Anodization of Nanoporous Carbons for Removal of Ammonia

2005 ◽  
Vol 23 ◽  
pp. 7-10
Author(s):  
Soo Jin Park ◽  
Jun-Sik Shin
Keyword(s):  
Carbon Adsorbent ◽  
Nanoporous Carbon ◽  
Ammonia Removal ◽  
Nanoporous Carbons ◽  
Ammonia Gas ◽  
Oh Groups ◽  
Surface Areas ◽  
Effective Removal ◽  
Acid And Base ◽  
Anodic Oxidation Treatment

In this study, a new nanoporous carbon was prepared by anodic oxidation treatment to remove noxic ammonia gas. The acid- and base values of the nanoporous carbon were determined by Boehm’s titration method. And, the surface properties of the carbons were investigated by XPS analysis. Also, N2/77K adsorption isotherm characteristics, including the specific surface areas and nano/micropore volumes were studied by BET and t-plot methods, respectively. The ammonia removal efficiency was confirmed by gas-detecting tube technique. As a result, it was revealed in the case of acidic treatment on nanoporous carbons that the ammonia removal was greatly effective due to the increase of OH groups in carbon surfaces without significant changes of nanostructural properties. It was then found that the acidic anodization of nanoporous carbons was a suitable method for the effective removal of ammonia gas, which could be attributed to the increase of acceptor-donor interactions between acidic oxygen functional groups of carbon adsorbent and basic adsorbate in an adsorbent-adsorbate system.

Treatment of leachate from the anaerobic fermentation of solid wastes using two biofilm support media

2004 ◽  
Vol 49 (11-12) ◽  
pp. 287-294 ◽  
Author(s):  
I. Comett ◽  
S. Gonzalez-Martinez ◽  
P. Wilderer
Keyword(s):  
Anaerobic Fermentation ◽  
Fixed Bed ◽  
Dry Mass ◽  
Ammonia Removal ◽  
Cod Removal ◽  
Solid Wastes ◽  
Support Materials ◽  
Surface Areas ◽  
Biofilm Support ◽  
Different Response

Biofilms growing on different carrier media have a different response to the nutrients contained in wastewater. Biofilms have proven to be an alternative to the treatment of wastewater containing higher concentrations of contaminants. The main objective of this research was to compare two biofilm support media for the treatment of leachate from the anaerobic fermentation of solid wastes. The removal of organic matter and ammonia was achieved in two fixed bed biofilm reactors containing Kaldnes® and Linpor® support materials with specific surface areas of 490 and 270 m2/m3, respectively, and operating under the sequencing batch procedure during 204 days. The Linpor reactor achieved higher total COD removal than the Kaldnes reactor (47% and 39%, respectively). Linpor was shown to be less sensitive to influent COD changes than Kaldnes. The effluent total COD values of Kaldnes were higher than Linpor. The dissolved COD removal was 21% for both reactors. The average ammonia removal for Linpor was 72% and 42% for Kaldnes. The matrix of Linpor allows higher concentrations of microorganisms (as dry mass) than Kaldnes. The dry mass concentration was related to the "active" exposed surface area of the biofilm. This is considered to be the cause for the better performance of Linpor when compared with Kaldnes.

scholarly journals Waffle-Like Carbons Combined with Enriched Mesopores and Highly Heteroatom-Doped Derived from Sandwiched MOF/LDH/MOF for High-Rate Supercapacitor

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2388
Author(s):  
Szu-Chen Wu ◽  
Po-Hsueh Chang ◽  
Syun-Hong Chou ◽  
Chih-Yang Huang ◽  
Ta-Chung Liu ◽  
...  
Keyword(s):  
Specific Surface ◽  
Discharge Rate ◽  
High Rate ◽  
Cycle Stability ◽  
Smart Power ◽  
Nanoporous Carbons ◽  
Surface Areas ◽  
Symmetric Supercapacitor ◽  
Specific Surface Areas ◽  
Power Capability

Supercapacitors (SCs) are promising for powering mobile devices, electric vehicles and smart power grids due to their fast charge/discharge rate, high power capability and robust cycle stability. Nitrogen-doped porous carbons are great alternatives because they provide pseudocapacitance without losing their power rate. Nanoporous carbon derived from metal organic frameworks (MOFs) is an ideal precursor for preparing heteroatom-doped carbons due to their abundant nitrogen contents and incredible specific surface areas. However, severe aggregations and the leakage of nitrogen can occur during harsh carbonization. In this study, we used CoAl-LDH (cobalt aluminum layered double hydroxide) as an in-situ growth substrate, allowing Co-based MOF to uniformly grow onto the CoAl-LDH to form a sandwiched MOF/LDH/MOF structure. After acid etching, we obtained waffle-like nanoporous carbons (WNPC). WNPC exhibited high nitrogen and oxygen retention (7.5 wt% and 9.1 wt%) and a broad mesopores distribution with specific surface areas of 594 m2g−1, which promoted a sieving effect. This renders a specific capacitance of 300.7 F·g−1 at 1 A·g−1 and the high retention (72%) of capacitance at 20 A·g−1, ensuring its use at high-rate supercapacitor electrodes. Finally, the WNPC symmetric supercapacitor reaches a superior specific energy of 27 W·h·kg−1 at a power of 500 W·kg−1, and a good cycle stability (85% capacitance retention after 10,000 cycles).

