Initial Adsorbate Concentration Research Articles

Efficient Adsorption of the Cd(II) and As(V) Using Novel Adsorbent Ferrihydrite/Manganese Dioxide Composites.

Ferrihydrite/manganese dioxide composites (FH–M) were synthesized from ferrihydrite (FH) and manganese compounds by ex situ synthesis and characterized using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy in the present work. The influences of experimental parameters such as the solution pH value and initial concentration of adsorbate on the adsorption uptake of Cd(II)/As(V) was systematically investigated. The adsorption kinetics was analyzed by fitting quasi-first-order and quasi-second-order kinetic equations. The results showed that with increase in the pH value, the adsorption rate of Cd(II) is increased, while that of As(V) is increased first and then decreased. For the kinetic adsorption process, the adsorption performance of FH–M to As(V) was better than that to Cd(II). The quasi-second-order kinetic equation and Freundlich equation were more suitable to describe the adsorption of Cd(II)/As(V). The ligand exchange of Cd(II)/As(V) with the −OH in the composites was confirmed by analyzing the characterization results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The high adsorption ability of the FH–M makes it a potentially attractive adsorbent for the removal to Cd(II) and As(V) with a good application prospect.

Adsorption and equilibrium studies of phenol and para-nitrophenol by magnetic activated carbon synthesised from cauliflower waste

In this study, waste cauliflower leaves were used for adsorbent preparation. The waste cauliflower leaves were converted into activated carbon by pyrolysis at two different temperatures 250˚C and 500˚C with magnetic property. The prepared adsorbents were denoted as CAC-250 and CAC-500 and characterized by the use of scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorbents were applied for the removal of phenol and PNP from their aqueous solutions. The adsorption of phenol was found very less by the application CAC-250, whereas by the application of CAC-500 the adsorption of both phenol and PNP was enhanced. The maximum adsorption of phenol was found 99% and that of PNP was found ~100% using CAC-500, with initial adsorbate concentration 5 mg/L at 25˚C. The adsorption data was analysed with Langmuir, Freundlich and Temkin isotherm models and different kinetic models that are pseudo first order, pseudo second order, Elovich, intraparticle and pore diffusion model.

Equilibrium and Kinetic Studies of Biosorptive Removal of 2,4,6-Trichlorophenol from Aqueous Solutions Using Untreated Agro-Waste Pine Cone Biomass

The present work discusses the adsorptive removal of a phenolic pollutant, i.e., 2,4,6-trichlorophenol (TCP), using low cost untreated agricultural waste pine cone powder (PCP). The present biosorbent was thoroughly characterized with the help of FTIR, SEM, XRD, and CHN analysis. The presence of amine (-NH2), hydroxyl (-OH) and carbonyl (C=O) functional groups was detected by the FTIR analysis. The important biosorption factors like agitation time, biomass dosage, initial adsorbate concentration, and the initial pH were examined by batch studies. The biosorption kinetic process was fast, reaching equilibrium in 75 min. The experimental kinetic data revealed an excellent agreement with the pseudo second order (PSO) model. On the other hand, the Langmuir isotherm model best described the equilibrium data with the maximum biosorption capacity (qmax) of 243.90 mg/g. These values are better than the adsorption capacities of most agro-based untreated adsorbents previously reported in the literature. Owing to fast removal rates and high biosorption capacity, PCP can be used for cost-effective treatment of TCP from aqueous streams.

Adsorption and Removal of Methylene Blue from Aqueous Solution Using Sterile Bract of Araucaria angustifolia as Novel Natural Adsorbent

The aim of this work was to study the adsorption and removal of methylene blue from aqueous solution using sterile bract of Araucaria angustifolia as novel natural adsorbent. Raw and boiling-treated sterile bract samples were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and point of zero charge. The contents of humidity, ash, total extractive content, lignin and cellulose were 13.20, 3.30, 7.12, 44.45 and 30.92%, respectively. The methylene blue adsorption mechanism in the sterile bract was evaluated using non-linear Langmuir, Freundlich, Redlich–Peterson and Sips isotherm models, whereas the adsorption kinetic was evaluated using pseudo-first- and pseudo-second-order kinetic models. The methylene blue removal efficiencies of the raw and boiling-treated bracts were 98.59 ± 0.01 and 99.90 ± 0.01%, respectively, after 480 min. The best adsorption efficiency was found within 480 min of contact, 5.0 g of adsorbent with 500 mesh granulometry, pH = 6, initial adsorbate concentration of 150 mg L−1 and temperature of 292 K. The maximum methylene blue adsorption capacities of the raw and boiling-treated bracts according to the non-linear Langmuir isotherm model were 125.34 and 138.65 mg dye per gram bract, respectively. The kinetic fit depends on the solution pH, determination coefficient and Chi square test statistic. From thermodynamic results, it was concluded that the adsorption process is favorable, spontaneous (ΔG 0). Overall, the sterile bract of Araucaria angustifolia could be applied as low-cost alternative adsorbent for the treatment of textile industry wastewater.

