Adsorption Properties For Cr Research Articles

Efficient removal of Congo Red by carbonized Ganoderma lucidum spore with Fe3O4

In this study, a biomass carbon magnetic adsorbent (Fe3O4@GLSM) was prepared by using carbonized G. lucidum spores and Fe3O4 nanoparticles. Scanning and transmission electron microscopy proved that the G. lucidum spores after carbonization (GLSM) have hollow cage structure and increased surface depression. X-ray diffraction, X-ray photoelectron spectroscopy, and vibrating sample magnetometer analysis demonstrated that magnetic Fe3O4 nanoparticles were successfully loaded on GLSM. We have investigated the affective adsorption factors of contact time, pH, and adsorbent dose on the adsorption properties of CR from aqueous solution. Adsorption process is less affected by acidity and alkalinity and can reach to adsorption equilibrium. The maximum Fe3O4@GLSM adsorption capacity is 58.4 mg. The kinetic data for the adsorption of CR were well fitted by the pseudo-second-order kinetic equation. The intra-particle diffusion model showed that the adsorption involved surface adsorption followed by diffusion. Freundlich isotherm models provided a more accurate representation of sorption isotherms than Langmuir model. The adsorption thermodynamics (ΔGθ, ΔHθ and ΔSθ) established that CR adsorption onto Fe3O4@GLSM was spontaneous and feasible. This novel magnetic biomass adsorbent can potentially serve as an effective method for removing and rapidly separating pollutants in wastewater treatment.

Artificial neural network approach to model Cr(III) and Cr(VI) adsorption by NCS, ACS and BCS

Adsorption properties of Cr(III) and Cr(VI) on natural (NCS), acid-activated (ACS) and base-activated (BCS) cherry stalks (CS) in Isparta were investigated in aqueous solutions. Batch adsorption studies had been completed with different initial chromium concentrations, pH, temperature, time and biosorbent dosage. Adsorption rapidly approached an equilibrium state between 10 and 60 min. The results displayed that the adsorption system was suitable for pseudo-second-order kinetics. Equilibrium isotherms (Langmuir, Freundlich and Dubinin–Radushkevich) were measured experimentally. The retention characteristics of Cr(III) onto NCS, ACS and BCS and Cr(VI) onto ACS were represented by Langmuir adsorption isotherms, while Cr(VI) ions onto NCS and BCS were compatible with Freundlich adsorption isotherms. The adsorption process was endothermic accompanied by a decrease in entropy and Gibbs energy. An artificial neural network (ANN) model was improved to estimate the efficiency of Cr(III) and Cr(VI) ion’s adsorption. The ANN model can predict the behaviour of the Cr(III) and Cr(VI) ion's adsorption under different circumstances. The results have shown that NCS, ACS and BCS biosorbents open up new possibilities and potential commercial uses in the cherry stalks.

High-Efficiency Adsorption of Cr(VI) and Mn(VII) from Wastewater by a Two-Dimensional Copper-Based Metal-Organic Framework.

Cr(VI) and Mn(VII) in industrial wastewater have certain toxicity, and they pose a threat to the environment and human health and safety. Metal-organic frameworks (MOFs) usually have rich adsorption sites and a large specific surface area. They can effectively adsorb Cr(VI) and Mn(VII) from wastewater. In this paper, a two-dimensional copper-based metal-organic framework, {[Cu·(4,4'-bpy)2·(H2O)]·2(NO3)·6(H2O)·(CH3OH)}n (1), is synthesized by hydrothermal synthesis. The structure of 1 is characterized by Fourier transform infrared (IR) spectroscopy, single-crystal X-ray diffraction, element analysis, and X-ray photoelectron spectroscopy (XPS). The results showed that 1 had a two-dimensional network structure, and the specific surface area of the nanostructure was 67.63 m2/g. The nanostructure of 1 could efficiently adsorb Cr(VI) and Mn(VII) from wastewater. The adsorption properties of Cr(VI) and Mn (VII) of 1 showed that the optimal concentration of both adsorbents was 0.2 g/L. It has good adsorption performance in the pH range 4-8. The adsorption performance is the best when pH is 7, which can reach 145 and 83 mg/g, respectively.

