Effects of Burn-off and Activation Temperature on Preparation of Activated Carbon from Corn Cob Agrowaste by CO(2) and Steam

Adsorption of Hydrogen Sulfide on Activated Carbon Materials Derived from the Solid Fibrous Digestate

The goal of this work is to develop a sustainable value chain of carbonaceous adsorbents that can be produced from the solid fibrous digestate (SFD) of biogas plants and further applied in integrated desulfurization-upgrading (CO₂/CH₄ separation) processes of biogas to yield high-purity biomethane. For this purpose, physical and chemical activation of the SFD-derived BC was optimized to afford micro-mesoporous activated carbons (ACs) of high BET surface area (590-2300 m²g^-1) and enhanced pore volume (0.57-1.0 cm³g^-1). Gas breakthrough experiments from fixed bed columns of the obtained ACs, using real biogas mixture as feedstock, unveiled that the physical and chemical activation led to different types of ACs, which were sufficient for biogas upgrade and biogas desulfurization, respectively. Performing breakthrough experiments at three temperatures close to ambient, it was possible to define the optimum conditions for enhanced H₂S/CO₂ separation. It was also concluded that the H₂S adsorption capacity was significantly affected by the restriction to gas diffusion. Hence, the best performance was obtained at 50 °C, and the maximum observed in the H₂S adsorption capacity vs. the temperature was attributed to the counterbalance between adsorption and diffusion processes.

Removal of NO at low concentration from air in urban built environments by activated miscanthus biochar

This work presents an innovative and sustainable approach to remove NO emissions from urban ambient air in confined areas (underground parking areas or tunnels) using low-cost activated carbons obtained from Miscanthus biochar (MSP700) by physical activation (with CO₂ or steam) at temperatures ranging from 800 to 900 °C. The NO removal capacity of the activated biochars was evaluated under different conditions (temperature, humidity and oxygen concentration) and compared against a commercial activated carbon. This last material showed a clear dependence on oxygen concentration and temperature, exhibiting a maximum capacity of 72.6% in air at 20 °C, whilst, its capacity notably decreased at higher temperatures, revealing that physical NO adsorption is the limiting step for the commercial sample that presents limited oxygen surface functionalities. In contrast, MSP700-activated biochars reached nearly complete NO removal (99.9%) at all tested temperatures in air ambient. Those MSP700-derived carbons only required low oxygen concentration (4 vol%) in the gas stream to achieve the full NO removal at 20 °C. Moreover, they also showed an excellent performance in the presence of H₂O, reaching NO removal higher than 96%. This remarkable activity results from the abundance of basic oxygenated surface groups, which act as active sites for NO/O₂ adsorption, along with the presence of a homogeneous microporosity of 6 Å, which enables intimate contact between NO and O₂. These features promote the oxidation of NO to NO₂, which is further retained over the carbon surface. Therefore, the activated biochars studied here could be considered promising materials for the efficient removal of NO at low concentrations from air at moderate temperatures, thus closely approaching real-life conditions in confined spaces.

Role of grinding method on granular activated carbon characteristics

A coconut shell (AC1230CX) and a bituminous coal based (F400) granular activated carbon (GAC) were ground with mortar and pestle (MP), a blender, and a bench-scale ball milling unit (BMU). Blender was the most time-efficient for particle size reduction. Four size fractions ranging from 20 × 40 to 200 × 325 were characterized along with the bulk GACs. Compared to bulk GACs, F400 blender and BMU 20 × 40 fractions decreased in specific surface area (SSA, -23% and -31%, respectively) while smaller variations (-14% to 5%) occurred randomly for AC1230CX ground fractions. For F400, the blender and BMU size fraction dependencies were attributed to the combination of (i) radial trends in the F400 particle properties and (ii) importance of shear (outer layer removal) versus shock (particle fracturing) size reduction mechanisms. Compared to bulk GACs, surface oxygen content (At%-O1s) increased up to 34% for the F400 blender and BMU 20 × 40 fractions, whereas all AC1230CX ground fractions, except for the blender 100 × 200 and BMU 60 × 100 and 100 × 200 fractions, showed 25-29% consistent increases. The At%-O1s gain was attributed to (i) radial trends in F400 properties and (ii) oxidization during grinding, both of which supported the shear mechanism of mechanical grinding. Relatively small to insignificant changes in point of zero charge (pHPZC) and crystalline structure showed similar trends with the changes in SSA and At%-O1s. The study findings provide guidance for informed selection of grinding methods based on GAC type and target particle sizes to improve the representativeness of adsorption studies conducted with ground GAC, such as rapid small-scale column tests. When GACs have radial trends in their properties and when the target size fraction only includes larger particle sizes, manual grinding is recommended.

