Defluoridation of Water Using Zirconium Impregnated Coconut Fiber Carbon

Abstract

In this study the applicability of Zirconium ion impregnated coconut fiber carbon (ZICFC) as an adsorbent for fluoride removal from water was investigated. The dependence of fluoride adsorption on the physicochemical properties includes pH, agitation time, adsorbent dosage, temperature, and the initial concentration of the adsorbate. Maximum defluoridation was obtained at an original pH value of 4.0 with a rapid 93% adsorption being achieved within 10 min of contact with ZICFC. Adsorption data for fluoride onto ZICFC were better correlated to the Langmuir isotherm and pseudo-second order chemical reaction provided the best fit for the experimental data as obtained from kinetic studies. A combination of chemisorption and physisorption processes in hand with intraparticle diffusion, account for the high defluoridation ability of ZICFC, with the thermodynamic parameters indicating an endothermic phenomenon. The fluoride adsorption capacity of ZICFC when compared with those of other commonly used fluoride adsorbents highlights the substantial improvement in fluoride adsorption capacity of coconut fiber carbon on zirconium impregnation.     

Removal of Fluoride from Aqueous Solution by CaO Nanoparticles

Abstract

Colloidal particles of CaO were synthesized by the sol-gel method. The particle morphology was characterized by FT-IR, TGA, DTA, and TEM analysis. The ability of the CaO nanoparticles for removal of fluoride from aqueous solution through adsorption has been investigated. All the experiments were carried out by batch mode. The effect of various parameters viz. contact time, pH effect (pH 2–10), adsorbent dose (0.01–0.1 g/100 ml), initial fluoride concentration (10–100 mg/l) and competitive ions has been investigated to determine the adsorption capacity of CaO nanoparticles. Almost complete removal (98%) of fluoride was obtained within 30 minutes at an optimum adsorbent dose of 0.6 g/L for initial fluoride concentration of 100 mg/L. The adsorption isotherm was also studied to find the nature of adsorbate-adsorbent interaction.     

Synthesis of graphene oxide decorated with strontium oxide (SrO/GO) as an efficient nanocomposite for removal of hazardous ammonia from wastewater

ABSTRACT

In this research, graphene oxide decorated with strontium oxide (SrO/GO) is introduced as a new adsorbent material for the efficient removal of ammonia from industrial wastewater. The new adsorbent was thoroughly studied in terms of morphology, crystallography and chemical composition using characterization techniques such as Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and zeta potential analysis. Several parameters such as pH, adsorbent dosage, contact time, and ammonia initial concentration were investigated and optimized. Ammonia adsorption onto SrO/GO was validated with kinetics and adsorption isotherms by adopting different models. The results revealed that ammonia adsorption kinetic was of pseudo-second order (R² = 0.999) implying that chemisorption behavior and the equilibrium isotherm follows Langmuir model. This behavior shows a high maximum monolayer sorption capacity of 90.1 mg g^?1 at pH equal to 7 and contact time of 120 min pointing out the synergism advantageous effect. The abundant oxygen functional groups on the graphene oxide surface and the integrated Sr-O nanoparticles could efficiently interact with ammonia species creating a surface for more favorable and efficient removal of ammonia.     

Equilibrium and Kinetic Studies for Fluoride Adsorption from Water on Zirconium Impregnated Coconut Shell Carbon

Abstract

The batch adsorptive fluoride removal from water by Zirconium ion impregnated coconut shell carbon (ZICSC) was investigated. ZICSC was found to have fluoride adsorption capacity, 25 to 30 times that of plain activated carbon. The effect of various parameters such as pH, agitation time, and adsorbent dosage on fluoride removal were studied. The fluoride adsorption by ZICSC was above 90% for the entire pH range of 2–9 and the adsorption rate was extremely rapid, with 91% of the adsorption being achieved within 10 min of ZICSC contact for an initial fluoride concentration of 10 mg/L. The experimental data have been analyzed by Langmuir, Freundlich, Redlich‐Peterson, and Temkin sorption isotherm models and the adsorption data for fluoride onto ZICSC were better correlated to the Langmuir isotherm. The batch adsorption kinetics have been tested by first order, pseudo‐first order, and pseudo‐second order kinetic models with the subsequent determination of the rate constants of adsorption. The comparison of ZICSC with other adsorbents suggests that ZICSC provides a cost‐effective working solution to the defluoridation problem in the developing countries by its great potential application in fluoride removal from water.     

