Elovich Models Research Articles

Investigation of Adsorption Parameters of Saxitoxin onto Loblolly Pine-derived Biochar Synthesized at Various Pyrolysis Temperature.

This study highlights the use of loblolly pine derived biochar for the removal of harmful algal bloom toxin, Saxitoxin (STX), from water. Biochar samples were prepared at varying pyrolysis temperatures (400, 600 and 800 °C) for 60 min. As pyrolysis temperature increases, enhancement in surface porosity was observed (SBET = 7.26 ± 0.2 m2/g to 408.15 ± 6.19 m2/g) while a decline in oxygen-containing functional groups was observed (1517.80 ± 14.98 μmol/g to 823.01 ± 7.72 μmol/g). This study aimed to discover the effects of adsorption parameters such as biochar dosage amount, contact time, initial concentration and initial pH on Saxitoxin adsorption. These studies revealed impressive results with > 90 % toxin removal with dosage rate of 0.01 g/L, contact time of 30 min, and increasing percent removal with increasing initial STX concentration and initial pH in water. Maximum uptake was calculated for P400 with adsorption capacity of 314.37 μg/g. This showed that surface functionality showed higher affinity for STX uptake, which may be possible due to hydrogen bonding, electrostatic interactions, ion-exchange, and π-π interactions. Applied kinetic models indicated both physisorption and chemisorption interactions with best fit supporting the Elovich models. Complementary, adsorption isotherm analysis confirmed the multilayer adsorption behavior of the Freundlich model. Therefore, these findings support the viable use of biochar material for the remediation of STX waters.

Insights into the removal mechanism of Cr(VI) from groundwater by polypyrrole modified sludge biochar

Taking sludge biochar as the raw material and using iron and magnesium as metal sources respectively, two composite materials, polypyrrole magnesium modified biochar (PPy/MBC) and polypyrrole nano-zero-valent iron modified biochar (PPy/nZVI/BC), were prepared by in-situ oxidation polymerization of pyrrole monomers. The removal effects and mechanisms of these composite materials on hexavalent chromium (Cr(VI)) in groundwater were studied. The research results showed that the removal effect of PPy/MBC was superior to that of PPy/nZVI/BC. The highest removal rates of Cr(VI) and Cr(Total) were 170 and 120 mg·g−1 respectively. The adsorption kinetics followed the quasi-second-order kinetics and the adsorption isotherm conformed to the Langmuir adsorption isothermal model. The Elovich model indicated that the adsorption of Cr(VI) by PPy/MBC was a heterogeneous diffusion adsorption dominated by chemical adsorption. Thermodynamic analysis demonstrated that the adsorption of Cr(VI) by PPy/MBC was a spontaneous endothermic reaction. The specific surface area of the modified PPy/MBC reached 26.0824 m2·g−1, which was 7.9 times higher than that of the unmodified biochar. Positively charged nitrogen (-NH·+-), Mg2+ and Cl− in PPy/MBC removed Cr(VI) from groundwater through electrostatic interaction and ion exchange. Most anions and humic acids in groundwater had no significant effect on the removal of chromium by PPy/MBC. In general, the preparation of PPy/MBC composite material was simple, green and environmentally friendly. It had high adsorption removal efficiency and adsorption stability for Cr(VI) in groundwater, and good anti-interference against the background matrix in groundwater. Therefore, it was a promising adsorbent that could efficiently treat Cr(VI) in groundwater.

MOFs and MOF‐Based Composites for the Adsorptive Removal of Ciprofloxacin

AbstractIn spite of greater efforts to address antibiotic resistance, Ciprofloxacin (CIP) buildup in the aqueous medium continues to rise. The negative effects of CIP on the environment can be minimized through a comprehensive understanding of the technological advancements in removal techniques. The exploration of adsorbents like metal–organic frameworks (MOFs), activated carbon, porous organic polymers, etc., have found major usage in the adsorptive removal of antibiotics to tackle contamination. This study aims to compare the MOF‐based adsorbents and provide a guide to developing such materials for the successful removal of CIP. The isotherm models of the adsorbents are studied using Langmuir, Freundlich, Temkin, and Sips isotherms. Furthermore, pseudo‐second‐order, pseudo‐first order, intra‐particle diffusion, and Elovich models are used to study the kinetic models. The major mechanisms of adsorption, such as π–π interactions, H‐bonding, electrostatic interactions, hydrophobic interactions, and pore filling, are also analyzed. This study contributes to the future scope for the development of these MOFs for further exploration and applications in environmental remediation.

