Adsorption Of Diazinon Research Articles

Exploring the mechanisms of diazinon adsorption onto alpha and beta cyclodextrins through molecular dynamics simulations: Insights into environmentally friendly pesticide remediation

This study investigated the adsorption of Diazinon on α and β-Cyclodextrins (CDs) through Molecular Dynamics Simulations. The entrance point variation in diazinon adsorption is analyzed, revealing distinct preferences for entry into α and β-CDs. The center of mass distance of diazinon and CDs is investigated, highlighting the dynamic behavior within β-CD. Interaction energies between diazinon, CD, and water are explored, emphasizing the significance of van der Waals interactions in diazinon adsorption. Hydrogen bonding analysis reveals preferential adsorption of diazinon on α-CD, attributed to the number and arrangement of hydrogen bonds. Free energy calculations using the Bennett acceptance ratio method indicate a stronger affinity of diazinon for α-CD, supported by molecular electrostatic potential maps. The study also examines the hydration capacity and water molecules' distribution, indicating differences between α and β-CD. Radial distribution function analysis (RDF) illustrates the adsorption process, emphasizing water molecule expulsion upon diazinon entry. Structural stability is assessed through root mean squared deviation, indicating equilibrium attainment. Gibbs free energy calculations suggest stronger hydrophobic interactions in the α-CD cavity. This comprehensive analysis contributes valuable insights into the MD of diazinon-CDs interactions, shedding light on their adsorption mechanisms and potential applications in wastewater treatment.

Adsorption of diazinon from aqueous solution using metal organic framework and functionalized graphene: Comparison of BBD, ANN models

In the present study, metal organic frameworks (MOFs) and aminated graphitic carbonaceous structure (ACS-RGO) through chemical synthesis prepared by a simple precipitation method and used for diazinon removal. Several techniques such as XRD , FESEM and FTIR were applied for identification of MOF-5 and ACS-RGO. Also, response surface methodology (RSM) was employed in this work to look at the effectiveness of diazinon adsorption. To forecast pesticide removal, we applied artificial neural network (ANN) and Box-Behnken Design (BBD) models. For the ANN model, a sensitivity analysis was also performed. The effect of independent variables like solution pH, various concentrations of diazinon, MOFs and ACS-RGO adsorbent dose and contact time were assessed to find out the optimum conditions. Based on the model prediction, the optimal condition for adsorption ACS-RGO and MOF-5 were determined to be pH 6.6 and 6.6, adsorbent dose of 0.59 and 0.906 g/L, and mixing time of 52.15 and 36.96 min respectively. These conditions resulted in 96.69% and 80.62% diazinon removal using ACS-RGO and MOF-5, respectively. Isotherm studies proved the adsorption of ACS-RGO and MOF-5 following the Langmuir isotherm model for diazinon removal. Diazinon removal followed by the pseudo-second and Pseudo-first order kinetics model provides a better fit for analyzing the kinetic data associated with pesticide adsorption for ACS-RGO and MOF-5, respectively. Based on the obtained results, the predicted values for the efficiency of diazinon removal with the ANN and BBD were similar (R2=0.98). Therefore, two models were able to predict diazinon removal by ACS-RGO and MOF-5.

Preparation of novel and recyclable chitosan-alumina nanocomposite as superabsorbent to remove diazinon and tetracycline contaminants from aqueous solution

