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Abstract In this study, activated carbon was synthesized using the almond shell and palm kernel by physical activation with water vapor and chemical activation with phosphoric acid (H3PO4) methods. Then, the structural and optical properties of the activated carbons were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and UV–Vis spectroscopy. The SEM images showed that in the raw sample of hard almond shell and palm kernel, there is no porosity and pores, but in the activated carbon samples, porosity and structural defects were clearly observed. The XRD patterns showed that porous and amorphous structure was formed in all samples synthesized with physical and chemical activation. The results of FTIR spectra of activated carbons showed that there are carbon functional groups in all samples. The optical absorption coefficient (α) of the activated carbon with physical and chemical activation methods was obtained in order of 105–106. The band gap measurement of porous nanostructures showed that the activated carbon synthesized with chemical and physical activation methods have energy gap (Eg) in region = 2.80 to 3.15 eV and urbach energy (EU) in region = 120 to 210 meV.

Waste biomass, a renewable energy source, is inexpensive material that has great potential in sorption and electrochemical application. The selected waste materials (corncobs, coconut shells, walnuts, and pistachio husks) allow to close the production cycle and enable material recycling, which are important aspects in the hierarchy of waste management. The proposed methodology for production and activation of biochars can be used industrially due to highly porous structure, developed surface area, and sorption ability of the obtained activated carbons (AC). A significant increase (from 4 up to more than 10 times) in specific surface area (SSA) is observed for all samples after the CO 2 activation process (0.5 h at 800 °C) up to 725 m 2 g -1 for corncobs, 534.9 m 2 g -1 for pistachio husks, 523 m 2 g -1 for coconut shells, and 393 m 2 g -1 for walnut husks. The highest value of SSA is achieved for the AC derived from corncobs. This material is evaluated for use as an adsorbent, revealing 99% removal of Rhodamine B (dye/AC ratio of 0.0017) and 69% removal of chromium (dye/AC ratio of 0.0028). Based on the adsorption kinetics analysis, it is demonstrated that the Cr(VI) undergoes physical adsorption, while RhB undergoes chemisorption. In addition, corncob-derived AC exhibits superior electrochemical performance in 6 M KOH compared to the nonactivated biochar. A specific capacitance of 70 F g -1 at 5 A g -1 is achieved, along with outstanding rate capability (45 F g -1 at 50 A g -1 ) and cycling stability (94% at 10 A g -1 after 10,000 cycles). In contrast, the nonactivated sample shows only 34 F g -1 at 5 A g -1 and 13 F g -1 at 50 A g -1 , with a stability of 91.4%., (© 2023. The Author(s).)

The increase in burning, deforestation, and the exorbitant use of fossil fuels have contributed to the increase in carbon dioxide emissions; this gas is responsible for the intensification of the greenhouse effect and radical climate changes. In this way, it becomes necessary to find alternatives to reduce its emission. Porous carbon materials synthesized from lignocellulosic waste can be employed in technologies for capture and utilization of CO 2 due to the advantages such as selectivity, low-cost synthesis, high surface area and pore volume, and thermal and chemical stability. Considering the availability of Brazil nut biomass residues in the Amazon region, this article proposes to synthesize activated carbon from the lignocellulosic residue using physical and chemical activation methods for CO 2 capture. The analysis of N 2 adsorption-desorption isotherms proves the predominance of a microporous structure when using the two synthesis methods described here. In physical activation, the surface area was 912 m 2 /g, while, in chemical activation, it was 1421 to 2730 m 2 /g. The sample treated via the chemical method (BS6-K1) showed better performance in CO 2 adsorption, with adsorption results of 3.8 and 6 mmol/g of CO 2 at 25 ℃ and 0 °C, respectively, at 101 kPa. CO 2 adsorption capacity is due to the high volume of ultramicropores. It is believed that the microporous carbon material synthesized from Brazil nut residues is an alternative precursor for carbon materials used as CO 2 capture., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Bark residues of the forest species Cedrela fissilis were physically and chemically modified with zinc chloride (ZnCl 2 ) as an activating agent. The two modified materials were analyzed as adsorbents in removing atrazine and 2,4-D herbicides from effluents. Firstly, the precursor material and the modified ones were characterized by different techniques to identify the structural changes that occurred in the surfaces. Through TGA, it was observed that both modified materials have thermal stability close to each other and are highly superior to the precursor. X-ray diffractions proved that the amorphous structure was not altered, the three materials being highly heterogeneous and irregular. The micrographs showed that the treatments brought new spaces and cavities on the surface, especially for the material carbonized with ZnCl 2 . The pH PZC of the modified materials was close to 7.5. The physically modified material had a surface area of 47.31 m 2 g -1 and pore volume of 0.0095 cm 3 g -1 , whereas the carbonized material had a surface area of 98.12 m 2 g -1 and pore volume of 0.0099 cm 3 g -1 . Initial tests indicated that none of the adsorbents were efficient in removing 2,4-D. However, they showed good potential for removing atrazine. The Koble-Corrigan isothermal model best fits the experimental data, with a maximum capacity of 3.44 mg g -1 and 2.70 mg g -1 for physically modified and with ZnCl 2 , respectively. The kinetic studies showed that the system tends to enter into equilibrium after 120 min, presenting good statistical indicators to the linear driving force model (LDF). The surface diffusion coefficients were 2.18×10 -9 and 2.37×10 -9 cm 2 s -1 for atrazine adsorption on the physically and chemically modified materials. These results showed that the application of residues from the processing of cedar bark is promising. However, new future studies must be carried out to improve the porous development of the material and obtain greater adsorption capacities., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This work aims to obtain activated carbon (AC) from yeast residue to boost up bioeconomy. In this way, carbon was prepared from yeast biomass produced by the ethanol industry and after beta-glucan extraction. Carbon was activated with CO 2 , water vapor, and a combination of both using an experimental design. The best conditions to produce AC were activation with CO 2 for 30 min at 850 °C and CO 2 flow of 0.09 L/min, set by experimental design and desirability function to optimize the yield, surface area, and microporosity. Thus, for physical activation with water vapor employing the optimized conditions, it was possible to achieve a yield of 56.6% (m/m) for AC with 1144 m 2 /g of surface area and mean micropore volume of 0.53 cm 3 /g. The maximum AC surface area reached 1616 ± 567 m 2 /g with a yield of 21 ± 1%. The prepared ACs were characterized by elemental analysis, X-ray diffractometry, infrared spectroscopy, thermogravimetry analysis, pH PZC , and potentiometric titration to determine the main functional groups of sorption sites. The carbon obtained from the desirability condition was used to remove dipyrone from synthetic aqueous effluent with an experimental sorption capacity of 88 ± 4 mg/g, being the phenomenon described by the Freundlich isotherm model.