Removal of fluoride ion from drinking water by a new Fe(OH)3/ nano CaO impregnated chitosan composite adsorbent

ABSTRACT

A novel adsorbent made of freshly obtained calcium oxide nanoparticles and ferric hydroxide dispersed in chitosan matrix (CHI-FCA) was prepared. Batch adsorption study was performed to analyze the effect of initial concentration, contact time, pH, and adsorbent dose on fluoride sorption on CHI-FCA. It was observed that maximum fluoride adsorption was achieved at pH 7.10 at an optimum equilibrium contact time of 180 min with an adsorbent dose of 8 g/L. Moreover, a synergistic effect was observed for fluoride remediation from aqueous medium. FTIR, XRD, DLS, TGA, DTA, and ESEM with EDX analysis were performed for the investigation reported here.     

Enhanced removal of naproxen from wastewater using silica magnetic nanoparticles decorated onto graphene oxide; parametric and equilibrium study

The present study describes the synthesis of silica and magnetic nanoparticle-decorated graphene oxide (GO-MNPs-SiO₂) and its application as an adsorbent for the removal of naproxen from wastewater. Nanocomposite was characterized utilizing FT-IR spectroscopy, FESEM microscopy, EDX and XPS spectroscopy. Under the optimum conditions, a high adsorption capacity (31 mg g^?1) was obtained toward naproxen at pH 5. The adsorption process was evaluated using isotherms; the Freundlich isotherm suggested a multilayer adsorption pattern for naproxen. Free energy confirmed a physisorption mechanism between naproxen and adsorbent. Lastly, the field application was performed in wastewater which obtained high removal efficiency percentages (83–94%).     

Defluoridation performance and mechanism of nano‐scale aluminum oxide hydroxide in aqueous solution

BACKGROUND: The present study has concentrated on investigating the fluoride removal potential of nano‐scale aluminum oxide hydroxide (nano‐AlOOH). A series of batch adsorption experiments were carried out to assess parameters that influence the adsorption process. The different parameters investigated include the effect of contact time, initial fluoride concentration, adsorbent dose, pH of the solution and co‐existing anions. RESULTS: Most of the adsorption took place during the first 30 min and kinetic and equilibrium adsorption data show that the process obeys a pseudo‐second‐order kinetic equation and the Langmuir adsorption model. The fluoride removal efficiency is greater than 90% between pH 6 and 8 and decreases as pH values increase to 11. The presence of SO₄^2? or PO₄^3? in aqueous solution was found to reduce the fluoride uptake. Desorption studies showed that the fluoride can easily be desorbed at pH 13. CONCLUSION: Nano‐AlOOH possesses a maximum fluoride capacity of 3259 mg F^? kg^?1, which is comparable with that of activated alumina. Maximum adsorption occurred at around pH 7, which makes nano‐AlOOH a potential adsorbent for drinking water treatment. Copyright © 2009 Society of Chemical Industry     

Comparative study of methylene blue dye adsorption onto activated carbon,graphene oxide,and carbon nanotubes

Three different carbonaceous materials, activated carbon, graphene oxide, and multi-walled carbon nanotubes, were modified by nitric acid and used as adsorbents for the removal of methylene blue dye from aqueous solution. The adsorbents were characterized by N₂ adsorption/desorption isotherms, infrared spectroscopy, particle size, and zeta potential measurements. Batch adsorption experiments were carried out to study the effect of solution pH and contact time on dye adsorption properties. The kinetic studies showed that the adsorption data followed a pseudo second-order kinetic model. The isotherm analysis indicated that the adsorption data can be represented by Langmuir isotherm model. The remarkably strong adsorption capacity normalized by the BET surface area of graphene oxide and carbon nanotubes can be attributed to π–π electron donor acceptor interaction and electrostatic attraction.     