Comparison of linearization methods for modeling the Langmuir adsorption isotherm

The Langmuir isotherm model is widely used for modeling adsorption equilibrium data. The linearization method is mostly applied for estimations of the Langmuir parameters. However, it is not unified and requires further study. In this paper, the applicability and accuracy of four linearization methods of the Langmuir isotherm (equilibrium adsorbate concentration (Ce)/equilibrium adsorption capacity (qe)-Ce, 1/qe-1/Ce, qe-qe/Ce and qe/Ce-qe) in parameter estimations by linear least squares regression (LSR) were compared. The influence of linearization on the assumption about errors in the LSR variables was analyzed. The results showed that Langmuir-1 (Ce/qe-Ce) and Langmuir-4 (qe/Ce-qe) followed the assumption for all evaluated conditions whereas Langmuir-3 (qe-qe/Ce) violated the assumption for all conditions. Langmuir-2 (1/qe-1/Ce) obeyed the assumption of LSR only when Ce approached the initial adsorbate concentration (C0). Langmuir-1 (Ce/qe-Ce) provided the most accurate estimations of the Langmuir parameters, particularly at low levels of random errors in Ce and when the errors (%) in estimated maximum adsorption capacity (qm) and constant (Ka) ranged from −5% to 5% and from −15% to 15% at low levels of errors (−0.5–0.5 mg/L), respectively. The Langmuir-1 isotherm model adequately represented the experimental equilibrium data of sulfamethoxazole (SMX) onto activated carbon with an R2 value of 0.96.

Ultrafast remediation of lead-contaminated water applying sphagnum peat moss by dispersive solid-phase extraction

ABSTRACT Lead poisoning, correlated to the high blood lead levels among the children of the Gaza Strip, is another severe problem for Palestinians. The paper reports a cost-effective and time-effective remediation by sphagnum moss, which can remove lead from aqueous solution through dispersive solid-phase extraction. The optimum conditions of adsorption such as equilibrium time, pH, adsorbate initial concentration and adsorbent mass were investigated. In conclusion, a cost-effective and ultrafast lead uptake of ~95% was established in 60 s as adsorption-equilibrium contact time. Thus, a design of flow-through remediation unit for lead removal from real-life contaminated water would provide healthy outflow water. Moreover, regeneration and reuse of sphagnum in lead removal is advantageous for less developed economies with a problem of lead pollution in their water.

Facile preparation of biosurfactant-functionalized Ti2CTX MXene nanosheets with an enhanced adsorption performance for Pb(II) ions

The aim of this study is to improve the adsorption performance for Pb(II) ions of a novel two-dimensional Ti2CTX MXene. Three biosurfactants, chitosan (CS, a cationic surfactant), lignosulfonate (LS, an anionic surfactant) and enzymatic hydrolysis lignin (EHL, a non-ionic surfactant), were used to functionalize the Ti2CTX nanosheets. The samples were characterized by using Field-emission scanning electron microscopy, Fourier infrared spectroscopy, X-ray diffraction and Nitrogen adsorption-desorption isotherms, their adsorption performances for Pb(II) ions were investigated by bath adsorption experiments under various adsorption conditions including different types of biosurfactants, pH value, initial Pb(II) ions concentration, adsorbent concentration, contact time and adsorption temperature. Results revealed that the non-ionic surfactant EHL prevents Ti2CTX nanosheets from restacking and introduces active functional groups so that the adsorption performances of the EHL-functionalized Ti2CTX nanosheets are promoted. The EHL-functionalized Ti2CTX displayed a maximum adsorption capacity of 232.9 mg g−1 for Pb(II) ions. Moreover, reaction kinetics, isotherms and thermodynamics studies were analyzed to describe the adsorption behaviors, and the experimental data were fitted well with pseudo-second order model and Frendlich isotherm. The results showed that the biosurfactants-functionalized Ti2CTX shows improved adsorption performances in removal of Pb(II) ions and has great potential as an environmental adsorption material.