This work presents a novel, strong and efficient adsorbent (CS@TDI@EDTA@γ-AlO(OH)) prepared through the green process using three components, chitosan, BNPs and EDTA using amide and ester bridges. An eco-friendly and easy approach was used for the preparation of this novel adsorbent, the low cost, easy access to the used materials, and the simplicity of the preparation method are some of the interesting advantages of this work. Also, this prepared adsorbent was used as an adsorbent to remove diazinon organophosphate poison and tetracycline antibiotic from aqueous solutions. In order to confirm the prepared adsorbent structure, the CS@TDI@EDTA@γ-AlO(OH) composite was investigated by various analyses including FT-IR, EDX, XRD, FESEM and TGA. The adsorption behavior of the adsorbent prepared for the removal of tetracycline and diazinon was investigated under different conditions by varying the concentration, temperature, the adsorbent dose, pH and contact time. Based on various tests, the highest diazinon adsorption capacity was obtained for 0.12 g/L adsorbent at pH 7 and 60 °C with 40 mg/L initial concentration. Also, the maximum adsorption capacity of the tetracycline was obtained for 0.12 g/L adsorbent at pH 9 and 60 °C with 30 mg/L initial concentration. The equilibrium results for diazinon and for tetracycline were in good accordance with the Langmuir and Freundlich isotherm models, respectively. Also, the highest adsorption capacities for diazinon at pH 7 and tetracycline at pH 9 were 1428.5 and 555.5 mg/g, respectively. Also the kinetic investigations revealed that the correlation factor (R2) of pseudo-second-order model obtained for the adsorption of diazinon and tetracycline was 0.9986 and 0.9988, while the coefficient k (g/mg.min) was 0.000084 and 0.0033, respectively. These results indicate that the adsorption of diazinon and tetracycline is pseudo-second-order kinetics model. Formation of hydrogen bonds between adsorbate and adsorbent as well as the high specific surface area and porosity of the adsorbent are the main mechanisms that contribute to the adsorption process. In addition, thermodynamic studies indicated that the adsorption of diazinon and tetracycline is a spontaneous endothermic process. The adsorbent prepared in this work was expected to have wide range of applications in wastewater treatment thanks to its good reusability in water and strong removal of diazinon and tetracycline compared to other adsorbents.

Preparation of novel Zn–Al layered double hydroxide composite as adsorbent for removal of organophosphorus insecticides from water

In this work, a new and efficient composite LDH with high adsorption power using layered double hydroxide (LDH), 2,4-toluene diisocyanate (TDI), and tris (hydroxymethyl) aminomethane (THAM) was designed and prepared, which was used as an adsorbent to adsorb diazinon from contaminated water. The chemical composition and morphology of the adsorbent were evaluated using Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Energy dispersive X-ray (EDX) and Field emission scanning electron microscopy (FESEM) techniques. Also, the optimal conditions for adsorption of diazinon from water were determined by LDH@TDI@THAM composite. Various parameters like the effect of adsorbent dosage, pH, concentration and contact time of diazinon were studied to determine the optimal adsorption conditions. Then, different isotherm models and kinetic adsorption were used to describe the equilibrium data and kinetic. Also, the maximum adsorption capacity is obtained when the pH of the solution is 7. The maximum adsorption capacity for LDH@TDI@THAM composite was 1000 mg/g at 65 °C and the negative values of ΔG indicate that the adsorption process is spontaneous. After that, studying the reusability of LDH@TDI@THAM composite showed that the removal of diazinon by LDH@TDI@THAM was possible for up to four periods without a significant decrease in performance.

Role of cellulose and lignin on biochar characteristics and removal of diazinon from biochar with a controlled chemical composition

In this study, the effects of carbohydrate and lignin content in biomass on the production of biochar were investigated, and the adsorption behaviors of diazinon on the biochar obtained from delignified oak were evaluated. The lignin content in biomass can be controlled by delignification. Biomass lignin content decreased and cellulose content increased with increasing delignification time, thereby increasing the crystallinity index of delignified oak. Although the biochar yield of the delignified oak decreased, its specific surface area (354.68–444.36 m2/g) and total pore volume (0.162–0.202 cm3/g) were higher than those of the biochar obtained from raw material (193.22 m2/g and 0.093 cm3/g). In the delignified oak, the specific surface area and total pore volume of biochar increased with increasing delignification time. Mesopores and micropores were more developed in the biochar obtained from the delignified oak than in the raw material. The removal efficiency of diazinon by biochar increased with increasing delignification time. Based on the Langmuir and Freundlich isotherms, diazinon adsorption to biochar was suitable for the Langmuir model.

