Adsorption of Co2+ by Oxides from Aqueous Solution

1972 ◽  
Vol 50 (11) ◽  
pp. 1642-1648 ◽  
Author(s):  
P. H. Tewari ◽  
A. B. Campbell ◽  
Woon Lee
Keyword(s):  
Solution Ph ◽  
Langmuir Adsorption ◽  
Adsorption Sites ◽  
Wide Range ◽  
Saturation Coverage ◽  
Endothermic Process ◽  
Adsorption Of Co ◽  
Adsorption Of Co2 ◽  
Hydrolysis Of ◽  
Marked Dependence

The adsorption of Co(II) by Fe3O4, Al2O3, and MnO2 has been studied as a function of Co(II) concentration, solution-pH, and temperature. It is observed that the adsorption of cobalt increases markedly with the solution pH between pH 5 and 7.5. Above pH 8 adsorption becomes increasingly masked by precipitation of Co(OH)2 and no resolution of these two contributions to the loss of Co(II) from solution is possible. A log θ/(1–θ) vs. pH plot is found to be linear between pH 5 and 7.5, where θ is the fraction of occupied adsorption sites. The presence of 0.1 m Ba2+ and Mg2+ in the solution does not seem to affect the hydrogen ion dependence of the adsorption of Co(II) on alumina.The adsorption results have been analyzed by the Langmuir adsorption isotherm over a wide range of Co(II) concentration (10−6–10−3 m). The adsorption of Co(II) is found to be an endothermic process and increases markedly with temperature between 30 and 100 °C. The heat of adsorption decreases with increasing surface coverage of the oxides. At saturation coverage, the heats of adsorption for Co(II) on Al2O3, MnO2, and Fe3O4 are −14.9, −14.3, and −6.3 kcal/mol, respectively. Hydrolysis of Co(II) is suggested as a possible mechanism for the marked dependence of adsorption on pH and temperature.

Study on Fluoride, Iron and Manganese Removal from Aqueous Solutions by a Novel Composite Adsorbent

2013 ◽  
Vol 821-822 ◽  
pp. 1085-1092
Author(s):  
Chi Zhu ◽  
Shui Wang ◽  
Kai Ming Hu ◽  
Wei Xia Wang ◽  
An Juan Cai ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
The Novel ◽  
Solution Ph ◽  
Composite Adsorbent ◽  
Langmuir Adsorption ◽  
First Order ◽  
Manganese Removal ◽  
Adsorption Capacities ◽  
Endothermic Process ◽  
Iron And Manganese

Batch test had been carried out to determine the potential and the effectiveness of the novel composite adsorbent in removal of fluoride, iron and manganese from aqueous solution. It was found that the composite adsorbent could effectively not only remove Fe (II) and Mn (II) also fluoride from water, the maximum adsorption capacities for F-, Fe (II) and Mn (II) were 4.09mg·g-1 4.00mg·g-1 and 3.50mg·g-1 respectively. Kinetics data obtained for the adsorption process fitted the Lagergren First-order equation. The Langmuir adsorption isotherm was found to fit the experimental data derived from F- (R2= 0.9992), Fe (II) (R2=0.9858) and Mn (II) (R2=0.9876) removal. Both Fe (II) and Mn (II) removal increased with increase in solution pH, but F- removal remained relatively stable in pH 4.0~9.0. The process of adsorption of F-, Fe (II) and Mn (II) from aqueous solutions by the composite adsorbent was an endothermic process. The above results indicated the composite adsorbent can be possibly applied in F-, Fe (II) and Mn (II) removal from drinking water.

Triazole, Benzotriazole, and Naphthotriazole as Corrosion Inhibitors for Brass

CORROSION ◽  
1976 ◽  
Vol 32 (10) ◽  
pp. 414-417 ◽  
Author(s):  
R. WALKER
Keyword(s):  
Corrosion Inhibitors ◽  
Lower Cost ◽  
Solution Ph ◽  
Inhibitor Efficiency ◽  
Wide Range ◽  
Better Than

Abstract The use of triazole, benzotriazole, and naphthotriazole as corrosion inhibitors for brass is briefly reviewed. The corrosion of 70/30 brass immersed in a wide range of solutions is reported both with and without the inhibitors. The inhibitor efficiency of benzotriazole is given as a function of the solution pH and the concentration used. Triazole was only effective in mildly corrosive solutions and benzotriazole and naphthotriazole were much better. Generally naphthotriazole was better than benzotriazole but is much more expensive and a higher concentration of benzotriazole can give the same protection as naphthotriazole at a much lower cost.

NOM and MIB, who wins in the competition for activated carbon adsorption sites?

