Is cocoa pod shell biochar activation a suitable way for water cadmium removal in the Ivory Coast?

High adsorption capacity of Mg–Al-modified biochar for phosphate and its potential for phosphate interception in soil

Measurement of the Performance of an Agricultural Residue-based Activated Carbon Aiming at the Removal of 4-chlophenol from Aqueous Solutions

Removal characteristics of copper by marine macro-algae-derived chars

A review of agricultural crop residue supply in Canada for cellulosic ethanol production

Response mechanism of typical wetland plants and removal of water pollutants under different levofloxacin concentration

Physicochemical characterization, chemical composition and antioxidant activities of pyroligneous acids from cocktails of wood and agricultural residues from Ivory Coast

Biochar heavy metal removal in aqueous solution depends on feedstock type and pyrolysis purging gas

Residue biochar can be utilized as an adsorbent for ammonium nitrogen (NH4 +-N) to prevent non-point source pollution. However, the limited adsorption capacity has restricted its extensive application. In this study, biochar was modified with hydrogen peroxide (H2O2), potassium permanganate (KMnO4), and sodium hydroxide (NaOH) to enhance its adsorption performance. A comparative analysis of the biochar surface characteristics was used to investigate the adsorption systems. The results indicated that the adsorption capacities of the modified biochar (MB) were significantly enhanced compared with the raw biochar (RB). At the highest NH4 +-N concentration of 150 mg L−1, the adsorption capacities of RB-H2O2, RB-NaOH, and RB-KMnO4 increased to 3.0, 3.2, and 4.0 times that of RB, respectively. As predicted by the Langmuir isotherm model, the maximum adsorption capacities of these three MB were 13.93, 41.00, and 68.15 mg g−1, respectively. Ammonium adsorption on the MB surfaces was affected by surface adsorption, liquid membrane diffusion, and intra-particle diffusion. The specific surface area and pore volume of RB-KMnO4 were significantly enhanced, with an increase in active sites on the pore surfaces, thereby strengthening its adsorption capacity for NH4 +-N. In contrast, the adsorption of NH4⁺-N by RB-H2O2 and RB-NaOH primarily relied on the substantial increase in –C–O functional groups, with additional contributions from other oxygen-containing functional (e.g. –OH, –COOH, and Fe–O). In conclusion, RB-KMnO4 exhibited the highest adsorption efficiency, with pore-based adsorption playing a dominant role over functional group-based adsorption. These findings highlight the critical role of pore structure optimization in enhancing the biochar adsorption capacity for NH4 +-N. Graphical Abstract

Chitosan-functionalized sodium alginate-based electrospun nanofiber membrane for As (III) removal from aqueous solution

Microporous- and mesoporous-activated carbons were produced from longan seed biomass through physical activation with CO2 under the same activation conditions of time and temperature. The specially prepared mesoporous carbon showed the maximum porous properties with the specific surface area of 1773 m2/g and mesopore volume of 0.474 cm3/g which accounts for 44.1% of the total pore volume. These activated carbons were utilized as porous adsorbents for the removal of methylene blue (MB) from an aqueous solution and their effectiveness was evaluated for both the adsorption kinetics and capacity. The adsorption kinetic data of MB were analyzed by the pseudo-first-order model, the pseudo-second-order model, and the pore-diffusion model equations. It was found that the adsorption kinetic behavior for all carbons tested was best described by the pseudo-second-order model. The effective pore diffusivity (De) derived from the pore-diffusion model had the values of 4.657 × 10−7–6.014 × 10−7 cm2/s and 4.668 × 10−7–19.920 × 10−7 cm2/s for the microporous- and mesoporous-activated carbons, respectively. Three well-known adsorption models, namely the Langmuir, Freundlich and Redlich–Peterson equations were tested with the experimental MB adsorption isotherms, and the results showed that the Redlich–Peterson model provided the overall best fitting of the isotherm data. In addition, the maximum capacity for MB adsorption of 1000 mg/g was achieved with the mesoporous carbon having the largest surface area and pore volume. The initial pH of MB solution had virtually no effect on the adsorption capacity and removal efficiency of the methylene blue dye. Increasing temperature over the range from 35 to 55 °C increased the adsorption of methylene blue, presumably caused by the increase in the diffusion rate of methylene blue to the adsorption sites that could promote the interaction frequency between the adsorbent surface and the adsorbate molecules. Overall, the high surface area mesoporous carbon was superior to the microporous carbon in view of the adsorption kinetics and capacity, when both carbons were used for the removal of MB from an aqueous solution.