Explosion Strategy Engineering Oxygen-Functionalized Groups and Enlarged Interlayer Spacing of the Carbon Anode for Enhanced Lithium Storage

Amorphous carbon monoliths with tunable microstructures are candidate anodes for future lithium-based energy storage. Enhancing lithium storage capability and solid-state diffusion kinetics are the precondition for practical applications. Transforming intrinsic oxygen-rich defects into active sites and engineering enlarged interlayer spacing are of great importance. Herein, a novel explosion strategy is designed based on oxalate pyrolysis producing CO and CO₂ to successfully prepare lignin-derived carbon monolith (LSCM) with active carbonyl (C═O) groups and enlarged interlayer spacing. Explosion promotes the demethylation of methoxyl groups and cleavage of carboxyl groups to form C═O groups. CO₂ etches carbon atoms in a short time to improve the heteroatom level, expanding the interlayer spacing. ZnC₂O₄ is decomposed at 400 °C, simultaneously producing CO and CO₂, which constructs less C═O groups and large interlayer spacing. MgC₂O₄ is decomposed at 450 and 480 °C, staged-weakly producing CO and CO₂, which constructs more C═O groups and larger interlayer spacing. CaC₂O₄ is decomposed at 480 and 700 °C, staged-uniformly producing CO and CO₂, which constructs abundant C═O groups and largest interlayer spacing. The LSCM prepared by staged-uniform explosion exhibits high lithium storage capacity, superior rate capability, and cycling performance. The assembled lithium ion capacitor device achieves excellent energy/power densities of 78 Wh kg^-1/100 W kg^-1 and superior durability (capacitance retention of 8 4.6% after 20,000 cycles). This work gives a novel insight to engineer advanced oxygen-functionalized carbons for enhanced lithium storage.

Value-Added Products from Catalytic Pyrolysis of Lignocellulosic Biomass and Waste Plastics over Biochar-Based Catalyst: A State-of-the-Art Review

As the only renewable carbon resource on Earth, lignocellulosic biomass is abundant in reserves and has the advantages of environmental friendliness, low price, and easy availability. The pyrolysis of lignocellulosic biomass can generate solid biochar with a large specific surface area, well-developed pores, and plentiful surface functional groups. Therefore, it can be considered as a catalyst for upgrading the other two products, syngas and liquid bio-oil, from lignocellulosic biomass pyrolysis, which has the potential to be an alternative to some non-renewable and expensive conventional catalysts. In addition, as another carbon resource, waste plastics can also use biochar-based catalysts for catalytic pyrolysis to solve the problem of accumulation and produce fuels simultaneously. This review systematically introduces the formation mechanism of biochar from lignocellulosic biomass pyrolysis. Subsequently, the activation and modification methods of biochar catalysts, including physical activation, chemical activation, metal modification, and nonmetallic modification, are summarized. Finally, the application of biochar-based catalysts for lignocellulosic biomass and waste plastics pyrolysis is discussed in detail and the catalytic mechanism of biochar-based catalysts is also investigated.

