Composites of furfuryl alcohol-formaldehyde resins and olive stones for production of activated carbons

Composites based on resin of furfuryl alcohol-formaldehyde or poly(furfuryl alcohol) and olive stones (pressed and extracted as received from industrial production) were cured as small cylinders and then pyrolyzed. The pyrolysis was studied by thermogravimetric analysis up to ～? 1000°C and by FTIR-spectroscopy for the initial composites and their pyrolysis residues up to 500°C. The specific surface areas of the carbonaceous residues and their discoloring ability for dyes of methylene blue and alizarin yellow were determined. The results are interpreted and discussed under the aspects of the pyrolysis process and the new carbonaceous materials produced. The usage of olive stones in mixture with resins based on furfuryl alcohol is more advantageous (e. g. leading to higher adsorption of the dyes) than the usage of the resin alone.     

Value-added products from waste: Slow pyrolysis of used polyethylene-lined paper coffee cup waste

The objectives of this study were to examine how to recycle cup waste efficiently and effectively and to determine if cup waste can be converted into liquid, solid, and gas value-added products by slow pyrolysis. The characteristics and potential utilizations of the pyrolysis products were investigated. The study included the effects of temperature, heating rate, and different feedstocks. The yield of pyrolysis oil derived from cup waste increased from 42% at 400°C to 47% at 600°C, while the yield of char decreased from 26% at 400°C to approximately 20% at 600°C. Acetic acid and levoglucosan were identified as the main components of the pyrolysis oil. The char obtained at 500°C was physically activated at 900°C for 3 h with CO₂. The adsorption capacity of the activated char was investigated with model compounds, such as methyl orange, methylene blue, ibuprofen, and acetaminophen. The results showed that the adsorption capacity of the activated char was similar to that of commercial activated carbon produced from peat. The higher heating value of the produced gas stream calculated at 400°C was 19.59 MJ/Nm³. Also, conventional slow pyrolysis (CSP) and microwave-assisted pyrolysis (MAP) technologies were compared to determine the differences in terms of products yields, composition and characteristics of the pyrolysis oil, and their potential applications. The CSP yields higher liquid products than MAP. Also, the pyrolysis oil obtained from the CSP had significantly more levoglucosan and acetic acid compared to that of the MAP.     

Spray pyrolysis synthesis of mesoporous TiO<Subscript>2</Subscript> microspheres and their post modification for improved photocatalytic activity

Mesoporous TiO₂ microspheres were prepared by spray pyrolysis for photocatalysis. Post modification of TiO₂ by heat treatment was performed to optimize its photocatalytic performance. First, spherical TiO₂ particles with mesoporous structure were synthesized at pyrolysis temperatures of 500, 600, and 700 °C. After characterization by XRD, SEM, and N₂ adsorption, a sample prepared at 500 °C was found to possess desirable properties for photocatalytic performance through post-modification. In methylene blue degradation, mesoporous TiO₂ microspheres synthesized at 500 °C outperformed other microspheres. Furthermore, samples obtained by spray pyrolysis at 500 °C were calcined at various temperatures as a post-modification process. The sample calcined at 350 °C showed improved photocatalytic activity due to optimal anatase crystallinity and surface area.     

Activated carbon from bacterial cellulose as an effective adsorbent for removing dye from aqueous solution

ABSTRACT

Novel activated carbon (AC) derived from bacterial cellulose (BC-AC) was produced by phosphoric acid activation at a carbonization temperature of 500 °C. BC-AC possesses mesoporous structures of 2.3 nm in diameter, porosity of 1.0 cm³/g and surface area of 1734 m²/g with high thermal stability between 100 and 500 °C. BC-AC could be used as an effective adsorbent for removing methylene blue (MB) from aqueous solutions with the maximum adsorption capacity of 505.8 mg/g. BC-AC presented physisorption and the adsorption of MB was most likely to be a monolayer adsorption. The Redlich–Peterson model displayed the best fit with the experimental data.     

Tubular structured ordered mesoporous carbon as an efficient sorbent for the removal of dyes from aqueous solutions

Tubular structured ordered mesoporous carbon CMK-5 was investigated for the adsorption of the industrial dyes reactive blue 19, acid red 57 and fuchsin basic in aqueous solutions at room temperature. It was found that CMK-5 exhibits an ultrahigh adsorption rate and superior adsorption capacities for these dyes. Its maximum adsorption capacities for reactive blue 19, acid red 57 and fuchsin basic were 733, 1131 and 1403 mg g⁻¹, respectively, and significantly greater than other literature reported results on porous carbons. Following adsorption of reactive blue 19, CMK-5 carbon could be regenerated by either ethanol extraction or thermal annealing at 600 °C, reaching ∼51% and ∼77%, respectively of the adsorption capacity of the original carbon. For comparison, ordered mesoporous carbon CMK-3 (rod structure), polymer based disordered mesoporous carbon, and steam and CO₂ activated commercial coconut carbons were investigated for the adsorption of reactive blue 19. The fast adsorption rate of CMK-5 carbon is due to its unique properties of tubular mesostructure, bimodal mesopore system and high surface area. In the case of requiring emergency removal of large amount of dyes in aqueous solution, CMK-5 would be an ideal choice.     

