Freundlich Constants Research Articles

RESEARCH OF PROCESSES OF SORPTION OF COPPER IONS BETWEEN NATURAL CLAY MATERIALS FOR PROTECTION AGAINST POLLUTION OF UNDERGROUND AQUIFER HORIZONS

Experimental experiments with white clay from three deposits of Mykolaiv and red clay from Cherkasy region regarding sorption properties in relation to Cu2+ ions confirmed the ability to use local natural materials in the processes of cleaning from pollution in the water environment. A comparative analysis of red and white clay samples showed that red clay has a greater sorption capacity. The experiment was performed for two stages of filtration - drip and suspended, which take place during the operation of reclamation facilities and treatment facilities. For the stage of supported filtration, the experiments conducted by the authors showed a decrease in the sorption capacity of all samples, which was also confirmed by the calculations of Freundlich adsorption constants, which quantitatively characterized the adsorption process for each sample, as well as an increase in the averaged filtration coefficients at the stage of supported filtration.Experimental studies on the extraction of heavy metal ions using Cu2+ as an example were carried out according to the standard method using the colometric method with the diethyldithiocarbamate reagent under the condition of an initial concentration of Cu2+ in the solution of 5.8 mg/dm3.Результати проведеного експерименту свідчать, що при облаштуванні екранованих спо-руд глинистим екраном, крім протифільтраційних властивостей облицювання, що залежать від його товщини, отриманої щільності та інших параметрів після укладки, слід враховувати сорбційні властивості такого облицювання, режиму роботи споруди і, відповідно, величину гідравлічного на-пору.The results obtained during this experiment can also be used in the installation of anti-filtration screens of settling tanks and tailings of various kinds, as well as in the sanitation of water bodies in order to prevent pollution of the underground aquifer.

Sorption Properties of Bentonite-Based Organoclays with Amphoteric and Nonionic Surfactants in Relation to Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are a major scientific challenge due to their profound impact on public and environmental health. Therefore, studying ways to detoxify PAHs is important. In this research, the adsorption ability of bentonite modified with five surfactants, including amphoteric (cocoamphodiacetate disodium and sodium cocoiminodipropionate) and nonionic (lauramine oxide, cocamide diethanolamine, and alkylpolyglucoside) substances for the adsorption of high-molecular benzo(a)pyrene and low-molecular naphthalene from the PAH group was studied. The bentonite and bentonite-based organoclays were characterized using X-ray diffraction and Fourier transform infrared spectroscopy. The results showed that the maximum adsorption of benzo(a)pyrene by organoclays increased compared with the initial mineral. The adsorption of benzo(a)pyrene is higher than that of naphthalene. The adsorption process of benzo(a)pyrene by bentonite and organoclays is predominantly monolayer, as it is better described by the Langmuir model (R2 0.77–0.98), while naphthalene is predominantly multilayer, described by the Freundlich model (R2 0.86–0.96). According to the effectiveness of sorption capacities of organoclays—including the degree of sorption, Langmuir and Freundlich constants, the value of maximum adsorption, Gibbs free energy, and the index of favorability of the adsorption process—the most effective modification was found. For the adsorption of benzo(a)pyrene the best was cocoamphodiacetate disodium, and for naphthalene it was sodium cocoiminodipropionate.

Unraveling latent affinity of strategically designed histidine-rich biosurfactant via tannery waste bio-upcycling in environmentally-relevant lignin removal from pulp and paper industry effluent

