Influence of alkaline activation temperature on the porous structure of the activated brown coal and its capacity to adsorb phenol

The purpose of this work was to evaluate the influence of alkaline activation temperature (t) on the pore structure of activated carbons produced from brown coal (ACs) and their adsorption capacity towards the sorption of phenol from aqueous solutions. The ACs were prepared by heating (t=400–8500C, 1 hr) of brown coal impregnated with KOH; the prepared samples were designated as AC(t). Based on the nitrogen adsorption-desorption isotherms (77 K), the total volume and surface (S) of all pores and separately micro- and subnanopores were determined. Maximum phenol adsorption capacities of ACs (Am) were registered at the temperature of 250С. The activation temperature was stated to be the most significant factor influencing the ACs capacity to adsorb phenol. The growth of temperature from 4000С to 8500С in the case of AC(800) results in an exponential increase in the value of Аm from 27 mg g–1 to 240 mg g–1 (a maximal value) according to the following equation: Аm=6.038exp(0.0045t) (R2=0.952). The kinetics of phenol adsorption obeys the second order model (R20.982). The AC(800) adsorption isotherm is described by the Freundlich equation (R2=0.988) within the equilibrium concentrations Ce=0.001–2.5 mg cm–3 with the heterogeneity factor nF=3.23 indicating physical adsorption. The same model for Ce0.001 mg cm–3 (R2=0.951) gives nF=0.52, which suggests chemical adsorption. The specific adsorptive capacity АS=Аm/S sharply decreases from 2.11 mg m–2 to 0.21 mg m–2 with increasing the temperature from 4000С to 5500С and remains constant (0.200.01 mg m–2) for ACs prepared at higher temperatures. The invariability of AS indicates the temperature independence of adsorption centers concentrations of ACs prepared within 550–8500С.

ADSORPTION OF 4-CHLORPHENOL BY BROWN COAL ACTIVATED BY POTASSIUM HYDROXIDE

WATER AND WATER PURIFICATION TECHNOLOGIES SCIENTIFIC AND TECHNICAL NEWS ◽

10.20535/2218-930012021233672 ◽

2021 ◽

Vol 29 (1) ◽

pp. 36-48

Author(s):

Yuliia Tamarkina ◽

Volodymyr Kucherenko ◽

Iryna Frolova

Keyword(s):

Adsorption Capacity ◽

Surface Area ◽

Brown Coal ◽

Activated Carbons ◽

Linear Equations ◽

Specific Capacity ◽

Total Pore Volume ◽

Koh Activation ◽

Activation Temperature ◽

Alkaline Activation

The purpose of work is to evaluate the 4-chlorophenol (CP) adsorption capacity of brown coal activated carbons (ACs) prepared at different temperature of KOH activation. ACs were obtained in three stages: 1) impregnation of coal with a KOH solution, 2) heating (4 deg/min) in argon to a given temperature t (400-800°C) and exposure for 1 h, 3) cooling, washing from KOH, drying. The samples are designated as AC(t). Based on the N2 adsorption-desorption isotherms, the ACs total pore volume (Vt, cm3/g) and specific surface area (S, m2/g) were determined. The ACs adsorption capacity were measured at 25°С, CP concentration ≤700 mg/L, АC dosage – 1 g/L. The alkaline activation temperature was found to be a key factor in forming porosity of ACs and ability to adsorb CP. The CP maximum capacity (ACP(m), mg/g) increases 6.6 times up to 307 mg/g for AC(800) having S=1142 m2/g. The specific adsorption capacity (ACP(S) = ACP(m)/S, mg/m2) sharply decreases in a sample range from AC(400) to AC(550) and weakly depends on temperature at 550-800°C. The kinetics of CP adsorption is best described by a pseudo-second order model. The rate determining stage is the interaction of CP molecules with AC surface. The CP adsorption isotherms are best described by the Langmuir model. The dependence of the ACP(m) from S can be approximated by three linear equations that probably correspond to the three regions of forming surface adsorbtion centers (AdCs). The first (S≤370 m2/g) is characterized by a small adsorption capacity increment (kS=0.103 mg/m2), but a significant (16.4 times) decrease in the specific capacity ACP(S). In the second region (S=370-770 m2/g, t=550-750°C), capacity increment is 10 times more (kS=0.985 mg/m2) and in the third region (S≥770 m2/g, t≥750°C) the increase in CP capacity is the smallest (kS=0.067 mg/m2). The thermoinitiated formation of AdCs is assumed to be not proportional to the increase in surface area, and their chemical structure and reactivity is determined by the alkaline activation temperature.

