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Activated carbons (JSAC45 and JSAC55) were fabricated via both processes of pyrolysis and gasification using steam with burn-off of 45 and 55%. These materials derived from Ziziphus jujube were characterized by the adsorption–desorption of N2, thermogravimetric analyzer coupled with mass spectrophotometer (TGA/MS), electron microscope (SEM), Fourier transform infrared spectroscope (FTIR), Boehm titration, and pHPZC. The specific surface area (SBET) of activated carbons was 953 m2/g for both materials with the predominance of basic character ( pH PZC ≅ 10) . Then, the prepared carbons were used to adsorb BEZAKTIV Red S-Max (RS). The effect of initial RS concentration (10–100 mg/L), contact time (0–1440 min), pH (2–10), and temperature (25–45 °C) on adsorption capacity of JSAC45 and JSAC55 were examined; and it was revealed that RS dye was well adsorbed at pH = 10. The equilibrium adsorption data suggested that the Langmuir model fitted well the RS dye adsorption, and the pseudo-second-order model best fitted the adsorption kinetic data. The maximum of adsorption capacity of RS onto JSAC55 was 113.3 mg/g. Thermodynamics studies of JSAC45 and JSAC55 indicated that the adsorption process was endothermic, spontaneous, and feasible. The activated carbons were reused after applying the thermal regeneration process. The Ziziphus jujube adsorbents could adsorb industrial wastewater (IW) with an elimination rate of about 40% for both adsorbents. These results confirm that the Ziziphus jujube stones may be considered as an inexpensive and promising precursor for commercial activated carbons production. [ABSTRACT FROM AUTHOR]

The persistent increase in the atmospheric concentration of carbon dioxide (CO2), the primary anthropogenic greenhouse gas contributing to global warming, makes research directed towards carbon capture and storage (CCS) imperative. In the past few years, among the available adsorbents, biochar has drawn significant interest as a promising carbon-based material for low-temperature CO2 capture from flue/fuel gas (such as biogas or gasification-derived syngas) owing to its environmentally friendly nature, cost-effective and facile preparation method, and sustainable adsorption performance. This work provides a review of recent studies on the development of biochar from biomass feedstocks and its subsequent modification through various approaches, including physical, chemical and physicochemical activations for post-combustion CO2 capture. An overview of the factors, including pyrolysis temperature, heating rate and time, and different modification methods, affecting the physicochemical attributes of biochar such as surface area, microporosity, surface properties and functional groups is presented. Biochar with a large micropore volume, a narrow microporosity (0.3–0.8 nm) and basic surface characteristics would be effective in adsorbing CO2 molecules. In this regard, physical modification of biochar is closely related to pore formation, whereas chemical modification emphasizes the creation of oxygen and nitrogen-containing functional groups; hence, they contribute to the enhanced CO2 capture through porosity development and surface chemistry alteration, respectively. Biochar has presented a strong selectivity towards CO2 compared to other gasses and has revealed a sustainable performance in multi-cycles of CO2 adsorption–desorption; these are crucial features to ensure the large-scale application of biochar for CO2 capture. [ABSTRACT FROM AUTHOR]

Beer is one of the most popular drinks in the world. In the process of beer brewing, the main solid by-products are brewers' spent grains. Those malt residues are produced in large quantities. This work focused on the utilization of BSG for the production of activated carbon. The raw material was obtained from the production of standard Pilsner beer. Technical and thermogravimetric analyzes were performed on BSG. The material was then subjected to low temperature carbonization to obtain semicoke, which was processed into activated carbon. During the experiments, two physical activation techniques and one chemical were tested: with CO2, with H2O, and solid NaOH. All of obtained materials were also examined by using FTIR technique. The results showed that steam activated carbon had bigger SBET (636 m2/g) than carbon dioxide activated (551 m2/g). The best results were obtained by using chemical activation by NaOH (3286 m2/g). Activated carbons obtained from BSG may be a feasible and cheap sorbent in water treatment plants, especially those located close to the brewery. [ABSTRACT FROM AUTHOR]

In the work, water caltrop husk (WCH), locally agricultural residue generated in large quantities, was evaluated as a potential precursor for preparing mesoporous activated carbon (AC) by physical activation under the matrix of activation temperature (600–900℃) and holding times (i.e., 0–150 min). The pore and chemical properties of the resulting AC products, including porosity, true density, elemental analysis (EA), scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDS), and Fourier-transform infrared spectroscopy (FTIR), were determined to find the optimal activation conditions. From the data on the analysis of AC properties, the activation temperature at around 800℃ for holding time of 45 min was observed to produce the optimal WCH-AC product with the Brunauer–Emmett–Teller (BET) surface area of 972.56 m2/g, total pore volume of 0.55 cm3/g, and porosity of 0.476. Its corresponding mesopore volume and mesopore percentage reached up to 0.19 cm3/g and 35%, respectively. In addition, the opposite effect was also observed for the resulting AC products activated at 800℃ under different holding times, indicating the pore enlargement and/or collapse at holding time increased from 45 to 60 min. Based on the chemical analyses, the high oxygen content was found on the surface of the resulting AC product, which could be indicative of slight polar nature (i.e., hydrophilicity) due to the oxygen-containing functional groups. [ABSTRACT FROM AUTHOR]

In this study, the production of activated carbon by physical and chemical activation methods from Rhododendron ponticum L. was studied. In the physical activation method, Rhododendron ponticum L. was directly heated in nitrogen atmosphere at temperatures of 450, 550, and 650 °C and subjected to CO2 atmosphere for 1 h. Chars produced from Rhododendron ponticum L. were used in the chemical activation method. The chars were obtained by heating to 450 °C at a nitrogen atmosphere and waiting at this temperature for 2 h. H3PO4, KOH, and K2CO3 were used as chemical agents, and the char and chemical agent mass ratio were ½, and the chars were carbonized to a temperature of 550 °C at a nitrogen atmosphere and allowed to stand at this temperature for 1 h. The structural characterization of the activated carbons produced by both methods was carried out using nitrogen adsorption at − 196 °C and scanning electron microscope. [ABSTRACT FROM AUTHOR]

In order to enhance the adsorption capacity of activated carbon (AC) from cocoa pod husk (CPH) and reuse the solution after the acid-leaching of CPH as a liquid fertilizer, CPH was first leached by acid and then used as a precursor (CPH-A) for preparing ACs by physical activation at a temperature range of 650-850 °C in this work. Based on the proximate analysis, mineral compositions, thermogravimetric analysis, and thermochemical properties, the differences between CPH and CPH-A were investigated. The chemical and pore properties of the resulting ACs were further studied. The results show that the pretreatment of CPH with hydrochloric acid led to removal of over 90% of the ash content in the CPH, mainly composed of potassium minerals. The Brunauer-Emmet-Teller (BET) surface area of the AC derived from CPH-A at 650 °C is 355.8 m2/g, significantly larger than that (i.e., 1.1 m2/g) of the AC derived from CPH. The higher activation temperature (e.g., 900 °C) is beneficial to the pore development of the resulting AC (e.g., BET surface area ˃ 1300 m2/g). In addition, the carbon (C) and sulfur (S) contents of the resulting ACs indicate an increasing trend as the temperature increased from 650 to 850 °C, but a decreasing trend in the hydrogen (H), nitrogen (N), and oxygen (O) contents. [ABSTRACT FROM AUTHOR]