Bioremediation of pulp and paper industry (PPI) effluent is hindered due to biorefractory lignin. Herein, we demonstrate a lignin-specific designer biosurfactant with synergistic binding sites for enhanced lignin removal from PPI effluent. The histidine rich-cationic lipoprotein biosurfactant (HR-CLB) was synthesized by Bacillus tropicus using tanning industry solid waste, animal fleshing by de novo substrate-dependent synthesis pathway. Interestingly, the HR-CLB anchored functionalized carbon (HR-CLBAFC) demonstrated a high lignin sequestration capacity of 93.2 mg/g HR-CLBAFC at optimized time, 60 min; pH, 5; temperature, 45 °C; and mass of HR-CLBAFC, 1.0 g. The sequestration was confirmed by HR-SEM, UV–Vis., FT-IR, and WCA analyses. The isotherm studies revealed the involvement of Freundlich isotherm (regression coefficient, R2: 0.988) in regulating lignin sequestration onto HR-CLBAFC with a Freundlich constant (Kf) of 16.46 ((mg/g)(L/mg)1/n). Moreover, the kinetics studies divulged the contribution of the pseudo-second-order kinetic model (R2: 0.992) in regulating the dynamic mechanism of lignin sequestration onto HR-CLBAFC with a rate constant (k2) of 0.00022 g/mg min. Additionally, the thermodynamics studies discovered a positive Gibbs free energy (ΔG: +170 kJ/mol) and entropy (ΔS°: +130 kJ/mol), indicating the involvement of chemical interaction during the sequestration. Furthermore, the mechanistic study confirmed the role of an incomplete valence shell of nitrogen in histidine centers of HR-CLB in regulating electrostatic interaction with lignin molecules during the sequestration process. Subsequently, the HR-CLBAFC applied for lignin sequestration from the real-time PPI effluent demonstrated an outstanding sequestration efficiency (>99.4%), confirming the unequivocal potential of the HR-CLBAFC matrix in lignin sequestration from real-time PPI effluent.

Estimated of Pomegranate Peel Waste for Biosorption of Cu (II) & Pb(II) Ions From Aqueous Solutions

This study intends to explore the waste natural materials’ adsorption capability. The use of pomegranate peels was investigated to see the chances of eradicating Pb(II) and Cu(II) ions from the aqueous solutions. Adsorption capability was evaluated using batch adsorption experiments, which also evaluated the impact of solution pH and initial metal concentration. The ideal biosorption conditions included a pH of 6.0, a dose of 0.1 g of biomass, and an equilibrium duration of 90 minutes. The adsorption data fit in a way that was comparable to the isotherm models by Freundlich and Langmuir. Pomegranate peel (PGP) was tested for its affinity and adsorption capability. Based on the values of the separation factor (RL) and Freundlich constant (n), it seems that the metal ions were taken up onto biosorbents in a preferred manner. According to this study's conclusions, the equilibrium data suit the Freundlich and Langmuir isotherms rather nicely. According to correlation coefficient data, the maximal sorption capacity of the produced pomegranate peel is 5000 mg/g. The Fourier Transform Infrared Spectrometer (FTIR), Energy Dispersive X-ray Spectrometer (EDX), and Scanning Electron Microscope (SEM) were utilised in the characterisation examinations. As a result, distinct aggregates formed on the surface of the biosorbent. In the characterisation experiments, an energy-dispersive X-ray spectrometer (EDX) and a scanning electron microscope (SEM) were employed. Different aggregates developed on the biosorbent surface as a result of contact with metal ions. On the surface of the biosorbent, distinct aggregates formed as a result of interaction with metal ions. Either via complexation or electrostatic attraction, the metal ions attached themselves to the biosorbents' active sites.

Date kernel biochar: A green approach to methylene blue removal from polluted water in Iraq

ABSTRACT This study investigated the potential use of biochar produced from Iraqi date kernels (Khestawi) as an adsorbent for methylene blue (MB) removal from polluted water. A full factorial design methodology was employed to examine the effects of heating rate, pyrolysis temperature and holding time on the performance of the produced biochar. The results showed that pyrolysis temperature and time had a strong effect on the biochar performance, while the heating rate had a weaker effect. The biochar produced at pyrolysis temperatures of 350°C and 550°C exhibited MB removal percentages (% R) of 48.9% and 30.9%, respectively. Similarly, biochar production through pyrolysis durations of 30 and 90 minutes resulted in MB removal rates of 47.5% and 30.3%, respectively. The adsorption experimental data was well-fitted by the Freundlich isotherm model, with a high value of the Freundlich constant (KF = 1.64), indicating a high adsorption capacity of the biochar. The activation of biochar using bio-oil (organic-1) led to a substantial enhancement in the adsorption capacity, with the activated biochar (ABC-1) exhibiting a higher adsorption capability and a higher value of the Freundlich constant (KF = 7.12). Overall, the results suggest that biochar produced from date kernels has the potential as an effective and sustainable adsorbent for MB removal from polluted water, with the potential for further enhancement through biochar activation.