Optimization of Production Conditions for Activated Carbons from Rice Husk by Potassium Carbonate Using Response Surface Methodology

10.4028/www.scientific.net/amr.1053.303 ◽

2014 ◽

Vol 1053 ◽

pp. 303-310 ◽

Cited By ~ 1

Author(s):

Mian Wu Meng ◽

Cong Liang Qi ◽

Qing Ye Liu ◽

Liang Lv ◽

Hao Ai ◽

...

Keyword(s):

Response Surface Methodology ◽

Adsorption Capacity ◽

Response Surface ◽

Rice Husk ◽

Activated Carbons ◽

Total Pore Volume ◽

Nitrogen Adsorption ◽

Average Pore ◽

Activation Temperature ◽

Nitrogen Adsorption Isotherm

A three-factor-three-level experiment was developed by the central composite design (CCD) and Response surface methodology to discuss the effects of concentration of K2CO3, activation temperature and time on the adsorption capacity of the activated carbon (AC) derived from the rice husk and to identify the key preparation parameters. The performance of the AC was characterized by nitrogen adsorption isotherm as Brunauer–Emmett–Teller (BET) and scanning electron microscope (SEM), respectively. The optimal parameters were obtained: Rice husk was soaked in K2CO3 solution (2.32 mol/L) with an impregnation ratio (rice husk: K2CO3=1:3) (wt. %), activated at 1239 K for 0.48 h. The results showed that iodine adsorption capacity of the AC was 1268.52 mg/g, the error between the models predicted (1356.98 mg/g) was only 6.2%. The AC has a large apparent surface area (SBET = 1312 m2/g), total pore volume (0.78 cm3/g) and average pore diameter (11.92 Å).

Removal of Cu, Fe, and Zn from Peat Water by Using Activated Carbon Derived from Oil Palm Leaves

10.4028/www.scientific.net/amr.1162.65 ◽

2021 ◽

Vol 1162 ◽

pp. 65-73

Author(s):

Rakhmawati Farma ◽

Ona Lestari ◽

Erman Taer ◽

Apriwandi ◽

Minarni ◽

...

Keyword(s):

Heavy Metal ◽

Activated Carbon ◽

Oil Palm ◽

Activated Carbons ◽

Nitrogen Adsorption ◽

Surface Characteristics ◽

Batch Adsorption ◽

X Ray ◽

Turbidity Level ◽

Heavy metal such as Cu, Fe, and Zn are the most serious contributers to environmental problems. The removal of heavy metal from the environment is the research interest nowdays. The adsorption of Cu, Fe and Zn from wastewater was investigated with various activated carbons as adsorbents. The activated carbons were produced from oil palm leaves by using multi-activation methods. The H3PO4, NaOH, ZnCl2 and KOH were chosen as chemical activating agents. Batch adsorption experiment was used to test the ability of activated carbon to remove Cu, Fe, and Zn from wastewater. The surface characteristics of activated carbon were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), and nitrogen adsorption-desorption isotherms. The Activated carbons were able to purify wastewater with a maximum turbidity level of 2.83 NTU. The AC-H3PO4 activated carbon showed the highest absorbability of Cu metal as 91.540%, while the highest absorbabilities of Zn and Fe metals were indicated by AC-KOH activated carbon of 22.853% and 82.244% absorption respectively. Therefore, these results enable the oil palm leaves to become a high potential for activated carbon as removal the heavy metals.

Microwave Preparation of Modified Activated Carbons for Phenol Adsorption in Aqueous Solution

10.4028/www.scientific.net/amr.726-731.1883 ◽

2013 ◽

Vol 726-731 ◽

pp. 1883-1889

Author(s):

Brim Stevy Ondon ◽

Bing Sun ◽

Zhi Yu Yan ◽

Xiao Mei Zhu ◽

Hui Liu

Keyword(s):

Aqueous Solution ◽

Activated Carbon ◽

Adsorption Capacity ◽

Activated Carbons ◽

Microwave Energy ◽

Adsorptive Capacity ◽

Obvious Effect ◽

Phenol Adsorption ◽

Adsorption Capacities ◽

Modified Activated Carbons

Microwave energy was used to prepare modified activated carbons (GAC, GAC/MW, GAC/Ni, and GAC/Cu). The modified activated carbons were used for phenol adsorption in aqueous solution. The adsorption conditions were optimized. Adsorption capacities of the different modified activated carbons were evaluated. The effect of microwave pretreatment of activated carbons was investigated. A comparative study on the activated carbons adsorption capacities was also investigated. Under optimal conditions the results showed that there was no obvious effect on activated carbons adsorption when rising temperature and pH during the adsorption process. Stirring has a very high effect on the activated carbons adsorption capacity. The adsorption capacity of the modified activated carbons reaches 95%. MW/GAC, GAC/Ni and GAC/Cu adsorptive capacity was higher compared to the Granulated Activated Carbon (GAC) used as received. GAC treated with microwave energy has highest adsorption capacity. The adsorption capacity of GAC loaded with ion Ni2+ is higher than the activated carbon loaded with Cu2+. The untreated GAC has the lowest adsorption capacity. These results can be explained by the effect of microwave irradiation on GAC.The activated carbon loaded with Ni2+ adsorbs more microwave energy than the GAC loaded with Cu2+.

