Coal-based humic acid (CBHA) is an ideal precursor for the preparation of carbon materials due to their high aromaticity and abundance of oxygen-containing functional groups. The resulting materials often exhibit...

Solar steam generation has been proven to be an efficient way for obtaining clean water from seawater or polluted water with solar energy as the only energy input. Due to the high porosity and light absorption, tunable micro–nano structure, and excellent thermal insulation, carbon aerogels as photothermal materials have attracted much attention. However, requirements of freeze drying and additional light absorbers as well as low strength restrict the large-scale utilization of carbon aerogels. Herein, self-floating and low-cost coal tar-based phenolic carbon aerogels (CPCAs) were fabricated using a facile method, that is, polymerization/gelation, vacuum drying, and carbonization. CPCAs with comparable light absorption (96.6%) to carbon nanotube can be used as intrinsic photothermal materials owing to the existence of considerable polycyclic aromatics in coal tar. In addition, CPCAs possess hierarchical porous architectures and abundant polar functional groups, delivering fast water transportation. Moreover, the latent heat is obviously reduced due to the regulation of the water state. Therefore, the evaporation rate can reach up to 2.23 kg m–2 h–1 with an energy efficiency of 92.5% under 1 sun employing a CPCA as a photothermal material. Additionally, CPCAs with high strength (more than 4 MPa under 90% compressive strain) have versatile applications in seawater desalination and industrial wastewater for long-term stability. The excellent performance of CPCAs was tentatively revealed by density functional theory and COMSOL calculation.

Preparing ash-less coal and further converting it into chemicals is an efficient and promising means for lignite utilization. This work performed depolymerization of lignite to prepare ash-less coal (SDP) and separated it into the hexane-soluble fraction (HS), toluene-soluble fraction (TS), and tetrahydrofuran-soluble fraction (THFS). The structure of SDP and those of subfractions were characterized by elemental analysis, gel permeation chromatography, Fourier transform infrared spectroscopy, and synchronous fluorescence spectroscopy. The results show that SDP is a mixture of aromatic derivatives containing alkyl substituents and oxygen-containing functional groups. The number of condensed aromatic rings, the amount of oxygen-containing functional groups, and the molecular weight gradually increase as HS < TS < THFS. SDP was further analyzed by 1H-NMR and 13C-NMR to calculate its structural parameters. The macromolecule of THFS contains 15.8 total ring systems with 9.2 aromatic rings and 6.6 naphthenic rings. On average, each THFS molecule contains 6.1 alcohol hydroxyl groups, 3.9 phenol hydroxyl groups, 1.4 carboxyl groups, and 1.0 inactive oxygen-containing functional groups. The dominant reactions occurred during depolymerization are the breakage of ether linkages. The average THFS molecule consists of 3.3 structural units with aromatic nuclei (2.8 rings on average) linked with methylene, naphthene, and so forth.