Sorption and mobility assessment of tembotrione in soils of upper, trans and middle Gangetic plain zones of India.

The presence of undesired agrochemicals residues in soil and water poses risks to both human health and the environment. The behavior of pesticides in soil depends both on the physico-chemical properties of pesticides and soil type. This study examined the adsorption-desorption and leaching behavior of the maize herbicide tembotrione in soils of the upper (UGPZ), trans (TGPZ) and middle Gangetic plain zones of India. Soil samples were extracted using acetone followed by partitioning with dichloromethane, whereas liquid-liquid extraction using dichloromethane was used for aqueous samples. Residues of tembotrione and its metabolite TCMBA, {2-chloro-4-(methylsulfonyl)-3-[(2,2,2-trifluoroethoxy) methyl] benzoic acid}, were quantified using liquid chromatography-tandem mass spectrometry. The data revealed that tembotrione adsorption decreased with increasing pH and dissolved organic matter but increased with salinity. The maximum adsorption occurred at pH4, 0.01m sodium citrate and 4g/L NaCl, with corresponding Freundlich constants of 1.83, 2.28 and 3.32, respectively. The hysteresis index <1 indicated faster adsorption than desorption. Leaching studies under different flow conditions revealed least mobility in UGPZ soil and high mobility in TGPZ soil, consistent with groundwater ubiquity scores of 4.27 and 4.81, respectively. Soil amendments decreased tembotrione mobility in the order: unamended > wheat straw ash > wheat straw > farm yard manure > compost. The transformation of tembotrione to TCMBA and its mobility in soil columns were also assessed.

Melamine-Maleic Acid Polyamide Adduct / Polyacrylonitrile Nanofibers as a Novel Adsorbent for Removal of Methyelene Blue Dye from Aqueous Solutions

Efficient removal of methylene blue (MB) dye from aqueous solutions is crucial for addressing environmental pollution. This study investigates the potential of Melamine-maleic acid polyamide adduct/polyacrylonitrile (ME-MA amide polymer/PAN) nanofibers as a novel adsorbent for MB dye removal. Characterization via scanning electron microscopy (SEM) revealed surface morphology changes, with fiber diameters ranging from 1 to 3 μm. Thermal stability analysis demonstrated enhanced stability for ME-MA/PAN compared to pure PAN fibers. Fourier transform infrared (FT-IR) analysis confirmed the presence of hydroxyl, amide, and thiol groups on the nanoparticle surface, covalently attached to the nanofiber surface. Through electrospinning, ME-MA/PAN composites were synthesized, showing promising capabilities for dye removal. Optimal conditions were observed at pH 12 and a ME-MA PAN dose of 0.02 g. MB removal efficiency increased with higher initial dye concentrations, peaking at 30 mg/L, and higher temperatures up to 40°C. Adsorption isotherm models indicated Langmuir adsorption capacity (Qm) of 111.10 mg g−1 and a separation factor (RL) of 0.297, with Freundlich constants (1/n) and KF values of 0.418 and 22.9, respectively. Kinetic and thermodynamic studies revealed favorable conditions for MB dye removal, validating ME-MA amide polymer/PAN nanofiber composites as environmentally friendly and effective materials for eliminating toxic MB dye from aqueous solutions. This research highlights the potential of ME-MA/PAN nanofibers in addressing dye pollution, suggesting their application in wastewater treatment for sustainable environmental management. Further investigation into regeneration methods and scalability is recommended for practical implementation in real-world scenarios.

Ruthenium sorption onto Fe3O4@MnO2: equilibrium, kinetic and thermodynamic study

Core–shell magnetic adsorbent Fe3O4@MnO2 was prepared and successfully used to ruthenium adsorption from aqueous solutions with 98% efficiency. The adsorption isotherms, kinetic and thermodynamic parameters for Ru(III) sorption onto Fe3O4@MnO2 were studied via a batch adsorption system. Adsorption isotherm models such as: Langmuir, Freundlich and Temkin were tested while the kinetic adsorption data were analyzed by pseudo-first order, pseudo-second order, and Weber-Morris models. It has been found that the adsorption process of Ru(III) onto Fe3O4@MnO2 can be describe by a Freundlich model whereas mechanism of sorption is presented better by kinetic Weber–Morris model. Freundlich adsorption isotherm constant is equal Kf = 30.62 mg/g and heterogenity factor n = 3.58. Sorption rate constant is k3 = 0.288 mg/(g·min1/2) and intraparticle diffusion rate constant C = 0.174 mg/g. Thermodynamic parameters such as free Gibb’s energy change (ΔG°), enthalpy change (ΔH°), entropy change (ΔS°) and energy activation Ea were determined. Calculated value of activation energy is equal 25.75 kJ/mol. The adsorption process of Ru(III) was found to be both spontaneous and thermodynamically preferable.

