scholarly journals Tailoring Properties of Resol Resin-Derived Spherical Carbons for Adsorption of Phenol from Aqueous Solution

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1736
Author(s):  
Karol Sidor ◽  
Tomasz Berniak ◽  
Piotr Łątka ◽  
Anna Rokicińska ◽  
Marek Michalik ◽  
...  
Keyword(s):  
Surface Composition ◽  
Micropore Volume ◽  
Gaseous Ammonia ◽  
Poly Vinyl Alcohol ◽  
Clear Correlation ◽  
Hno3 Solution ◽  
Synthesis Conditions ◽  
Adsorption Of Nitrogen ◽  
Oxygen Groups ◽  
Size Of Particles

The polycondensation of resorcinol and formaldehyde in a water–ethanol mixture using the adapted Stöber method was used to obtain resol resins. An optimization of synthesis conditions and the use of an appropriate stabilizer (e.g., poly(vinyl alcohol)) resulted in spherical grains. The resins were carbonized in the temperature range of 600–1050 °C and then chemically activated in an aqueous HNO3 solution, gaseous ammonia, or by an oxidation–reduction cycle (soaking in a HNO3 solution followed by treatment with NH3). The obtained carbons were characterized by XRD, the low-temperature adsorption of nitrogen, SEM, TGA, and XPS in order to determine degree of graphitization, porosity, shape and size of particles, and surface composition, respectively. Finally, the materials were tested in phenol adsorption. The pseudo-second order model perfectly described the adsorption kinetics. A clear correlation between the micropore volume and the adsorption capacity was found. The content of graphite domains also had a positive effect on the adsorption properties. On the other hand, the presence of heteroatoms, especially oxygen groups, resulted in the clogging of the pores and a decrease in the amount of adsorbed phenol.

scholarly journals Sorption and Diffusion Properties of H- and Modified Forms of ZSM-5 Zeolites

1996 ◽  
Vol 13 (6) ◽  
pp. 495-508 ◽  
Author(s):  
P. Hudek ◽  
D. Bobok ◽  
A. Smiešková ◽  
Z. Židek
Keyword(s):  
Physical Adsorption ◽  
Gravimetric Method ◽  
Equilibrium Concentration ◽  
Sorption Isotherms ◽  
Effective Diffusivity ◽  
Micropore Volume ◽  
Unit Cell ◽  
Adsorption Of Nitrogen ◽  
Effective Diffusivities ◽  
Modified Forms

The sorption properties of samples of H-ZSM-5 zeolite and their forms modified with P, B and Mg were determined by the physical adsorption of nitrogen and evaluated by BET isotherm and t-plot methods. The diffusivities of the samples were measured using a new flow gravimetric method involving the sorption of p- and o-xylenes. The BET specific surface area decreased from 358 m2/g to 35–90 m2/g mainly because of a decrease in micropore volume as determined by the t-plot method. The rate of sorption of p-xylene on all the samples investigated followed Fick's second law of diffusion, leading to an effective diffusivity of ca. 1.7 × 10−11 m2/s, irrespective of whether the H-form or the modified forms were investigated. The sorption isotherms for o-xylene showed some unusual steps. Values for the effective diffusivities decreased from 2.6 × 10−12 m2/s for the H-form to 2.0–2.3 × 10−12 m2/s for the modified forms. The equilibrium concentration of o-xylene at P/P0 = 0.1 was only 0.38–0.68 mol/unit cell, while that of p-xylene was 4.40–5.98 mol/unit cell.