Adsorptive removal of fluoride using polymer-modified ceria nanoparticles: determination of equilibrium,kinetic and thermodynamic parameters

ABSTRACT

Polyaniline/Ceria nanocomposite is prepared in two steps: CeO₂ by gel combustion method and it’s polymer nanocomposite by in situ polymerization. The as-synthesized nanocomposite is characterized by X-Ray Diffractometer, Scanning Electron Microscopy, Brunauer–Emmett–Teller technique, etc. Its efficacy in adsorptive removal of fluoride in water is investigated by the batch method under various experimental conditions including contact time, pH, initial concentration, temperature, etc. The maximum adsorption capacity is obtained at neutral pH within 1 h. The adsorption kinetics data is well fitted into the pseudo-second order model and Langmuir model. The results of the adsorption thermodynamic study evidenced a spontaneous, exothermic and entropy-driving adsorption process.     

铁铝复合氧化物吸附砷氟性能实验研究

采用共沉淀法制备了复合铁铝氧化物吸附剂,并对其表面ξ电位和砷氟共存时除砷氟性能进行了初步研究。ξ电位表明铁铝复合氧化物pHzpc在9.0附近;铁铝复合氧化物对砷氟共存溶液中As(V)和F-均表现出很强的吸附能力,决定F-的去除率的是铝含量;该吸附剂对砷氟共存溶液As(V)在广谱pH范围内具有很高的去除能力,对F-在pH为6~7之间时去除率最高;砷氟共存溶液中As(V)对F-具有竞争吸附作用。     

Application of graphene-based adsorbents in the treatment of dye-contaminated wastewater; kinetic and isotherm studies

The adsorption of methylene blue (MB) on graphene-based adsorbents was tested through the batch experimental method. Two types of graphene-based adsorbents as graphene oxide (GO) and reduced graphene oxide (RGO) were compared to investigate the best adsorbent for MB removal. So that optimizing the MB removal for the selected type of graphene-based adsorbent, the diverse experimental factors, as pH (2–10), contact time (0–1440 min), adsorbent dosage (0.5–2 g/L), and initial MB concentration (25–400 mg/L) were analyzed. The conclusions indicated that the MB removal rised with an increase in the initial concentration of the MB and so rises in the amount of adsorbent used and initial pH. Maximum dye removal was calculated as 99.11% at optimal conditions after 240 min. Adsorption data were compiled by the Langmuir isotherm (R²: 0.999) and pseudo-second-order kinetic models (R²: 0.999). The Langmuir isotherm model accepted that the homogeneous surface of the GO adsorbent covering with a single layer. And the adsorption energy was calculated as 9.38 kJ mol⁻¹ according to the D-R model indicating the chemical adsorption occurred. The results show that GO could be utilized for the treatment of dye-contaminated aqueous solutions effectively.     

Kinetic and Equilibrium Study for the Fluoride Adsorption using Pyrophyllite

Batch adsorption study was carried out to remove excess fluoride from water using pyrophyllite. Result showed that adsorption of fluoride was rapid in first 20 min and thereafter increased slowly to reach the equilibrium in about 2 hrs. About 85% removal efficiency was obtained within 2 hrs at an adsorbent dose of 4 g/L for initial fluoride concentration of 10 mg/L. Maximum fluoride adsorption takes place at pH 4.9. Thermodynamic parameters such as Gibb's free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) changes were determined for the adsorption process. Negative ΔH° value signified that the adsorption process was exothermic in nature. From the kinetic study it was found that fluoride adsorption by pyrophyllite followed pseudo-second-order kinetics with an average rate constant of 0.92 g/mg · min. Intraparticle diffusion model was studied to determine the rate limiting step of the adsorption process. The system followed the Langmuir isotherm with maximum adsorption capacity of 2.2 mg/g of fluoride.     