Selective removal and monitoring of Pb(II) ions in wastewater using fluorescence-enhanced silicon quantum dot composites

In this study, we developed a novel composite film composed of silicon quantum dot (SiQD)-nanoSiO2-polyvinyl alcohol (PVA) (referred to as SSP). This composite film exhibits dual functionality for monitoring and removing heavy metal ions from wastewater. The composition and structure of the SSP composite film were confirmed through various techniques, such as via Fourier-transform infrared spectroscopy, thermogravimetry/differential scanning calorimetry, scanning electron microscopy SEM, and X-ray photoelectron spectroscopy. The evaluation of film adsorption performance revealed that the thermodynamic behavior of the adsorption process was consistent with the theoretical predictions of the Freundlich model. However, the adsorption kinetics were more accurately described by the Elovich model. At pH 6.0, SSP achieved a maximum adsorption capacity of 263.66 mg/g at 20 °C, as determined by the Langmuir model. Additionally, the adsorption of Pb(II) ions increased the fluorescence intensity of the composite material, enabling the monitoring of Pb(II) ion concentrations in wastewater. This composite film efficiently removed Pb(II) ions with high selectivity and sustained strong adsorption performance through five cycles, emphasizing its outstanding regeneration capability. Therefore, the proposed composite material exhibits significant potential for practical applications in wastewater treatment.

Design of some ferrite-based nanoparticles for uranium removal from Sella leach liquor

ABSTRACT Uranium is a non-biodegradable, toxic and radioactive inorganic pollutant that can cause serious human health impacts. This work aims to dip magnesium and lanthanum in ferrite nanoparticles and study their ability to bind uranium ions from uranium leach liquor. MgFe2O4, LaFe2O4 and CeFe2O4 nano-adsorbents were synthesised and characterised. Comparative studies of uranium sorption on the synthesised nano-adsorbents were achieved through a series of experiments at different adsorption conditions. The results show fast uranium sorption on the nanoparticles (with a high efficiency of 86.4 to 91.6), which reflects their higher affinities towards uranium ions. There is a clear improvement in the adsorption capacities of the nanoparticles for uranium binding in adsorption systems at higher temperatures. The maximum adsorption capacity of the MgFe2O4, LaFe2O4 and CeFe2O4 nano-adsorbents was obtained at pH 5, 0.5 g/L (S/L), 400 mg/L (Ci), 333 K and 90 min. The maximum adsorption capacities of uranium on MgFe2O4, LaFe2O4 and CeFe2O4 nanoparticles are 160.4, 118.8 and 129.2 mg/g, respectively. The assessment of the kinetic, isotherm and thermodynamic models was studied to evaluate the reliability and accuracy of these models in predicting the behaviour of uranium adsorption onto the used nanoparticles under various conditions. The outcome of these models confirms the hypothesis of the Elovich, pseudo-second order, Bangham, Langmuir, Dubinin and Radushkevich models to describe the adsorption process. Additionally, it suggests that uranium removal by the nanoparticles takes place through endothermic and spontaneous physio-chemical adsorption reactions. The nanoparticles show high capacity (115.7–142.3 mg/g) and efficiency (78.1–81.7%) for the uranium ions from different uranium-containing samples. These results confirm the high affinity of the synthesised nanoparticles for uranium adsorption in different media.

