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This study aimed to investigate the effect of different activations on the properties of bio-based activated carbons (BACs) for water treatment. BACs were produced via pyrolysis by the carbonization stage and were followed by four different activation procedures. Chemical activation included the introduction of metal oxides or alkali on the structure of the sawdust-derived BACs, resulting in iron-activated carbon (BAC-Fe), copper-activated carbon (BAC-Cu), and sodium-activated carbon (BAC-Na). The physical activation was conducted in a CO2 environment with the usage of two types of locally available biomasses, resulting in husk-activated carbon (HAC) and wood-activated carbon (WAC). Depending on the activation, BACs can be developed with high porosity, active sites, and different additional functionalities such as antimicrobial and magnetic. The adsorption of natural organic matter (NOM) with chemically activated BACs yielded high removal percentages (97, 87, and 80% for BAC-Fe, BAC-Cu, and BAC-Na, respectively). The physically activated BACs demonstrated high adsorption capacities for dye – 278 mg/g for WAC and 213 mg/g for HAC. This outlines a wide range of BAC production possibilities with advanced functionalities. HIGHLIGHTS Various production parameters and methods allow the modification of final properties of bio-based activated carbons.; Physical activation provides sufficient surface area for pollutants such as dye; it is cheap and environmental friendly.; Chemical activation allows the implementation of functional groups on carbon surfaces to improve adsorbent selectivity and reach specific properties.;

Low-cost activated carbon (AC) samples obtained from waste coffee grounds were used for CO2 and CH4 adsorption. ACs were prepared by chemical activation and carbonized at three different temperatures. AC carbonized at 800°C showed a relatively high surface area (582.92 m² g-1) and high adsorption capacities of 2.6 mmol g-1 and 1.1 mmol g-1 at 25°C for CO2 and CH4, respectively. Adsorbent samples were prepared by loading of Fe3+ metal ions onto ACs and their adsorption capacities were compared with those of nonloaded ACs. As expected, the loading of Fe3+ metal ions increased the adsorption capacities at all temperatures and the adsorption capacity of Fe3+ -loaded AC carbonized at 800°C was 3.1 mmol g-1 for CO2 and 1.2 mmol g-1 for CH4 at 25°C. The isosteric heats of adsorption were calculated at 0–35°C with the range of 20–35 kJ mol-1 and 18–23 kJ mol-1 for CO2 and CH4, respectively. According to our findings, bio-based ACs can be used as an effective and alternative adsorbent for capturing different gas molecules. [ABSTRACT FROM AUTHOR]

Activated carbons (AC) serve as adsorbents in various applications requiring specific functionalities. In this study, the effects of biomass type, pre-carbonization process, and activation method on the properties of ACs were investigated. Chemical (KOH and H3PO4) and physical (CO2) activations were performed on slow pyrolyzed and hydrothermally carbonized (HTC) biochars produced from two feedstocks, willow and Scots pine bark (SPB). In addition, the adsorption capacities of the ACs were tested with two dyes and zinc metal. Distinct differences were found between the biochars and ACs regarding pore size distributions, surface area (238 - 3505 m2 g-1), and surface chemistry. KOH activation produced highly microporous ACs from all biochars, whereas with H3PO4 and CO2 there was also increase in the meso- and macroporosity with the HTC biochars. Adsorption capacity for dyes was dependent on the surface area, while for zinc it depended on AC's pH. The results provide interesting insights into tailoring ACs for specific applications. [ABSTRACT FROM AUTHOR]

Activated bio-based carbons produced from vine shoots (VSAC) and grape stalks (GSAC), which have larger surface area and total pore volume than most of the commercially available activated carbons, are used as supports for palladium nanoparticles (Pd NPs). The prepared materials are characterised by elemental analysis, N2-sorption, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, and transmission electron microscopy analysis and are then assessed as potential cathodes for the hydrogen evolution reaction (HER) in alkaline media. The electrocatalysts' performance for HER is evaluated from cathodic polarisation curves at different temperatures and compared to that of Vulcan XC72-supported Pd NPs. Additional chronoamperometry studies helped to assess the electrocatalysts' activity stability. The novel VSAC-supported Pd electrocatalyst exhibits good HER activity in terms of high current density at low overpotentials, leading to the best performance. [ABSTRACT FROM AUTHOR]

Artocarpus integer is widely cultivated in Malaysia for its edible fruit which is used as an ingredient in the production of various confectioneries. The large amount of thick solid peel waste formed from processing of this fruit is a burden to local Artocarpus integer fruit processing industries. In this work, the feasibility of converting Artocarpus integer fruit processing waste into an industrially viable and low-cost green-activated carbon was evaluated. The novel activated carbon was prepared by physical activation with steam and characterized by elemental analysis, Boehm titration method, Fourier Transform Infrared Spectroscope (FTIR), Scanning Electron Microscope (SEM) and X-ray powder Diffraction (XRD). In addition, the potential use of the prepared activated carbon as an adsorbent and the effects of activation temperature and duration on iodine adsorption were examined. Experimental results revealed the suitability of Artocarpus integer fruit processing waste to be used as a precursor for activated carbon. The raw waste material was found to be a lignocellulosic biomass which is rich in cellulose (53.6 wt%) and carbon (60.8 wt%). Steam activation temperature, 750 ° C and a short activation time of 60 min were appropriate to attain a high quality activated carbon with a large iodine adsorption capacity (1411 mg/g), highly micro-porous and amorphous structure with predominantly basic surface functional groups which are all advantageous properties for adsorption applications. The newly developed activated carbon is a promising cost-effective (∼1.67 US$ per kg) alternative to commercial carbon which may be used as a cleaner and ecologically compatible adsorbent for improving water and air quality, consequently, benefiting human health and wellbeing. [ABSTRACT FROM AUTHOR]

Analytical pyrolysis-comprehensive two-dimensional gas chromatography/mass spectrometry (Py-GC × GC/MS) was used for the on-line analysis of pyrolysis vapors. Bio-based activated carbon (B-AC) catalysts were used to produce highly selectivity valuable chemicals such as furans and phenols. B-AC catalyst was subjected to several characterizations to investigate the physicochemical properties of the catalyst and its relationship with products distribution. The results showed that B-AC catalyst showed high catalytic activity and selectivity for the production of furans and phenols under mild catalytic temperature (350 °C). Furans are mainly from pyrolysis of cellulose and hemicellulose, while phenols are mainly from pyrolysis of lignin. Methylfurans and phenol were dominated compounds. With the use of B-AC, the relative peak area of methylfurans increased from 6.58% to 39.35% (cellulose), 0%–27.79% (xylan), 0.54%–26.82% (corncob); the relative peak area of phenol increased from 6.31% to 53.83% (lignin) and 2.77%–12.34% (corncob). A significant reduction of aldehydes, ketones, and sugars was also observed over B-AC catalyst. The higher total acidity (weak acidity and Lewis acidity) of B-AC favored the formation of 2-methylfuran and phenol. Ex-situ catalytic fast pyrolysis vapors upgrading of biomass into methyl-furans and phenol over bio-based activated carbon catalyst-feasible & efficient. Image 1 • Bio-based activated carbon (B-AC) was used for catalytic upgrading of biomass pyrolysis vapors. • Relative content of furans and phenols are 61.83% and 82.97%, respectively, from catalytic upgrading of cellulose and lignin pyrolysis vapors. • Relative content of methylfurans and phenol as high as 32.77% and 47.52%, respectively, from catalytic upgrading of cellulose and lignin. • Thermal degradation and catalytic upgrading mechanism were proposed. [ABSTRACT FROM AUTHOR]