An increasing level of carbon dioxide (CO 2 ) in the atmosphere has ultimately resulted in global warming and climate change. The high-performance activated carbon (AC-WL) was synthesized from walnut shell, a low-cost biomass by-product, by physical activation using a tube furnace. The adsorption behavior of CO 2 from the CO 2 /N 2 mixture was investigated using a fixed bed. The surface and morphological characterizations of the produced activated carbons were measured using a BET analyzer and a scanning electron microscope (SEM). The effect of temperature, flow rate, CO 2 level, and partial pressure on breakthrough behavior was analyzed, and the adsorption response presented in terms of breakthrough point and adsorption capacity. The breakthrough and saturation periods vary significantly with change in temperature. The steepness of the breakthrough curves signifies good utilization of adsorbent capacity at breakthrough point. The increase in temperatures and flow rates lead to an increase in the length of mass transfer zone. The adsorption capacity of 1.58 mmol/g was obtained at 1.30 bars and 293 K with higher capacity utilization factor of 0.8492.These results suggest that the walnut-based activated carbon is favorable for capturing CO 2 .

Two-step physical activation was used to prepare activated carbon from textile waste jute. Raw material was first carbonized under nitrogen and then activated by CO 2 . Based on yield and pore structure, the optimal carbonization temperature and time were 500 °C and 60 min, respectively. Carbonized sample was next activated. The development of porosity and surface chemistry was highly dependent on activation temperature and time. Activated carbon produced at 800 °C was predominantly microporous while that produced at 900 °C was more mesoporous and macroporous. The shift from microporosity to mesoporosity could be used to produce either microporous or mesoporous carbon just by changing the activation temperature. Activation also changed the surface chemistry and created a more carbonaceous structure. The jute-based activated carbon was mostly powdered in form, slightly acidic and effective in adsorbing both heavy metals and organics.

The nanostructure of poly(acrylic acid) (PAA) adsorption layer on the surface of mesoporous-activated carbon HPA obtained by physical activation of residue after supercritical extraction of hops was characterized. This characterization has been done based on the analysis of determination of adsorbed polymer amount, surface charge density, and zeta potential of solid particles (without and in the PAA presence). The SEM, thermogravimetric, FTIR, and MS techniques have allowed one to examine the solid surface morphology and specify different kinds of HPA surface groups. The effects of solution pH, as well as polymer molecular weight and concentration, were studied. The obtained results indicated that the highest adsorption on the activated carbon surface was exhibited by PAA with lower molecular weight (i.e., 2000 Da) at pH 3. Under such conditions, polymeric adsorption layer is composed of nanosized PAA coils (slightly negatively charged) which are densely packed on the positive surface of HPA. Additionally, the adsorption of polymeric macromolecules into solid pores is possible.

The aim of this review was to evaluate current evidence regarding the effects of interventions on physical activity in the subgroup of nursing home residents as well as to critically review the assessment methods used in this regard. Published studies through January 2015 were searched in The Cochrane Library, PubMed, CINAHL, Web of Knowledge, PsycInfo, Psyndex, Psycarticles, CC Med, and DissOnline; and by manual search. For randomized controlled trials (RCTs) to be included, an intervention had to be conducted with nursing home residents aged 65 years and above and physical activity had to be assessed using standardized, quantitative methods. Study quality was evaluated using an established Cochrane rating tool for RCTs. Eight studies met the inclusion criteria. Only one intervention study with main focus on a modification of physical activity behavior could be identified. Physical activity assessments used in the studies were partly limited regarding objectivity or psychometric quality. Hence, the documentation of effects of interventions is restricted. Six studies reported significant increases of physical activity in nursing home residents and thus positive intervention effects, which points at the feasibility and high potential of intervention programs to promote physical activity in this setting. Enhanced individual contact as well as physical exercise combined with behavioral interventions and the inclusion of nursing staff seems to be most effective in this regard. As only one study involved post-intervention follow-up assessments, sustainability of effects remained unclear.