Comparative Study of Three Dyes' Adsorption onto Activated Carbon from Chenopodium quinoa Willd and Quillaja saponaria

The present study shows porous activated carbon obtained from Chenopodium quinoa Willd and Quillaja saponaria and their use as potential adsorbents to remove three types of dyes from aqueous solutions. The adsorption results were compared with commercial charcoal to check their efficiency. All porous carbon materials were activated using carbon dioxide and steam and fully characterized. Moreover, the steam-activated samples exhibited a high total pore volume with a BET surface area of around 800 m2 g−1. Batch adsorption experiments showed that commercial charcoal is the charcoal that offered the best adsorption efficiency for tartrazine and sunset yellow FCF. However, in the case of crystal violet, all activated carbons obtained from Chenopodium quinoa Willd and Quillaja saponaria showed the best captures, outperforming commercial charcoal. Molecular dockings of the dyes on the commercial charcoal surface were performed using AutoDock Vina. The kinetic results of the three isotherm’s models for the present data follow the order: Langmuir~Freundlich > Temkin.

Advanced Material-oriented Biomass Precise Reconstruction: A Review on Porous Carbon with Inherited Natural Structure and Created Artificial Structure by Post-treatment

Manufacturing of porous carbon with biomass resources has been intensively investigated in recent decades. The diversity of biomass species and great variety of processing methods enable the structural richness of porous carbon as well as their wide applications. In this review, we specifically focused on the structure of biomass-derived porous carbon either inherited from natural biomass or created by post-treatment. The intrinsic structure of plant biomass was briefly introduced and the utilization of the unique structures at different length-scales were discussed. In term of post-treatment, the structural features of activated carbon by traditional physical and chemical activation were summarized and compared in a wide spectrum of biomass species, statistical analysis were performed to evaluate the effectiveness of different activation methods in creating specific pore structures. The similar pore structure of biomass-derived carbon and coal-derived carbon suggested a promising replacement with more sustainable biomass resources in producing porous carbon. In summary, using biomass as porous carbon precursor endows the flexibility of using its naturally patterned micro-structure and the tunability of controlled pore-creation by post treatment. This article is protected by copyright. All rights reserved.

Dye contaminated wastewater treatment through metal–organic framework (MOF) based materials

A complete discussion of MOFs and MOF composites such as MOF-based membranes, magnetic MOFs, and metal–organic gels (MOGs) used for dye removal along with their adsorption efficiency has been done.

Biomass-Derived Carbon Materials: Controllable Preparation and Versatile Applications

Biomass-derived carbon materials (BCMs) are encountering the most flourishing moment because of their versatile properties and wide potential applications. Numerous BCMs, including 0D carbon spheres and dots, 1D carbon fibers and tubes, 2D carbon sheets, 3D carbon aerogel, and hierarchical carbon materials have been prepared. At the same time, their structure-property relationship and applications have been widely studied. This paper aims to present a review on the recent advances in the controllable preparation and potential applications of BCMs, providing a reference for future work. First, the chemical compositions of typical biomass and their thermal degradation mechanisms are presented. Then, the typical preparation methods of BCMs are summarized and the relevant structural management rules are discussed. Besides, the strategies for improving the structural diversity of BCMs are also presented and discussed. Furthermore, the applications of BCMs in energy, sensing, environment, and other areas are reviewed. Finally, the remaining challenges and opportunities in the field of BCMs are discussed.

The Analysis of Pore Development and Formation of Surface Functional Groups in Bamboo-Based Activated Carbon during CO2 Activation