Molecular modeling investigation on mechanism of diazinon pesticide removal from water by single- and multi-walled carbon nanotubes

In this study, the mechanism of diazinon adsorption on single-walled carbon nanotubes (SWNTs), as well as multi-walled carbon nanotubes (MWNTs), was investigated using molecular modelling. Determination of the lowest energy sites of different types of carbon nanotubes (CNTs) was demonstrated. The adsorption site locator module was used for this purpose. It was found that the 5-walled CNTs are the best MWNTs for diazinon elimination from water due to their higher interactions with diazinon. In addition, the adsorption mechanism in SWNT and MWNTs was determined to be wholly adsorption on the lateral surface. It is because the geometrical size of diazinon molecules is larger than the inner diameter of SWNT and MWNTs. Furthermore, the contribution of diazinon adsorption on the 5-wall MWNTs was the highest, for the lowest diazinon concentration in the mixture.

Adsorption of Pesticides, Antibiotics and Microcystin-LR by Graphene and Hexagonal Boron Nitride Nano-Systems: A Semiempirical PM7 and Theoretical HSAB Study

In recent years, graphene (CC) and hexagonal boron nitride (h-BN) have been widely used in water purification and environmental remediation because of their unique physical and chemical properties. Therefore, based on the reaction enthalpy, equilibrium structure, atomic charge, molecular, orbital and electronic spectrum provided by a semiempirical PM7 method, the adsorption of pesticides, antibiotics and microcystin-LR on graphene and hexagonal boron nitride (h-BN) nano-systems was examined. For the adsorption of diazinon, parathion, oxacillin and ciprofloxacin, the results show that as the bond length decreases and the atomic partial charge increases, the adsorption energy increases. The removal efficiency for antibiotics is higher than that for pesticides. Regarding the co-adsorption of pesticides/antibiotics and microcystin-LR on nano-systems, hydrogen bonds play a crucial role in stabilizing the whole structure. In addition, the non-covalent interaction (NCI) diagrams show the adsorption strength of the nano-systems to the pesticides/antibiotics. The energy gap and HSAB global descriptors are calculated based on the energy values of HOMO and LUMO. It is proved that the graphene nano-system has excellent electron-accepting ability, and suitable sensor materials can be designed.

Adsorption of diazinon using Cd-MOF nanoparticles before determination by UV-Vis spectrometer: isotherm, kinetic and thermodynamic study

In this work, Cd MOF has been prepared using a hydrothermal method and characterized by the SEM, elemental mapping, XRD, EDS, and BET analysis. The diazinon stability has been investigated in various pH (4-8) and temperature (298oK – 323oK) using UV-Vis spectrometer in the range of 230 – 280 nm, at its main absorption peak at 247 nm. Adsorption behaviors of diazinon on the Cd MOF were considered in different conditions. UV-Vis spectroscopy was used to monitor the removal of diazinon using the Cd MOF. The adsorption capacity of 138 mg g-1 was obtained. The effect of temperature (298 K -323 K), pH (4-8), adsorbent dose (1-7 mg), initial concentration (4-12 mg L-1), stirring speed (0-500 rpm), and adsorption kinetics were studied using batch rout. All the studied parameters have shown significant effects on the efficiency of removal of diazinon by the Cd MOF. The adsorption thermodynamic was investigated in the temperature range of 298 k to 323 K and it has shown the endothermic nature of adsorption of diazinon using prepared Cd MOF. The adsorption isotherm follows by the Langmuir isotherm model. It was demonstrated that synthesized adsorbent could be effectively used for the removal of diazinon from water.

Evaluation of sulfuric acid-pretreated biomass-derived biochar characteristics and its diazinon adsorption mechanism

In this study, hemicellulose was mostly removed from biomass (larch and oak) using a sulfuric acid pretreatment. Biochar was then prepared from raw and pretreated biomass using a carbonization process. Biochar derived from pretreated biomass had an aromatic and graphitized structure, and functional groups were observed on the surface. The specific surface area was higher for biochar obtained from pretreated biomass than biochar derived from raw biomass. The biochar obtained from pretreated biomass contained a greater number of micropores than biochar derived from raw biomass. The diazinon removal rate was the highest for biochar that was obtained from pretreated biomass when 10% of the biochar was added to the soil. As a result of the adsorption of diazinon onto the biochar obtained from pretreated biomass, the R2 value of the Langmuir isotherm was higher than that of the Freundlich’s R2.

