Charge vs. Porosity - Some Influences on the Adsorption of Natural Organic Matter (NOM) by Activated Carbon

1999 ◽  
Vol 40 (9) ◽  
pp. 191-198 ◽  
Author(s):  
G. Newcombe
Keyword(s):  
Activated Carbon ◽  
Pore Volume ◽  
Activated Carbons ◽  
Surface Concentration ◽  
Volume Distribution ◽  
Electrostatic Effects ◽  
Adsorption Mechanisms ◽  
Enhanced Adsorption ◽  
Aromatic Ring Interactions ◽  
Filling Mechanism

The adsorption of NOM ultrafiltration fractions onto ten activated carbons was studied. The aim of the research was the clarification of the effects of carbon charge and pore volume distribution and NOM charge and molecular weight on adsorption. The effect of pH and ionic strength on adsorption mechanisms was determined, and it was found that, in the absence of strong electrostatic effects, adsorption occurred by a pore filling mechanism in which the available pore volume was filled. At neutral pH the NOM has a significant negative charge which can affect the adsorption in several ways. At low surface concentrations on activated carbon with positive surface groups there is direct surface-NOM electrostatic attraction (screening reduced adsorption). At higher surface concentrations the adsorption becomes predominantly a physical surface-NOM attraction, possibly due to hydrophobic or aromatic ring interactions. The electrostatic effects are mainly caused by the lateral repulsion of the NOM that prevents the close-packed arrangement apparent at pH 3 (screening enhanced adsorption). For one activated carbon it was shown that the degree of ionisation of the adsorbed NOM is strongly dependent on the surface concentration.

Changes of adsorption capacity and pore distribution of biological activated carbon on advanced water treatment

1997 ◽  
Vol 35 (7) ◽  
pp. 155-162 ◽  
Author(s):  
Takashi Kameya ◽  
Tatsuya Hada ◽  
Kohei Urano
Keyword(s):  
Activated Carbon ◽  
Water Treatment ◽  
Pore Volume ◽  
Activated Carbons ◽  
Sodium Hydroxide Solution ◽  
Volume Distribution ◽  
Organic Substances ◽  
Adsorption Effect ◽  
Biological Activated Carbon ◽  
Volume Decrease

Several problems such as unpleasant odor, taste and toxic halogenated organic compounds which are produced by the reaction of organic substances with chlorine that is used for disinfection have occurred in water purification plant for drinking water. Advanced water treatment with biological activated carbon (BAC) has been focused on, but there are few papers about pore volume decrease of activated carbon in BAC. In this study, the changes in cumulative TOC removal and pore volume distribution for two types of activated carbon from a bench-scale apparatus and a mini-column apparatus, to which river water was supplied after coagulation-sedimentation for a period of over 1200 days, were investigated. Adsorption abilities decreased considerably after ca 1000 days and the activated carbons became like sand. The cumulative TOC removals by the adsorption effect were asymptotic to constant values for each empty bed contact time. Though the removal efficiencies for both the activated carbons were approximately equivalent, the pore volume decreases were not uniform. The volume of smaller pores under 2 nm in diameter mainly decreased. Accumulations of minerals such as aluminium and calcium were small, and the pore volume decreases were mainly caused by the accumulation of organic substances. Almost all of the organic substances that accumulated in the activated carbon could be extracted by sodium hydroxide solution. The mean density of the organic substances that accumulated in the activated carbon was estimated to be 0.91 g/ml. Since the pore volume decrease of the activated carbon was small compared with the removal amounts by the adsorption effect, a large amount of organic substances that had adsorbed once disappeared and the pore volume of the activated carbon was regenerated.

scholarly journals Phenol adsorption on high microporous activated carbons prepared from oily sludge: equilibrium, kinetic and thermodynamic studies

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
N. Mojoudi ◽  
N. Mirghaffari ◽  
M. Soleimani ◽  
H. Shariatmadari ◽  
C. Belver ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Pore Volume ◽  
Activated Carbons ◽  
Ph Value ◽  
Chemical Activation ◽  
Bet Surface Area ◽  
Polluted Water ◽  
Oily Sludge ◽  
Maximum Adsorption Capacity ◽  
Adsorption Desorption