Adsorption of MnO4− from aqueous solution by Nitraria retusa leaves powder; kinetic, equilibrium and thermodynamic studies

Nitraria retusa leaves Powder was used for adsorption of Potassium Permanganate (KMnO4) from aqueous solutions. The most important physical and chemical adsorptive properties were examined by Brunauer–Emmett–Teller surface analyzer, Fourier transforms infrared spectroscopy, scanning electron microscopy and Theydan and Ahmed method. The surface area, pore-volume, average pore width, density and pHZPC of the adsorbent were found to be 57.8 m2 g−1, 0.092 cm3 g−1, 13.8 Å, 0.808 g/cc and 6.2, respectively. The most important factors impact the adsorption capacity were studied. The adsorbate initial concentration 600 mg l−1, temperature 60 °C, pH 1 and contact time 60 min were found to be the optimal experimental conditions. The isotherm and kinetic experimental data were described well by Langmuir isotherm model and pseudo 2nd order kinetic model, respectively. The adsorption capacities of 312.50, 333.33 and 344.83 mg g−1 were obtained at 30, 50 and 60 °C, in that order. Thermodynamic parameters indicated that the adsorption obtained in this research is an endothermic and spontaneous process.

Facile synthesis of protonated g-C3N4 and acid-activated montmorillonite composite with efficient adsorption capacity for PO43− and Pb(II)

A novel protonated graphite carbon nitride and acid-activated montmorillonite (g-C3N4/Mt) composite was prepared and evaluated its removal efficiency for PO43− and Pb(II) from aqueous media. The as-prepared composite was characterized by XRD, FT-IR, TG, XPS, SEM, BET and Zeta potential. Batch experiments were carried out under various conditions such as the amount of adsorbent, initial adsorbate concentration (Co), solution pH, temperature, and contact time. 2.0%-g-C3N4/Mt presented maximum adsorption capacity for PO43− and Pb(II) as compared to single g-C3N4, Mt or other synthesized composites. The removal efficiency of the as-prepared composite (2.0%-g-C3N4/Mt) was significantly elevated owing to the synergistic effects and the saturated adsorption capacities of PO43− and Pb(II) on 2%-g-C3N4/Mt was 5.06mg/g and 182.7mg/g respectively. While the saturated adsorption capacity of bare g-C3N4 was only 1.56mg/g and 22.3mg/g for PO43− and Pb(II) respectively, and bare Mt showed adsorption capacity of 0.65mg/g and 124.2mg/g for PO43− and Pb(II) respectively. The adsorption process for both contaminants showed well-fitting with the pseudo-second-order kinetic model, and the adsorption isotherm for both contaminants followed the Langmuir model. The thermodynamic study suggested that the adsorption of Pb(II) was a spontaneous and endothermic process.

Antagonistic and synergistic analysis of antibiotic adsorption on Prosopis juliflora activated carbon in multicomponent systems

The synergistic and antagonistic adsorption involved in the removal of antibiotics in multicomponent systems was investigated. In this study, potassium hydroxide (KOH) activated Prosopis juliflora activated carbon (KPAC) was prepared, characterized and used for the removal of sulfadiazine (SDZ), metronidazole (MET) and tetracycline (TET) antibiotics from single, binary and ternary adsorption systems. The effects of experimental parameters i.e. contact time, adsorbent dose, pH and initial adsorbate concentration was investigated. Traditional kinetic and isotherm models were utilized to model experimental kinetic and equilibrium data. Meanwhile, Langmuir’s competitive model was used to investigate adsorption capacity in multicomponent systems. Subsequently, kinetics and equilibrium data were better represented by pseudo-second-order and Langmuir isotherm models, respectively. The results showed that maximum sorption capacity of KPAC was 18.48, 25.06 and 28.81 mg/g for removal of SDZ, MET and TET, respectively, in single-component adsorption system. Moreover, total adsorption yield of single-component system was higher in comparison with multicomponent adsorption systems. Furthermore, the results showed that multicomponent systems exhibited both antagonistic and synergistic adsorption of antibiotics. Desorption study showed that maximum desorption of SDZ, MET and TET was 11.7%, 22.5% and 13.9%, respectively. In conclusion, KPAC has potential to be used as an adsorbent for removal of antibiotic(s).