Effect of different ratio KOH treatment on neem bark in the formation of activated carbon: Adsorption characteristics study

In this study, mature neem tree bark (NB) was chemically transformed into an activated carbon (NBAC) through different ratios (1:1, 1:2, 2:1, 1:3, 3:1) of KOH and NB biomass. The obtained Neem bark-activated carbons (NBAC-1, NBAC-2, NBAC-3, NBAC-4, and NBAC-5) were tested for methylene blue (MB) dye removal efficiency. The NBAC-1 was found to be highly effective against MB dye. The NBACs have a low Brunauer-Emmet-Teller (BET) surface area (10.8 m2/g) with surface functional groups dominated by -OH and -CO. It is thermally stable up to 700°C, and its surface elemental composition is mainly carbon, oxygen, and potassium. The adsorption characteristics against MB dye show that 99.15% of dye from 100 mg/L initial concentration solution was removed with 4 g/L NBAC-1 dosage in 200 min of contact time at 50°C solution temperature, and pH of 10 (pHzpc = 7.85), resulting in an adsorption capacity of 24.79 mg/g. Kinetic studies indicated that the adsorption process of MB dye utilizing NBAC-1 adhered to the linear pseudo-second-order (R2 = 0.9726) and nonlinear Elovich model (R2 = 0.9419), signifying chemisorption, alongside the nonlinear Weber-Morris model (R2 = 0.9231), highlighting the significance of mass diffusion of MB dye onto the NBAC-1 surface in multilayers. Isotherm investigations favored better conformity with the Freundlich model, exhibiting a higher R2 value of 0.999, suggesting a heterogeneous multilayer adsorption mechanism. Adsorption thermodynamics analysis inferred that the adsorption was feasible (∆G = -4.342 KJ/mol), endothermic (∆H = +50.0203 KJ/mol), and demonstrated a high affinity of NBAC-1 towards MB dye (∆S = +168.2255 J/K/mol). Recyclability of the NBAC-1 adsorbent was also conducted to check for its sustainable usage.

Determination of strobilurin fungicides residual in vegetables based on amino modified magnetic graphene oxide solid phase extraction coupled with GC–MS/MS

This research investigated the creation and utilization of an amino-functionalized magnetic graphene oxide (Fe₃O₄-NH₂@GO) nanocomposite as a selective sorbent for extracting and identifying strobilurin fungicides (SFs) from vegetable samples. The investigation utilized a method where magnetic solid phase extraction (MSPE) was integrated with Gas chromatography-triple quadrupole mass spectrometer (GC–MS/MS) for analysis. The physicochemical properties of synthesized sorbent were characterized using Scanning electron microscope (SEM) , Fourier infrared transform spectrum (FT-IR) , X Ray Diffraction (XRD), and vibrating sample magnetometry (VSM) techniques. The adsorption performance of Fe₃O₄-NH₂@GO aligned with the pseudo-second-order kinetics, Elovich, and Freundlich isothermal adsorption models, suggesting various interactions with SFs, including π-π interactions, hydrogen bonding, and electrostatic forces. The maximum adsorption capacity of two selected representative SFs (Picoxystrobin and E-metominostrobin) for the adsorbent were 55.85 mg/g and 47.35 mg/g, respectively. Additionally, the amino group exhibited notable potential for SFs adsorption. Parameters for MSPE, such as the quantity of sorbent, adsorption duration, eluent types and volumes, and sample pH, were optimized. Under optimal conditions, the developed method showed satisfactory performance within a range of 10 to 2000 µg L⁻¹ (R² ≥ 0.9969), low detection limits (0.01–0.080 µg/kg), high analyte recovery (80.5–104.3 %), and good precision (RSD ≤ 4.96 %, n = 6). This method is rapid, straightforward, environmentally friendly, demonstrates good sensitivity and providing a new perspectives on developing sorbents for SFs in complex food matrices. Also Fe₃O₄-NH₂@GO as a sorbent firstly used for extraction and enrichment of phenyl fungicides residues in food samples exhibits remarkable promise, thereby contributing to the advancement of pesticides residue determination methodologies.

