Structural characteristics and thermal performances of lauric-myristic-palmitic acid introduced into modified water hyacinth porous biochar for thermal energy storage

Ball Milling and Magnetic Modification Boosted Methylene Blue Removal by Biochar Obtained from Water Hyacinth: Efficiency, Mechanism, and Application

Ball milling is a feasible and promising method of biochar modification that can significantly increase its adsorption ability to methylene blue (MB). This study synthesized nine biochars derived from water hyacinth under different pyrolysis temperatures and modified with ball milling and Fe3O4. The structural properties of the pristine and ball-milled magnetic biochars were investigated and employed to adsorb MB. The results showed that ball milling significantly enhanced the specific surface area, total pore volume, and C-, N-, and O-containing groups of biochars, especially in low-temperature pyrolysis biochars. The Langmuir isotherm and the pseudo-secondary kinetic model fitted well with the MB adsorption process on biochars. After ball-milled magnetic modification, the adsorption capacity of biochar at 350 °C for MB was increased to 244.6 mg g-1 (8-fold increase), owing to an increase in accessible functional groups. MB removal efficiencies by low-temperature pyrolysis biochars were easily affected by pH, whereas high-temperature pyrolysis biochars could effectively remove MB in a wide pH range. WQM1, with the high adsorption capacity and stability, provided the potential to serve as an adsorbent for MB removal. Based on DFT calculations, the chemisorption and electrostatic interactions were the primary mechanism for enhancing MB removal with ball-milled magnetic biochar at low-temperature pyrolysis, followed by H-bonding, π-π interaction, hydrophobic interaction, and pore filling.

Loofah sponge crosslinked polyethyleneimine loaded with biochar biofilm reactor for ecological remediation of oligotrophic water: Mechanism, performance, and functional characterization

The removal of complex pollutants from oligotrophic water is an important challenge for researchers. In this study, the HCl-modified loofah sponge crosslinked polyethyleneimine loaded with biochar (LS/PEI@biochar) biofilm reactor was adapted to achieve efficient removal of complex pollutants in oligotrophic water. On the 35 d, the average removal efficiency of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), calcium (Ca2+), and phosphate (PO43--P) in water was 51, 95, 81, and 77 %, respectively. Additionally, it effectively used a low molecular weight carbon source. Scanning electron microscopy (SEM) results showed that the LS/PEI@biochar biocarrier had superior biofilm suspension performance. Meanwhile, analysis of the biocrystals confirmed Ca2+ and PO43- removal through the generation of CaCO3 (calcite and vaterite) and Ca5(PO4)3OH. This study demonstrated that the system has great efficiency and application prospect in treating oligotrophic water on the laboratory scale, and will be further validated for practical application on large-scale oligotrophic water.

Zinc and sulfur functionalized biochar as a peroxydisulfate activator via deferred ultraviolet irradiation for tetracycline removal

To enhance the degradation of tetracycline class (TC) residuals of high-concentration from pharmaceutical wastewater, a novel zinc (Zn) and sulfur (S) functionalized biochar (SC-Zn), as a peroxydisulfate (PDS) activator, was prepared by two-step pyrolysis using ZnSO4 accumulated water-hyacinth. Results showed that the removal rate of 50, 150, and 250 mg per L TC reached 100%, 99.22% and 94.83% respectively, by the SC-Zn/PDS system at a dosage of 0.3 g per L SC-Zn and 1.2 mM PDS, via the deferred ultraviolet (UV) irradiation design. Such excellent performance for TC removal was due to the synergetic activation of PDS by the biochar activator and UV-irradiation with biochar as a responsive photocatalyst. The functionalization of the co-doped Zn and S endowed the biochar SC-Zn with a significantly enhanced catalytic performance, since Zn was inferred to be the dominant catalytic site for SO4˙- generation, while S played a key role in the synergism with Zn by acting as the primary adsorption site for the reaction substrates. The employed SC-Zn/PDS/UV system had excellent anti-interference under different environmental backgrounds, and compared with the removal rate of TC by adsorption of SC-Zn, the increasing rate in the SC-Zn/PDS/UV system (18.75%) was higher than the sum of the increases in the SC-Zn/PDS (9.87%) and SC-Zn/UV systems (3.34%), furtherly verifying the systematic superiority of this synergy effect. This study aimed to prepare a high-performance functionalized biochar activator and elucidate the rational design of deferred UV-irradiation of PDS activation to efficiently remove high-concentration antibiotic pollutants.

Energy storage and key derives of octadecane thermal stability during phase change assembly with animal manure-derived biochar

The design of eco-friendly and renewable energy infrastructure is highly desirable to advance the global energy landscape. Phase-change materials (PCMs) are used to mitigate intermittency issues and reversibly store high densities of thermal energy in the form of heat during the phase transition process and provide ample potential for the advancement of renewable energy infrastructure. However, the leakage and low thermal stability of pristine PCMs along with the complicated synthesis strategies and environmental issues of the supporting materials cause significant drawbacks, thereby requiring a sustainable confining agent. In this study, a green phase change composite was developed using biowaste-derived biochar and octadecane via a vacuum impregnation strategy. The structural, morphological, thermal, and shape stabilities, as well as the chemical compatibilities of both the composite components and the octadecane-biochar composite, were investigated. The supporting biochar provides sufficient physical and thermal support besides high encapsulating capacity due to high specific surface area (135.2 m2 g-1) and predominant mesoporous proportion (86%). The results displayed that the composite material revealed a high leakage-proof capability (above the melting point of pure octadecane) with a low leakage rate (<12.5%) for a long heating time, excellent thermal stability, and high latent heat retention (89.5%) after 1000 heating-cooling cycles. The fabricated composite attained satisfactory phase change enthalpy storage, which was 130% and 168.9% higher than that of rice-husk-paraffin and garlic peel-derived carbon-paraffin, respectively, indicating promising thermal management performance. This study opens avenues for the development of green composite materials and renewable energy storage and conversion, which will play a significant role in various sectors such as building energy-saving and heat recovery systems.

Expanded vermiculite supported capric-palmitic acid composites for thermal energy storage

In this study, the potential application of expanded vermiculite (EVM) as the supporting material and capric-palmitic acid (CA-PA) binary eutectic as the adsorbent mixture to fabricate a form-stable composite CA-PA/EVM by a vacuum impregnation method was investigated. The prepared form-stable composite CA-PA/EVM was then characterized by scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TG), differential scanning calorimetry (DSC) and a thermal cycling test. The maximum loading capacity and melting enthalpy of CA-PA/EVM could reach 51.84% and 67.5 J g^-1. Meanwhile, the thermal physical and mechanical properties of the CA-PA/EVM-based thermal energy storage mortars were examined to determine if the composite material based on the newly invented CA-PA/EVM material can be employed for energy conservation and efficiency in the building field. In addition, the law of full-field deformation evolution of CA-PA/EVM-based thermal energy storage mortar under uniaxial compression failure was studied based on digital image correlation (DIC) technology, which provides certain guiding significance for the application of CA-PA/EVM-based thermal energy storage mortars in practical engineering.