Pore development and the formation of oxygen functional groups were studied for activated carbon prepared from bamboo (Bambusa bambos) using a two-step activation with CO2, as functions of carbonization temperature and activation conditions (time and temperature). Results show that activated carbon produced from bamboo contains mostly micropores in the pore size range of 0.65 to 1.4 nm. All porous properties of activated carbons increased with the increase in the activation temperature over the range from 850 to 950 °C, but decreased in the temperature range of 950 to 1000 °C, due principally to the merging of neighboring pores. The increase in the activation time also increased the porous properties linearly from 60 to 90 min, which then dropped from 90 to 120 min. It was found that the carbonization temperature played an important role in determining the number and distribution of active sites for CO2 gasification during the activation process. Empirical equations were proposed to conveniently predict all important porous properties of the prepared activated carbons in terms of carbonization temperature and activation conditions. Oxygen functional groups formed during the carbonization and activation steps of activated carbon synthesis and their contents were dependent on the preparation conditions employed. Using Boehm's titration technique, only phenolic and carboxylic groups were detected for the acid functional groups in both the chars and activated carbons in varying amounts. Empirical correlations were also developed to estimate the total contents of the acid and basic groups in activated carbons in terms of the carbonization temperature, activation time and temperature.

Magnetic bio-activated carbons production using different process parameters for phosphorus removal from artificially prepared phosphorus-rich and domestic wastewater

A series of magnetic bio-activated carbon (MBAC) has been produced from lignin and ferrous salts following to the process including impregnation, carbonization, and steam activation. The influence of the impregnation methods and the steam flow rate on the quality and the maximum phosphorus adsorption capacity of the produced MBACs has been investigated. The phosphorus adsorption performance in real domestic wastewater of the MBAC with the highest maximum phosphorus adsorption capacity has been investigated. The results show that all of the produced MBACs have a relatively rich porous structure, and all surface iron species exist as magnetite (Fe₃O₄). Compared with the MBACs that are produced via the dry impregnation method using a lower steam flow rate, the MBACs that are produced via the wet impregnation method using a higher steam flow rate are believed to have a higher iron content and better iron species dispersion. The highest maximum phosphorus adsorption capacity of all the produced MBACs is estimated to be as high as 69.80 mg-P/g according to the best-fitting Langmuir model. The MBAC that shows the highest maximum phosphorus adsorption capacity could also remove 84.65% and 96.97% of the total phosphorus from the filtered raw domestic wastewater (FRDW) and treated domestic wastewater (TDW), respectively, which indicates a good potential for using MBACs for domestic wastewater treatment.

Reduction of chlordecone environmental availability by soil amendment of biochars and activated carbons from lignocellulosic biomass

Chlordecone (kepone or CLD) was formerly used in French West Indies as an insecticide. Despite its formal ban in 1993, high levels of this pesticide are still found in soils. As such, sequestering matrices like biochars or activated carbons (ACs) may successfully decrease the bioavailability of halogenated compounds like CLD when added to contaminated soils. The present study intends (i) to produce contrasted sequestering matrices in order to (ii) assess their respective efficiency to reduce CLD environmental availability. Hence, the work was designed following two experimental steps. The first one consisted at producing different sequestering media (biochars and ACs) via pyrolysis and distinct activation processes, using two lignocellulosic precursors (raw biomass): oak wood (Quercus ilex) and coconut shell (Cocos nucifera). The chemical activation was carried out with phosphoric acid while physical activation was done with carbon dioxide and steam. In the second step, the CLD environmental availability was assessed either in an OECD artificial soil or in an Antillean contaminated nitisol (i.e., 2.1^-1μg CLD per g of soil dry matter, DM), both amended with 5 wt% of biochar or 5 wt% of AC. These both steps aim to determine CLD environmental availability reduction efficiency of these media when added (i) to a standard soil material or (ii) to a soil representative of the Antillean CLD contamination context. Textural characteristics of the derived coconut and oak biochars and ACs were determined by nitrogen adsorption at 77 K. Mixed microporous and mesoporous textures consisting of high pore volume (ranging from 0.38 cm³.g^-1 to 2.00 cm³.g^-1) and specific (BET) surface areas from 299.9 m².g^-1 to 1285.1 m².g^-1 were obtained. Overall, soil amendment with biochars did not limit CLD environmental availability (environmental availability assay ISO/DIS 16751 Part B). When soil was amended with ACs, a significant reduction of the environmental availability in both artificial and natural soils was observed. AC soil amendment resulted in a reduced CLD transfer by at least 65% (P < 0.001) for all lignocellulosic matrices (excepted for coconut sample activated with steam, which displayed a 47% reduction). These features confirm that both pore structure and extent of porosity are of particular importance in the retention process of CLD in aged soil. Owing to its adsorptive properties, AC amendment of CLD-contaminated soils appears as a promising approach to reduce the pollutant transfer to fauna and biota.