Adsorption Study of Reactive Violet 8 and Congo Red Dyes onto Aloe Vera Micropowder Impregnated with Cu Atoms as a Natural Modified Sorbent and Related Kinetics and Thermodynamics

In this research, at first ordinary Aloe Vera micropowder (OAMP) and its impregnated form (IAMP) as the natural sorbents were prepared and then characterized by several techniques such as Fourier transform spectrophotometry (FT-IR), Scanning electron microscopy (SEM), Elemental analysis (EA), Brunauer–Emmett–Teller and Barrett-Joyner-Halenda (BET/BJH) essay and X-ray powder diffraction (XRD). The removal efficiencies of the prepared adsorbents were assessed upon their capacities for removing Reactive violet 8 (RV8) and Congo red (CR) dyes as the organic pollutants. Our preliminary adsorption experiments showed that the OAMB ability for removing RV8 and CR is very less than the IAMP form, so we focused on the IAMP removal ability and we used it as a fairy powerful adsorbent in this study. The effect of several parameters such as initial adsorbate concentration (C0), adsorbent dosage, contact time, temperature and solution pH on the adsorption capacity of IAMP adsorbent were investigated and then several isotherm models were examined to fit the experimental results. Consequently, we concluded that the Langmuir and Freundlich models fit reasonably the experimental results. In addition, thermodynamic and kinetic studies of the adsorption process were also done and the corresponding thermodynamic and kinetic parameters were concluded and reported.

Adsorption and Statistical Analysis of Textile Effluent Contaminated with Congo red On Orange Peel

In the present study we made an effort to deploy orange peel as adsorbent to remove Congo red dye from a synthetic media. Adsorption of Congo red dye was carried out using Response Surface Methodology (RSM).The influence of various factors such as adsorbent dosage, initial concentration of adsorbate and agitation time on adsorption was analyzed. A total no of 13 runs of experiments were conducted by using the detailed conditions which is designed by RSM based Box-Behnken Design. Contour plots and surface plots were analyzed to know the effect of factors. Activated orange peel could adsorb a maximum of 96.776% of congo red dye. The values observed in the experiment well agreed with the RSM predicted values .Activated orange peel seems to be better adsorbent and RSM could be a great tool undertake adsorption.: Congo Red Dye, Adsorption, Response Surface Methodology, Orange Peel, Box-Behnken Design.

Synthesis of cellulose acetate/chitosan/SWCNT/Fe3O4/TiO2 composite nanofibers for the removal of Cr(VI), As(V), Methylene blue and Congo red from aqueous solutions

The potential of electrospun cellulose acetate/chitosan/single walled carbon nanotubes/ferrite/titanium dioxide (CA/chitosan/SWCNT/Fe3O4/TiO2) nanofibers was investigated for the removal of Cr(VI), As(V), Methylene blue and Congo red from aqueous solutions via the adsorption and photocatalytic reduction processes. The properties of synthesized SWCNT/Fe3O4/TiO2 and fibers were characterized using TEM, SEM, FTIR, XRD, TGA and BET analysis. In adsorption process, the influence of adsorbent type including SWCNT to Fe3O4 ratio, TiO2 to SWCNT/Fe3O4 ratio and SWCNT/Fe3O4/TiO2 concentration as well as the adsorption parameters including pH, contact time, and initial concentration of adsorbates on the Cr(VI), As(V), Methylene blue and Congo red adsorption in a batch mode was investigated. The reusability of nanofibers was also investigated for five adsorption-desorption cycles. The photocatalytic reduction of Cr(VI), As(V), Methylene blue and Congo red was also investigated using various nanofibrous catalysts. The obtained results indicated that the removal of Cr(VI) and As(V) using CA/chitosan/SWCNT/Fe3O4/TiO2 nanofibrous adsorbent via adsorption process could be preferred for the lower concentrations of metal ions. The photocatalytic reduction was an effective method for the Cr(VI), As(V) removal at higher concentrations and degradation of Methylene blue and Congo red under both lower and higher concentrations of azo dyes.

Polyaniline coated nickel oxide nanoparticles for the removal of phenolic compounds: Equilibrium, kinetics and thermodynamic studies

