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Biochar synthesized from algal biomasses acts as an efficient adsorbent to remove tetracycline (TC) from aqueous solutions. In this study, a mixture of Enteromorpha (EN) and Chlorella vulgaris (CV) was pyrolyzed at 500 °C, then activated with NaOH at 800 °C to prepare composite biochar (EC A -B). The effects of TC concentration (50–500 mg·L−1), pH (3–11), temperature (30 °C–50 °C), and contact time (0–960 min) on TC absorption were investigated. Results revealed that in aqueous solutions, the biochar (EC 4:1 -0.5)prepared with CV and EN at the mass ratio of 4:1 and the impregnation ratio of 0.5 had the optimal TC adsorption capacity (Q m = 376.878 mg·g−1). The removal rate of EC 4:1 -0.5 remained above 80 % after five cycles. The surface area of EC 4:1 -0.5 (583.329 m2·g−1) increased by three and four times that of EN and CV, respectively. Intraparticle diffusion was considered as the major limitation for the adsorption of TC onto EC 4:1 -0.5. This investigation provides a method for the synthesis and optimization of algal biomass-based activated carbon for the absorption of organic pollutants in wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

• This study promoted the cycling of carbon and nitrogen in wastewater systems. • The "adsorption-catalysis-adsorption" strategy improved the recovery of waste. • Improved quality of bio-oil obtained with regenerated catalyst. • The maximum adsorption capacity of regenerated bio-char was 554.38 mg·g−1. This study proposes an "adsorption-catalysis-adsorption" strategy to improve the recycling capacity of bio-char, which has implications for improving bio-char utilization and reducing greenhouse gas emissions. A porous bio-char (EPAC) was prepared and used for effective methylene blue (MB) adsorption. The adsorbent after MB adsorption was used to fabricate a new carbon catalyst (EPMCC), which exhibited an excellent catalytic capacity for low N/O bio-oil. The nitrogen content of the bio-oil catalyzed by EPMCC decreased from 34.46 wt% to 17.04 wt%, and the hydrocarbon content increased from 15.52 wt% to 29.09 wt% compared to the pyrolysis of Enteromorpha clathrate alone. The used EPMCC was then regenerated to obtain a new EPMNC adsorbent with a high specific surface area (1097.99 m2·g−1). The maximum adsorption capacity of EPMNC was 554.38 mg·g−1, and the adsorption mechanisms involved electrostatic interactions, π-π interactions, and hydrogen bonding. This study promotes the cycling of carbon and nitrogen in organic wastewater systems containing nitrogen. [ABSTRACT FROM AUTHOR]

[Display omitted] • BNNSs/rGO heterostructure is synthesized by self-assembly crosslinking approach. • The mediator can suppress the shuttle effect of LiPSs by superior adsorption. • It can markedly catalyze the conversion of liquid-phase LiPSs and solid-phase Li 2 S. • BNNSs/rGO-based Li-S batteries show improved electrochemical reaction kinetics. Lithium-sulfur (Li-S) battery with high theoretical specific capacity (1675 mAh/g), has been deemed as one of the most potential candidates of secondary energy storage system. However, the large-scale applications of Li-S batteries have been obstructed by internally sluggish multi-step redox reaction and terrible shuttle effect of lithium polysulfides (LiPSs). Herein, boron nitride nanosheets/reduced graphene oxide (BNNSs/rGO) heterostructure prepared by self-assembly crosslinking method has been designed to modify commercial separator for Li-S batteries. The hierarchical pores, physical and chemical cross-links within heterostructure can significantly enhance the adsorption capacity for LiPSs, uniquely physical and electronic interaction between BNNSs and rGO can effectively catalyze the conversion of sulfurated species. Benefiting from the synergistic adsorption-catalysis effect, BNNSs/rGO not only greatly inhibits the shuttle behaviors, but also considerably accelerates the electrochemical reaction kinetics for LiPSs and Li 2 S. Attributed to these merits, Li-S battery with BNNSs/rGO heterostructure mediator delivers superiorly reversible capacity as high as 915.0 mAh/g at 1 C. Even at high sulfur loading of 3.9 mg cm−2, the cell delivers ultra-stable specific capacity of 629.1 mAh/g at 1 C, and still maintains 605.5 mAh/g over 500 cycles corresponding to a capacity fade of merely 0.0075% per cycle. [ABSTRACT FROM AUTHOR]

[Display omitted] • The formation mechanism of porous BN foams (BNFs) is studied in-depth. • BNFs exhibit hierarchical pore structures and robust mechanical integrity. • BNFs possess high adsorption capacities for CO 2 , liquid nitrogen and naphthalene. • BNFs are designed as permeation-separation and filtration-adsorption columns. Boron nitride (BN) bulk adsorbents replace their powder ones, which indeed make up for many shortcomings of BN's powders in practical adsorption application and become the most promising BN-based multifunctional adsorption materials. However, the difficulty of synthesis greatly limits their development. Here, we prepare a series of highly porous BN foams (BNFs), via a facile compression forming and controllable high-temperature nitriding method. The BNFs have hierarchical pore characteristics, including abundant micropores (~40 vt.%), and various mesopores and macropores (~60 vt.%), while they possess a robust three-dimensional integrality with maximum compression strength up to ~ 2.2 MPa. These properties make the BNFs kinds of desired bulk adsorbents for application in advanced multifunctional adsorption. Firstly, they can capture various gas molecules, including ultrahigh CO 2 capacities of ~ 3.05 mmol/g (0 °C) and ~ 1.75 mmol/g (25 °C), naphthalene of ~ 155 wt% (80 °C) and 89 wt% (20 °C), and liquid nitrogen quantity of ~6.6-times weight of their own weight. In addition, the BNFs with a well hydrophobic-lipophilic surface exhibit remarkable adsorption for a wide range of organic reagents and oils, up to very high capacity of 600–1830 wt%, and show high-end permeation-separation and filtration-adsorption application in oil–water systems. Moreover, as a kind of static block adsorbents, the BNFs also have outstanding pollutant adsorption performances for S 8 and Li 2 S x in organic solvents, and the Ni(II) ions and methylene blue molecules in water. We believe that our new BNFs materials will be of great significance to lead the BN-based bulk adsorbents for continuous application in more sophisticated fields. [ABSTRACT FROM AUTHOR]