Study on the Adsorption Properties of Cr(VI) by Biochar with Different Treatments

The paper investigated the adsorption of Cr(VI) on biochar in simulated wastewater by static adsorption method, Fourier Transform Infrared spectra (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and transmission electron microscope (TEM) characterization analysis. The results show that biochar can effectively remove Cr(VI) in wastewater, and the adsorption equilibrium can be quickly reached within 100 min. The kinetic analysis shows that the quasi-second-order kinetic model can better fit the kinetic process of Cr(VI) adsorption by biochar, which shows that the main mechanism of the adsorption is the chemical bonding cooperation between Cr(VI) and the functional groups on the surface of biochar. Fit analysis of the isotherm at different temperatures shows that temperature increase promotes the adsorption of Cr(VI) on biochar, and thermodynamic analysis reveals that the adsorption of Cr(VI) on biochar is a spontaneous endothermic process. The Freundlich model effectively fits the adsorption isotherm of Cr(VI), indicating that the surface of biochar is uneven and Cr(VI) has undergone multilayer adsorption. The adsorption isotherm of Cr(VI) under the influence of HA and FA can be effectively fitted by the Freundlich model, and the adsorption efficiency is the highest when FA is added. The national analysis of Fourier Transform Infrared spectra (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and transmission electron microscope (TEM) further reveals the bond cooperation between Cr(VI) and the surface functional groups of biochar. The results show that biochar has potential application value in treating chrome-containing wastewater.

Valorisation of Lignocellulosic Wastes, the Case Study of Eucalypt Stumps Lignin as Bioadsorbent for the Removal of Cr(VI).

The main objective of this work was to assess Eucalyptus globulus lignin as an adsorbent and compare the results with kraft lignin, which has previously been demonstrated to be an effective adsorbent. Eucalypt lignin was extracted (by the dioxane technique), characterised, and its adsorption properties for Cr(VI) ions were evaluated. The monomeric composition of both types of lignin indicated a high content of guaiacyl (G) and syringyl (S) units but low content of p-hydroxyphenyl (H), with an H:G:S ratio of 1:50:146 (eucalypt lignin) and 1:16:26 (kraft lignin), as determined by Py-GC/MS. According to elemental analysis, sulphur (2%) and sodium (1%) were found in kraft lignin, but not in eucalypt lignin. The adsorption capacity of the eucalypt lignin was notably higher than the kraft lignin during the first 8 h, but practically all the ions had been absorbed by both the eucalypt and kraft lignin after 24 h (93.4% and 95%, respectively). Cr(VI) adsorption onto both lignins fitted well using the Langmuir adsorption isotherm model, with capacities of 256.4 and 303.0 mg/g, respectively, for eucalypt and kraft. The study’s overall results demonstrate the great potential of eucalypt lignin as a biosorbent for Cr(VI) removal from aqueous solutions.

Preparation of orange peel loaded Zn/Al-HT and its adsorption for Cr(VI) in water

The orange peel loaded Zn/Al Hydrotalcite (Zn/Al-HT) was prepared by coprecipitation method. The effects of calcination temperatures, initial concentrations and pH on the adsorption properties of Cr(VI) were investigated, and the results showed that the calcined orange peel loaded Zn/Al-HT at 300°C(Mod2-LDO-300) had best removal rate of Cr(VI), it can be 96%, and the adsorption capacity is 38.5-106.2mg/g in the range of Cr (VI) initial concentration of 20-80mg/L. The Mod2-LDO-300 has a good adsorption effect at pH 2-8. It is a kind of environmental protection and industrial adsorption material.