Removal of Fluoride from Contaminated Drinking Water using Unmodified and Aluminium Hydroxide Impregnated Blue Lime Stone Waste

Abstract

The adsorption of fluoride on lime stone (LS) and aluminium hydroxide impregnated lime stone (AlLS) was investigated using a batch adsorption technique. A series of experiments were under taken in an agitated batch adsorber to assess the effect of the system variables such as solution pH, dye concentration and temperature. Removal of fluoride was observed to be the most effective at pH 8. The langmuir and Freundlich isotherm models were applied to the equilibrium data. The results showed that the Freundlich equation fits better than the Langmuir equation. The maximum sorption capacities for the LS and AlLS adsorbents were found to be 43.10 mg/g and AlLS 84.03 mg/g respectively. The FTIR studies indicate that the adsorption of fluoride is physiorption. The adsorption of fluoride onto AlLS proceeds according to a pseudo-first-order model. The results reveal that the LS and AlLS can be economical for the removal of fluoride compared to many other expensive adsorbents.     

Graphene oxide & reduced graphene oxide polysulfone nanocomposite pellets: An alternative adsorbent of antibiotic pollutant-ciprofloxacin

Efficient nanocomposites, GO-Psf and RGO-Psf has been synthesised from polysulfone and graphene oxide. The synthesised nanomaterials were characterised using contact angle measurements, SEM, TEM, XRD, TGA, DSC, Raman and FT-IR analytical techniques. The reported polymeric nanomaterials are attractive due to their high surface area and thermal stability. The maximum adsorption capacity for ciprofloxacin is 82.781 mg/g and 21.486 mg/g on GO-Psf and RGO-Psf, respectively. The kinetic and adsorption analysis identifies the nanomaterials as attractive adsorbents for removal of antibiotic pollutant, ciprofloxacin from aqueous solution.     

Performance of Unmodified Paper Solid Waste for Cadmium Removal From Aqueous Phase: Equilibrium and Kinetic Studies

The reuse of paper solid waste (PSW) as a low-cost sorbent for Cd removal from aqueous phase was investigated. Batch experiments were conducted to study the effects of pH (3.5, 5.5, 7.5), contact time (10–360 min), PSW dose (2.5–20 g L^?1), and Cd concentration (5–50 mg L^?1) at an ionic strength of 0.01 M NaNO₃ on adsorption efficiency and capacity. Cd removal of ～96% occurred in 20 mg L^?1 Cd solution at pH 5.5 containing 20 g L^?1 PSW. Equilibrium was attained after 120 min and the equilibrium adsorption capacity of PSW increased with increasing Cd concentration from 5 to 50 mg L^?1. The kinetic process of Cd adsorption obeyed the pseudo-second-order kinetic model. Langmuir and Freundlich models described equally well the experimental data and the maximum adsorption capacity was 4.89 mg g^?1. PSW can be used for reducing Cd concentration in Cd-contaminated water systems.     

EMF measurements of cells employing metal—metal oxide electrodes in aqueous chloride and sulphate electrolytes at temperatures between 25–250°C

EMF measurements are reported on chemically prepared platinum—platinum oxide, iridium—iridium oxide, rhodium—rhodium oxide and zirconium—zirconium oxide electrodes over a temperature range of 25–250dgC and a pH range of 1–12 using chloride and sulphate aqueous electrolytes. The effects of temperature, pressure, concentration and time are discussed. The platinum—platinum oxide electrode is shown to have an apparent oxygen and sulphate response at 25°C in concentrated sulphuric acid. A less than ideal pH response is observed for all the oxide electrodes in air-equilibrated solutions. Electron microscopic studies provided information on the nature of the electrode surface.     