Capillary Adsorption of Nanostructure Carbonic Materials for Nitrobenzene in Wastewater

10.4028/www.scientific.net/amr.415-417.1717 ◽

2011 ◽

Vol 415-417 ◽

pp. 1717-1720

Author(s):

Yu Feng Sun ◽

Ai Min Zhang ◽

Bing Cheng Peng ◽

Zong Tang Liu ◽

Zheng Hao Fei ◽

...

Keyword(s):

Carbon Nanotubes ◽

Activated Carbon ◽

Carbon Black ◽

Adsorption Mechanism ◽

Capillary Condensation ◽

Nitrogen Adsorption ◽

Adsorptive Capacity ◽

Experimental Conditions ◽

Surface Areas ◽

The aims of this work were to make use of carbonic materials to remove nitrobenzene in wastewater and investigate adsorption mechanism. The adsorption ability of different carbonic materials for nitrobenzene was compared. It was found that carbon nanotubes and carbon black exhibited higher adsorptive capacity than coconut activated carbon and granular activated carbon at the same experimental conditions. The specific surface areas and pore distribution was obtained by low-temperature nitrogen adsorption-desorption. We concluded that the capillary condensation in mesopores played an important role in the adsorption process owing to special nanostructure of carbon nanotubes and carbon black.

Preparation and characterization of activated carbons obtained from the waste materials impregnated with phosphoric acid(V)

Applied Nanoscience ◽

10.1007/s13204-020-01419-6 ◽

2020 ◽

Vol 10 (12) ◽

pp. 4703-4716 ◽

Cited By ~ 1

Author(s):

Magdalena Zięzio ◽

Barbara Charmas ◽

Katarzyna Jedynak ◽

Monika Hawryluk ◽

Karolina Kucio

Keyword(s):

Thermal Analysis ◽

Phosphoric Acid ◽

Activated Carbons ◽

Nitrogen Adsorption ◽

Amorphous Structure ◽

Raw Material ◽

X Ray Diffraction ◽

Coffee Grounds ◽

Potentiometric Titration Method ◽

AbstractIn the paper spent coffee grounds were used as a precursor to obtain activated carbons. The raw material was impregnated with phosphoric acid(V) at the different impregnations ratios: 0.5, 1, 1.5, 2. Carbonization was carried out according to two procedures differing in activation atmosphere (N2 or CO2). The obtained activated carbons were characterized on the basis of low-temperature nitrogen adsorption/desorption, thermal analysis, potentiometric titration method, X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Carbons obtained according to procedure 2 (activation in CO2) were characterized by better developed porosity, e.g. surface (SBET to 720.9 m2/g) and pore volume (Vp to 0.334 cm3/g). All obtained carbons had surface acidic (mainly carboxyl) groups and exhibited the amorphous structure. The thermal analysis showed that the obtained materials were thermally stable up to the temperature ~ 420 °C.

INFLUENCE OF ALKALINE ACTIVATION TEMPERATURE ON POROSITY CHARACTERISTICS OF SORBENTS BASED ON BROWN COAL

Vestnik of Kuzbass State Technical University ◽

10.26730/1999-4125-2018-5-68-75 ◽

2019 ◽

Vol 129 (5) ◽

pp. 68-75

Author(s):

Alexey P. Kozlov ◽

◽

Alexey P. Kozlov ◽

Igor Yu. Zykov ◽

Yuliya N. Dudnikova ◽

...

Keyword(s):

Brown Coal ◽

Activation Temperature ◽

Alkaline Activation

Highly Effective Adsorption of Caffeine by a Novel Activated Carbon Prepared From Coconut Leaf

10.21203/rs.3.rs-901559/v1 ◽

2021 ◽

Author(s):

Elvio N. Oliveira ◽

Alex T. Meneses ◽

Samara F. de Melo ◽

Franciele M. R. Dias ◽

Maisa T. B. Perazzini ◽

...