Engineered biochar via microwave CO2 and steam pyrolysis to treat carcinogenic Congo red dye

We developed an innovative single-step pyrolysis approach that combines microwave heating and activation by CO₂ or steam to transform orange peel waste (OPW) into microwave activated biochar (MAB). This involves carbonization and activation simultaneously under an inert environment. Using CO₂ demonstrates dual functions in this approach, acting as purging gas to provide an inert environment for pyrolysis while activating highly porous MAB. This approach demonstrates rapid heating rate (15-120 °C/min), higher temperature (> 800 °C) and shorter process time (15 min) compared to conventional method using furnace (> 1 h). The MAB shows higher mass yield (31-44 wt %), high content of fixed carbon (58.6-61.2 wt %), Brunauer Emmett Teller (BET) surface area (158.5-305.1 m²/g), low ratio of H/C (0.3) and O/C (0.2). Activation with CO₂ produces more micropores than using steam that generates more mesopores. Steam-activated MAB records a higher adsorption efficiency (136 mg/g) compared to CO₂ activation (91 mg/g), achieving 89-93 % removal of Congo Red dye. The microwave pyrolysis coupled with steam or CO₂ activation thereby represents a promising approach to transform fruit-peel waste to microwave-activated biochar that remove hazardous dye.

Sustainable production of nanoporous carbons: Kinetics and equilibrium studies in the removal of atrazine

Nanoporous carbons have been prepared from mangosteen peels-derived chars by physical activation under CO₂ flow as a function of temperature. As an example of circular bioeconomy, these sustainable adsorbents were used to remove atrazine, a common pesticide from the agroindustry. Several adsorption models such as Langmuir (two parameter), Sips and Redlich-Peterson (three parameters) were applied to verify the influence of carbon's properties on the uptake of atrazine. Additional kinetic models (pseudo-first order, pseudo-second order and Avrami's) allowed to establish that a mixture of physisorption and chemisorption describes the interaction between the nanoporous carbons and atrazine. As a general fact, an important diffusion of atrazine from the bulk of solution to the surface of carbons was observed. All samples were able to remove atrazine, but the highest uptake was found in the carbon with the highest contribution of micropores to the total pore of volume and with the lowest content of basic surface groups. Several correlations between the kinetic and equilibrium parameters for the atrazine adsorption were found as a function of the textural properties and surface chemistry. Based on the kinetics and equilibrium parameters, the present work proposes a mechanism for the atrazine adsorption on nanoporous carbons contributing to the understanding of the interactions between pollutant molecules and the surface functional groups on nanoporous carbons in the liquid-solid interface.

Solid-Waste-Derived Carbon Dioxide-Capturing Materials

Solid sorbents are considered to be promising materials for carbon dioxide capture. In recent years, many studies have focused on the use of solid waste as carbon dioxide sorbents. The use of waste resources as carbon dioxide sorbents not only leads to the development of relatively low-cost materials, but also eliminates waste simultaneously. Different types of waste materials from biomass, industrial waste, household waste, and so forth were used as carbon dioxide sorbents with sufficient carbon dioxide capture capacities. Herein, progress on the development of carbon dioxide sorbents produced from waste materials is reviewed and covers key factors, such as the type of waste, preparation method, further modification method, carbon dioxide sorption performance, and kinetics studies. In addition, a new research direction for further study is proposed. It is hoped that this critical review will not merely sum up the major research directions in this field, but also provide significant suggestions for future work.