Nanocomposites of transition metal oxides with polymeric fabrication have gained much interest as adsorbents for contaminated water remediation. Here, nickel oxide-polyaniline (NiO-PANI) nanocomposite was synthesized and has been employed as adsorbent for organic pollutants like p-nitrophenol and resorcinol in water. The structural, surface and thermal properties of the prepared adsorbents has been studied by using Fourier-transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). Batch adsorption experiments were performed to study the effect of contact time, initial adsorbate concentration, adsorbent amount, solution pH and temperature on the adsorption of resorcinol and p-nitrophenol. The adsorption process follows pseudo-second order kinetics suggesting chemical interaction between the adsorbent and the adsorbate. Equilibrium studies showed that the adsorption process is best fitted with Temkin isotherm model for resorcinol while for p-nitrophenol Freundlich isotherm model gives the best fit. The maximum Langmuir adsorption capacity for resorcinol and p-nitrophenol has been found to be 19.53 mg/g and 29.78 mg/g respectively at 303 K. Thermodynamic studies showed the adsorption process to be endothermic, spontaneous and entropically driven. The reusability study of the adsorbent has been performed upto four cycles which shows that the adsorbent can be regenerated and reused. The results of this work show that the polyaniline (PANI) fabricated nickel oxide (NiO) nanoparticles effectively adsorbs resorcinol and p-nitrophenol from aqueous medium. This paves the way for its use in environmental remediation.

Evaluation of Low Cost-Activated Carbon Produced from Waste Tyres Pyrolysis for Removal of 2-Chlorophenol

A low cost Activated Carbon (AC) was prepared by using waste tyres as raw material for the removal of 2-chlorophenol (2-CP). The AC adsorbent was prepared and activated by pyrolysis process at 900 ºC under constant nitrogen flow. The physical properties of the AC produced was characterized using X-ray Diffraction (XRD), Brunauer-Emmett-Teller (BET), Field Emission Scanning Electron Microscopy (FESEM), and Fourier Transform Infra Red (FTIR). The influence of initial adsorbate concentration, pH and adsorbent dosage on the removal of 2-CP in the batch-operational mode at ambient temperature were also investigated. The results obtained showed the AC presence of an amorphous carbon with high BET surface area and a total pore volume of 208 m2.g-1 and 0.5817 cm3, respectively. The highest adsorption capacity of 2-CP by the AC absorbent was achieved at an initial concentration of 10 mg.L-1, pH 5, and adsorbent dosage of 0.5 g in the first 10 min of contact time. This finding proves that the low cost-AC produced from waste tyres can be utilized for an effective removal of chemical plant wastewater containing toxic chlorine substances. Copyright © 2019 BCREC Group. All rights reserved

Defluoridation of water using a new biosorbent developed from Ficus glomerata Roxb. bark

Defluoridation of water through adsorption using biosorbents is currently attracting attention. A thermo-chemically developed biosorbent derived from Ficus glomerata bark was used in the present study. The adsorption data were analysed using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models at varying initial adsorbate concentrations (2–25 mg/l). It was found that the adsorption of fluoride onto F. glomerata biosorbent followed the Langmuir isotherm and the Langmuir isotherm constants a and b obtained were 2·27 mg/g and 0·651 l/mg, respectively, at an adsorbent dose of 5 g/l and temperature of 26 ± 1°C. The mean free sorption energy was found to be 8·770 kJ/mol, indicating that the adsorption of fluoride onto F. glomerata bark adsorbent was by a chemisorption mechanism. The kinetic study also supported chemisorption, with the adsorption data fitting well with pseudo-second-order kinetic model. The thermodynamic study indicated the spontaneous and endothermic nature (ΔH° = 15 430·78 J/mol) of fluoride adsorption onto F. glomerata adsorbent. Field scanning electron microscopy and energy dispersive spectroscopy, Brunauer–Emmett–Teller analysis and Fourier transform infrared spectroscopy were used to analyse the surface morphology of the adsorbent before and after the fluoride adsorption process. Practical application of F. glomerata Roxb. biosorbent to a fluoride-contaminated groundwater sample showed encouraging results.

Fabrication of novel chitosan-g-PNVCL/ZIF-8 composite nanofibers for adsorption of Cr(VI), As(V) and phenol in a single and ternary systems

The chitosan-grafted-poly(N-vinylcaprolactam) (chitosan-g-PNVCL) nanofibers were synthesized via electrospinning method. ZIF-8 metal-organic frameworks nanoparticles were incorporated into the nanofibers for adsorption of Cr(VI), As(V) and phenol from water. The BET, FTIR, XRD and SEM analysis were carrfried out to obtain the characteristics of nanofibers. The optimum parameters of ZIF-8 content, pH, contact time, adsorbent dosage, and initial concentration of adsorbates on the Cr(VI), As(V) and phenol removal were studied. The reusability of synthesized nanofibers for five sorption-desorption cycles was also examined. The maximum experimental adsorption capacity of the chitosan-g-PNVCL/ZIF-8 nanofibers for Cr(VI), As(V) and phenol sorption were 269.2, 258.5 and 152.3 mg g−1, respectively under ZIF-8 concentration of 3 wt.%, adsorbent dosage of 0.5 g/L, pH of 3, equilibrium times of 30 min, and temperature of 25 °C. The kinetic, and isotherm parameters of adsorption process using chitosan-g-PNVCL/ZIF-8 nanofibers were evaluated. In ternary system, the central composite design was applied to investigate the interaction influence of initial concentrations of selected metal ions and phenol on the performance of nanofibrous adsorbent. The obtained results showed the high capability of nanofibers for the removal of heavy metals and organic pollutants from water.

