Removal of heavy metal ions from wastewaters: A review

http://hywr.kuciv.kyoto-u.ac.jp/lecture/gss/SBabel/E3-20130118PM/Hazardous%20material_2003.pdf

Low-cost adsorbents for heavy metals uptake from contaminated water: a review.

This article reviews the progress made in CO2 separation and capture research and engineering. Various technologies, such as absorption, adsorption, and membrane separation, are thoroughly discussed. New concepts such as chemical-looping combustion and hydrate-based separation are also introduced briefly. Future directions are suggested. Sequestration methods, such as forestation, ocean fertilization and mineral carbonation techniques are also covered. Underground injection and direct ocean dump are not covered.

Progress in carbon dioxide separation and capture: a review.

Physico-chemical treatment techniques for wastewater laden with heavy metals

Activated carbons and low cost adsorbents for remediation of tri- and hexavalent chromium from water.

In this work, the adsorption of Pb(II) from aqueous solution was investigated on various types of activated carbon fibers (ACFs) manufactured from polyacrylonitrile and phenolic resin. The textural and physicochemical properties of the ACFs were determined by the N2-BET method and acid-base titration. The experimental adsorption equilibrium data of Pb(II) on the ACFs were obtained in a batch adsorber, and the Langmuir isotherm model better fitted the experimental data. The effects of the type of ACF and precursor of ACF, solution pH and temperature upon the adsorption of Pb(II) on the ACFs were examined in detail. The adsorption capacity was highly dependent upon the precursor of ACF. The Pb(II) adsorption capacity of the ACFs augmented when the solution pH and temperature were increased from 2 to 4 and from 288 to 308 K, respectively. The effect of the pH was attributed to the interactions between the surface of the ACF and Pb2+ ions present in the water solution. The Pb(II) adsorption capacity of the ACFs was enhanced by oxidation with HNO3 solution and the enhancement factor was between 1.1 and 1.4. The reversibility of the adsorption of Pb(II) was investigated by first adsorbing Pb(II) on an ACF and then desorbing the Pb(II). It was noticed that Pb(II) was substantially desorbed from ACF while reducing the solution pH to 2. It was concluded that the Pb(II) was mainly adsorbed on the ACFs by chemisorption, electrostatic interactions and ion exchange.

Adsorption of lead(II) from aqueous solution onto several types of activated carbon fibers

The effects of surface properties and solution pH and temperature on the adsorption of cadmium(II) onto activated carbon fiber cloth (ACC) made from polyacrylonitrile (PAN) were investigated in this work. The ACC was oxidized with HNO3 solution and the concentration of acidic sites increased during oxidation whereas that of basic ones diminished. The adsorption capacity of the oxidized ACC was higher than that of ACC without oxidation because the ACC contained greater concentration of acidic sites. It was found that the maximum adsorption took place at pH 8 and the adsorption capacity increased near 22 times, augmenting the pH from 2 to 8. The adsorption capacity diminished on the average twofold, increasing the temperature from 15 to 35°C. Cd(II) adsorbed on ACC at pH 6 can be almost completely desorbed by reducing the solution pH to 2. The adsorption capacity is considerably dependent upon the characteristics of the ACC surface and temperature and pH of the solution.

Adsorption of Cadmium(II) from an Aqueous Solution onto Activated Carbon Cloth

The adsorption capacity of sepiolite towards the removal of heavy metal ions from aqueous solution was studied in this work, with adsorption equilibrium data being obtained with a bath adsorber. The sepiolite sample was chemically stable over the pH range 2-12, but dissolved in acidic solutions with pH values less than 2. The Langmuir isotherm gave a better fit of the experimental adsorption equilibrium data, since the average absolute percentage deviation of the Langmuir isotherm was lower than that of the Freundlich isotherm. The adsorption capacity of sepiolite towards metal ions decreased in the following order: Cr(III) > Cd(II) > Cu(II) > Zn(II) > Ni(II) > Ag(I). Increasing the temperature from 15 °C to 35 °C led to an increase in the adsorption capacity. The capacity of sepiolite towards the adsorption of Cd(II) ions was diminished considerably on reducing the solution pH from 7 to 3. The effect of the solution pH was attributed to electrostatic interaction between the negatively charged sepiolite s...

https://journals.sagepub.com/doi/pdf/10.1260/0263-6174.29.6.569

Adsorption of Heavy Metal Ions from Aqueous Solution onto Sepiolite

Single and simultaneous Cd(II) and Zn(II) adsorption isotherms from aqueous solution onto activated carbon were determined experimentally. Single isotherms for these ions fit the Langmuir isotherm well, and the maximum molar uptake of Zn(II) averaged 1.6 times that of Cd(II). The simultaneous adsorption isotherms also fit the bisolute Langmuir isotherm modified with an interaction factor. Adsorption of each single ion was reduced by the presence of the other ion, which competed for some of the same active sites. The Zn(II) isotherm proved to be more sensitive to the presence of the competing ion than did the Cd(II) isotherm.

COMPETITIVE ADSORPTION OF Cd(II) AND Zn(II) FROM AQUEOUS SOLUTION ONTO ACTIVATED CARBON

This work investigated the adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) on various activated carbon cloths (ACCs) prepared from a phenolic resin commercially known as Novoloid. Experimental adsorption equilibrium data were obtained in a batch adsorber. The effects of temperature and pH on the adsorption capacity of ACCs were studied and it was found that the adsorption capacity decreased by augmenting the temperature from 15 to 35 °C and also the solution pH from 4 to 10. The speciation diagram of 2,4-D in water solution demonstrated that the 2,4-D was adsorbed on the ACCs as the deprotonated species. Adsorption of 2,4-D on ACCs was ascribed to both electrostatic attraction forces (adsorption on a basic site) and dispersion forces caused by π-π interactions. Both adsorption mechanisms are due to weak interactions explaining why adsorption of 2,4-D on the ACCs was reversible. It was concluded that the adsorption of 2,4-D on the ACCs was highly dependent on the textural and surface properties of the ACCs as well as the solution pH.

R.M. Guerrero-Coronado

Papers

Adsorption of lead(II) from aqueous solution onto several types of activated carbon fibers

Adsorption of Cadmium(II) from an Aqueous Solution onto Activated Carbon Cloth

Adsorption of Heavy Metal Ions from Aqueous Solution onto Sepiolite

COMPETITIVE ADSORPTION OF Cd(II) AND Zn(II) FROM AQUEOUS SOLUTION ONTO ACTIVATED CARBON

Adsorption of 2,4-dichlorophenoxyacetic acid from aqueous solution on activated carbon cloth