Preparation and characterization of β-cyclodextrin capped magnetic nanoparticles anchored on cellulosic matrix for removal of cr(VI) from mimicked wastewater: Adsorption and kinetic studies

Hexavalent Chromium (Cr(VI)) is essential in many industrial processes. However, it finds its way into water bodies, posing health problems, including lung cancer and the inhibition of DNA and RNA in biological systems. Several chemical and traditional water purification methods have been developed in the past, but most are expensive, tedious and ineffective. This study aimed to prepare and characterize a low-cost hybrid adsorbent, β-Cyclodextrin capped magnetic nanoparticles anchored on a cellulosic matrix (CNC-Fe3O4NP-CD). The characterization techniques confirmed the integration of CNCs, Fe3O4NP and CD into the prepared CNC-Fe3O4NP-CD nanocomposite adsorbent. The adsorbent was employed in batch adsorption experiments by varying adsorption parameters, including solution pH, adsorbent dosage, initial Cr(VI) concentration, and contact time. From the findings, the nanocomposite adsorbent achieved a maximum Cr(VI) removal efficiency of 97.45%, while the pseudo-second-order kinetic model best fitted the experimental data with high linear regression coefficients (R2 > 0.98). The Elovich model indicated that the adsorption process was driven by chemisorption on heterogeneous surface sites, with initial sorption rates surpassing desorption rates. These findings established that CNC-Fe3O4NP-CD presents high efficiency for Cr(VI) removal under acidic pH, offering the potential for optimization and application in real-world wastewater treatment.

Eco-friendly property modulation of biobased gels of carboxymethyl cellulose-integrated poly(tertiary amine)s for the removal of azo-food dyes

Anionic polysaccharide-based gels enable the design of biobased materials with biochemical properties, non-toxic and natural origin. A new set of cationic gels was prepared from carboxymethylcellulose (CMC)-doped tertiary amino functional cationic monomers 2-(dimethylamino)ethyl methacrylate and N-(3-(dimethylamino)propyl) methacrylamide via the formation of semi-interpenetrated network (semi-IPN) at different polymerization temperatures, Tprep. A detailed understanding of the temperature-dependent synthesis and physicochemical response is required for the design of interpenetrating networks with CMC as an adsorbent that provides effective sources for the removal of azo-food dyes such as tartrazine and carmoisine from aqueous solutions. The variation of elasticity and swelling properties with respect to polymerization temperature was investigated. CMC-integration and polymerization temperature played a decisive role in the compressive elasticity. Incorporation of CMC into copolymer matrix led to a significant increase in elasticity of semi-IPNs, while mechanically weaker gels were obtained with increasing Tprep. Addition of CMC increased the swelling modulus of semi-IPNs formed at −18 °C by 2.6-fold. While the transparency changed depending on Tprep and microstructure, addition of CMC decreased the swelling rate of gels at all polymerization temperatures. The compressive modulus decreased with the swelling process in accordance with the Rubber elasticity theory. Semi-IPN gels showed stable swelling against pH-change in aqueous solutions and exhibited excellent pH-sensitivity significantly in low pH. A 4 to 12 fold decrease in maximum volume was observed by varying the pH between 2.1 and 9.8. The correlation between polymerization temperature and removal of azo-food dyes; tartrazine and carmoisine from contaminated wastewater with CMC-based gels was studied. Dynamic adsorption equilibrium was reached in 30 min, and tartrazine and carmoisine removal performances varied between 92.8 % and 98.4 %. respectively. The adsorption data for azo-dyes were evaluated by Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Redlich-Patterson, Sips, and Tooth isotherm models, but were best described by Langmuir and Redlich-Patterson models as they gave the highest correlation. Pseudo-first order, pseudo-second order, Elovich, Avrami kinetic and intra-particle diffusion models were investigated and dye adsorption was represented by pseudo-second-order model. After the adsorption process, semi-IPNs can easily be regenerated and effectively reused over five cycles. The study provided new insights towards the facile and sustainable synthesis of eco-friendly multifunctional CMC-based gels carrying tertiary amino groups for effective removal of azo-based food colorants.