Investigation of rice husk derived activated carbon for removal of nitrate contamination from water

Development of porous carbons with high specific surface area (>1200mg^-1) targeted at nitrate removal from aqueous solutions is investigated by chemical activation of carbonized rice husk. Potassium carbonate is used as activating and desilicating agent. The effect of post-synthetic treatment by gas phase ammoxidation with ozone/ammonia or oxidation with concentrated nitric acid followed by nitrification with urea on main physicochemical properties and on the effectiveness of the activated carbons in nitrate removal is compared with those determined for a pristine activated carbonized rice husk sample. The two-fold enhancement of nitrate removal by the urea-modified activated carbon in comparison with pristine and ammoxidated sample is in direct correlation with the development of surface basic groups.

H2O2 treatment enhanced the heavy metals removal by manure biochar in aqueous solutions

The physicochemical properties and adsorption capacities of yak manure biochar (SP350-YMB) and modified yak manure biochar by H₂O₂ (AC-YMB) were investigated. Results showed the oxygen content and the carboxyl group content of manure biochar increased by 63.4% and 101%, and the ash content decreased 42% after modification, respectively. Compared to SP350-YMB, the adsorption capacities of heavy metal ions (Pb²⁺, Cu²⁺, Cd²⁺ and Zn²⁺) were enhanced by AC-YMB in single-metal and multi-metal solutions. The maximum adsorption capacity of Pb²⁺ increased from 76.41mgg^-1 by SP350-YMB to 169.57mgg^-1 by AC-YMB based on Langmuir-Freundlich model in single-metal solutions. Pseudo-first and Pseudo-second-order model were used to predict the Pb²⁺ adsorption kinetics by AC-YMB. H₂O₂ modification reduced ash content and increased carboxyl content resulting in the major mechanism of heavy metal sorption shifting from precipitation with carbonate/phosphate to complexation with carboxyl. Results from this study indicated that H₂O₂ modified biochar could act as effective surface sorbent to remove heavy metals, but its ability to remove multi-metal ions needs to be carefully evaluated on an individual basis.

Food wastes derived adsorbents for carbon dioxide and benzene gas sorption

Food wastes are produced worldwide in large quantities that could have potential to produce higher value products, including industrial adsorbents. The present work attempts valorization of food waste by CO₂ activation and functionalization through nitric acid and melamine treatment. The prepared porous materials were subjected to gas phase adsorption of CO₂ and benzene gases. The resultant highly porous carbon materials with surface area range from 797 to 1025 m²/g were synthesized showing uptake capacities of 4.41, 4.07, 4.18 and 4.36 mmol/g of CO₂ and 345, 305, 242.5 and 380.7 mg/g of C₆H₆ respectively for PyF515, PyF520, PyF715 and PyF720 in the absence of doped carbon matrix. Differential thermogravimetric (DTG) analysis showed the thermostability of the precursors to validate selected initial pyrolysis temperatures (500 and 700 °C). C₆H₆ sorption lies mainly in the physisorption region for all adsorbents ensuring re-generation potential. PyF720 and PyF520 recorded the highest isosteric enthalpy of 64.4 kJ/mol and 48.7 kJ/mol respectively, despite the low degree of coverage of the latter. Thus, PyF515 and PyF720 demonstrated the potential for use as sustainable and cost effective adsorbents for benzene gas containment suitable for swing adsorption system.

Physically (CO2) activated hydrochars from hickory and peanut hull: preparation, characterization, and sorption of methylene blue, lead, copper, and cadmium

CO₂ activation of hydrochar resulted in improved physicochemical properties and greater sorption of various contaminants.