Efficient Rhodamine B dye uptake onto MgZrO3@g-C3N4 nanostructures: Fabrication and adsorption mechanism

Pristine graphitic carbon nitride (g-C3N4) was synthesized by calcination of urea under elevated temperature. A blend of g-C3N4 nanosheets and nanosized ZrO2 and MgO precursors were used to prepare MgZrO3@g-C3N4 hybrid nanocomposite (MZCN) then it was assessed for the adsorption of Rhodamine B (RhB) dye from aqueous solution. The X-ray diffraction analysis revealed the development of the monoclinic ZrO2, cubic MgO, and hexagonal graphitic carbon nitride phases. The energy diffraction X-rays (EDX), photoelectron electron, and Fourier transformed infrared (FT-IR) spectroscopy analyses collectively validated the formation of the presumed composite. An improved porosity with a surface area 35.86 m2.g−1 and pore volume 0.087 cm3.g−1 were determined by N2 adsorption setup. The adsorption kinetics fitted well with the pseudo-first-order model (R2 > 0.99), which designated an adsorption process influenced by physisorption. The kinetics models investigations revealed a film diffusion control of the adsorption process. The adsorption equilibrium matched perfectly with the Langmuir isotherm model (R2 > 0.99) marking a maximum adsorption capacity of 370.8 mg g−1, demonstrating outstanding monolayer adsorption process. In addition, the Freundlich constant (n = 1.76) value is falling in the range 1–10 suggested a favorable adsorption of RhB onto the composite surface. The mechanistic enquiry suggested van der Waal, hydrogen bonds and π–π electron–donor interactions between the electron-rich RhB and the functional groups in the adsorbent’s molecule. This work stipulates that MgZrO3@g-C3N4 holds promise as efficient adsorbent for organic dyes from contaminated wastewater.

Nitrogen Removal from Landfill Leachate Using Biochar Derived from Wheat Straw.

Landfill leachate (LLCH) disposal poses challenges due to high pollutant concentrations. This study investigates the use of biochar (BC) derived from wheat straw for nitrogen content reduction. Laboratory experiments evaluated BC's adsorption capacity (qm) for nitrogen removal from ammonium chloride solution (NH4Cl) and LLCH, along with testing isotherm models. The results demonstrated that BC was more efficient (95.08%) than commercial activated carbon AC (93.11%), the blank, in adsorbing nitrogen from NH4Cl. This superior performance of BC may be attributed to its higher carbon content (57.74%) observed through elemental analysis. Lower results for BC/LLCH may be due to LLCH's complex chemical matrix. The Langmuir isotherm model best described BC/NH4Cl adsorption (qm = 0.5738 mg/g). The AC/NH4Cl data also fitted into the Langmuir (R2 ˃ 0.9) with a qm of 0.9469 mg/g, and 26.667 mg/g (R2 ˂ 0.9) was obtained for BC/LLCH; the BC/LLCH also gave higher qm (R2 ˃ 0.9) using the Jovanovich model (which also follows Langmuir's assumptions). The mean energy of the adsorption values estimated for the AC/NH4Cl, BC/NH4Cl, and BC/LLCH processes were 353.55, 353.55, and 223.61 kJ/mol, respectively, suggesting that they are all chemisorption processes and ion exchange influenced their adsorption processes. The Freundlich constant (1/n) value suggests average adsorption for BC/LLCH. The BC/LLCH data followed the Harkins-Jura model (R2: 0.9992), suggesting multilayered adsorption (or mesopore filling). In conclusion, biochar derived from wheat straw shows promising potential for landfill leachate remediation, offering efficient nitrogen removal capabilities and demonstrating compatibility with various adsorption models. This research also lays the groundwork for further exploration of other biochar-based materials in addressing environmental challenges associated with landfill leachate contamination.