AbstractThe purpose of this study was the preparation, characterization and application of high-performance activated carbons (ACs) derived from oily sludge through chemical activation by KOH. The produced ACs were characterized using iodine number, N2 adsorption-desorption, Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The activated carbon prepared under optimum conditions showed a predominantly microporous structure with a BET surface area of 2263 m2 g−1, a total pore volume of 1.37 cm3 g−1 and a micro pore volume of 1.004 cm3 g−1. The kinetics and equilibrium adsorption data of phenol fitted well to the pseudo second order model (R2 = 0.99) and Freundlich isotherm (R2 = 0.99), respectively. The maximum adsorption capacity based on the Langmuir model (434 mg g−1) with a relatively fast adsorption rate (equilibrium time of 30 min) was achieved under an optimum pH value of 6.0. Thermodynamic parameters were negative and showed that adsorption of phenol onto the activated carbon was feasible, spontaneous and exothermic. Desorption of phenol from the adsorbent using 0.1 M NaOH was about 87.8% in the first adsorption/desorption cycle and did not decrease significantly after three cycles. Overall, the synthesized activated carbon from oily sludge could be a promising adsorbent for the removal of phenol from polluted water.

scholarly journals Specific adsorption sites and conditions derived by thermal decomposition of activated carbons and adsorbed carbamazepine

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Daniel Dittmann ◽  
Paul Eisentraut ◽  
Caroline Goedecke ◽  
Yosri Wiesner ◽  
Martin Jekel ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Activated Carbon ◽  
Activated Carbons ◽  
Evolved Gas Analysis ◽  
Gas Analysis ◽  
Specific Adsorption ◽  
Adsorption Mechanisms ◽  
Adsorption Sites ◽  
Adsorption Processes ◽  
Inorganic Constituents

AbstractThe adsorption of organic micropollutants onto activated carbon is a favourable solution for the treatment of drinking water and wastewater. However, these adsorption processes are not sufficiently understood to allow for the appropriate prediction of removal processes. In this study, thermogravimetric analysis, alongside evolved gas analysis, is proposed for the characterisation of micropollutants adsorbed on activated carbon. Varying amounts of carbamazepine were adsorbed onto three different activated carbons, which were subsequently dried, and their thermal decomposition mechanisms examined. The discovery of 55 different pyrolysis products allowed differentiations to be made between specific adsorption sites and conditions. However, the same adsorption mechanisms were found for all samples, which were enhanced by inorganic constituents and oxygen containing surface groups. Furthermore, increasing the loadings led to the evolution of more hydrated decomposition products, whilst parts of the carbamazepine molecules were also integrated into the carbon structure. It was also found that the chemical composition, especially the degree of dehydration of the activated carbon, plays an important role in the adsorption of carbamazepine. Hence, it is thought that the adsorption sites may have a higher adsorption energy for specific adsorbates, when the activated carbon can then potentially increase its degree of graphitisation.

Effect of Activating Agent on the Preparation of Bamboo-Based High Surface Area Activated Carbon by Microwave Heating

2016 ◽  
Vol 35 (6) ◽  
pp. 535-541 ◽  
Author(s):  
Hongying Xia ◽  
Jian Wu ◽  
Chandrasekar Srinivasakannan ◽  
Jinhui Peng ◽  
Libo Zhang
Keyword(s):  
Activated Carbon ◽  
Microwave Heating ◽  
Surface Area ◽  
Pore Volume ◽  
Activated Carbons ◽  
High Surface ◽  
High Surface Area ◽  
Significant Proportion ◽  
Mixture Ratio ◽  
Activating Agent

AbstractThe present work attempts to convert bamboo into a high surface area activated carbon via microwave heating. Different chemical activating agents such as KOH, NaOH, K2CO3 and Na2CO3 were utilized to identify a most suitable activating agent. Among the activating agents tested KOH was found to generate carbon with the highest porosity and surface area. The effect of KOH/C ratio on the porous nature of the activated carbon has been assessed. An optimal KOH/C ratio of 4 was identified, beyond which the surface area as well as the pore volume were found to decrease. At the optimized KOH/C ratio the surface area and the pore volume were estimated to be 3,441 m2/g and 2.093 ml/g, respectively, with the significant proportion of which being microporous (62.3%). Activated carbon prepared under the optimum conditions was further characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Activated carbons with so high surface area and pore volume are very rarely reported, which could be owed to the nature of the precursor and the optimal conditions of mixture ratio adopted in the present work.