Treatment of pollutants in wastewater: Adsorption of methylene blue onto olive-based activated carbon

This study used olive stone-based activated carbon for the removal of methylene blue from wastewater in order to evaluate the adsorption capacity of the carbon. The equilibrium and kinetics of adsorption were examined at 25°, 30°, 35° and 40 °C and several agitation speeds. Type III adsorption isotherms corresponding to physical adsorption in a multilayer system were used for the methylene blue system. The equilibrium data for methylene blue adsorption showed a good fit to the Freundlich equation. The kinetic data was analysed to determine kinetic constants and order of reaction. Kinetics was evaluated by means of an n-order model, showing that the reaction was a first-order reaction. The results indicated that olive stone-based activated carbon could be used as a low-cost alternative to commercial activated carbon for the removal of organic compounds from wastewater. However, due to its microporosity, the application of this type of activated carbon was found to be suitable for molecules smaller than methylene blue.     

SYNTHESIS OF ACTIVATED CARBON FROM JATROPHA SEED COAT AND APPLICATION TO ADSORPTION OF IODINE AND METHYLENE BLUE

This article provides evidence that jatropha seed coat residues can be used as a carbon source for preparing activated carbons that have good adsorption properties for iodine and methylene blue. Activated carbons were prepared using three different methods of activation, physical, chemical, and physico-chemical, for a range of activation temperatures (600°, 700°, 800°, and 900°C) and activation hold times (1, 2, and 3 h). The highest BET surface area (1479 m² g^?1) and the highest iodine adsorption (1511 mg g^?1) were obtained with physico-chemical activation at a temperature of 900°C and a hold time of 2 h. This activated carbon gave higher BET surface area and iodine adsorption than commercial activated carbon (1169.1 m² g^?1 and 1076 mg g^?1). The activated carbons prepared by physico-chemical activation at 900°C and 2 h were then tested for adsorption of methylene blue at a range of concentrations of methylene blue (100, 200, 300, 400, and 500 mg L^?1). It was found that a Langmuir isotherm gave a better fit (R ² = 0.999) to the observed adsorptions than a Freundlich isotherm (R ² = 0.884). For the adsorption kinetics, a pseudo-second-order model gave a better fit (R ² > 0.998, Δq _e  = 3.7%) than a pseudo-first-order model (R ² ≈ 0.95, Δq _e  = 85.6%). These results suggest that chemisorption is the rate-controlling step for the adsorption of methylene blue. The experimental results show that jatropha seed coat is a lignocellulosic waste precursor for preparation of activated carbon that is an alternative source for preparation of commercial-grade activated carbons.     

Combined processes of glycerol polymerization/carbonization/activation to produce efficient adsorbents for organic contaminants

BACKGROUND: Glycerol was used to produce efficient adsorbents with a high surface area for organic contaminants by a combined process based on polymerization, carbonization and activation. RESULTS: Glycerol and sulfuric acid catalyst at concentrations of 0, 0.5, 1, 2 and 5 mol% were heated to 150 °C to form polyglycerol, which was then decomposed at 580 °C and activated with CO₂ at 850 °C. The resulting activated carbons had a high specific area (1630 m²g^?1) and high adsorption capacity of methylene blue used as a model organic contaminant. This process was also used to produce a special composite adsorbent based on expanded vermiculite (EV) coated with activated carbon. These composites were produced by impregnation of EV with glycerol followed by polymerization, thermal decomposition and activation with CO₂ to produce up to 25 wt% carbon and a surface area of 835 m²g^?1. CONCLUSIONS: The carbon layer present in the EV composite/activated carbon (GVE4CA2) produces a remarkable increase in the methylene blue adsorption capacity of the expanded vermiculite and strongly decreases undesirable water absorption. Copyright © 2012 Society of Chemical Industry     