Adsorptive Removal of Selected Toxic Metals from Pharmaceutical Wastewater using Fe&lt;sup&gt;3&lt;/sup&gt;O&lt;sup&gt;4&lt;/sup&gt;/ZnO Nanocomposite

Pharmaceutical wastewater is a major source of environmental contamination, often containing toxic metals that pose significant threats to ecosystems and public health. This study explores the potential of magnetite/zinc oxide (Fe3O4/ZnO) nanocomposites prepared using a sol-gel method for the removal of lead, cadmium, and copper ions from pharmaceutical wastewater. The nanocomposite was characterized using X-ray diffraction (XRD), High-resolution scanning electron microscopy (HRSEM)/energy dispersive spectroscopy (EDS) and Fourier transmission infrared spectroscopy (FTIR). The XRD analysis of the nanocomposite identified 2θ (theta), of 31.7º, 34.4º, 36.2º, 47.5º, 56.6º, 62.8º, 66.3º, and 67.9º which correspond to the crystal planes of (100), (002), (101), (102), (110), (103), (200), and (112), respectively. The diffraction peaks associated with Fe3O4 at 2θ of 18.02º, 29.4º, and 43.3º, related to the crystal planes of (111), (220), and (400), respectively of the Fe3O4 phase. The HRSEM image of the nanocomposite exhibited spherical-shaped structures of Fe3O4/ZnO, and some irregular shapes. The effects of the contact time, dosage and temperature on the removal percentage of toxic metal ions were studied. Freundlich and Langmuir isotherm constants and correlation coefficients were determined and the equilibrium process was better described by the Langmuir isotherm. The adsorption process followed a second order kinetics and the thermodynamic parameters showed that the involved process was spontaneous. These findings contribute to the advancement of environmentally friendly technologies for the pharmaceutical industry and the broader field of wastewater remediation.

Crafting an innovative bimetallic MOF-on-MOF/TiO2 composite for effective removal of Imatinib anticancer agent through adsorption and photodegradation

Imatinib (IMB), a widely employed anticancer agent, poses significant environmental concerns due to its release into aquatic ecosystems via pharmaceutical industries and hospital effluents, contributing to water source contamination and consequential impacts on both human and animal health. In light of this, a novel bimetallic MIL-53(Co-Fe)@MIL-53(Ni)/TiO2 composite material has been synthesized utilizing hydrothermal approaches for the efficient adsorption and photodegradation of IMB. Comparative assessments were conducted between this composite and MIL-53(Ni), bimetallic MIL-53(Co-Fe)@MIL-53(Ni), bare TiO2 for their respective capacities in IMB removal through adsorption and photodegradation. Remarkably enhanced efficacy was observed in the synthetic composite's performance for both adsorption and photodegradation, surpassing that of other compounds. Through systematic exploration, critical parameters influencing the adsorption and photodegradation processes were meticulously examined and subsequently optimized utilizing experimental design strategies. Optimal conditions led to the identification of a pseudo-second-order kinetic model for IMB adsorption with a notable rate constant of 8.39 and an equilibrium time of 75 min. The adsorption process conformed favorably to the Freundlich isotherm, as evidenced by the Freundlich constant of 25.498 mg g−1 and adsorption intensity of 2.09. These values underscored the heightened affinity of the synthetic composite relative to IMB, ascribed to the favorable absorption. A complementary investigation into the kinetics of IMB photodegradation unveiled a substantially elevated rate constant of 0.0407 min−1, coupled with a proper half-life of 17.03 min. These collective findings validate the exceptional capacity of the synthesized composite for dual-mode IMB elimination, encompassing both adsorption and photodegradation pathways. This advancement holds significant promise for addressing the environmental repercussions of IMB contamination and points to the potential for broader applications in wastewater treatment and ecological restoration endeavors.

Effect of Mixed Manure and Inorganic Fertilizer on Phosphorus Adsorption and Desorption Characteristics of Vertisols in Haramaya District, Eastern Ethiopia.