Preparation and characterization of humic acid-carbon hybrid materials as adsorbents for organic micro-pollutants

The present work involves the preparation of novel adsorbent materials by the insolubilization and hybridization of humic acid (HA) with carbon. The prepared materials were characterized by N2 adsorption, elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, solid-state (13)C cross polarization magic angle spinning nuclear magnetic resonance, and low-field nuclear magnetic resonance (NMR) relaxometry on wetted samples. The water solubility of these materials and the lack of effect of oxidants were also confirmed. With this background, the adsorption capacities toward phenol, 2,4,6-tricholrophenol, and atrazine were evaluated, using these as model compounds for organic micropollutants of concern in water. Experimental results show that the prepared materials are mesoporous and have a higher surface area than humic acid and even than the porous carbon in the case of carbon coating. They retain the basic features of the starting materials with lowered functional group content. Moreover, there are interesting new features. NMR relaxometry shows that equilibration of water uptake is very fast, making use in water simple. They have higher adsorption capacities than the pure materials, and they can be applied under a wide range of environmental conditions.

Production of granular activated carbon from food-processing wastes (walnut shells and jujube seeds) and its adsorptive properties

Commercial activated carbon is a highly effective absorbent that can be used to remove micropollutants from water. As a result, the demand for activated carbon is increasing. In this study, we investigated the optimum manufacturing conditions for producing activated carbon from ligneous wastes generated from food processing. Jujube seeds and walnut shells were selected as raw materials. Carbonization and steam activation were performed in a fixed-bed laboratory electric furnace. To obtain the highest iodine number, the optimum conditions for producing activated carbon from jujube seeds and walnut shells were 2 hr and 1.5 hr (carbonization at 700 degrees C) followed by 1 hr and 0.5 hr (activation at 1000 degrees C), respectively. The surface area and iodine number of activated carbon made from jujube seeds and walnut shells were 1,477 and 1,184 m2/g and 1,450 and 1,200 mg/g, respectively. A pore-distribution analysis revealed that most pores had a pore diameter within or around 30-40 angstroms, and adsorption capacity for surfactants was about 2 times larger than the commercial activated carbon, indicating that waste-based activated carbon can be used as alternative. Implications: Wastes discharged from agricultural and food industries results in a serious environmental problem. A method is proposed to convert food-processing wastes such as jujube seeds and walnut shells into high-grade granular activated carbon. Especially, the performance of jujube seeds as activated carbon is worthy of close attention. There is little research about the application ofjujube seeds. Also, when compared to two commercial carbons (Samchully and Calgon samples), the results show that it is possible to produce high-quality carbon, particularly from jujube seed, using a one-stage, 1,000 degrees C, steam pyrolysis. The preparation of activated carbon from food-processing wastes could increase economic return and reduce pollution.

Co-production of activated carbon, fuel-gas, and oil from the pyrolysis of corncob mixtures with wet and dried sewage sludge

This study explored the amount and composition of pyrolysis gas and oil derived from wet material or dried material during the preparation of sludge-corncob activated carbon, and evaluated the physicochemical and surface properties of the obtained two types of sludge-corncob-activated carbons. For wet material, owing to the presence of water, the yields of sludge-corncob activated carbon and the oil fraction slightly decreased while the yield of gases increased. The main pyrolysis gas compounds were H2 and CO2, and more H2 was released from wet material than dried material, whereas the opposite holds for CO2 Heterocyclics, nitriles, organic acids, and steroids were the major components of pyrolysis oil. Furthermore, the presence of water in wet material reduced the yield of polycyclic aromatic hydrocarbons from 6.76% to 5.43%. The yield of furfural, one of heterocyclics, increased sharply from 3.51% to 21.4%, which could be explained by the enhanced hydrolysis of corncob. In addition, the surface or chemical properties of the two sludge-corncob activated carbons were almost not affected by the moisture content of the raw material, although their mesopore volume and diameter were different. In addition, the adsorption capacities of the two sludge-corncob activated carbons towards Pb and nitrobenzene were nearly identical.