木焦油基活性碳的制备及其对亚甲基蓝的吸附性能研究

木焦油是木质生物质材料的高温裂解产物。以木焦油为碳源,以甲醛化处理后的木焦油为前体,通过碳化-活化制备木焦油基活性碳材料。并以制备的木焦油基活性碳为吸附剂,研究了其对模拟水体中亚甲基蓝的吸附性能。结果表明,以木焦油为前驱体经高温碳化活化制备的多孔活性碳,比表面积可达1373Sm_²?g_^-1,表面含有丰富的含氧官能团。木焦油基活性碳对亚甲基蓝具有良好的吸附性能,准二级动力学模型能更准确的描述木焦油基活性碳吸附亚甲基蓝的动力学过程。吸附等温线更符合Langmuir等温吸附模型,木焦油基活性碳对亚甲基蓝的最大吸附容量可达559 mg?g_^-1。热力学分析表明亚甲基蓝在木焦油基活性碳上的吸附是放热和自发的。利用木焦油制备的活性碳材料对亚甲基蓝具有较高的吸附容量,是一种具有潜在应用前景的吸附材料。     

Synthesis of an ordered mesoporous carbon with graphitic characteristics and its application for dye adsorption

An ordered mesoporous carbon (OMC) was prepared by a chemical vapor deposition technique using liquid petroleum gas (LPG) as the carbon source. During synthesis, LPG was effectively adsorbed in the ordered mesopores of SBA-15 silica and converted to a graphitic carbon at 800 °C. X-ray diffraction and nitrogen adsorption/desorption data and high-resolution transmission electron microscopy (HRTEM) of the OMC confirmed its ordered mesoporous structure. The OMC was utilized as an adsorbent in the removal of dyes from aqueous solution. A commercial powder activated carbon (AC) was also investigated to obtain comparative data. The efficiency of the OMC for dye adsorption was tested using acidic dye acid orange 8 (AO8) and basic dyes methylene blue (MB) and rhodamine B (RB). The results show that adsorption was affected by the molecular size of the dye, the textural properties of carbon adsorbent and surface-dye interactions. The adsorption capacities of the OMC for acid orange 8 (AO8), methylene blue (MB) and rhodamine B (RB) were determined to be 222, 833, and 233 mg/g, respectively. The adsorption capacities of the AC for AO8, MB, and RB were determined to be 141, 313, and 185 mg/g, respectively. The OMC demonstrated to be an excellent adsorbent for the removal of MB from wastewater.     

β-Cyclodextrin functionalized graphene oxide: an efficient and recyclable adsorbent for the removal of dye pollutants

A novel method for the preparation of β-cyclodextrin grafted graphene oxide (GO-β-CD) has been developed. The GO-β-CD was characterized by Fourier transform infrared spectroscopy, ¹³C NMR spectroscopy, Raman spectroscopy and thermogravimetric analysis. The ability of GO-β-CD to remove fuchsin acid from solution was also studied. The GO-β-CD had an excellent adsorption capacity for fuchsin acid and could be recycled and reused. The adsorption capacities of GO-β-CD for other dye pollutants such as methyl orange and methylene blue were also investigated. The absorption capacities for the three dyes are in the order: fuchsin acid>methylene blue>methyl orange.     

Preparation and adsorption properties of amphoteric viscose fiber

Among the regenerated cellulosic fibers, viscose fiber is the most harmless material on human skin. Nonetheless, viscose fiber has some disadvantages such as low wet strength, high elongation, flammability, and poor color fastness. To improve adsorption and color fastness properties of viscose fiber, amphoteric viscose fibers were prepared. In the current study, viscose fiber was modified with 2,3-epoxy propyltrimethyl ammonium chloride and sodium chloroacetate using sodium hydroxide as catalyst. With adsorption performance of methyl orange and methylene blue as target dyes, the modification conditions were optimized in terms of temperature, time, and catalyst dosage with orthogonal test and single-factor experiment. The modified product was characterized using Fourier transform infrared spectrometry, scanning electron microscopy, ultraviolet spectrophotometry. Meanwhile, nitrogen content, degree of substitution, tensile strength, and adsorption property were measured. It was concluded that the best cationic reaction process conditions were reaction temperature of 70 °C, reaction time of 1 h, and sodium hydroxide dosage of 0.09 g, which was 1% of the amount of viscose fiber when the amount of etherifying agent was 30% of viscose fiber. The best anionic reaction conditions were reaction temperature of 70 °C, reaction time of 1 h, and 3.3 g of 10% sodium hydroxide solution. The adsorption properties of amphoteric modified viscose fiber towards methylene blue and methyl orange were excellent. The maximum adsorption of methylene blue and methyl orange was obtained at 1.483 and 0.234 mg g^?1, respectively.     