2004 ◽  
Vol 49 (9) ◽  
pp. 257-265 ◽  
Author(s):  
C. Hepplewhite ◽  
G. Newcombe ◽  
D.R.U. Knappe
Keyword(s):  
Molecular Weight ◽  
Activated Carbons ◽  
Background Concentration ◽  
Low Molecular Weight ◽  
Activated Carbon Adsorption ◽  
Microporous Carbons ◽  
Adsorption Sites ◽  
Carbon Adsorption ◽  
Competitive Mechanism ◽  
Wide Range

The adsorption of an odour compound common in drinking water, 2-methylisoborneol (MIB), was studied on two activated carbons in the presence of 13 well-characterised natural organic matter (NOM) solutions. It was found that, although the carbons and the NOM solutions had a wide range of characteristics, the major competitive mechanism was the same in all cases. The low molecular weight NOM compounds were the most competitive, participating in a direct competition with the MIB molecule for adsorption sites. Equivalent background concentration (EBC) calculations indicated a relatively low concentration of directly competing compounds in the NOM. Some evidence of pore restriction was also seen, with microporous carbons most affected by low molecular weight NOM, and mesoporous carbons impacted by the higher molecular weight compounds.

scholarly journals Phosphatase synthesis in Klebsiella (Aerobacter) aerogenes growing in continuous culture

1972 ◽  
Vol 127 (1) ◽  
pp. 87-96 ◽  
Author(s):  
P. G. Bolton ◽  
A. C. R. Dean
Keyword(s):  
Alkaline Phosphatase ◽  
Acid Phosphatase ◽  
Continuous Culture ◽  
Activity Profile ◽  
Glucose Effect ◽  
Ph Values ◽  
Nitrophenyl Phosphate ◽  
Wide Range ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

1. Phosphatase synthesis was studied in Klebsiella aerogenes grown in a wide range of continuous-culture systems. 2. Maximum acid phosphatase synthesis was associated with nutrient-limited, particularly carbohydrate-limited, growth at a relatively low rate, glucose-limited cells exhibiting the highest activity. Compared with glucose as the carbon-limiting growth material, other sugars not only altered the activity but also changed the pH–activity profile of the enzyme(s). 3. The affinity of the acid phosphatase in glucose-limited cells towards p-nitrophenyl phosphate (Km 0.25–0.43mm) was similar to that of staphylococcal acid phosphatase but was ten times greater than that of the Escherichia coli enzyme. 4. PO43−-limitation derepressed alkaline phosphatase synthesis but the amounts of activity were largely independent of the carbon source used for growth. 5. The enzymes were further differentiated by the effect of adding inhibitors (F−, PO43−) and sugars to the reaction mixture during the assays. In particular, it was shown that adding glucose, but not other sugars, stimulated the rate of hydrolysis of p-nitrophenyl phosphate by the acid phosphatase in carbohydrate-limited cells at low pH values (<4.6) but inhibited it at high pH values (>4.6). Alkaline phosphatase activity was unaffected. 6. The function of phosphatases in general is discussed and possible mechanisms for the glucose effect are outlined.

scholarly journals Water and Carbon Dioxide Adsorption on CaO(001) Studied via Single Crystal Adsorption Calorimetry

2021 ◽  
Author(s):  
J. Seifert ◽  
S. J. Carey ◽  
S. Schauermann ◽  
S. Shaikhutdinov ◽  
H.-J. Freund
Keyword(s):  
Adsorption Energy ◽  
Adsorbed Water ◽  
Spectroscopic Studies ◽  
Detector Response ◽  
Adsorption Calorimetry ◽  
Instrument Response Function ◽  
Line Shapes ◽  
Adsorption Sites ◽  
Saturation Coverage ◽  
Initial Adsorption

AbstractA new method to analyze microcalorimetry data was employed to study the adsorption energies and sticking probabilities of D2O and CO2 on CaO(001) at several temperatures. This method deconvolutes the line shapes of the heat detector response into an instrument response function and exponential decay functions, which correspond to the desorption of distinct surface species. This allows for a thorough analysis of the adsorption, dissociation, and desorption processes that occur during our microcalorimetry experiments. Our microcalorimetry results, show that D2O adsorbs initially with an adsorption energy of 85–90 kJ/mol at temperatures ranging from 120 to 300 K, consistent with prior spectroscopic studies that indicate dissociation. This adsorption energy decreases with increasing coverage until either D2O multilayers are formed at low temperatures (120 K) or the surface is saturated (> 150 K). Artificially producing defects on the surface by sputtering prior to dosing D2O sharply increases this adsorption energy, but these defects may be healed after annealing the surface to 1300 K. CO2 adsorbs on CaO(001) with an initial adsorption energy of ~ 125 kJ/mol, and decreases until the saturation coverage is reached, which is a function of surface temperature. The results showed that pre-adsorbed water blocks adsorption sites, lowers the saturation coverage, and lowers the measured adsorption energy of CO2. The calorimetry data further adds to our understanding of D2O and CO2 adsorption on oxide surfaces.