Al‐Li Alloy Chemical Milling Waste Solution Synthesis of γ‐AlOOH Bundles for Cr(VI) Rapid Adsorption

AbstractAl‐Li alloy chemical milling waste solution (AlCM) was utilized for the first time to prepare γ‐AlOOH(boehmite) as highly efficient adsorbent for Cr(VI). The NaAlO2 in AlCM reacted with H2O2 at room temperature for 0.25 h to prepare porous γ‐AlOOH bundles with the specific surface area of 232.2 m2 g‐1. The possible growth mechanism of γ‐AlOOH under CTAB and time was proposed. The kinetics and adsorption properties of Cr(VI) adsorbed by γ‐AlOOH were also investigated. The porous γ‐AlOOH bundles can quickly adsorb Cr(VI) within 20 minutes and show stable recyclability. This study shows that it is a cost‐effective way to treat and recycle AlCM that the γ‐AlOOH is synthesized from AlCM as an adsorbent to remove Cr (VI) heavy metals in wastewater.

Highly Efficient Removal of Cr(VI) from Aqueous Solutions by Polypyrrole/Monodisperse Latex Spheres.

Pyrrole (Py) is easily agglomerated during the polymerization process, affecting its performance. In this paper, polypyrrole/monodispersed latex sphere (PPy/MLS) composites were prepared using in-situ polymerization for the adsorption of hexavalent chromium (Cr(VI)). The specific surface area of PPy/MLS (39.30 m2/g) was increased relative to that of PPy (24.82 m2/g), thus providing more effective adsorption sites. In addition, the adsorption properties of Cr(VI) under different conditions, including Py content, pH of the aqueous solution, and PPy/MLS dosage, were investigated to reveal the adsorption mechanism. The results showed that PPy/MLS possessed high Cr(VI) adsorption capacities when the Py content was 50 wt %. The maximum adsorption capacity was 343.64 mg/g at pH 2.0 and 25 °C. Remarkably, the adsorbents exhibited an excellent removal rate of Cr(VI) after three cycles of adsorption–desorption (over 99%), suggesting that the adsorbents had exceptional recyclability. Furthermore, the adsorption process followed quasi-second-order kinetics and Langmuir isothermal adsorption model. The high adsorption performance, sustainability, and cost-efficiency make this adsorbent a promising candidate for large-scale Cr(VI) contaminant removal.

Effect of Flower‐Like and Spherical Nanostructured MoS2 on the Adsorption Properties of Cr(VI) Ions

AbstractMoS2 nanostructures with different morphologies were synthesized using a simple in‐situ hydrothermal process by different surfactants like hexadecyl trimethyl ammonium bromide (CTAB) and polyvinyl pyrrolidone (PVP), and the effect of morphologies on the adsorption property for Cr(VI) were investigated. It can be found that flower‐like and spherical MoS2 nanostructures were synthesized and their morphologies largely effected the adsorption performance toward Cr(VI) ions. Flower‐like MoS2 exhibited the surface area of 41.9 m2 g−1 with fairly high adsorption capacity of 66.1 mg g−1 toward Cr(VI), fitting well to pseudo‐second order kinetic model and Langmuir isotherm model. Moreover, this as‐prepared nanostructured MoS2 also presented satisfying reusability for removal of Cr(VI) and were even suitable for the selective removal of Cr(VI) in the presence of NO3−. It may provide a potential route to enhance the adsorption property of MoS2 toward heavy metal ions through adjusting the morphology of the MoS2 sample, which would expand the applications of MoS2 in the field of treatment of the heavy metal wastewater.

Novel functional fiber loaded with carbon dots for the deep removal of Cr(VI) by adsorption and photocatalytic reduction

A novel functional fiber (PAN-CDs) loaded with carbon dots (CDs) with excellent photoreduction and adsorption properties for Cr(VI) was prepared via an amidization reaction between the CDs' carboxyl groups and amine groups on polyacrylonitrile (PAN)-based ion exchange fibers, which could completely preserve the fluorescence properties of the CDs. The photoluminescence (PL), photocatalysis and adsorption properties of PAN-CDs were characterized and analyzed. The PAN-CDs possess high adsorption capacity (297.6 mg/g) and excellent kinetic behavior (attaining adsorption equilibrium in 30 min) for Cr(VI) adsorption. Furthermore, the residual Cr(VI) (approximately 3 mg/L) after adsorption could be removed completely by subsequent photoreduction by the PAN-CDs. The Cr-saturated PAN-CDs could be easily separated by filtering and regenerated, with no observable decay of removal efficiency after five regeneration cycles. In addition, due to the PL quenching action of Cr(VI), the PAN-CDs can also be used as sensor for quantitative detection of trace Cr(VI) in aqueous solution.