Thermodynamic Studies on the Adsorption of Organophosphate Pesticides (Diazinon) onto ZnO/Polyethersulfone Nanocomposites

AbstractThis study reports experimental analyses of adsorption thermodynamics using the polymeric adsorbent surface, polyethersulfone (PES), with different molar ratios of ZnO nanoparticles. Fourier transform infrared (FTIR), X‐ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) were performed to study the adsorbent structure and morphology. FTIR results showed that both PES and ZnO nanoparticles were successfully incorporated into the nanocomposite, while the XRD analysis showed that the crystal adsorbent characteristics did not change. FESEM of the ZnO exhibits the formation of aggregates in the form of small spherical grains, and the sizes were in the range of 45–65 nm. The effects of different parameters (contact time, pH, temperature, adsorbent dosage, and diazinon concentrations) were investigated to find the optimal conditions of the prepared adsorbents. The equilibrium data for diazinon adsorption onto PES and ZnO/PES were analyzed using the Langmuir, Freundlich, Temkin, Dubinin‐Radushkevich, Jovanovic, and Flory‐Huggins models. Based on the values of the correlation coefficient, Langmuir and pseudo‐second‐order were found to be the best‐fitting model. In addition, adsorption at different temperatures (288.15–303.15 K) was used to determine thermodynamic parameters such as free energy, enthalpy, and entropy changes. Finally, these results allow designing different processing units for pollution removal.

Total phenolics, flavonoids, and antioxidant activity of agricultural wastes, and their ability to remove some pesticide residues

Organophosphorus pesticides (OPPs) cause great risk to human health as they are used globally. Therefore, the purpose of this research was to determine the total phenolics, flavonoids, and antioxidant activity of agricultural waste, as well as to control the pesticide residues (diazinon, and parathion) at a laboratory scale level using dried-milled fruit wastes. The pesticide residues parathion and diazinon were used at concentrations of 0.094, and 1.90 mg/mL respectively. The fruit wastes used in this study were orange and banana peels, as well as date stones, and they were used in two concentrations (3 and 9 g/30 mL deionized water). The total phenolic and flavonoid contents and the antioxidant activity were measured in fruit wastes. Also, the Fourier transmitted infrared (FTIR) spectra of fruit wastes were established to figure out the nature of the functional groups found before and after pesticide residues removal. The ability of fruit wastes to remove pesticides residues was determined using Gas Chromatography/Mass spectrometry (GC/MS). Data showed that date stones contained a higher amount of total phenolic content than orange and banana peels. However, orange peels contained a higher amount of total flavonoid contents than those of date stones and banana peels. As for antioxidant activity, banana peels recorded the higher antioxidant activity, followed by orange peels and date stones respectively. Results revealed that there was no relation between total phenolic content, total flavonoid content, and antioxidant activity. Results also indicated that date stones at a concentration of 9 g successfully reduced diazinon (81.18%), followed by banana (63.86%) and orange peels (43.42%) respectively, whereas parathion was reduced by banana peels at a concentration of 9 g (50.34%), followed by orange peels (45.28%), and date stones (39.52%) respectively. This study demonstrated that agricultural wastes were effective in the adsorption of diazinon from water, and their use is considered safe for the environment.