Applying inorganic phosphorus fertilizer is less effective in increasing crop yields in tropical soils due to precipitation and adsorption reactions. However, research suggests that partial substitution of organic and inorganic fertilizers has shown to improve the efficiency of applied phosphorus fertilizer by reducing its adsorption and enhancing desorption due to their synergistic effects. This study aimed to investigate the impact of treating the soil with mixed manure (MM) rates and blended nitrogen, phosphorus, sulfur, and boron (NPSB) fertilizer on the soil's phosphorus adsorption and desorption characteristics. Results showed increased adsorbed phosphorus in all treatments, with increased added phosphorus (P) concentration from 100 to 500 mg kg-1. However, the efficiency of adsorbed P decreased significantly as added P concentration rates increased from 100 to 400 mg·kg-1 in all treatments and then decreased as the added P concentration advanced to 500 mg·kg-1. Moreover, in all treatments that received combined applications of MM and blended NPSB, both quantity and percentage of desorbed P showed a significant increase. The Freundlich adsorption coefficient and constant were also significantly reduced because of the combined application of MM and blended NPSB, compared to the control and their sole applications. Overall, the soil treated with a combined application of 15 t·ha-1 of MM with 100 kg·ha-1 of blended NPSB showed the highest reduction in the efficiency of adsorbed P, percentage of desorbed P, Freundlich adsorption capacity, and intensity by 8%, 37.5%, 60%, and 58%, respectively, as compared to the control. These findings indicate that the combined application of MM and blended NPSB can improve the P availability and uptake by maize by reducing its adsorption while increasing desorption characteristics. Finally, this experiment recommends further research on the long-term effects of MM and blended NPSB on P adsorption and desorption characteristics of vertisols.

Tempeh Industry Wastewater Treatment using Mix Natural Adsorbents (Zeolite, Bentonite, Water Hyacinth-Activated Carbon): Effect of Mass Ratio and Dosage of Mix Adsorbents on Turbidity and pH

Adsorption is the process of agglomeration of dissolved substances in solution by the surface of an absorbent substance which makes the material enter and collect in an absorbent substance. Natural adsorbents that function to treat tempe liquid waste are zeolite, bentonite, and water hyacinth activated carbon. The purpose of this study was to determine the effect of the mass ratio and dose of natural adsorbents on the turbidity and pH values of tempe wastewater. The mass ratio variation used was the ratio of each material in the form of zeolite: bentonite: active carbon of water hyacinth in the form of R1 (1:1:1); R2 (2:1:1); R3 (1:2:1); and R4 (1:1:2). The adsorbent dose carried out was 1.5 gr; 3 grams; and 4.5 gr per 100 ml volume of liquid waste. The contact time between the adsorbent and the liquid waste is every 15, 30, 60, 90, 120, 150 minutes. Processing of tempe liquid waste was carried out in laboratory-scale batches with 120 rpm stirring. The analysis was carried out in form of turbidity, pH, COD, BOD, and TSS. The results showed that the adsorption was able to reduce turbidity and increase the pH level up to 99% by stirring the mass ratio R2 (2:1:1) for 150 minutes with a dose of 4.5 grams. It was found that the turbidity value decreased from 520.5 NTU to 2.47 NTU =ncrease in pH levels reaching 75% at 150 minutes of stirring at a dose of 4.5 grams. Decreased pH value from 3.7 to 6.4. The maximum adsorption capacity validation results were obtained based on the Frendulinch analysis of 7.07-49.75 mg/g with a Freundlich constant of 0.67-0.70 at a dose of 4.5 grams.

Sorption studies of Tetraoxophosphate (v) ions on some agricultural soils in Akwa Ibom State, eastern Niger Delta, Nigeria