Keyword(s):

Activated Carbon ◽

Activated Carbons ◽

Physical Adsorption ◽

Average Pore Size ◽

Kinetic Studies ◽

Amorphous Structure ◽

Operating Conditions ◽

Average Pore ◽

Pseudo Second Order ◽

Abstract The disposal of coconut wastes is costly and damaging to the environment, but its uses are advantageous activated carbons production. Coconut leaves waste were used for activated carbon production by pyrolysis at 500º C and activation with potassium carbonate. The activated carbon was used for caffeine removal from aqueous solution. The coconut leaves activated carbon showed a predominantly amorphous structure from X-ray diffraction analysis and a pH at the zero charge point of 7.9. From the N2 adsorption/desorption method, the adsorbent showed a predominance of mesopores, with average pore size of 45.48 ηm and a surface area of 678.03 m2/g. From kinetic studies the data followed the pseudo-second order, where the intraparticle diffusion can be neglected. The adsorption isotherms were satisfactorily adjusted for the Redlich-Peterson model and a type curve L was identified. The thermodynamic parameters showed that adsorption occurred spontaneously, was exothermic and governed by physical adsorption. The artificial neural networks developed were capable of predicting both kinetics and equilibrium adsorption data under different operating conditions and was comparable to the traditional models available in literature in the training experiments, encouraging its use for data generalization when an efficient dataset is used. In conclusion, coconut leaves waste showed to be a promising feedstock to produce activated carbon aiming caffeine removal from water and wastewater.

Simultaneous activation/sulfurization method for production of sulfurized activated carbons: characterization and Hg(II) adsorption capacity

Water Science & Technology ◽

10.2166/wst.2013.741 ◽

2013 ◽

Vol 69 (3) ◽

pp. 546-552 ◽

Cited By ~ 7

Author(s):

Hadi ShamsiJazeyi ◽

Tahereh Kaghazchi

Keyword(s):

Specific Surface ◽

Adsorption Capacity ◽

Activated Carbons ◽

Nitrogen Adsorption ◽

Surface Charges ◽

Ph Values ◽

Surface Areas ◽

Simultaneous Activation ◽

Adsorption Desorption ◽

Significant Attention

As an inexpensive method for modification of activated carbons (ACs), sulfurization has attracted significant attention. However, the resulting sulfurized activated carbons (SACs) often are less porous than the original ACs. In this work, we propose a new method for concurrent sulfurization/activation that can lead to preparation of SACs with more porosity than the corresponding non-sulfurized ACs. By using scanning electron microscopy, nitrogen adsorption/desorption, and iodine number experiments, the porous structure of the SACs has been compared with that of non-sulfurized ACs. The specific surface areas of SACs are higher than the corresponding ACs, regardless of the type of activation agents used. For instance, the specific surface area of SAC and AC activated with phosphoric acid is 1,637 and 1,338 m2/g, respectively. Additionally, sulfur contents and surface charges (pHpzc) of the SACs and non-sulfurized ACs are compared. In fact, the SACs have higher sulfur contents and more acidic surfaces. Furthermore, the Hg(II) adsorption capacity of SACs has been compared with the corresponding non-sulfurized ACs. The Hg(II) adsorption isotherms on a selected SAC is measured at different pH values and temperatures. Hg(II) adsorptions as high as 293 mg/g are observed by using SACs prepared by the method proposed in this study.

Characterization of Chemically Activated Carbons Prepared from Miscanthus and Switchgrass Biomass

Materials ◽

10.3390/ma13071654 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1654 ◽

Cited By ~ 2

Author(s):

Beata Doczekalska ◽

Monika Bartkowiak ◽

Bogusława Waliszewska ◽

Grażyna Orszulak ◽

Joanna Cerazy-Waliszewska ◽

...

Keyword(s):

Activated Carbons ◽

Nitrogen Adsorption ◽

Crop Species ◽

Alternative Source ◽

Surface Oxygen Groups ◽

Surface Areas ◽

Oxygen Groups ◽

Adsorption Desorption ◽

Chemical Groups

Lignocellulosic biomass, including that of energy crops, can be an alternative source to produce activated carbons (ACs). Miscanthus and switchgrass straw were used to produce ACs in a two-step process. Crushed plant material was carbonized at 600 °C and then obtained carbon was activated using NaOH or KOH at 750 °C. The content of surface oxygen groups was determined using Boehm’s method. The porosity of ACs was assayed using the nitrogen adsorption/desorption technique, while their thermal resistance using the thermogravimetric method. The ACs derived from miscanthus and switchgrass were characterized by surfaces rich in chemical groups and a highly developed porous structure. The highest specific surface areas, over 1600 m2/g, were obtained after carbon treatment with NaOH. High values of iodine number, 1200–1240 mg/g, indicate an extensive system of micropores and their good adsorption properties. The type of activator affected the contents of oxygen functional groups and some porosity parameters as well as thermal stability ranges of the ACs. Among obtained carbons, the highest quality was found for these derived from M. sacchariflorus followed by switchgrass, after activation with NaOH. Hence, while these crop species are not as effective biomass sources as other energy grasses, they can become valuable feedstocks for ACs.