Adsorption of potentially harmful elements by metal-biochar prepared via Co-pyrolysis of coffee grounds and Nano Fe(III) oxides

Enhancing indigenous plant growth in metal(loid) contaminated soil using biochar

Soil around mines contaminated with metal(loid) is not suitable for growing plants and it is necessary to select indigenous plants with tolerance for metal(loid) and ameliorate metal toxicity in soil using soil amendments. Therefore, the purpose of this study was to improve the soil environment to make it suitable for plant growth by treating chicken manure derived-biochar in soil contaminated with arsenic (As), cadmium (Cd), and lead (Pb). Biochar application increased soil pH and significantly reduced bioavailable As, Cd and Pb, thereby lowering toxicity in plants. Indigenous plant growth also increased by 30.2 and 91.3% in As and Pb contaminated soil under biochar treatment, respectively. Especially, Artemisia japonica Thunb. was effective for phytoextraction due to its accumulation of metals from contaminated soil, along with biochar application. Carex breviculmis R. Br. and Lespedeza cuneata (Dum. Cours.) G. Don. showed decreased above-ground Cd uptake by 57.6 and 44.9%, respectively, and As, Cd and Pb uptake by Juncus decipiens (Buchenau) Nakai decreased by 47.3, 65.7, and 94.1%, respectively, following biochar treatment. Juncus decipiens (Buchenau) Nakai, displayed tolerance in As, Cd and Pb contaminated soils and showed similar growth with or without biochar treatment, while the other three indigenous plant species failed to grow in the absence of biochar treatment. Therefore, J. decipiens is the most suitable candidate for the phytoremediation of metal-contaminated soils, and biochar further promoted plant health and growth.

Unlocking Biochar's Potential: Innovative Strategies for Sustainable Remediation of Heavy Metal Stress in Tobacco Plants

Tobacco, being a globally cultivated crop, holds significant social and economic importance. Tobacco plants are susceptible to the adverse effects of heavy metals (HMs), particularly cadmium (Cd), which hinders root development, disrupts water balance, and impedes nutrient absorption. Higher concentrations of HMs, especially Cd, naturally accumulate in tobacco leaves due to complex interactions within the plant-soil continuum. The uptake of Cd by plants from the soil is influenced by several factors, including soil type, pH, irrigation water quality, and the chemical composition of the metal involved. Different techniques, such as bioremediation, phytoremediation, and mycoremediation, have been employed to tackle the issue of HMs. The use of biochar offers a practical solution to mitigate this problem. With its large surface area and porous nature, biochar can effectively alleviate HMs contamination. Under biochar application, metal adsorption primarily occurs through physical adsorption, where metal ions are trapped within the pores of the biochar. Additionally, electrostatic attraction, in which negatively charged biochar surfaces attract positively charged metal ions, is another major mechanism of metal remediation facilitated by biochar. In this review, we documented, compiled, and interpreted novel and recent information on HMs stress on tobacco plants and explored biochar's role in alleviating HMs toxicity. By providing a comprehensive review of the persistent threat posed by Cd to tobacco crops and exploring biochar's potential as a remediation measure, this work aims to enhance our understanding of HMs stress in tobacco and contribute to the development of sustainable agricultural practices.

Recycling alkali lignin-derived biochar with adsorbed cadmium into cost-effective CdS/C photocatalyst for methylene blue removal

Cadmium (Cd)-enriched adsorbents wastes possess great environmental risk due to their large-scale accumulation and toxicity in the natural environment. Recycling spent Cd-enriched adsorbents into efficient catalysts for advanced applications could address the environmental issues and attain the carbon neutral goal. Herein, a facile strategy is developed for the first time to reutilize the alkali lignin (AL)-derived biochar (ALB) absorbed with Cd into cadmium sulphide (CdS)/C composite for the efficient methylene blue (MB) removal. The ALB is initially treated with Cd-containing solution, then the recycling ALB samples with adsorbed Cd are converted to the final CdS/C composite using NaS2 as the sulphurizing reagent for vulcanization reaction. The optimal ALB400 demonstrates a high adsorption capacity of 576.0 mg g-1 for Cd removal. Then the converted CdS/C composite shows an efficient MB removal efficiency of 94%. The photodegradation mechanism is mainly attributed to carbon components in the CdS/C composite as electron acceptor promoting the separation of photoelectrons/holes and slowing down the abrasion of CdS particles. The enhanced charge transfer and contact between the carrier and the active site thus improves the removal performance and reusability. This work not only develops a method for removing Cd from wastewater effectively and achieving the waste resource utilization but also further offers a significant guidance to use other kinds of spent heavy metal removal adsorbents for the construction of low-cost and high value-added functional materials.

Efficient Removal of Nickel from Wastewater Using Copper Sulfate-Ammonia Complex Modified Activated Carbon: Adsorption Performance and Mechanism

The necessity to eliminate nickel (Ni) from wastewater stems from its environmental and health hazards. To enhance the Ni adsorption capacity, this research applied a copper sulfate-ammonia complex (tetraamminecopper (II) sulfate monohydrate, [Cu(NH3)4]SO4·H2O) as a modifying agent for a Phragmites australis-based activated carbon preparation. The physiochemical properties of powdered activated carbon (PAC) and a modified form ([Cu(NH3)4]-PAC) were examined by measuring their surface areas, analyzing their elemental composition, and using Boehm's titration method. Batch experiments were conducted to investigate the impact of various factors, such as Ni(II) concentration, contact time, pH, and ionic strength, on its substance adsorption capabilities. Additionally, the adsorption mechanisms of Ni(II) onto activated carbon were elucidated via Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The findings indicated that modified activated carbon ([Cu(NH3)4]-PAC) exhibited a lower surface area and total volume than the original activated carbon (PAC). The modification of PAC enhanced its surface's relative oxygen and nitrogen content, indicating the incorporation of functional groups containing these elements. Furthermore, the modified activated carbon, [Cu(NH3)4]-PAC, exhibited superior adsorption capacity relative to unmodified PAC. Both adsorbents' adsorption behaviors conformed to the Langmuir model and the pseudo-second-order kinetics model. The Ni(II) removal efficiency of PAC and [Cu(NH3)4]-PAC diminished progressively with rising ionic strength. Modified activated carbon [Cu(NH3)4]-PAC demonstrated notable pH buffering and adaptability. The adsorption mechanism for Ni(II) on activated carbon involves surface complexation, cation exchange, and electrostatic interaction. This research presents a cost-efficient preparation technique for preparing activated carbon with enhanced Ni(II) removal capabilities from wastewater and elucidates its underlying adsorption mechanisms.

Carbon dioxide-assisted thermochemical conversion of magnetically harvested harmful algae into syngas and metal biochar

With rising of harmful algae blooming and toxin exposure, practical utilization of harmful algae has been developed. This work aimed to magnetically harvest Microcystis aeruginosa (MA) using iron oxides and investigate the feasibility of algae/iron oxides mixture as feedstock in pyrolytic platform to produce syngas and metal biochar. Carbon dioxide (CO2) was used as a feeding gas to enhance the production efficiency of syngas and also functioned pH controller for better MA harvesting and toxin removal. CO2 support brought multiple benefits: magnetite (Fe3O4) and maghemite (γ-Fe2O3) recovered MA in a relatively short period of time (∼1 min), the recovered biomass generated 34-fold increased carbon monoxide, and metal biochar adsorbed higher amount of toxin from MA (2.8-fold). Pyrolytic utilization of harmful algae supported by CO2 and iron oxides could be one of promising techniques for evolution of metal biochar to remove toxin, while efficiently recover biomass and enhance syngas production.