Comprehensive study on copper adsorption using an innovative graphene carbonate sand composite adsorbent: Batch, fixed-bed columns, and CFD modeling insights

This study focused on an innovative graphene carbonate sand composite adsorbent, synthesized from carbonated porous sand and sucrose as raw materials, for the removal of copper ions via the adsorption process. The characteristics of this adsorbent are determined through comprehensive experiments and numerical simulations in batch and fixed-bed column conditions, which has not been extensively explored. Extensive experimentation demonstrated a remarkable 100 % removal efficiency under optimal conditions, which included a copper ion concentration of 3 g/L, a contact time of 10 h, and an adsorbent dosage of 35 g/L. The adsorption kinetics and isotherm results exhibited that the Elovich model (R² = 0.998) and the Langmuir model (R² = 0.996 for linear with qm=123.91 mg g-1, and R² = 0.993 for nonlinear fitting) more effectively described the adsorption of copper onto the adsorbent. In the fixed-bed column studies, among the well-known analytical models, the Log-Gompertz model showed better compatibility (R2 = 0.97∼0.99) between breakthrough curves with experimental results for various copper inlet concentrations. Also, numerical results obtained using computational fluid dynamics and mass transfer simulations with the linear driving force model were successfully validated by experimental results, particularly in the initial and transition zones of the breakthrough curve.

Construction and demolition waste as a low-cost adsorbent for water treatment: kinetics, isotherm, thermodynamics, and Fenton regeneration.

The present study proposes to investigate the feasibility of using construction and demolition waste (CDW) as an aqueous remediation agent through adsorption. The CDW, with and without chemical and thermal pre-activation, was evaluated to remove the methylene blue (MB) dye from the water solution. Variables interfering with adsorption processes, such as adsorbent dosage, solution pH, and particle size, were evaluated. The material was characterized by pHZPC, FTIR, XRD, SEM, EDS, and TG. The kinetic and equilibrium data better fitted the Elovich and Sips models, respectively. A maximum adsorption capacity of 18.62mgg-1 at 60°C was observed. Thermodynamic data indicated that adsorption occurred through a spontaneous and favorable process governed mainly by physical processes. The regeneration studies were carried out using processes based on the Fenton reaction, where the catalytic action of the iron naturally present in the CDW was evaluated. The results showed that the desorption balance was the main limiting factor for the effective regeneration of the saturated material. Adding Fe2+ to the system made this process suitable for the regeneration of the CDW and degradation of the pollutant in the aqueous phase. A regeneration efficiency of 65%, maintained practically constant during five adsorption-regeneration cycles, was observed. These results highlight the high potential of using CDWs as an adsorbent material.

Highlighting the adsorption mechanism of a fluoroquinolone antibiotic from wastewater on carbon xerogel by experiments, characterization, modelling and DFT simulation.

The application of a synthesized carbon xerogel (RFX) for the adsorptive removal from water of ciprofloxacin (CPX), a widely used fluoroquinolones-group antibiotic for humans and animals, has been reported in this work. The carbon xerogel was characterized by N2 adsorption-desorption isotherms, FTIR, Raman spectroscopy, TPD studies, elemental analysis, determination of isoelectric point (pHIEP) and scanning electron microscopy (SEM). CPX adsorption experiments were conducted in batch mode, using results obtained with F400 commercial activated carbon for comparison purposes. CPX adsorption kinetics were well-described by the pseudo-second-order model for both adsorbents and by the Elovich model in the case of F400 activated carbon. Therefore, CPX equilibrium adsorption capacity values were of 457 and 72mgg-1 for RFX xerogel and F400 activated carbon, respectively. This significant difference can be attributed to the higher specific surface area and micropores volume values of F400 carbon; in this sense, this material led to a slower CPX kinetic adsorption. Also, the Dual-site Langmuir model best-described the experimental CPX adsorption isotherms in both cases. By the adsorption studies at different solution pH, it could be concluded that several mechanisms, e.g., hydrophobic and π-π interactions, and electrostatic forces highly influenced CPX adsorption capacity. Furthermore, adsorption tests using several environmentally relevant aqueous matrices have been accomplished. In this case, a competitive effect between the natural organic matter (NOM) and the target pollutant occurred in all the tested real matrices, decreasing CPX adsorption capacity, especially remarkable for F400 activated carbon. Finally, Density Functional Theory (DFT) has been used to elucidate the interactions between CPX and adsorbents, finding a high relevance of the π-π electron donor-acceptor interactions in which CPX acts as an acceptor.