Removal of plant poisoning dyes by adsorption on Tomato Plant Root and green carbon from aqueous solution and its recovery

The organic dyes directly pollute the soil, water, plants and all living systems in the environment. The dyes like cationic Methylene blue (MB) and Crystal violet (CV) adsorption has been studied on Tomato Plant Root powder (TPR) and green carbon from aqueous solution for identifying the plant poisoning nature of cationic dyes. TPR powder is a cellulose material and green carbon is prepared from TPR powder by an ecofriendly method. The dyes adsorption mechanism on basic surface of cellulose and neutral surface of green carbon are correlated to evaluate the plant poisoning nature of organic dyes. The adsorption parameters were optimized to maximum adsorption. The maximum uptake of both dyes on TPR was 97% at 15 min and on carbon is 18% (CV) & 20% (MB) at 30 min. The adsorptions of MB and CV on TPR powder followed Freundlich and Langmuir adsorption isotherms and pseudo second order kinetics. The ?S^o, ?H^o and ?G^o of adsorption on TPR are calculated. The dyes recovery has been studied from dyes adsorbed TPR and green carbon. The adsorption mechanism and dye recovery studies proved the plant poisoning nature of MB and CV.     

Microwave-assisted preparation of mesoporous-activated carbon from coconut (Cocos nucifera) leaf by H3PO4 activation for methylene blue adsorption

Mesoporous-activated carbon was prepared from fallen coconut (Cocos nucifera) leaf, an agricultural waste through a microwave-induced H₃PO₄ activation process. The characterization of the coconut leaf–activated carbon (CAC) was evaluated through the iodine number, ash content, bulk density, and moisture content. Fourier transform infrared spectroscopy, scanning electron microscope, Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction, and pH_PZC. CAC has a mesopore content of 84% with an average pore size of 36.5?Å and a large BET surface area of 632?m²/g. The uptake properties of the CAC with methylene blue was evaluated at different CAC dosage levels (0.2–10?g/L), initial pH (3–10), methylene blue concentration (50–350?mg/L), and time (0–360?min) using batch mode operation. The kinetic profiles were described by the pseudo-second-order kinetics. The equilibrium data were well fitted to the Langmuir model with a maximum monolayer adsorption capacity of 250?mg/g at 30°C. Thermodynamic functions indicate a spontaneous and exothermic nature of the adsorption process. This study indicates that coconut leaves are a promising renewable precursor that can be utilized to develop an efficient mesoporous-activated carbon.     

Preparation of High Surface Area Mesoporous Activated Carbon: Kinetics and Equilibrium Isotherm

Activated carbon prepared from palm shell by phosphoric acid impregnation, at significantly favorable experimental conditions is characterized for the porous nature and adsorption of methylene blue dye molecules. The activation is carried out using a 2-stage activation process with the activation in a self-generated atmosphere. An activation temperature of 500°C, with an activation time of 75 minutes using a phosphoric acid impregnation ratio of 3 has yielded an activated carbon having unique characteristics. An activated carbon with a yield of 48%, total pore volume of 1.9 cm³/g, surface area of 1956 m²/g, an average pore diameter of 3.8 nm, with the ratio of the mesopore to the total surface area in excess of 75% has been prepared. The activated carbon exhibits a high methylene blue equilibrium adsorption capacity of 438 mg/g with the adsorption isotherm increasing with an increase in the adsorption temperature. Among the various adsorption isotherm models, the Langmuir model is able to explain the adsorption process well, evidenced by the proximity of the model with the experimental data. Among the different kinetic models tested with the experimental kinetic data, a pseudo-second-order model is found to fit the experimental data with close proximity.     

The adsorption of dyes from aqueous solution using diatomite

Raw diatomite was calcined at 450 °C for dyes removal from aqueous solution. SEM and FTIR analysis show that the raw diatomite contains organic impurities, which are removed after the calcination. The impurities removal decreases the specific surface area and increases the average pore diameter of raw diatomite, while improves its adsorption capability of dyes. The adsorption isotherm and kinetics experiments of methylene blue onto calcined diatomite were then carried out to investigate the adsorption property. It shows that the adsorption capacity of methylene blue is about 50 mg/g. The adsorption isotherm was fitted by the Langmuir, Freundlich and Redlich-Peterson models, which reveals that the Redlich-Peterson isotherm is the best one. Two kinetic models, pseudo-first order and pseudo-second order, were rearranged for expediently investigating the adsortpion mechanisms. Fitting results show that the pseudo-first-order model is better in describing the adsorption process.     

