Sustainable Biomass Glucose-Derived Porous Carbon Spheres with High Nitrogen Doping: As a Promising Adsorbent for CO2/CH4/N2 Adsorptive Separation

An Ultramicroporous Graphene-Based 3D Structure Derived from Cellulose-Based Biomass for High-Performance CO2 Capture

The use of powered activated carbon is often limited by inconsistent particle sizes and porosities, leading to reduced adsorption efficiencies. In this study, we demonstrated a practical and environmentally friendly method for creating a 3D graphene nanostructure with highly uniform ultramicropores from wood-based biomass through a series of delignification, carbonization, and activation processes. In addition, we evaluated the capture characteristics of this structure for CO2, CH4, and N2 gases as well as its selectivity for binary-mixture gases. Based on textural and chemical analyses, the delignified monolith had a lamellar structure interconnected by cellulose-based fibers. Interestingly, applying the KOH vapor activation technique solely to the delignified samples led to the formation of a monolithic 3D network composed of interconnected graphene sheets with a high degree of crystallinity. Especially, the Act. 1000 sample exhibited a specific surface area of 1480 m2/g and a considerable pore volume of 0.581 cm3/g, featuring consistently uniform ultramicropores over 90% in the range of 3.5-11 Å. The monolithic graphene-based samples, predominantly composed of ultramicropores, demonstrated a notably heightened capture capacity of 6.934 mol/kg at 110 kPa for CO2, along with favorable selectivity within binary gas mixtures (CO2/N2, CO2/CH4, and CO2/CH4). Our findings suggest that this biomass-derived 3D structure has the potential to serve as a monolithic adsorbent in gas separation applications.

N-rich chitosan-derived porous carbon materials for efficient CO2 adsorption and gas separation

Capturing and separating carbon dioxide, particularly using porous carbon adsorption separation technology, has received considerable research attention due to its advantages such as low cost and ease of regeneration. In this study, we successfully developed a one-step carbonization activation method using freeze-thaw pre-mix treatment to prepare high-nitrogen-content microporous nitrogen-doped carbon materials. These materials hold promise for capturing and separating CO2 from complex gas mixtures, such as biogas. The nitrogen content of the prepared carbon adsorbents reaches as high as 13.08 wt%, and they exhibit excellent CO2 adsorption performance under standard conditions (1 bar, 273 K/298 K), achieving 6.97 mmol/g and 3.77 mmol/g, respectively. Furthermore, according to Ideal Adsorption Solution Theory (IAST) analysis, these materials demonstrate material selectivity for CO2/CH4 (10 v:90 v) and CO2/CH4 (50 v:50 v) of 33.3 and 21.8, respectively, at 1 bar and 298 K. This study provides a promising CO2 adsorption and separation adsorbent that can be used in the efficient purification process for carbon dioxide, potentially reducing greenhouse gas emissions in industrial and energy production, thus offering robust support for addressing climate change and achieving more environmentally friendly energy production and carbon capture goals.

Sorption based easy-to-use low-cost filters derived from invasive weed biomass for dye contaminated water cleanup

Today, the development of functional nanostructured materials with specified morphologies utilizing environmentally friendly techniques is a very appealing topic in materials chemistry. Much emphasis has recently been paid to the utilization of biomass to make functional carbonaceous materials of varying forms, specifically carbon helices, with greater implications for the environment, economy, and society. A metal-catalyzed chemical vapour deposition technique has been developed for the fabrication of such carbon helices from nonrenewable hydrocarbons. Also, functionalization approaches were seen to necessitate high temperatures, hazardous gases, and multi-step processes. Herein, we have synthesized tendril-like functional carbon helices (HTCs) from toxic bio-weed, Parthenium hysterophorus as the carbon source by a greener solvothermal method employing deep eutectic solvent (DES) as both soft template and catalyst. Further, for the first time by taking advantage of the in-built chemical functionalities, HTCs were physically activated in an inert atmosphere at 900 °C (AHC) and functionalized with manganese oxide at room temperature by employing DES. Furthermore, the materials were characterized using FE-SEM, EDX, FT-IR, XRD, and BET analysis, where a surface area of 313.12 m² g⁻¹ was achieved with a robust removal of 99.68% of methylene blue (MB) dye with a flux rate of 7432.71 LMH in a simulated continuous flow system. The obtained material was also evaluated for its specificity towards contaminant removal from an aqueous medium. Thus, Mn₃O₄/AHC membranes exhibited great promise as an easy-to-use filter for organic contaminant cleanup, with about 91% rejection of MB even at the end of the 10^th cycle, indicating its potential.

Today, the development of functional nanostructured materials with specified morphologies utilizing environmentally friendly techniques is a very appealing topic in materials chemistry.

Allomelanin: A Biopolymer of Intrinsic Microporosity

Melanin is a ubiquitous natural pigment found in a diverse array of organisms. Allomelanin is a class of nitrogen-free melanin often found in fungi. Herein, we find artificial allomelanin analogues exhibit high intrinsic microporosity and describe an approach for further increasing and tuning that porosity. Notably, the synthetic method involves an oxidative polymerization of 1,8-DHN in water, negating the need for multiple complex templating steps and avoiding expensive or complex chemical precursors. The well-defined morphologies of these nanomaterials were elucidated by a combination of electron microscopy and scattering methods, yielding to high-resolution 3D reconstruction based on small-angle X-ray scattering (SAXS) results. Synthetic allomelanin nanoparticles exhibit high BET areas, up to 860 m²/g, and are capable of ammonia capture up to 17.0 mmol/g at 1 bar. In addition, these nanomaterials can adsorb nerve agent simulants in solution and as a coating on fabrics with high breathability where they prevent breakthrough. We also confirmed that naturally derived fungal melanin can adsorb nerve gas simulants in solution efficiently despite lower porosity than synthetic analogues. Our approach inspires further analysis of yet to be discovered biological materials of this class where melanins with intrinsic microporosity may be linked to evolutionary advantages in relevant organisms and may in turn inspire the design of new high surface area materials.