Low-valent manganese active sites: Insight into reinforced interaction with sulfonated anthraquinone dye and kinetic adsorption studies over iron-modified cryptomelane

This study presents a facial co-precipitation method to enrich low-valent manganese sites for iron-doped cryptomelane. Fourier-transform infrared spectroscopy exhibits a noticeable enhancement of both vibrations at 1041 and 1116 cm-1 ascribed to Mn3+-OH bond over as-prepared materials. X-ray diffraction, scanning electron microscopy, Raman spectroscopy, the temperature-programmed desorption of oxygen and inductively coupled plasma-mass spectrometry results all verify the increase in oxygen vacancies on iron-doped cryptomelane. The vital role of Mn3+-OH sites for adsorptive removal of acid blue 62 (AB62) was experimentally evident when adsorption capacity (Qe, mgAB62/gadsorbent) increased from 54 ± 1.3 mg/g (for non-doped cryptomelane) to 161 ± 6.7 mg/g (for Fe-0.15) at initial pH 5.7. The decrease of Qe from 313 mg/g (for initial pH 3.70) to 67 mg/g (for initial pH 9.95) over Fe-0.15 suggests protonation in acid media and deprotonation in basic media, reflecting efficient Mn3+-OH sites for reinforced interaction with sulfonate groups. The disappearance of sharp bands at 1041 and 1116 cm-1 after adsorption and the replenishment of a broad band at ∼1250 cm-1 over Fe-0.15 demonstrate the displacement of sulfonate groups by -OH species (from Mn3+-OH sites). Moreover, the deterioration of two stretching modes for O=S=O at 1187 and 1230 cm-1 after adsorption reveals the formation of a monodentate or bidentate complex. Kinetic studies confirm the compatibility of AB62 chemisorption over Fe-0.15 with the pseudo-second-order kinetic, Elovich, and Langmuir isotherm models. The current findings first support evidences for the AB62 chemisorption on iron-doped cryptomelane and a Fe-0.15-feasible adsorbent for removal of sulfonated anthraquinone dye.

Kinetic and Mechanistic Analysis of Phenol Adsorption on Activated Carbons from Kenaf

Activated carbons were prepared from kenaf (Hibiscus cannabinus L.). Carbonization was carried out at 600 °C for 2 h, and activation was performed using air at 600 °C and using CO2 at 750 °C. The activated carbons obtained were treated with HNO3 and H2SO4. The samples were characterized by their chemical and physical structure. The activated carbons obtained were mainly macroporous, and their structure underwent major changes with the activation method and acid treatment. Activated carbons were alkaline and acid-treated carbons were neutral. They were used for phenol adsorption and a kinetic and mechanistic study of adsorption was carried out. The fit to the pseudo-second order and Elovich models was predominant. The rate-limiting step of the process was determined to be diffusion within the pores, as the experimental data fit the Bangham model. DFT simulation showed that the preferred adsorption position involves π-π stacking and that oxidation enhances this interaction. Furthermore, the simulation showed that the interaction of phenol with oxygenated functional groups depends on the type of functional group.

A Sustainable Solution for the Adsorption of C.I. Direct Black 80, an Azoic Textile Dye with Plant Stems: Zygophyllum gaetulum in an Aqueous Solution.

