Luffa leaf (LL) is an agricultural waste produced by loofah. In this work, LL was used as biomass carbon source for biochars for the first time. After carbonization, activation, and chemical co-precipitation treatments, a magnetic lignocellulose-derived hierarchical porous biochar was obtained. The specific surface area and total pore volume were 2565.4 m²/g and 1.4643 cm³/g, and the surface was rich in carbon and oxygen functional groups. The synthetic dye rhodamine B (RhB) and the antibiotic tetracycline hydrochloride (TH) were selected as organic pollutant models to explore the ability to remove organic pollutants, and the results showed good adsorption performances. The maximum adsorption capacities were 1701.7 mg/g for RhB and 1755.9 mg/g for TH, which were higher than most carbon-based adsorbents. After 10 cycles of use, the removal efficiencies were still maintained at more than 70%, showing good stability. This work not only verified the feasibility of lignocellulose LL as a carbon source to prepare biochar but also prepared a magnetic hierarchical porous adsorbent with good performances that can better treat RhB and TH, which provided a new idea and direction for the efficient removal of organic pollutants in water.

This study developed mycelial biochar composites, BQH-AN and BQH-MV, with stable physicochemical properties and significantly improved adsorption capabilities through microbial modification. The results showed that the specific surface area and porosity of BQH-AN (3547.47 m² g⁻¹ and 2.37 cm³ g⁻¹) and BQH-MV (3205.59 m² g⁻¹ and 2.46 cm³ g⁻¹) were significantly higher than those of biochar BQH (2641.31 m² g⁻¹ and 1.81 cm³ g⁻¹), which was produced without microbial treatment. In adsorption experiments using rhodamine B (RhB), tetracycline hydrochloride (TC), and Cr (VI), BQH-AN showed maximum adsorption capacities of 1450.79 mg g⁻¹ for RhB, 1608.43 mg g⁻¹ for TC, and 744.15 mg g⁻¹ for Cr(VI). BQH-MV showed similarly strong performance, with 1329.85 mg g⁻¹ for RhB, 1526.46 mg g⁻¹ for TC, and 752.27 mg g⁻¹ for Cr(VI). These values were not only higher than those of BQH but also outperformed most other biochar adsorbents. Additionally, after five reuse cycles, the pollutant removal efficiency of the mycelial biochar composites remained above 69%, demonstrating excellent regenerative ability. This study not only produced biochar with superior adsorption properties but also highlighted microbial modification as an effective way to enhance lignocellulosic biochar performance, paving the way for further biomass development.

In this work, garden waste Clivia miniata leaves (CL) were used as a feedstock to produce high performance biochar (BCL-K-H) through the pretreatment processes of alkali hydrolysis combined with acid hydrolysis. Specifically, CL is subjected to a two-step pretreatment process to destroy its dense wood fibre structure, and then the pretreatment product is processed into biochar by carbonation activation. The results demonstrated that the physicochemical properties of the modified Clivia miniata leaves biochar (BCL-K-H) prepared by the pretreatment process were altered in comparison with those of Clivia miniata leaves biochar (BCL). The specific surface area increased from 3052.12 to 3555.31 m²/g, and the total pore volume increased from 1.94 to 2.91 cm³/g. The characterisation results demonstrated that the surface of BCL-K-H contained a significant number of reactive functional groups (e.g. hydroxyl, hydrocarbon and carboxyl groups, etc.), which may provide a substantial number of active sites during the adsorption of pollutants and enhance the adsorption performance. The pollutants tetracycline hydrochloride (TH) and synthetic dye Rhodamine B (RhB) were studied to gain insight into biochars’ performance. The maximum adsorption capacity of BCL-K-H for pollutants was found to be 1436.56 mg/g (TH) and 1505.47 mg/g (RhB). The adsorption process of BCL-K-H on the pollutants was found to be in accordance with the proposed second-order kinetic model and the Freundlich isotherm model. This finding suggests that the adsorption process may involve electron transfer between the pollutant and the adsorbent, as well as adsorption on heterogeneous surfaces. The presence of a large number of reactive functional groups (e.g. hydroxyl, hydrocarbon and carboxyl groups, etc.) within the adsorbent material has been postulated to provide a substantial number of active sites during the adsorption of pollutants, thereby enhancing the adsorption performance. Following 10 cycles, the removal of pollutants by BCL and BCL-K-H remained above 60%. All data demonstrate that the pre-treatment of biomass precursors is effective and feasible in further improving the performance of biochar, thus providing a new strategy for the further development of lignocellulosic garden waste.