Microstructure and Bio-Mineralization Behavior of the Sol-Gel Derived Bioactive Materials

2007 ◽  
Vol 280-283 ◽  
pp. 1609-1612 ◽  
Author(s):  
Xiao Feng Chen ◽  
Ying Jun Wang ◽  
Na Ru Zhao ◽  
Jian Dong Ye ◽  
Yu Dong Zheng ◽  
...  
Keyword(s):  
Sol Gel ◽  
Glass Ceramics ◽  
Tissue Engineering Scaffolds ◽  
Bioactive Materials ◽  
Electrode Layer ◽  
Oh Groups ◽  
Surface Areas ◽  
Gel Layer ◽  
Double Electrode ◽  
Sbf Solution

The biomaterials in system CaO-P2O5-SiO2 were synthesized via sol-gel method. The biomaterials can be applied to bone reparation and bone tissue engineering scaffolds The nano-pore structure, degradability, bioactivity and bio-mineralization characteristic of the biomaterials were investigated in details using XRD, SEM/EDX, FTIR, BET and DSC/TG techniques. It was indicated that the sol-gel derived biomaterials have a higher bioactivity than that of the melt derived bioactive glasses or glass-ceramics. It just takes 4-8 hours for HCA to form on the surface of the sol-gel samples in SBF solution at 37°C. The spherical HCA crystal clusters formed on the surface of the sol-gel derived samples immersed in SBF for 8 hours have a low crystallinity. Owing to their interconnected nano-sized pores, the sol-gel samples possess much higher surface areas and the hydrous porous SiO2 gel layer containing a great amount of ºSi-OH groups can be rapidly formed on the biomterials’ surface through a quick ion exchange between H3O+ in the solution and Ca2+ in the surface of the materials. ºSi-OH groups can play a very important role in inducing formation of HCA. They make the material surfaces electronegative, which resulted in a double electrode layer formed between the samples surface and SBF solution. The double electrode layer is in favor of formation of HCA on the surface of the materials.

Biological treatment of ammonia gas at high loading

2004 ◽  
Vol 50 (4) ◽  
pp. 283-290 ◽  
Author(s):  
T. Kanagawa ◽  
H.W. Qi ◽  
T. Okubo ◽  
N. Tokura
Keyword(s):  
Removal Rate ◽  
Space Velocity ◽  
Packed Bed ◽  
Porous Ceramics ◽  
Ammonia Removal ◽  
Ammonium Ion ◽  
Nitrifying Bacteria ◽  
High Concentration ◽  
Ammonia Gas ◽  
Cylinder Diameter

The exhaust gas from compost processing plants contains a large amount of ammonia. To treat ammonia gas at high loads, bench-scale experiments were carried out. First, nitrifying bacteria were enriched from soil and immobilized on porous ceramics. The ceramics were packed in an acrylic cylinder (diameter, 100 mm; packed height, 190 mm) and ammonia gas was introduced to the top of the cylinder. The concentration and flow rate of ammonia gas were gradually increased and finally 85 ppm was introduced at a space velocity of 800 h-1 (empty bed residence time (EBRT), 4.5 sec). The ammonia load was 1.0 kg N/m3 day-1. The exhaust contained 1.5-2 ppm of ammonia. Then the packed ceramics were transferred to another acrylic cylinder (diameter, 50 mm; packed height, 800 mm). A high concentration of ammonia gas (1,000 ppm) was introduced at a space velocity of 96 h-1 (ammonia loading, 1.44 kg N/m3 day-1; EBRT, 37.5 sec). The exhaust contained 2 ppm of ammonia (removal rate, 99.8%). The packed bed was washed with water intermittently or continuously, and the wastewater from the cylinder contained a large amount of ammonium and nitrate ions of at a 1:1 ratio. Stoichiometric analysis showed that half of the introduced ammonia was oxidized to nitrate, and the rest was converted to ammonium ion. Thus, ammonia gas was effectively treated at a high load by biofiltration with nitrifying bacteria.