The phosphate sorption capacity regulates principally the phosphorus concentration and available phosphorus in any soil solution. This work aims to study the phosphate sorption characteristics of five agricultural soils in Akwa Ibom State, Nigeria. The phosphate adsorption isotherm was obtained by shaking each soil sample with 20, 40, 60, 80, 100 and 120 mgL–1 for 24 h with 20 mL of KH2PO4 in 0.01 M CaCl2 solution. The Langmuir, Freundlich, Van Huay and Temkin isotherms were applied to study the PO43-sorption characteristics of the soil samples. The Freundlich model provided the best choice for phosphate sorption with mean R2 value of 0.9872. Results obtained for the phosphate sorbed (µg g–1soil) with 120 mgL-1 solution, heterogeneity factor of adsorption sites (nF), and the Freundlich constant (KF) (Lg–1) were 101(84.3), 0.515 and 7.355 for Onna soil; 62.8(52.3), 0.641 and 2.464 for Ikot-Amama 2; 60.6(50.5), 0.708 and 3.985 for Ogu-Itumbonuso soil; 59.3(49.5), 0.652 and 2.505 for Ikot-Amama 1 soils; 58.0(48.3), 0.704 and 3.682 for Ikot-Nkon soils, respectively. The equilibrium concentration for phosphates (EC-P) were used as desorption index to determine whether the soils could serve as potential sources for their bioavailability to plants and results ranged from 5.0 to 9.90 mgL–1, indicating high vulnerability to phosphate loss. The relationship between phosphate sorption parameters and soil physicochemical properties showed that the Freundlich adsorption intensity factor, nF, strongly correlated negatively with organic carbon and organic matter (r = -0.953 and -0.947; P&lt;0.01), Fe and Mn (r = -0.911 and -0.812, P&lt;0.05). The EC-P correlated strongly with soil pH(H2O) (r = 0.959, P&lt;0.01), clay (r = 0.913, P&lt;0.05), cation exchange capacity (CEC) (r = -0.824, P&lt;0.05), Mn (r = -0.792, P&lt;0.05) and Fe (r = -0.826, P&lt;0.05). The study illustrated that soil management practices which involves the using organic fertilizers as the basis for PO43- sorption in relation to soil properties can be a useful tool for sustainable crop production and environmental soil-water contamination.

Purification of Aqueous Solutions from Nickel Using Ceramic Waste

This study aims to test ceramic waste's capacity to remove nickel from aqueous solutions through adsorption. Ceramic wastes were collected from the Refractories Manufacturing Plant in Ramadi. Through a series of lab tests, the reaction time (5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 minutes, and Ni concentrations (20, 40, 60, and 80) were tested using ceramic wastes with a solid to liquid ratio of 2g/30ml. At a temperature of 30ºC, the pH, total dissolved solids (TDS), and electrical conductivity (EC) were all measured. The equilibrium time was set at 30 min. Thereafter, the sorption (%) somewhat increased positively with the Ni concentration. Freundlich's equation showed that the adsorption intensity is 1.1827 and the Freundlich constant is 58.15, Langmuir Equation showed the sorption capacity is 1.8779, and the sorption of Ni fit with the Langmuir and Freundlich equations. It was clarified how ceramic waste material can reduce the Ni concentrations from aqueous solutions protecting the environment.

Direct Adsorption of Graphene Oxide on a Glassy Carbon Electrode: An Investigation of Its Adsorption and Electrochemical Activity.

Different modes of attachment of graphene oxide (GO) on an electrode surface resulted in unusual catalytic behavior respective of attachment because of film thickness. The present work investigates the direct adsorption of GO to the surface of a glassy carbon (GC) electrode. Scanning electron microscopy images revealed that multilayers of GO get adsorbed on the GC substrate and the adsorption was limited by folding up of the GO sheets at their edges. π-π and hydrogen bonding interactions between the GO and GC substrate flagged the adsorption of GO. pH studies revealed that higher adsorption of GO was achieved at pH = 3 rather than at pH = 7 and 10. Even though the electroactive surface area of adsorbed GO (GOads) was not remarkable (0.069 cm2), upon electrochemical reduction of GOads (Er-GOads), the electroactive surface area was escalated to be 0.174 cm2. Similarly, the RCT of Er-GOads was boosted to 2.9 kΩ compared to GOads which is 19 kΩ. Open circuit voltage was recorded to study the adsorption of GO on the GC electrode. Multilayered GO best fitted with the Freundlich adsorption isotherm, and the Freundlich constants like n and KF were found to be 4 and 0.992, respectively. The Freundlich constant "n" revealed the adsorption of GO on the GC substrate to be a physisorption process. Furthermore, the electrocatalytic performance of Er-GOads was demonstrated by taking uric acid as a probe. The modified electrode showed excellent stability toward the determination of uric acid.