Design and synthesis of a new magnetic molecularly imprinted polymer nanocomposite for specific adsorption and separation of diazinon insecticides from aqueous media

Today, molecularly imprinted polymers have received much engrossment as selective adsorbents and substrates. In the present study, a magnetic molecularly imprinted polymer (MIP) based on clay, graphene oxide and polydopamine was synthesized and used for adsorption and specific entrapment of Diazinon pesticide. The magnetic MIP nanocomposite was characterized by XRD, FT-IR, SEM, VSM, and AFM methods. The response surface method (RSM) was used to optimize and modeling the effective parameters of the adsorption of Diazinon by this polymer, and the results were compared with an artificial neural network (ANN). The results showed magnetic saturation of GO/Clay/Fe3O4@PDA MIP nanocomposite is equal to 8.28 emu/g, average particle size, average surface roughness and imprinting factor of this polymer are equal to 105 nm, 66.72 nm and 2.35, respectively. This polymer has a very selective ability to adsorption of Diazinon by removal percentage equal to 99.85 at pH = 7, the concentration of Diazinon = 1.45 ppm, the dosage of polymer = 1.24 g/L, time = 16 min. Also, the RSM results showed that the model included the effect of parameters on the absorption efficiency is a quadratic polynomial equation with the coefficient of determination equal to 0.98% and the most effective parameter on removal percentage is the dosage of the polymer. The artificial neural network with 11 neurons in the hidden layer with the coefficient of determination of 0.96% was also suitable for modeling the absorption process. Compared to the ANN model, the RSM model has better capability and lower error values. Freundlich isothermal models and pseudo-second-order and Elovich kinetic models in different concentrations of Diazinon were appropriate for explanation the adsorption process. The mechanism of Diazinon adsorption by MIP nanocomposite was influenced by intraparticle and extraparticle diffusion. Also, GO/Clay/Fe3O4@PDA MIP nanocomposite has an adsorption capacity of more than 98% up to nine cycles of the adsorption/desorption process.

Synthesis of spherical SBA-15 by poly (vinyl alcohol)/ Hydroxyl-terminated polybutadiene supermicelles as co-surfactant and its application for removal of diazinon from aqueous solution

A low-cost and facile strategy was successfully developed to produce spherical micrometer-sized SBA-15 with cylindrical pores arranged in a hexagonal order using pluronic triblock-copolymer P123 as template and poly (vinyl alcohol) (PVA)/hydroxyl-terminated polybutadiene (HTPB) supermicelles as co-surfactant. Herein, a solvent evaporation induced aggregating assembly (EIAA) method was reported for the preparation of SBA-15 microspheres. The materials were characterized by Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmet–Teller (BET) method. The diazinon adsorption properties of spherical SBA-15 were studied to find out the effect of various experimental factors. Results exhibited that the highest diazinon removal efficiency (95.2%) was achieved at pH 6, initial concentration of 50 mg L −1 , temperature of 318 K, and the adsorbent dosage of 0.1 g L −1 for 60 min. The adsorption behavior of diazinon was described by the Langmuir isotherm and pseudo-second-order model (R 2 > 0.99). Maximum adsorption capacity obtained 526.3 mg g −1 . The apparent activation energy for spherical SBA-15 was 16.69 kJ mol −1 . Thermodynamic studies illustrated that the adsorption process was exothermic with spontaneous nature. The efficiency of diazinon removal was not considerably affected by the presence of the lindane. Moreover, the spherical SBA-15 retained its adsorbing properties after sixteen cycles. • Spheres obtained using P123–PVA/HTPB as a template in the THF/H 2 O/ethanol mixture. • Spherical SBA-15 adsorbent was highly effective to diazinon removal. • The adsorption process was described by the Langmuir isotherm. • The pseudo-second-order model is the best to adsorption kinetic.

Equilibrium and kinetic study of adsorption of diazinon from aqueous solutions by nano-polypropylene-titanium dioxide: Optimization of adsorption based on response surface methodology (RSM) and central composite design (CCD)

Equilibrium and kinetic study of adsorption of diazinon from aqueous solutions by nano-polypropylene-titanium dioxide: Optimization of adsorption based on response surface methodology (RSM) and central composite design (CCD)

Adsorption of diazinon residues from water by Strychnos potatorum seed flakes: Equilibrium isotherm and thermodynamic analysis