Kinetic and Thermodynamic Adsorption of Cr(VI) onto Dried Oscillatoria Splendida in Aqueous Solution

Kinetic and thermodynamic adsorption study of Cr(VI) ion in aqueous solutions by dried Oscillatoria Splendida biomass was investigated in the batch system. The Oscillatoria Splendida was isolated and cultured from algae swamp ecosystem in South Sumatera. The adsorption properties of Cr(VI) onto dried Oscillatoria Splendida biomass was studied by the influences of contact time, initial Cr(VI) ion concentration and temperature of reaction. The experimental results were the rate of adsorption followed the second-order kinetic model with the rate of reaction k2 is 0.00181 mg g-1 min-1 and the adsorption thermodynamic agree to the Langmuir’s model with amount of Cr(VI) removed from aqueous solution increased with increasing Cr(VI) concentration with the higher adsorption energy was 8.46 kJ/mol at 50 °C.

Research on the Evaluation Method of Cr(VI) Migration Parameters in Topsoil and Its Application

ABSTRACTCr(VI) is a characteristic soil and groundwater contaminant in the chromite ore processing residue (COPR) disposal regions. Investigation of Cr(VI) adsorption and migration characteristics in topsoils has great significance for the supervision of contaminated sites. The methods of adsorption and soil column leaching experiments were used to study Cr(VI) migration characteristics in this research, and a Cr(VI) contaminated site in Hanqingba region of Baotou was chosen as the study area. Based on the adsorption experiment results, the soil adsorption properties of Cr(VI) were interpreted by the Langmuir and Freundlich adsorption isotherm, and the saturation adsorption capacity of the soil sample for Cr(VI) was 70.4 mg/kg. Cr(VI) migration characteristic in the soils was studied through the tracer and migration experiments. The permeability coefficient of the soil sample was 0.059 m/d, and the dispersion coefficient was 0.0371 cm2/s. The breakthrough curves of Br and Cr(VI) showed that the retardation effect of Cr(VI) in the soil was not obvious, and the computed retardation factor was 2.39. Under the circumstances of precipitation or irrigation, Cr(VI) in the COPR could be leached out, and the groundwater may be polluted for the weak soil adsorption capacity of Cr(VI). The research results could provide scientific support for the soil and groundwater pollution prevention and control plan of local government.

Chromium(VI) removal from aqueous medium by maize cane and agave bagasse biomasses

ABSTRACTChromium(VI) is a major water pollutant from industrial effluents whose concentration is to be reduced within the permissible limits. In this paper, the use of maize cane and agave bagasse as inexpensive adsorbent for the removal of Cr(VI) from aqueous solutions is considered. In the first place, they were conditioned and characterized to determine their physicochemical properties with scanning electron microscopy; the elemental composition with energy-dispersive x-ray spectroscopy (EDS); the principal functional groups with Fourier transform infrared spectroscopy; thermal stability with thermogravimetric analysis; and surface properties by specific surface hydration kinetics, point of zero charge determination by mass titration, and active site density are described. In the second place, their adsorption properties for Cr(VI) from aqueous solution were evaluated in a batch system. The kinetics of Cr(VI) sorption with both natural adsorbents were described with a pseudo-second-order model. Equilibrium data were found to be best represented for both adsorbents by the Freundlich isotherm model. Maize cane and agave bagasse can be effectively used as an adsorbents for the removal of Cr(VI) ions from the aqueous solution.