New chitosan-biochar composite derived from agricultural waste for removing sulfamethoxazole antibiotics in water

This study aims to develop a new chitosan-biochar composite derived from agricultural waste for removing sulfamethoxazole (SMX) antibiotics in water. Biochar was prepared from orange peel (OB) and spent coffee grounds (SCB). To fabricate chitosan-biochar composites, chitosan and biochar were crosslinked with glutaraldehyde. Results showed that pH, adsorbent dosage, time, temperature, and initial concentrations have a significant impact on the SMX adsorption. The adsorption data was better described by Langmuir (with good regression) than Freundlich model. The highest adsorption capacity (Qmax) of SMX on OB, SCB, CTS-OB, and CTS-SCB were 3.49, 7.65, 7.24, and 14.73 mg/g, respectively. The Freundlich constant (KF) values for adsorption capacity were 1.66, 1.91, 2.57, and 5.57 (mg1-nLn/g), respectively, for OB, SCB, CTS-OB, and CTS-SCB. Ion exchange, π bonding, hydrogen bonding and pore filling, were proposed as dominant mechanisms of SMX removal process.

Investigation of the performance of activated carbon cloth to remove glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos from aqueous solutions by adsorption/electrosorption.

The present study investigates the removal of glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos herbicides from their 5 × 10-5M aqueous solutions onto activated carbon cloth by adsorption and electrosorption. Analysis of these highly polar herbicides was achieved by UV-visible absorbance measurements, after derivatization with 9-fluorenylmethyloxycarbonyl chloride. The limit of quantification values of glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos were 1.06 × 10-6mol L-1, 1.38 × 10-6mol L-1, 1.32 × 10-6mol L-1 and 1.08 × 10-6mol L-1, respectively. Glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos were removed from their aqueous solutions with higher efficiencies by means of electrosorption (78.2%, 94.9%, 82.3% and 97%, respectively) than of open-circuit adsorption (42.5%, 22%, 6.9% and 81.8%, respectively). Experimental kinetic data were fitted to pseudo-first order and pseudo-second order kinetic models. It was determined that pseudo-second order kinetic model represents experimental data better with satisfactory coefficient of determination, r2 (> 0.985) and normalized percent deviation, P (< 5.15) values. Adsorption isotherm data were treated according to Freundlich and Langmuir isotherm models. Based on the r2 (> 0.98) and P (< 5.9) values, it was found that experimental data well fitted to Freundlich isotherm model. Adsorption capacities of activated carbon cloth for glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos, expressed in terms of Freundlich constant, were calculated as 20.31, 118.73, 239.33 and 30.68mmolg-1, respectively. The results show that the studied ACC can be used in home/business water treatment systems as an adsorbent due to its high adsorption capacity.

Fundamental kinetic constants for breakthrough of per- and polyfluoroalkyl substances at varying empty bed contact times: Theoretical analysis and pilot scale demonstration

Successful treatment of per- and polyfluoroalkyl substances (PFAS) contamination by adsorptive fixed bed media has been well established in literature and practice, but kinetic effects are important for these compounds. Common kinetic models of adsorption are descriptively fit to experimental data obtained from a particular design case, leading previous literature to dismiss these models as unable to provide useful information across changes to key operational variables. However, some descriptive models, such as the Clark and Bohart-Adams models, have mechanistic derivations with fundamental constants. The objective of this study was to evaluate the consistency of these fundamental constants across different experimental empty-bed contact times (EBCTs), and to evaluate the accuracy of using fundamental constants obtained at one EBCT to predict breakthrough at another EBCT.A total of 53 pilot-scale PFAS breakthrough curves through granular activated carbon (GAC) and ion exchange (IX) media were fitted to the Bohart-Adams and Clark models. Models were used to generate fundamental bed capacity, Freundlich, and kinetic constants. For each solute-media pair, the fundamental bed capacity and Freundlich constants had good agreement and low error across different EBCTs, while the kinetic constant had higher error with some EBCT dependance, but good order-of-magnitude agreement. The fundamental constants provided insights into the solute-media interaction, and predictive curves based on these fundamental constants provided reasonable estimates of breakthrough. The measurement of consistent values of underlying constants measured at different EBCT in this study suggests that the Clark and Bohart-Adams models can indeed be used to make predictions by varying parameters that are explicitly accounted for in the models, allowing for breakthrough curves generated at one EBCT to be used to predict breakthrough at another EBCT.