scholarly journals Carbonization Temperature Effect over Activated Carbon Porosity Derived from Industrial Processing Waste

2019 ◽  
Vol 2 (3) ◽  
pp. 1205-1209
Author(s):  
Hasan Sayğılı
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Pore Volume ◽  
Activated Carbons ◽  
Waste Product ◽  
Total Pore Volume ◽  
Carbonization Temperature ◽  
Bet Surface Area ◽  
Processing Waste ◽  
Industrial Processing

The influence of carbonization temperature (CT) on pore properties of the prepared activated carbon using lentil processing waste product (LWP) impregnated with potassium carbonate was studied. Activated carbons (ACs) were obtained by impregnation with 3:1 ratio (w/w) K2CO3/LWP under different carbonization temperatures at 600, 700, 800 and 900 oC for 1h. Activation at low temperature represented that micropores were developed first and then mesoporosity developed, enhanced up to 800 oC and then started to decrease due to possible shrinking of pores. The optimum temperature for LWP was found to be around 800 oC on the basis of total pore volume and the Brunauer-Emmett-Teller (BET) surface area. The optimum LWPAC sample was found with a CT of 800 oC, which gives the highest BET surface area and pore volume of 1875 m2/g and 0.995 cm3/g, respectively.

scholarly journals Adsorption of Heavy Metals from Industrial Wastewater using Nanoparticles from Agro Wastes

2021 ◽  
Author(s):  
Lekan Taofeek Popoola ◽  
Alhaji Shehu Grema
Keyword(s):  
Heavy Metals ◽  
Activated Carbon ◽  
Industrial Wastewater ◽  
Activated Carbons ◽  
Textural Properties ◽  
Isotherm Models ◽  
Heavy Metals Removal ◽  
Adsorption Mechanisms ◽  
Body Tissues ◽  
Metals Removal

Effluents from essential industries have been characterized with heavy metals which are non-biodegradable in nature and also detrimental to health when accumulated in body tissues over long exposure. Adsorption was proved as the best efficient process amongst others to remove these heavy metals from industrial wastewater due to its excellent features. Activated carbons from nanoparticles of agricultural wastes such as pods, shells, husks, peels, shafts and many prepared via calcination process at high temperature can be used as active adsorbent for the industrial wastewater treatment involving heavy metals removal. This chapter discusses heavy metals in industrial wastewater effluents and potential agro wastes from which nanoparticles of activated carbon for industrial wastewater purification could be generated. The transformation of agro wastes nanoparticles into activated carbons via calcination and their applications for heavy metals removal from industrial wastewater via adsorption were examined. Various characterization techniques to study the effects of calcination on structural, morphological and textural properties of activated carbon prepared from agro waste nanoparticles were also discussed. Various isotherm, kinetics, mechanistic and thermodynamics models to investigate the adsorptive nature of the process were presented. Error functions and algorithms for both the linear and non-linear isotherm models regression to affirm their fitness for prediction were presented. Lastly, proposed adsorption mechanisms of heavy metals removal from industrial wastewater using activated carbons from nanoparticles of agro wastes were presented.

Adsorption and Desorption Behavior of Herbicide Using Bio-Based Materials

2019 ◽  
Vol 62 (6) ◽  
pp. 1435-1445 ◽  
Author(s):  
Saravanan Ramiah Shanmugam ◽  
Sushil Adhikari ◽  
Hyungseok Nam ◽  
Vivek Patil
Keyword(s):  
Activated Carbon ◽  
Pore Volume ◽  
Activated Carbons ◽  
Total Pore Volume ◽  
Agricultural Runoff ◽  
Kraft Lignin ◽  
Douglas Fir ◽  
Bet Surface Area ◽  
Runoff Water ◽  
Sorption Ability