Performances and behavior of a water-soluble and pH-sensitive polycarboxybetaine used for metal ion recovery

Zwiterionic functional groups give polycarboxybetaines a great ability to chelate copper and their use for metal ions recovery was suggested in previous studies. The use of a water-soluble and pH-sensitive polymer (polycarboxy-ethyl-3-aminocrotonate - PCEAC) was investigated for the removal of copper from aqueous solution. The equilibrium adsorption level was determined as a function of temperature, pH and initial adsorbate concentration. The good fit to the Langmuir model offered various information about copper uptake mechanisms. The maximal adsorption capacities were found to reach 253 ± 11 mg of copper per g of PCEAC at pH = 6. The thermodynamic parameters such as free energy, enthalpy and entropy changes for the adsorption of copper were computed to predict the nature of adsorption process. The removal of copper was varying from 2% to 97% depending on pH and initial copper concentration. A particular behavior of PCEAC at pH = 4 is discussed and explained by viscosity measurements as a particular conformation of the polymer. The effect of cadmium on copper adsorption was also tested. Some co-adsorption phenomena were observed at low cadmium concentrations ([Cd]/[Cu]≤1), while copper desorption in favor of cadmium adsorption were quantified at higher cadmium concentrations ([Cd]/[Cu]>1).

Adsorption-desorption of cypermethrin and chlorfenapyr on Jordanian soils

In this study, adsorption kinetic experiments were conducted on agricultural soil samples from Southern Jordan to investigate the adsorption behavior of the heavily used insecticide cypermethrin and the pesticide chlorfenapyr. Soil samples classified as sand and loamy sand with 1.77–2.02% organic matter content were collected from two locations within 0–30 cm depths in Tafilah, Jordan, and tested as adsorbents, and it was found that the adsorption of the two substances followed pseudo-second-order kinetics which implies that the adsorption process is chemisorption. The second-order rate constants were 1.01–2.03 g/mg h for cypermethrin and 11.38–13.03 g/mg h for chlorfenapyr. Adsorption isotherm experiments were also carried out at a constant temperature and variable initial adsorbate concentrations and it was found that the Langmuir model provided a slightly better fit to the adsorption data in comparison with the Freundlich model. The Langmuir maximum adsorption capacities were 8.88–9.08 mg/g for cypermethrin and 36.23–45.25 mg/g for chlorfenapyr while the Langmuir constants were 0.0123–0.0157 L/mg for cypermethrin and 0.003–0.0037 L/mg for chlorfenapyr. Higher adsorption rates were observed in the loamy sand soil due to the higher organic matter, clay, and silt contents. Nonetheless, it was concluded that the leaching potential of these substances to groundwater is low due to the physical nature of these chemicals as well as the adsorption behavior of the soil.

Micro-encapsulation and hydrothermal tuning of amine decorated magnetic alginate hybrid beads for nitrate and phosphate remediation

The magnetic iron oxide (Fe3O4)/alginate (Alg) (MAlg) composite beads were synthesized and utilized for the nitrate (NO3−) and phosphate (PO43−) retention. To enhance the functional behaviour and sorption capacity of MAlg composite beads, the amine groups were grafted to get the amine functionalized MAlg (AFMAlg) composite beads via, in situ precipitation (In situ) and hydrothermal (Hydro) techniques. The hydro assisted AFMAlg composite beads hold the unique advantages like high porous nature and large surface area than the other adsorbents prepared by in situ method for NO3− and PO43- removal. Several characterization studies such as XRD, FTIR, SEM, VSM, BET and EDAX analysis were explored. The parameters responsible for sorption process like contact time, solution pH, co-anions, adsorbent dosage, initial adsorbate concentration and temperature were optimized in batch scale. The nature of NO3− and PO43− sorption was verified by fitting the experimental data with various isotherms, kinetics and thermodynamic parameters. The field applicability and regeneration studies of the AFMAlg composite beads were also performed.