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 Facile synthesis of lignosulfonate-graphene porous hydrogel for effective removal of Cr(VI) from aqueous solution

BioResources ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. 7001-7014
Author(s):  
Zhili Zhang ◽  
Fengfeng Li ◽  
Xingxiang Ji ◽  
Jiachuan Chen ◽  
Guihua Yang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Self Assembly ◽  
Free Standing ◽  
Environmental Friendliness ◽  
Surface Areas ◽  
Assembly Method ◽  
Effective Removal ◽  
The Cost ◽  
Adsorption Desorption ◽  
Porous Hydrogel

A green and facile fabrication strategy for synthesis of lignosulfonate-graphene porous hydrogel (LGPH) was designed via incorporation of lignosulfonate (LS) into graphene oxide (GO). This process was achieved by a simple self-assembly method at low temperature, with LS serving as surface functionalization agent. Benefiting from the abundant functional groups of LS and the large surface areas of graphene oxide, the prepared LGPH hydrogel displayed 3D interconnected pores and exhibited an excellent adsorption capacity for Cr(VI) (601.2 mg/g) ions dissolved in water. Importantly, the free-standing LGPH was easily separated from water after the adsorption process, and the adsorption capacities of Cr(VI) onto LGPH maintained 439.1 mg/g after 5 adsorption-desorption cycles. The cost-effectiveness and environmental friendliness of LGPH make it a promising material for removing heavy metals from wastewater.

scholarly journals Development of ammonia gas sensor based on Ni-doped reduce graphene oxide

2018 ◽  
Vol 192 ◽  
pp. 02048
Author(s):  
Thanva Tubthong ◽  
Anurat Wisitsoraat ◽  
Chookiat Tansarawiput ◽  
Pakorn Opaprakasit ◽  
Paiboon Sreearunothai
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Gas Sensor ◽  
Reduce Graphene Oxide ◽  
Low Cost ◽  
Nickel Sulfate ◽  
Ammonia Removal ◽  
Resistance Change ◽  
Ammonia Gas ◽  
Reduced Graphene

The work aims to develop a simple and low cost ammonia gas sensor based on reduced graphene oxide (rGO). Reduced graphene oxide doped with nickel sulfate (NiSO4/rGO) was used as a sensing material. The sensor was fabricated by a simple drop-cast and spin-coat technique. The performance of the nickel-doped reduce graphene oxide were studied in terms of electrical changes as well as chemical interactions. It was found that after the fabricated sensor was exposed to ammonia vapour for 10 min, the average resistivity was increased to 43% from initial resistance and retained about 8% resistance change upon ammonia removal. The mechanism of the sensor reaction with the ammonia gas is also studied using Fourier Transform Infrared Spectroscopy (FTIR) and is discussed. This preliminary work may help develop the highly sensitive ammonia gas sensor.

scholarly journals Recent Progress in Heavy Metal Ion Decontamination Based on Metal–Organic Frameworks

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1481
Author(s):  
Yajie Chen ◽  
Xue Bai ◽  
Zhengfang Ye
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
High Surface ◽  
Metal Organic Frameworks ◽  
Environmental Safety ◽  
Surface Areas ◽  
Effective Removal ◽  
Pore Size Distributions ◽  
Metal Organic

Heavy metals are inorganic pollutants which pose a serious threat to human and environmental safety, and their effective removal is becoming an increasingly urgent issue. Metal–organic frameworks (MOFs) are a novel group of crystalline porous materials, which have proven to be promising adsorbents because of their extremely high surface areas, optimizable pore volumes and pore size distributions. This study is a systematic review of the recent research on the removal of several major heavy metal ions by MOFs. Based on the different structures of MOFs, varying adsorption capacity can be achieved, ranging from tens to thousands of milligrams per gram. Many MOFs have shown a high selectivity for their target metal ions. The corresponding mechanisms involved in capturing metal ions are outlined and finally, the challenges and prospects for their practical application are discussed.

scholarly journals Photoelectrochemical Response of WO3/Nanoporous Carbon Anodes for Photocatalytic Water Oxidation

2018 ◽  
Vol 4 (3) ◽  
pp. 45 ◽  
Author(s):  
Alicia Gomis-Berenguer ◽  
Jesús Iniesta ◽  
David Fermín ◽  
Conchi Ania
Keyword(s):  
Water Oxidation ◽  
Carrier Transport ◽  
Hexagonal Phase ◽  
Nanoporous Carbon ◽  
Photoelectrochemical Performance ◽  
Nanoporous Carbons ◽  
Photoelectrochemical Activity ◽  
Photoelectrochemical Response ◽  
Carbon Anodes ◽  
The Impact

This work demonstrates the ability of nanoporous carbons to boost the photoelectrochemical activity of hexagonal and monoclinic WO3 towards water oxidation under irradiation. The impact of the carbonaceous phase was strongly dependent on the crystalline structure and morphology of the semiconductor, substantially increasing the activity of WO3 rods with hexagonal phase. The incorporation of increasing amounts of a nanoporous carbon of low functionalization to the WO3 electrodes improved the quantum yield of the reaction and also affected the dynamics of the charge transport, creating a percolation path for the majority carriers. The nanoporous carbon promotes the delocalization of the charge carriers through the graphitic layers. We discuss the incorporation of nanoporous carbons as an interesting strategy for improving the photoelectrochemical performance of nanostructured semiconductor photoelectrodes featuring hindered carrier transport.

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