The removal of water pollutants through adsorption by porous materials has been demonstrated to be an effective method due to its relatively low cost, simple design, ease of operation, and regeneration capabilities. In this study, we assembled three robust porous organic cages (POCs), namely CPOC-109, CPOC-110, and CPOC-111, from the same tetraformyl-functionalized calix[4]resorcinarene (C4RACHO) cap and three different types of diamino linkers, with the number of sulfur atoms ranging from 0 to 2. Single X-ray crystallographic analysis reveals that all three CPOCs exhibit [2 + 4] lantern-shaped structures with large intrinsic cavities, having heights and cavity volumes ranging from 1.74 to 1.80 nm and 1023.42 to 1157.66 Å3, respectively. Furthermore, 77 K N2 gas adsorption measurements suggest that all CPOCs exhibit high porosity, with Brunauer–Emmett–Teller (BET) specific surface areas reaching up to 700 m2 g–1. Leveraging their porous nature and rich coordination sites (N, O, and S), the application of these CPOCs for the adsorptive removal of Hg(II) from aqueous solutions was explored. Notably, CPOC-111 demonstrated superior Hg(II) adsorption capacity (220.26 mg/g) compared to CPOC-109 and CPOC-110. Additionally, CPOC-111 exhibited excellent cycling performance and maintained good adsorption stability within a broad pH range of 3 to 11. This study serves as a compelling example of using POC adsorbents for the removal of Hg(II) ions from water and highlights the potential for expanding the application of POC materials in environmental remediation and pollution control.

The potential of direct air capture using adsorbents in cold climates.

Adsorption of hexavalent chromium from aqueous solutions by bio-chars obtained during biomass pyrolysis

The application of hydrochar as a cost-effective solution has received much attention for the remediation of contaminated water. An economical and environmental approach to enhancing the physicochemical and adsorption performance of hydrochar is essential. In this study, the green technology of ball-milling was firstly employed to improve the adsorption capacity of hydrochar for the typical antibiotics norfloxacin. Aqueous batch adsorption experiment using both pristine and ball milled hydrochar derived from water hyacinth, prepared by hydrothermal carbonization at three temperatures (180, 200, 220 °C) was conducted. The results showed that ball-milling decreased the specific surface area of hydrochar, but still greatly enhanced their performance on the adsorption of norfloxacin. Surface functional groups, aromatization degree, and hydrophobicity of hydrochar were increased after ball-milling, as evidenced by measurements of Boehm titration, Raman spectra, and contact angle, respectively. With these changes, all the ball-milled water hyacinth hydrochar exhibited a better performance on the adsorption of norfloxacin than pristine hydrochar. Ball-milled 220 °C water hyacinth hydrochar showed the greatest norfloxacin adsorption (68.53 mg g−1) compared to unmilled hydrochar (24.29 mg g−1), and the enhancement was effective in a wide pH range (5–9) in aqueous solutions. The thermodynamics study indicated that the norfloxacin adsorption on ball-milled hydrochar was both physically spontaneous and exothermic. Combined physicochemical characterization of hydrochar and batch experiment results suggest that the enhanced adsorption capacity was owing to boosting H-bonds, π-π electron-donor–acceptor, and hydrophobic interaction. This study suggested that ball-milling can be served as a facile, green, and cost-effective method to obtain modified hydrochar for the removal of pollutants in water.

Probing the efficiency of magnetically modified biomass-derived biochar for effective phosphate removal