C/W emulsion-templated macroporous anionic monolith: Application for dye removal

A clean, sulfonated, highly adsorptive macroporous monolith was constructed using a carbon dioxide-in-water (C/W) high internal phase emulsion template. The random copolymerization of N-hydroxyethyl acrylamide and sodium styrene sulfonate in the water phase was initiated with persulfate. The chemical composition of the novel sulfonated monolith was confirmed by Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy, and the interconnected pore structure was confirmed by scanning electron microscopy (SEM). Results showed that the void sizes were 47–92 μm and that the interconnected pore throats were approximately 10–30 μm. Such a hydrophilic, anionic macroporous material exhibited excellent adsorption properties for cationic dyes. The maximum adsorption capacity of the monolith for methylene blue (MB) and malachite green (MG) reached 1,316 and 2,624 mg/g, respectively, in 500–800 mg/L dye solution at 25°C. Furthermore, the kinetics and thermodynamic parameters of the adsorption process were examined. Experimental data exhibited that adsorption kinetically followed the pseudo-second-order model. The removal rates of MG and MB both exceeded 90% after six regenerations. The adsorption mechanism of the adsorbent was demonstrated preliminarily. The dynamic adsorption operation of MB was conducted in a fixed column, and the breakthrough curve data were fitted using the Thomas and bed depth service time models. All these findings indicated the potential industrial applications of adsorptive sulfonated macroporous monolith.     

Fe3O4@SA/CTS凝胶球对亚甲基蓝及碱性品红的吸附

为解决染料对水体污染问题,本工作以海藻酸钠为骨架,结合Fe3O4及壳聚糖,制备了Fe3O4@SA/CTS凝胶球,并对制备的材料进行了微观表征。研究了不同影响因素下,吸附剂对MB及CB的吸附效果,同时研究了不同pH下对混合液的吸附性能,以及吸附剂循环利用性实验。结果表明,MB或CB初始浓度为100 mg/L、吸附剂投加量为1.0 g/L、MB的pH为11或CB的pH为8、反应时间4 h、MB和CB的去除率分别可以达到91.9%和21.5%。Langmuir模型能够更好反应对MB或CB的吸附,吸附以单分子物理吸附为主。吸附动力学符合伪二级动力学方程,吸附过程更容易受到化学吸附影响。不同pH下,Fe3O4@SA/CTS对混合液中的MB吸附优于CB,5次脱附循环使用后对MB保持在70%以上,对CB的去除率保持在15%以上。     

Thermal conductivity of MgO-C refractory ceramics: Effects of pyrolytic liquid and pyrolytic carbon black obtained from waste tire

In the present study, thermal conductivity and mechanical properties of MgO-C refractory ceramic bricks were investigated. Pyrolytic liquid and pyrolytic carbon black obtained from pyrolysis of waste tires were used as a resin and carbon source, respectively. The pyrolysis of the tires was conducted in a fixed bed reactor at the temperature of 500?°C with a 15?°C/min heating rate under nitrogen flow (0.5?lt/min). Before using in MgO-C refractory ceramic blends, pyrolytic products were purified with the acidic extraction methods which resulted in 61and 66?wt%. decreases in sulfur and ash contents in pyrolytic carbon, respectively. After this treatment of pyrolytic liquid, the sulfur content was reduced by 24?wt%. Eight different blends of MgO-C refractory ceramics consisting of different pyrolytic product contents were prepared, pressed, and tempered at 250?°C, and then characterized in terms of porosity, thermal conductivity, and density. The mechanical behavior of the samples was tested using a three-point bending test. Archimedes test was employed to determine the porosity and density. Surface properties of the bricks were analyzed by scanning electron microscopy (SEM). The obtained results were compared with a reference consisting of graphite and resin. The results revealed that mechanical and thermal properties of the developed bricks were highly sensitive to the porosity and the carbon source as well as the type of binder.     

Thermally modified acrylic polymers as sorbents

Acrylic fibres were modified with ethylene diamine and pyrolysed at temperatures up to 600°C. According to IR spectroscopy, polymers pyrolysed at 300°C contain nitrile and other groups which are present in the initial polymer. The specific surface area is decreased by increasing the pyrolysis temperature. The pore size distribution reveals mainly the presence of macropores. Acrylic polymers and those pyrolysed at 300°C sorb more methylene blue and alizarin yellow from aqueous solution than a non-polar commercial sorbent of high specific surface area. The experimental results for dye sorption were treated theoretically using a diffusion-limited sorption method. The polymers can be ranked by the parameters of this method or their sorption ability. The dye sorption is little affected by the pores of the polymers and is mainly affected by the interactions between the functional groups of the polymers and those of the dyes.