Effect of Temperature on Microstructure and Cr(VI) Adsorption Capacity of MgAl Metal Oxides

The adsorption properties of Cr(VI) on the double oxides(LDO) from calcined MgAl hydrotalcites(LDH) were investigated. The effect of temperature on the adsorption performances of the LDO was studied,and the adsorption kinetics and thermodynamics were studied at different adsorption temperatures. The samples were characterized by XRD and FT-IR to clarify the adsorption mechanism.The results indicated that CrO4 2– had intercalated into the interlayer structures of Mg-Al hydrotalcites. Moderately increasing temperature was beneficial for the reconstruction of LDH crystalline structure from LDO. In the temperature range of 20℃–60℃,adsorption capacity of the LDO was increased with temperature rising,it reached 91 mg/g in the temperature range from 50℃to 60℃. The experimental data were well fit to the Langmuir equation. The negative values of ΔGo indicated that the adsorption process was spontaneous,and positive values of ΔHo and ΔSo showed the endothermic and entropy-increasing nature of the process. The adsorption was consistent with the pseudo-second order kinetic model. The active energy value was 20.04 kJ/mol,which implying that the internal diffusion was the rate-determining step in the chemical adsorption.

Investigation on the adsorption properties of Cr(vi) ions on a novel graphene oxide (GO) based composite adsorbent

In this study, we prepare a polyethyleneimine (PEI) and graphene oxide (GO) composite adsorbent through an amidation reaction between the amine groups of the PEI and the carboxyl groups of the GO.

Adsorption of hexavalent chromium from aqueous solutions by graphene modified with cetyltrimethylammonium bromide

In this study, cetyltrimethylammonium bromide was chosen to modify graphene, which was prepared using a modified Hummers’ method. The characteristics of graphene and modified graphene were characterized by X-ray diffraction, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. The effect factors including pH, contact time, temperature, and dosage on the adsorption properties of Cr(VI) onto graphene and modified graphene were investigated. Batch experiments were conducted to evaluate the adsorbance of Cr(VI) from aqueous solution using graphene and modified graphene as the adsorbent under different conditions. The results revealed that the optimal pH for the adsorption was about 2, and the best suitable temperature was at 293K. The adsorption processes were rapid within the first 5min and reached equilibrium in about 40min. The adsorption kinetics fitted well with pseudo-second-order model. The adsorption capacity of Cr(VI) on modified graphene inferred from the Langmuir model was 21.57mg/g at 293K. The thermodynamic parameters indicated that the adsorption of Cr(VI) onto modified graphene was an exothermic and spontaneous process.

Preparation of Activated Carbon from Blue Coke Powder and its Adsorption Properties of Cr(VI)

Activated carbon was prepared from blue coke powder by physical activation. The results show that the specific surface area (BET) is 697.05m2/g, the total pore volume is 0.4569cm3/g and the average pore size is 2.6221nm. The adsorption properties of Cr( ) onto blue coke powder activated carbon are discussed from the kinetics and thermodynamics viewpoints. The pseudo-second-order kinetic model shows the best correlation with experimental data. Langmuir and Freundlich models are used to fit the equilibrium, and it is indicated that Freundlich best fits these data. The adsorption of Cr( ) onto blue coke powder activated carbon is found to be an endothermic process in nature.

Preparation and characterization of a novel xanthated chitosan

A novel xanthated chitosan derivative was prepared by the chemical reaction of CS 2 under alkaline conditions. Spectroscopic studies like FTIR, 13C NMR, TGA and XRD, SEM, and EPR were used for its characterisation. The chemically modified chitosan (CMC) was evaluated for its adsorption properties for Cr(VI). For a 100 mg/L solution of Cr(VI), the uptake of Cr(VI) by CMC at pH 3, was found to be much enhanced (71 mg/L) compared to the control chitosan (49 mg/L). The CMC can be a potential adsorbent for tannery wastewater treatment.

The Kinetics and Thermodynamics of Sorption of Chromium(VI) onto the Iron(III) Complex of a Carboxylated Polyacrylamide-Grafted Sawdust

A novel adsorbent was prepared and its adsorption properties for Cr(VI) were studied. The iron(III) complex of a carboxylated polyacrylamide-grafted sawdust has been found to be an effective adsorb...