Carbon Derived from Jatropha Seed Hull as a Potential Green Adsorbent for Cadmium (II) Removal from Wastewater

Carbon from jatropha seed hull (JC) was prepared to study the adsorption of cadmium ions (Cd²⁺) from aqueous solutions under various experimental conditions. Batch equilibrium methods have been used to study the influences of the initial metal ion concentration (0.5-50 ppm), dosage (0.2-1 g), contact time (0-300 min), pH (2-7), and temperature (26-60 °C) on adsorption behavior. It has been found that the amount of cadmium adsorbed increases with the initial metal ion concentration, temperature, pH, contact time, and amount of adsorbent. A kinetic study proved that the mechanism of Cd²⁺ adsorption on JC followed a three steps process, confirmed by an intraparticle diffusion model: rapid adsorption of metal ions, a transition phase, and nearly flat plateau section. The experimental results also showed that the Cd²⁺ adsorption process followed pseudo-second-order kinetics. The Langmuir and Freundlich adsorption isotherm models were used to describe the experimental data, with the former exhibiting a better correlation coefficient than the latter (R² = 0.999). The monolayer adsorption capacity of JC has been compared with the capacities of the other reported agriculturally-based adsorbents. It has been clearly demonstrated that this agricultural waste generated by the biofuel industry can be considered a potential low-cost adsorbent for the removal of Cd²⁺ from industrial effluents.

Removal of nitrate from aqueous solutions by activated carbon prepared from sugar beet bagasse

In this study, activated carbons were prepared from sugar beet bagasse by chemical activation and the prepared activated carbons were used to remove nitrate from aqueous solutions. In chemical activation, ZnCl(2) was used as chemical agent. The effects of impregnation ratio and activation temperature were investigated. The produced activated carbons were characterized by measuring their porosities and pore size distributions. The microstructure of the activated carbons was examined by scanning electron microscopy (SEM). The maximum specific surface area of the activated carbon was about 1826m(2)/g at 700 degrees C and at an impregnation ratio of 3:1. The resulting activated carbon was used for removal of nitrate from aqueous solution. The effects of pH, temperature and contact time were investigated. Isotherm studies were carried out and the data were analyzed by Langmuir, Freundlich and Temkin equations. Three simplified kinetic models were tested to investigate the adsorption mechanism.

Adsorptive removal of the pesticide methomyl using hypercrosslinked polymers

The hypercrosslinked polymers Macronet MN-150 and MN-500 (denoted as MN-150 and MN-500) were investigated to remove the pesticide methomyl from aqueous solutions via adsorption. Furthermore, the effect of humid acid (used as background organic compound) on the adsorption capacity of methomyl for MN-150 was examined. The equilibria and kinetics of the adsorption of methomyl onto MN-150 and MN-500 can be well correlated with Langmuir and Freundlich isotherms, and conventional kinetic models (e.g., surface and pore diffusion models), respectively. The polymer MN-150 possesses a high potential to be applied as adsorbent for the removal of methomyl from aqueous solution when compared with MN-500. Furthermore, the competitive effect of humic acid on adsorption of methomyl on MN-150 can be ignored at low equilibrium concentrations. The transport of methomyl from solution into the polymer adsorbents is controlled by both, external and internal mass transfer mechanisms with film-surface diffusion model offering the better description. The surface mobility and flux of surface diffusion increase as the initial concentration increases.

Characteristic and mercury adsorption of activated carbon produced by CO2 of chicken waste

Preparation of activated carbon from chicken waste is a promising way to produce a useful adsorbent for Hg removal. A three-stage activation process (drying at 200 degrees C, pyrolysis in N2 atmosphere, followed by CO2 activation) was used for the production of activated samples. The effects of carbonization temperature (400-600 degrees C), activation temperature (700-900 degrees C), and activation time (1-2.5 h) on the physicochemical properties (weight-loss and BET surface) of the prepared carbon were investigated. Adsorptive removal of mercury from real flue gas onto activated carbon has been studied. The activated carbon from chicken waste has the same mercury capacity as commercial activated carbon (Darco LH) (Hg(v): 38.7% vs. 53.5%, Hg(0): 50.5% vs. 68.8%), although its surface area is around 10 times smaller, 89.5 m2/g vs. 862 m2/g. The low cost activated carbon can be produced from chicken waste, and the procedure is suitable.