Investigation, using density function theory, of coverage of the kaolinite (001) surface during hydrogen adsorption

Clay Minerals ◽  
2018 ◽  
Vol 53 (3) ◽  
pp. 393-402 ◽  
Author(s):  
Jian Zhao ◽  
Wei Gao ◽  
Zhi-Gang Tao ◽  
Hong-Yun Guo ◽  
Man-Chao He
Keyword(s):  
Density Functional ◽  
Hydrogen Adsorption ◽  
Function Theory ◽  
Lattice Relaxation ◽  
Electronic Density ◽  
Functional Theory ◽  
Adsorption Sites ◽  
Coverage Dependence ◽  
Hydrogen Molecules ◽  
Wide Range

ABSTRACTKaolinite can be used for many applications, including the underground storage of gases. Density functional theory was employed to investigate the adsorption of hydrogen molecules on the kaolinite (001) surface. The coverage dependence of the adsorption sites and energetics was studied systematically for a wide range of coverage, Θ (from 1/16 to 1 monolayer). The three-fold hollow site is the most stable, followed by the bridge, top-z and top sites. The adsorption energy of H2 decreased with increasing coverage, thus indicating the lower stability of surface adsorption due to the repulsion of neighbouring H2 molecules. The coverage has obvious effects on hydrogen adsorption. Other properties of the H2/kaolinite (001) system, including the lattice relaxation and changes of electronic density of states, were also studied and are discussed in detail.

Adsorption mechanism of CO molecule on Al(111) surface: periodic DFT investigation

2018 ◽  
Vol 96 (12) ◽  
pp. 993-999 ◽  
Author(s):  
Chenhong Xu ◽  
Suqin Zhou ◽  
Jing Chen ◽  
Yuxiang Wang ◽  
Lei He
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Adsorption Mechanism ◽  
Bond Activation ◽  
Aluminum Surface ◽  
Hollow Site ◽  
Functional Theory ◽  
Wide Range ◽  
Adsorption Of Co ◽  
Adsorption Energies

The adsorption mechanism of the CO molecule on Al(111) surface has been investigated systematically at the atom-molecule level by the method of periodic density functional theory. The adsorption energies, adsorption structures, charge transfer, and density of states have been calculated in a wide range of coverage. It is found that the hcp-hollow site is the energetically favorable site. A significant positive correlation has been found between the adsorption energy (Eads) and coverage. The adsorbed CO molecules are almost perpendicular on the surface with the C atom facing the surface. There is an obvious charge transfer from Al atoms to the C atom; the Al atoms that have interaction with the C atom offer the most charge. The 4σ, 1π, and 5σ molecular orbitals of CO are found to contribute to bonding with the Al. The charges filling in the 2π molecular orbital contribute to C–O bond activation. In conclusion, the passivation of aluminum surface and the activation of CO molecule occur simultaneously in the adsorption of CO on Al surface.

Immobilization of Chaetomium erraticum dextranase (CED) by adsorption on carboxylated multi walled carbon nanotubes (c-MWCNT)

2021 ◽  
Author(s):  
Yakup Aslan ◽  
Barzan Ismael Ghafour
Keyword(s):  
Storage Conditions ◽  
Reducing Sugar ◽  
Solution Ph ◽  
Multi Walled Carbon Nanotubes ◽  
Activity Yield ◽  
Walled Carbon Nanotubes ◽  
Hydrolysis Of ◽  
Dextran Solution ◽  
Burk Plot

Abstract In this study, CED was immobilized onto c-MWCNT by adsorption. Optimization of immobilization conditions (immobilization buffer's pH and molarity, c-MWCNT amount, and immobilization time) was resulted in 100% immobilization yield and 114.13% activity yield. Further, characterization of FCED and ICED was also studied. After immobilization, the optimum pH shifted from 5.0 to 6.0, while the optimum temperature (55 °C) did not change. Furthermore, kinetic constants for FCED and ICED were also determined using the Lineweaver-Burk plot. The Km value for both FCED and ICED were 54.35 g / L, while Vmax values for FCED and ICED were 2.77 μmol reducing sugar / L.mg.min and 3.19 μmol reducing sugar / L.mg.min, respectively. Moreover, there was no reduction in the initial activity of ICED after 20 consecutive uses and 30 days of storage at optimal storage conditions. Finally, 17.15% and 17.53% of the dextran in 10% dextran solution (pH 6.0) were converted to reduced sugars (IMOs and Glucose) in 12 hours using FCED and ICED, respectively. Consequently, it can be concluded that ICED obtained in this study can be effectively used for industrial production of IMOs and for hydrolysis of dextran.