The presence of pollutants in water sources, particularly dyes coming by way of the textile industry, represents a major challenge with far-reaching environmental consequences, including increased scarcity. This phenomenon endangers the health of living organisms and the natural system. Numerous biosorbents have been utilized for the removal of dyes from the textile industry. The aim of this study was to optimize discarded Zygophyllum gaetulum stems as constituting an untreated natural biosorbent for the efficient removal of C.I. Direct Black 80, an azo textile dye, from an aqueous solution, thus offering an ecological and low-cost alternative while recovering the waste for reuse. The biosorbent was subjected to a series of characterization analyses: scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), and infrared spectroscopy (IR) were employed to characterize the biosorbent. Additionally, the moisture and ash content of the plant stem were also examined. The absorption phenomenon was studied for several different parameters including the effect of the absorption time (0 to 360 min), the sorbent mass (3 to 40 g/L), the pH of the solution (3 to 11), the dye concentration (5 to 300 mg/L), and the pH of the zero-charge point (2-12). Thermodynamic studies and desorption studies were also carried out. The results showed that an increase in plant mass from 3 to 40 g/L resulted in a notable enhancement in dye adsorption rates, with an observed rise from 63.96% to 97.08%. The pH at the zero-charge point (pHpzc) was determined to be 7.12. The percentage of dye removal was found to be highest for pH values ≤ 7, with a subsequent decline in removal efficiency as the pH increased. Following an initial increase in the amount of adsorbed dye, equilibrium was reached within 2 h of contact. The kinetic parameters of adsorption were investigated using the pseudo-first-order, pseudo-second-order and Elovich models. The results indicated that the pseudo-first-order kinetic model was the most appropriate for the plant adsorbent. The isotherm parameters were determined using the Langmuir, Frendlich, Temkin, and Dubinin-Radushkevich models. The experimental data were more satisfactory and better fitted using the Langmuir model for the adsorption of dye on the plant. This study demonstrated that Zygophyllum gaetulum stems could be employed as an effective adsorbent for the removal of our organic dye from an aqueous solution.

Biochar-based fertilizers from co-pyrolysis of algae and hazelnut shell with triple superphosphate: Physicochemical properties and slow release performance.

Phosphorus (P) is a vital nutrient for plant growth and food production. Excessive amounts of P fertilizers to a greater extent of crop P offtake are inevitably applied due to low utilization efficiency, causing environmental pollution. This study aimed to evaluate biochar-based fertilizers (BBFs) produced by co-pyrolyzing algae (A) and hazelnut shell (H) biomasses with triple superphosphate (TSP) at a ratio of 4:1 (w/w). The potential of the slow-release performance of BBFs was studied during kinetics experiments. The co-pyrolysis of biomasses with TSP yielded BBFs with significantly different properties, including electrical conductivity, pH, elemental ratios, functional groups, specific surface area and pore size characteristics. Phosphorus release from all biochars and BBFs followed the Elovich model, except for TSP and H+TSP. Kinetic studies revealed prolonged P-release times and slower release rates for BBFs compared to conventional TSP. So that, TSP released 100% of the total P, whereas H+TSP and A+TSP biochars released only 3.14% and 5.14% of the total P, respectively, during a 240-hour experiment. The slow-release performance of BBFs suggests their potential as promising alternatives to conventional phosphate fertilizers. BBFs have the potential to enhance P utilization efficiency, increase crop yield and mitigate the environmental impact of P fertilizer runoff.

Food dye adsorption in single and ternary systems by the novel passion fruit peel biochar adsorbent

This study evaluated the passion fruit peel biochar (PFPB) as a novel adsorbent for synthetic food dyes indigotine blue (IB), tartrazine yellow (TY), and ponceau 4R (P4R) removal in single and ternary systems. A macroporous structure and a predominance of basic groups characterized PFPB. The pH study revealed better adsorption at pH 2.0. The response surface methodology optimization for adsorbent dosage and temperature predicted removal efficiencies of 100 % for IB, 79.8 % for TY, and 84.4 % for P4R. Elovich and Redlich-Peterson models better described kinetic and equilibrium, respectively, suggesting the contribution of chemical interactions. Thermodynamic data revealed endothermic, with an inordinate degree and spontaneous adsorption. In the ternary systems, antagonistic effects of interaction were noticed. The adsorption of synthetic effluents showed promising results with removal efficiencies of 99.6 % (IB), 60.2 % (TY), and 51.8 % (P4R). Therefore, we concluded that PFPB is a potential alternative low-cost synthetic food dye removal adsorbent.