EFFECT OF TEMPERATURE ON THE ADSORPTION OF METHYLENE BLUE DYE ONTO SULFURIC ACID–TREATED ORANGE PEEL

The present study explains the preparation and application of sulfuric acid–treated orange peel (STOP) as a new low-cost adsorbent in the removal of methylene blue (MB) dye from its aqueous solution. The effects of temperature on the operating parameters such as solution pH, adsorbent dose, initial MB dye concentration, and contact time were investigated for the removal of MB dye using STOP. The maximum adsorption of MB dye onto STOP took place in the following experimental conditions: pH of 8.0, adsorbent dose of 0.4 g, contact time of 45 min, and temperature of 30°C. The adsorption equilibrium data were tested by applying both the Langmuir and Freundlich isotherm models. It is observed that the Freundlich isotherm model fitted better than the Langmuir isotherm model, indicating multilayer adsorption, at all studied temperatures. The adsorption kinetic results showed that the pseudo-second-order model was more suitable to explain the adsorption of MB dye onto STOP. The adsorption mechanism results showed that the adsorption process was controlled by both the internal and external diffusion of MB dye molecules. The values of free energy change (ΔG ^o) and enthalpy change (ΔH ^o) indicated the spontaneous, feasible, and exothermic nature of the adsorption process. The maximum monolayer adsorption capacity of STOP was also compared with other low-cost adsorbents, and it was found that STOP was a better adsorbent for MB dye removal.     

Adsorption and diffusion of cesium ions in zirconium(IV) iodomolybdate exchanger

Tetravalent metal acid (TMA) salt zirconium(IV) iodomolybdate ion exchanger was chemically synthesized under different conditions and subjected into batch reactor for cesium removal investigation. The properties of synthesized exchangers were characterized using X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Data revealed that the prepared beads are amorphous in nature and thermally stable up to 350 °C. The influences of contact time, pH, ionic strength, and organic acids were investigated. Results illustrated that cesium uptake reached equilibrium within 2 h and it is strongly dependent on ionic strength and nearly independent of pH values. Speciation of cesium ions and their ability to form ternary complexes less adhered to the applied exchangers predominate their adsorption behavior. The prepared exchangers had a good ion-exchange capacity ranged from 7.94 to 9.62 mmol g⁻¹.     

Thermodynamic and kinetic studies of crystal violet dye adsorption with poly(methyl methacrylate)–graphene oxide and poly(methyl methacrylate)–graphene oxide–zinc oxide nanocomposites

We successfully prepared poly(methyl methacrylate) (PMMA)–graphene oxide (GO) and PMMA–GO–zinc oxide (ZnO) nanocomposites and characterized them using different techniques. The adsorption performances of the as-prepared composites were investigated for crystal violet (CV) dye removal. The contact time as a main factor affecting the adsorption process by adsorbents was studied. Because the adsorption capacity value for CV was found to show no extensive changes after 35 min, 35 min was selected as the best contact time for our system. The adsorption results revealed that the best capacity of CV adsorption onto the PMMA–GO and PMMA–GO–ZnO nanocomposites occurred at pH 12 and 298 K. The respective entropies (−0.208 and −0.168 kJ mol⁻¹ K⁻¹) and enthalpies (−72.86 kJ/mol, and −55.54 kJ/mol) for PMMA–GO and PMMA–GO–ZnO and Gibbs energy revealed that the process of adsorption was exothermic. In addition, the Elovich, pseudo-first-order, intraparticle diffusion, and pseudo-second-order (four types) models were applied to our kinetic study. Our results indicate that CV adsorption onto PMMA–GO and PMMA–GO–ZnO was good with the pseudo-second-order (type 1) and pseudo-first-order models because of the low χ² value and the high correlation coefficient value. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47495.     

Removal and recovery of fluoride from wastewater by crystallization: effect of aluminum

The effect of aluminum on the treatment of fluorine-containing synthetic wastewater by crystallization was investigated. The results showed that the optimal conditions for fluoride removal were found at pH 7.2–10.5, and at an aluminum concentration of 80–700 mg/L. During operation of the fluidized bed reactor, the effluent fluoride concentration was 13–25 mg/L at an influent aluminum concentration of 80–150 mg/L. The recovered pellets matched well with the national standard of fluorspar in China (GB19321-88). It was feasible to recover calcium fluoride from fluorine and aluminum-containing wastewater by crystallization.