Objectives: Contamination of pesticide residues due to agricultural activities is a major concern of aquatic pollution and most of the agriculture based rural communities in developing countries are still consuming water from those contaminated water bodies. Therefore, development of readily available user-friendly low cost pesticide contaminant removal methods is still in need for above communities. In this study the suitability of Strychnos potatorum seed flakes (SPSF) on effective removal of diazinon residues in water was investigated. Methods: SPSF was prepared and characterized using SEM and FTIR analysis. Batch adsorption studies, isotherm studies and thermodynamic studies were carried out to determine the removal efficiency of diazinon by SPSF. Findings: The maximum removal of diazinon residues (75.9%) was obtained within 10 min at pH 6. Therefore, SPSF are efficient adsorbent for diazinon removal due to fast and efficient removal of diazinon at ambient conditions. The removal of diazinon residues by SPSF was expressed with Langmuir isotherm model. The maximum adsorption capacity of SPSF, obtained from Langmuir isotherm for diazinon adsorption was found to be 2.5mg/g. Thermodynamic studies revealed that the removal of diazinon by the SPSF was spontaneous and exothermic at relatively low temperatures. Novelty: The SPSF adsorbent is a naturally available cost effective and ecofriendly adsorbent which has not been extensively studied for the removal of frequently used pesticides such as diazinon. The findings of the study revealed that the SPSF adsorbent can be considered as a promising remedy for house hold purification of diazinon contaminated waters. Keywords: Adsorption; diazinon; Strychnos potatorum seed flakes; water

Equilibrium, kinetic and thermodynamic study of diazinon adsorption from water by clay/GO/Fe3O4: Modeling and optimization based on response surface methodology and artificial neural network

In this study, a new magnetic composite consisted of clay/graphene oxide/Fe3O4 was used for elimination of Diazinon (pesticide) from aqueous solutions. Analysis of the structural properties and surface morphology of the composite showed that the composite was well-synthesized and had a crystalline and multilayere structure. Magnetic saturation value was determined to be 39.9 emu/g. Its pHZPC value and active surface area was 7.1 and 185.7m2/g, respectively.In order to investigate the effects of pH, temperature, contact time, initial concentration of Diazinon and composite dosage on adsorption efficiency and modeling adsorption process, the response surface methodology-central composite design (RSM-CCD) and artificial neural network methods (ANN) were used. The results obtained through analysis using response surface methodology showed that the maximum amount of adsorption was 98.79% at 25.91 °C, while pH, initial concentration, contact time, and adsorbent dose were 6.9, 1.2 ppm, 24.6 min, and 1.1 g/L, respectively. Comparison between results obtained from CCD modeling and artificial neural network proved that both methods had high ability to predict the adsorption process but the CCD method had higher coefficient of determination and lower error. The equilibrium and kinetic study of the process showed that the Langmuir-Freundlich isotherm model, pseudo-second-order, and Elovich kinetics are all suitable for expressing the adsorption process. In addition, the adsorption mechanism obeyed double-exponential model that combines external and internal diffusions.Results of thermodynamic study suggested that the Diazinon adsorption on clay/GO/Fe3O4 was a spontaneous and exothermic process. The results of the equilibrium process study revealed that the adsorption process was physical and desirable. Therefore, the adsorption-desorption process was performed which showed that the composite was reusable up to 20 cycles.

Evaluation of Sulfuric Acid-Pretreated Biomass -Derived Biochar Characteristics and its Diazinon Adsorption Mechanism

Evaluation of Sulfuric Acid-Pretreated Biomass -Derived Biochar Characteristics and its Diazinon Adsorption Mechanism

Grafting β-Cyclodextrin/allyle glycidyl ether/thermosensitive containing polymer onto modified Fe3O4@SiO2 for adsorption of diazinon from aqueous solution

