increasing the specific surface area. During the adsorption experiments, nFeS-FA reacted with Cr(VI), and the generated Fe3+ mainly existed as FeOOH precipitation, while S2− reacted with Cr(III) to produce Cr2S3 precipitation. Therefore, nFeS-FA exhibited excellent adsorption performance towards Cr(VI) and total Cr. It can serve as a technological reference for the remediation of heavy metal chromium pollution in the field of water treatment.

Exploring the impact of Sm3+ doping on the structural, optical, and photocatalytic properties of ZnAl2O4 spinels

The development of novel nano-photocatalysts to address the ongoing water purification and organic dye degradation issues is a major concern to the research community today. In view of it, in the present study, Sm3+-doped ZnAl2O4, (ZnAl2-2xSm2xO4; x = 0, 0.005, 0.01, 0.02 & 0.03) nano-catalysts were prepared through solution combustion method using Isoleucine as a fuel. Systematic studies were conducted to evaluate their structural, microstructural and band structure properties to ascertain the feasibility of their use as photocatalysts against acid orange 8 dye under visible light irradiation. It was observed that the substitution of Sm3+ at the Al3+ site has a greater impact on the formation of single-phase spherical nanoparticles of the sample crystallized in the cubic crystal structure. With the increase in the concentration of Sm3+, the average crystallite size was found to decrease towards the quantum limit. Additionally, BET analysis reveals an increase in specific surface area and pore size, accompanied by a reduction in pore volume with higher Sm3+ concentrations. SEM micrographs reveal that the prepared samples are highly porous in nature, supporting the XRD and BET analysis. Also, the band gap was found to increase with Sm3+ concentration. It is worth noting that ZnAl2-2xSmxO4 nanoparticles demonstrate significant photocatalytic activity against Acid Orange 8 dye under visible light, although the band gap increases with Sm3+ concentration. Notably, 3 mol% Sm3+-doped ZnAl2O4 achieves 92 % degradation efficiency of Acid Orange 8 under visible light due to its high surface area, increased active sites, and reduced photogenerated charge carrier recombination. The photocatalytic dye degradation mechanism highlights the role of dye sensitization in enabling visible light photocatalytic activity for Sm3+-doped ZnAl2O4, which primarily absorbs in the UV region. The process relies on the efficient transfer of electrons from the excited dye to the photocatalyst, followed by the formation of reactive species that drive the degradation of pollutants. The corresponding mechanism for this is proposed in detail.