Removal of Ammonia from Aqueous Solution Using Activated Carbons

1996 ◽  
Vol 13 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Th. El-Nabarawy ◽  
G.A. Fagal ◽  
L. B. Khalil
Keyword(s):  
Activated Carbons ◽  
Surface Acidity ◽  
Surface Oxidation ◽  
Ammonia Removal ◽  
Carbon Surface ◽  
Ammonia Adsorption ◽  
Surface Areas ◽  
Adsorption Of Nitrogen ◽  
Oxygen Groups ◽  
Modified Activated Carbons

The surface areas of non-activated, activated and modified activated carbons were determined from the adsorption of nitrogen at −196°C and of carbon dioxide at 25°C. The base neutralization capacities were determined from the adsorption of NaOH, Na2CO3, NaHCO3 and NH4OH. The amount of oxygen combined to the carbon surface was estimated by measuring the pressure of CO and CO2 obtained on outgassing the carbon sample in the temperature range 300–1000°C. The surface area of activated carbon is not a determining factor in its ammonia adsorption. The surface acidity of the active carbon is a good measure of its capacity for ammonia removal. Ammonia adsorption increases appreciably upon surface oxidation of carbons with oxidizing gases and solutions. The acidic groups on the surface of carbons differ in their strength. Only a fraction of the surface covered by the carbon–oxygen groups is responsible for the capacity of the carbon towards ammonia. Most of the adsorbed ammonia is recovered upon treatment with dilute hydrochloric acid leaving the surface free for successive ammonia adsorption cycles.

scholarly journals Silver–Graphene Oxide Nanohybrids for Highly Sensitive, Stable SERS Platforms

2021 ◽  
Vol 9 ◽  
Author(s):  
Mateusz Kasztelan ◽  
Anna Studzinska ◽  
Grażyna Zofia Żukowska ◽  
Barbara Pałys
Keyword(s):  
Raman Spectroscopy ◽  
Ascorbic Acid ◽  
Graphene Oxide ◽  
Silver Nanoparticle ◽  
Surface Composition ◽  
Surface Enhanced Raman Spectroscopy ◽  
Ammonia Solution ◽  
Synthesis Conditions ◽  
Sers Enhancement ◽  
Surface Enhanced Raman

Graphene oxide–silver nanoparticle nanohybrids were synthesized by simple reduction of the silver nitrate and graphene oxide (GO) mixture in water using the mild reducing agent ascorbic acid. The concentration of ascorbic acid was varied to verify the possible influence of the GO surface composition on the efficiency of the hybrid material as substrates for surface enhanced Raman spectroscopy (SERS). Furthermore, the composites were conditioned in ammonia solution or in potassium hydroxide diluted solution. For comparison, the graphene oxide–silver nanoparticle composite has been synthesized using the ammonia-treated GO. All materials were characterized using spectroscopic and microscopic methods including UV–Vis, infrared, and Raman spectroscopy and scanning electron microscopy. The SERS efficiency of the nanohybrids was tested using 4-aminothiophenol (PATP). The optimal synthesis conditions were found. Ammonia and potassium peroxide drop-casted on the composite changed the SERS properties. The sample treated with KOH showed the best SERS enhancement. The variation of the SERS enhancement was correlated with the shape of the UV–Vis characteristics and the surface structure of the composites.

scholarly journals Preparation and Identification of Optimal Synthesis Conditions for a Novel Alkaline Anion-Exchange Membrane

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 913 ◽  
Author(s):  
Aitor Marcos-Madrazo ◽  
Clara Casado-Coterillo ◽  
Leticia García-Cruz ◽  
Jesús Iniesta ◽  
Laura Simonelli ◽  
...  
Keyword(s):  
Anion Exchange ◽  
Oxidation State ◽  
Water Vapor Permeability ◽  
Filler Loading ◽  
Poly Vinyl Alcohol ◽  
Vapor Permeability ◽  
Mechanical Resistance ◽  
Anion Exchange Membranes ◽  
Copper Oxidation ◽  
Synthesis Conditions