Performance study of phenol sequestration from agricultural wastewater by chemical activated Montmorillonite

Agricultural by-products possess potential as cost-effective adsorbents for the remediation of phenolic contaminants in environmentally treated wastewater. This research focuses on the utilization of Algerian montmorillonite clay, specifically modified montmorillonite (Mo-5N), treated with 5N hydrochloric acid (HCl), compared to its untreated form (Mo-0N), for phenol sequestration from pesticide-laden waters. We employed various analytical techniques, such as chemical analysis, X-ray diffraction (XRD), and Fourier Transform Infrared (FTIR) spectroscopy, to characterize these adsorbents. The adsorption behavior was scrutinized under varying conditions, including pH, contact time, phenol concentration, and temperature. The maximum adsorption capacities achieved were 119.12 mg/g for Mo-5N and 100.89 mg/g for Mo-0N under optimal conditions of pH 5.72, a contact time of 120 minutes, and a temperature of 40°C. The kinetics of adsorption were best described by the pseudo-second-order and Elovich models, while the Freundlich isotherm model aptly described the equilibrium data. Thermodynamic analyses revealed that the phenol removal process using both forms of montmorillonite is spontaneous and endothermic. This study demonstrates the efficacy of Algerian montmorillonite clay in the removal of phenolic pesticides from agricultural wastewater.

Use of Chitosan-Iron Oxide Gels for the Removal of Cd2+ Ions from Aqueous Solutions.

High-quality water availability is substantial for sustaining life, so its contamination presents a serious problem that has been the focus of several studies. The presence of heavy metals, such as cadmium, is frequently studied due to the increase in the contamination levels caused by fast industrial expansion. Cadmium ions were removed from aqueous solutions at pH 7.0 by chitosan-magnetite (ChM) xerogel beads and chitosan-FeO (ChF) xerogel beads in batch systems. Kinetic studies were best modeled by the Elovich model. The adsorption isotherms obtained showed an inflection point suggesting the formation of a second layer, and the BET model adjusted to liquid-solid systems was adequate for the description of the experimental data. Maximum uptake capacities of 36.97 ± 0.77 and 28.60 ± 2.09 mg Cd/g xerogel were obtained for ChM and ChF, respectively. The studied composites are considered promising adsorbent materials for removing cadmium ions from aqueous systems.

Sensor parameters and adsorption behaviour of rhodamine-based polyacrylonitrile (PAN) nanofiber against dichloromethane vapour

This study is focused on the determination of sensor and adsorption parameters ofrhodamine-based polyacrylonitrile (PAN) nanofiber during the dichloromethane vapour exposure due to a very limited investigation of the rhodamine-based PAN nanofiber sensor. Quartz crystal microbalance (QCM) measurement system is employed to monitor the sensor response to dichloromethane vapour. This nanofiber sensor demonstrates a highly sensitive, stable, reproducible response and concentration dependence behaviour. A good stability, with an excellent recovery occurred. Sensor parameters such as the limit of detection (153 ppm), the limit of quantification (465 ppm), the sensitivity (0.0215 Hz/ppm), response (2 s) and recovery (3 s) times are determined using QCM measurement results. Pseudo first-order and Elovich adsorption models have proved that dichloromethane vapours are adsorbed bythis nanofiber sensor andthe amount of vapour adsorption rate is increased when the concentration of dichloromethane vapour increases.Owing to its achieved sensor parameters, high adsorption feature and simple fabrication process with a low cost, this proposed sensing device is expected to be a promising alternative for monitoring dichloromethane vapour sensing application at room temperature.