ABSTRACT In the present study, β-cyclodextrin/Allyl Glycidyl Ether (AGE)/thermo-sensitive polymer was grafted onto modified Fe3O4@SiO2 to be utilised as a possible adsorbent for diazinon removal from an aqueous solution. The modified magnetite Nano-Particles (NPs) were examined by using several techniques, including X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Elemental Analysis (EA), Vibrating Sample Magnetometry (VSM), and Thermo-Gravimetric Analysis (TGA). The effects of different parameters, such as pH, contact time, adsorption isotherm, reaction temperature, ultrasonic desorption, and reusability was evaluated. The results demonstrated that the best adsorption of diazinon on the modified magnetite nano-sorbent occurred at 20°C at the optimum pH of 6. The initial concentration and adsorbent dosage were 100 mg L−1 and 0.01 g, respectively. The kinetic study showed that the best time for the pesticide sorption was 2 min. Also, the Pseudo-Second-Order (PSO) model employed fitted the adsorption kinetics well, thus exhibiting high correlation coefficients. Diazinon adsorption capacity was found to be 34 mg g−1. The equilibrium data of diazinon modified by the magnetite nano-sorbent were suitably shown by Langmuir, Freundlich, Redlich-Peterson, and Temkin models. The data fitted well to Langmuir equation, thus indicating the monolayer adsorption. The reusability experiments revealed excellent removal capabilities of at least 10 times. The results demonstrated that the proposed method had the significant advantages of simplicity and efficiency for diazinon determination from real water samples.

Highly efficient removal of diazinon pesticide from aqueous solutions by using coconut shell-modified biochar

This study evaluates the adsorption of diazinon from aqueous solutions onto coconut shell-modified biochar using a batch system. The amount of dosage and initial pH are the main parameters being studied to obtain maximum adsorption capacity of the probe molecules. The carbonized coconut shell biochar (BC1), activated coconut shell biochar (BC2), chemically modified phosphoric acid (BC3) and sodium hydroxide coconut shell biochar (BC4) were prepared and tested as variables in the adsorption experiment. The characteristic of biochar via SEM, EDX and BET analysis revealed the large porous of surface morphology and slight changes in the composition with high surface area (405.97 – 508.07 m2/g) by following the sequence of BC3 > BC2 > BC4. Diazinon removal percentage as high as 98.96% was achieved at pH 7 with BC3 as adsorbent dosing at 5.0 g/L. The high coefficient of determination, R2 with a small value of ERRSQ and χ2 error analysis present the BC1 (0.9971) and BC2 (0.9999) are best fitted with Freundlich isotherm indicates multilayer sorption onto heterogeneous surface whereby the Langmuir isotherm model is the best fitting is described of monolayer adsorption process onto the homogenous surface of BC3 and BC4. The results indicated the maximum adsorption capacity (qm) was achieved by BC3 with 10.33 mg/g, followed by BC2 (9.65 mg/g) in accordance to the Langmuir isotherm while Freundlich isotherm showed the highest adsorption capacity (kF) with 1.73 mg/g (L/mg)1/n followed by BC4 with 0.63 mg/g (L/mg)1/n at favorable adsorption isotherm (1 ≤ n ≤ 10). Thus, the results obtained depicted that BC2 and BC3 are highly efficient adsorbents and both exhibit great potential in removing diazinon from aqueous solutions.

FIXED-BED COLUMN STUDY OF DIAZINON ADSORPTION ON THE CROSS-LINKED CHITOSAN/CARBON NANOTUBE

Adsorption of diazinon from aqueous solution was studied by using cross-linked Chitosan/Carbon Nanotube (CHN-CNT) in a fixed-bed column. The cross linked CHN-CNT with 2.5% of MWCNT was prepared with a protected crosslinking method. The effects of the initial concentration of diazinon, bed-height, and flow rate on the adsorption of diazinon onto the cross linked CHN-CNT were investigated. The highest bed capacity of 29.47 mg/g was obtained at the initial concentration of 50 mg/L, flow rate of 10.5 mL/min, and fixed bed-height of 4 cm. Three models, namely Bohart Adams, Thomas, and Yoon Nelson, were investigated to predict the breakthrough curves and to determine the characteristic parameters. The experimental data were well fitted with the Yoon Nelson model, indicating that it was suitable for continuous adsorption of diazinon onto cross-linked CHN-CNT in a fixed-bed column. The findings of this study revealed that the cross-linked CHN-CNT not only has a simple synthesis method and good strength but also adsorbs the diazinon well.