HighlightsGlyphosate sorption using bio-based adsorbents was investigated in this study.Biochars showed poor sorption of glyphosate in comparison to the activated carbons.Total pore volume of bio-based adsorbents played a key role in sorption of glyphosate.Abstract. This study examined the glyphosate sorption ability of different bio-based materials, including biochars and activated carbons synthesized from Douglas fir, kraft lignin, and mixed wood pellets. All the biochars showed poor sorption of glyphosate in comparison to the activated carbons derived from biochars and the commercial powdered activated carbon (PAC) investigated in this study. All the biochar-derived activated carbons produced in the laboratory showed comparable glyphosate sorption in comparison to PAC. The activated carbons synthesized from Douglas fir biomass showed the highest glyphosate sorption among the activated carbons investigated. Langmuir and Freundlich isotherms were used to describe the adsorption kinetics of glyphosate onto activated carbons. Adsorption capacity showed better correlation (R2 = 0.989) with the total pore volume in comparison to the Brunauer-Emmett-Teller (BET) surface area and microporosity. The results of batch desorption tests indicated that the biochar-derived activated carbons and PAC showed >60% glyphosate retention. The results of this study indicate that activated carbons derived from biochars produced with thermochemical conversion processes could effectively sorb herbicide such as glyphosate similarly to commercial activated carbon and could be used either as a replacement for PAC in water treatment plants or for on-site treatment of agricultural runoff water. Keywords: Adsorption, Desorption, Herbicides, Kraft lignin, Model isotherms, Pore volume.

scholarly journals Effect of Mesopore Development on Butane Working Capacity of Biomass-Derived Activated Carbon for Automobile Canister

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 673
Author(s):  
Byeong-Hoon Lee ◽  
Hye-Min Lee ◽  
Dong Chul Chung ◽  
Byung-Joo Kim
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Volume Fraction ◽  
Activated Carbons ◽  
Total Pore Volume ◽  
Working Capacity ◽  
Activation Time

Kenaf-derived activated carbons (AKC) were prepared by H3PO4 activation for automobile canisters. The microstructural properties of AKC were observed using Raman spectra and X-ray diffraction. The textural properties were studied using N2/77 K adsorption isotherms. Butane working capacity was determined according to the ASTM D5228. From the results, the specific surface area and total pore volume of the AKC was determined to be 1260–1810 m2/g and 0.68–2.77 cm3/g, respectively. As the activation time increased, the butane activity and retentivity of the AKC increased, and were observed to be from 32.34 to 58.81% and from 3.55 to 10.12%, respectively. The mesopore ratio of activated carbon increased with increasing activation time and was observed up to 78% at 973 K. This indicates that butane activity and retentivity could be a function not only of the specific surface area or total pore volume, but also of the mesopore volume fraction in the range of 2.8–3.8 nm and 5.5-6.5 nm of adsorbents, respectively. The AKC exhibit enhanced butane working capacity compared to commercial activated carbon with the high performance of butane working capacity due to its pore structure having a high mesopore ratio.

scholarly journals The effects of activation conditions on physical properties of activated carbon

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 7640-7647
Author(s):  
Yan Luo ◽  
Kang Wang ◽  
Ling Fei
Keyword(s):  
Activated Carbon ◽  
Physical Properties ◽  
Surface Area ◽  
Pore Volume ◽  
Specific Volume ◽  
Activated Carbons ◽  
Weight Ratio ◽  
Total Pore Volume ◽  
High Porosity ◽  
Activation Conditions

Porous carbons with a high porosity were successfully produced from fast pyrolysis pine wood char via a thermochemical method in which KOH was used as chemical activator. The effects of various weight ratios of KOH to pyrolysis char (0.65:1, 0.7:1, 1.0:1, 1.35:1, and 1.7:1) on the physical properties of activated carbons were investigated. When the weight ratio of KOH to pyrolysis char was 1.35:1, the prepared activated carbon had the highest surface area of 1140 m2/g with a total pore volume of 0.71 cm3/g, a microporous surface area of 957 m2/g, and a microporous specific volume of 0.51 cm3/g. As the weight ratio of KOH to pyrolysis char increased from 0.65 to 1.35, the prepared activated carbon had increases in total surface area, total pore volume, microporous surface area, and specific volume of micropores. However, there was a reverse trend when the weight ratio of KOH to pyrolysis char was higher than 1.35. The use of nitrogen as a flow gas resulted in much more developed activated carbon than without nitrogen. The experiment results suggested that activated carbon with high surface area could be prepared from pyrolysis char by adjusting the activation conditions.

Sign in / Sign up

Export Citation Format

Share Document