# Special Issue on New Carbon Materials from Biomass and Their Applications
## 2 New Carbon Materials from Biomass and Their Applications  
This special issue includes relevant works about the synthesis of carbon-based materials from biomass waste and their use in different applications, with special attention to biochar. In this sense, [PERSON] et al. [2] synthesized several brochars from municipal sewage sludge that showed high adsorption capacities of methylene blue dye. A subsequent KOH treatment enhanced adsorption capacity, which seems to be controlled by a complex result of various phenomena, including physi- and chemisorption and acid-base and redox equilibria. The adsorption of this same dye was analyzed by [PERSON] et al. [3], who used _Artemisiu selengensis_ to produce biochar by microwave pyrolysis. The results indicated that the increase of the pyrolysis temperature results in a decrease of the yield but an increase of the dye adsorption. The use of biochars as adsorbents for water purification was also analyzed by [PERSON] et al. [4]. In this case, the biochars from pine and spruce bark were subsequently activated with steam at 800 \({}^{\circ}\)C and studied in the removal of phenol, and microplastics retention and cation exchange capacity were employed as key test parameters. The work concluded that ultra-high porosities are not necessary for satisfactory water purification, supporting the economic feasibility of bio-based adsorbent production. Similarly, [PERSON] et al. [5] reported the preparation of low-cost activated grape seed-derived hydrocarbon through hydrothermal carbonization and chemical activation with different chemical activating agents (KOH, FeCl\({}_{3}\), and H\({}_{3}\)PO\({}_{4}\)) for sulfamethoxazole adsorption. The hydrocarbons showed low porosity, however their activation with KOH resulted in highly porous activated carbons (2200 m\({}^{2}\).g\({}^{-1}\)). The adsorption capacity was determined by the porous texture, achieving a high saturation capacity of 650 mg\(\cdot\)g\({}^{-1}\). [PERSON] et al. [6] detailed the zinc adsorption using activated carbon prepared from sawdust waste. Carbonization and activation were performed in a single stage using steam as a physical activation agent at 800 \({}^{\circ}\)C. The adsorption capacity towards zinc was tested and compared favorably to those of the materials reported in the literature. Not only liquid-phase but also gas-phase adsorption applications are included in this special issue. [PERSON] et al. [7] analyzed the dynamic CO\({}_{2}\) capture on physically activated biochars. Those were obtained from vine shoots and wheat straw pellets through an initial slow pyrolysis and further activation with CO\({}_{2}\) up to different degrees of burn-off. The adsorbent prepared from the vine shoots-derived biochar with the most hierarchical pore size distribution exhibited a good and stable performance under dry conditions. However, the presence of relatively high concentrations of water vapor in the feeding gas clearly interfered with the CO\({}_{2}\) adsorption mechanism, leading to significantly shorter breakthrough times. Besides biochar, many of the publications collected in this special issue were devoted to soil enrichment. [PERSON] et al. [8] reported the use of mixed hardwood and sugarcane bagasse biochar as potting mix components for container tomato and basil seedling production. The study concluded that 70% mixed hardwood biochar could be amended with peat moss for tomato and basil seedling production without negative effects on plant biomass. Similarly, [PERSON] et al. [9] investigated the stimulation and conditioning of seeds with biochar and the effects observed in the germination and emergence of Virginia mallow seedlings. The biochars, applied as conditioner added to water in the process of seed hydration, improved the germination capacity. The beneficial effects of biochar application were also reflected in the increased mass of Virginia mallow seedlings. [PERSON] el al. [10] used nutrient uploaded biochar pellets as slow release fertilizers.