The physicochemical and mechanical properties of new alkaline anion-exchange membranes (AAEMs) based on chitosan (CS) and poly(vinyl alcohol) (PVA) polymers doped with unsupported copper nanoparticles (NPs) and copper exchanged over different porous materials were investigated regarding ion-exchange capacity (IEC), OH− conductivity, water uptake (WU), water vapor permeability (WVP), and thermal and mechanical resistance. The influence of the type of filler included in different morphologies and filler loading has been explored using copper exchanged materials such as the layered porous titanosilicate AM-4, layered stannosilicate UZAR-S3, and zeolites Y, MOR, and BEA. Compared to commercially available anion-exchange membranes, the best performing membranes in terms of WU, IEC, OH− conductivity and WVP in this study were those containing 10 wt % of Cu-AM-4 and Cu-UZAR-S3, although 10 wt % Cu-MOR provided better mechanical strength at close values of WVP and anion conductivity. It was also observed that when Cu was exchanged in a porous silicate matrix, its oxidation state was lower than when embedded as unsupported metal NPs. In addition, the statistical analysis of variance determined that the electrochemical properties of the membranes were noticeably affected by both the type and filler loading, and influenced also by the copper oxidation state and content in the membrane, but their hydrophilic properties were more affected by the polymers. The largest significant effects were noticed on the water sorption and transport properties, which gives scope for the design of AAEMs for electrochemical and water treatment applications.

Adhesion of Hydrated Silicate Films

1988 ◽  
Vol 121 ◽  
Author(s):  
Terry A. Michalské ◽  
Keith D. Keefer
Keyword(s):  
Silica Glass ◽  
Room Temperature ◽  
Surface Composition ◽  
Adsorbed Water ◽  
Adhesive Bond ◽  
Silicate Solution ◽  
Heat Treatments ◽  
Hydrated Silicate ◽  
Surface Oxygen Groups ◽  
Oxygen Groups

ABSTRACTWe used fracture mechanics test techniques to measure the adhesive bond energy formed between hydrated silica glass surfaces and silicate species deposited from solution. In the case of silicate surfaces hydrated in room temperature water vapor, intermolecular bonding between hydrated surfaces can be attributed to either hydrogen bonding interactions between adsorbed water molecules (0.15 J/m2) or electrostatic bonds formed between adsorbed cations and anionie-nonbridging surface oxygen groups (2.0 J/m2). The bonding interaction observed at room temperature depends upon the glass surface composition and the degree of surface hydration. When hydrated silicate solution species are added to the interface and heat treated, adhesion energies as large as the cohesive energy of silica glass can be obtained with heat treatments as low as 200 C. The adhesion of the silicate interfacial film produced by the addition of solution species is greatest for silicate precursors showing a low degree of molecular crosslinking. In addition, the presence of alkali in the silicate solution greatly enhances interface adhesion for heat treatments below 200 C.

Surface Modification of Activated Carbon and its Effects on Methane Adsorption

2013 ◽  
Vol 395-396 ◽  
pp. 605-609
Author(s):  
Shi Xiong Hao ◽  
Zu Xiao Yu ◽  
Xing Yong Liu
Keyword(s):  
Activated Carbon ◽  
Adsorption Capacity ◽  
Micropore Volume ◽  
Methane Adsorption ◽  
Surface Oxygen Groups ◽  
Two Samples ◽  
Boehm Titration ◽  
Adsorption Data ◽  
Oxygen Groups ◽  
Oxygen Surface

In this work, one activated carbon (AC) was modified with H2O2, (NH4)2S2O8saturated solution and H2SO4/(NH4)2S2O8mixture respectively. The oxygen groups on ACs surface were characterized by Boehm titration. The textures of the ACs were investigated by N2adsorption at 77 K. The influence of surface oxygen groups on methane adsorption on ACs has been studied. The results of Boehm titration showed that the concentration of acidic oxygen functional groups on the AC surface increased after modification. N2adsorption data showed that the specific surface areaSBETand the micropore volumeVmicof AC were changed lightly after modification. It was observed that there was, in general, a positive correlation between the methane saturated adsorption capacity and theSBETof ACs while a negative correlation between methane saturated adsorption capacity and the total surface acidic groups. The methane saturated adsorption capacity was determined by the ACs surface chemistry when the microporosity parameters of two samples were similar. AC with a higher amount of oxygen surface groups, and consequently with a less hydrophobic character, had lower methane adsorption capacity.

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