scholarly journals Effective Removal of Pb(II) Ions by Electrospun PAN/Sago Lignin-Based Activated Carbon Nanofibers

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3081 ◽  
Author(s):  
Nurul Aida Nordin ◽  
Norizah Abdul Rahman ◽  
Abdul Halim Abdullah
Keyword(s):  
Activated Carbon ◽  
Adsorption Capacity ◽  
Carbon Nanofibers ◽  
Langmuir Isotherm ◽  
Human Life ◽  
Order Kinetic ◽  
Solution Ph ◽  
Adsorption Sites ◽  
Activated Carbon Nanofibers ◽  
Adsorption Technology

Heavy metal pollution, such as lead, can cause contamination of water resources and harm human life. Many techniques have been explored and utilized to overcome this problem, with adsorption technology being the most common strategies for water treatment. In this study, carbon nanofibers, polyacrylonitrile (PAN)/sago lignin (SL) carbon nanofibers (PAN/SL CNF) and PAN/SL activated carbon nanofibers (PAN/SL ACNF), with a diameter approximately 300 nm, were produced by electrospinning blends of polyacrylonitrile and sago lignin followed by thermal and acid treatments and used as adsorbents for the removal of Pb(II) ions from aqueous solutions. The incorporation of biodegradable and renewable SL in PAN/SL blends fibers produces the CNF with a smaller diameter than PAN only but preserves the structure of CNF. The adsorption of Pb(II) ions on PAN/SL ACNF was three times higher than that of PAN/SL CNF. The enhanced removal was due to the nitric acid treatment that resulted in the formation of surface oxygenated functional groups that promoted the Pb(II) ions adsorption. The best-suited adsorption conditions that gave the highest percentage removal of 67%, with an adsorption capacity of 524 mg/g, were 40 mg of adsorbent dosage, 125 ppm of Pb(II) solution, pH 5, and a contact time of 240 min. The adsorption data fitted the Langmuir isotherm and the pseudo-second-order kinetic models, indicating that the adsorption is a monolayer, and is governed by the availability of the adsorption sites. With the adsorption capacity of 588 mg/g, determined via the Langmuir isotherm model, the study demonstrated the potential of PAN/SL ACNFs as the adsorbent for the removal of Pb(II) ions from aqueous solution.

scholarly journals Efficient Removal of Diclofenac from Aqueous Solution by Potassium Ferrate-Activated Porous Graphitic Biochar: Ambient Condition Influences and Adsorption Mechanism

2019 ◽  
Vol 17 (1) ◽  
pp. 291 ◽  
Author(s):  
Nguyen Thi Minh Tam ◽  
Yunguo Liu ◽  
Hassan Bashir ◽  
Zhihong Yin ◽  
Yuan He ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Adsorption Capacity ◽  
Diclofenac Sodium ◽  
Maximum Adsorption Capacity ◽  
Potassium Ferrate ◽  
Solution Ph ◽  
Modified Biochar ◽  
Prepared Material ◽  
Endothermic Process ◽  
One Step

Porous graphitic biochar was synthesized by one-step treatment biomass using potassium ferrate (K2FeO4) as activator for both carbonization and graphitization processes. The modified biochar (Fe@BC) was applied for the removal of diclofenac sodium (DCF) in an aqueous solution. The as-prepared material possesses a well-developed micro/mesoporous and graphitic structure, which can strengthen its adsorption capacity towards DCF. The experimental results indicated that the maximum adsorption capacity (qmax) of Fe@BC for DCF obtained from Langmuir isotherm simulation was 123.45 mg·L−1 and it was a remarkable value of DCF adsorption in comparison with that of other biomass-based adsorbents previously reported. Thermodynamic quality and effect of ionic strength studies demonstrated that the adsorption was a endothermic process, and higher environmental temperatures may be more favorable for the uptake of DCF onto Fe@BC surface; however, the presence of NaCl in the solution slightly obstructed DCF adsorption. Adsorption capacity was found to be decreased with the increase of solution pH. Additionally, the possible mechanism of the DCF adsorption process on Fe@BC may involve chemical adsorption with the presence of H-bonding and π–π interaction. With high adsorption capacity and reusability, Fe@BC was found to be a promising absorbent for DCF removal from water as well as for water purification applications.

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