Search Results (43)

Phosphorus, a crucial yet nonrenewable resource, is essential for agriculture, life processes, and various industries. In this study, we employed co-pyrolysis of eggshells and peanut shells to prepare calcium-based biochar (EPB) with a high adsorption capacity and ecological non-toxicity, enabling effective phosphorus recovery from wastewater. EPB was characterized via X-ray diffraction, scanning electron microscopy, electron probe microanalysis, and Brunauer–Emmett–Teller analysis. Additionally, its phosphate adsorption characteristics were investigated under varying temperature, pH, and coexisting ion conditions. Phosphate adsorption followed the Langmuir isotherm with a maximum adsorption capacity of 178.08 mg/g, and the kinetics aligned with those of the quasi-second-order kinetic model. Phosphate adsorption by EPB was driven by electrostatic attraction and chemical precipitation. Moreover, we investigated the effects of phosphorus-enriched biochar on the growth and development of tobacco and soil microbial communities. Phosphorus-enriched biochar increased organic and inorganic phosphorus levels and promoted tobacco growth compared with conventional fertilizers. Phosphorus-enriched biochar reshaped tobacco rhizosphere microbial communities, promoting beneficial taxa, such as Nitrospira. Structural equation analysis showed that EPB enhanced microbial alpha diversity and key microbial communities, improving phosphorus availability and tobacco growth and development. Conclusively, this study provides a theoretical reference for phosphorus-containing wastewater treatment and reuse. Full article

The escalating accumulation of industrial solid wastes (e.g., copper slag: CS, ground-granulated blast furnace slag: GGBS) and carbon-intensive cement production has intensified environmental challenges, driving the demand for sustainable construction materials that synergize waste valorization with carbon sequestration. This study investigates the evaluation of the compressive strength, mineralogical evolution, and real-time CO₂ capture of the alkali-activated geopolymer composite materials by optimizing the mixed design of precursor materials (CS/GGBS ratio: 7/3) with MgO (0–10%) and coconut shell (CSB), peanut shell (PSB), and durian shell biochar (DSB) (0–3%). Results reveal that the 5% MgO addition achieves an 89.5% early-age compressive strength increase versus the MgO-free specimen. The compressive strength of the geopolymer composite could be further increased by a 1.5% dosage of DSB with an average pore size of 8.98 nm. In addition, the incorporation of an appropriate amount of porous biochar could not only enhance the CO₂ capture capacity of the geopolymer composite, but also further improve the CO₂ mineralization efficiency. The optimal formulation (5% MgO + 1.5% DSB) could mineralize 40.2 kg CO₂ per ton of solid waste at least. This work highlights a sustainable strategy for synchronizing industrial solid waste valorization with carbon-negative construction providing scalable CO₂ sequestration solutions. Full article

In this study, sulfur-doped biochar (SBC) was successfully synthesized using peanut shells as the raw material and sulfur powder as the sulfur source. The composition, structural characteristics, and catalytic performance of SBC in the degradation of phenol via persulfate (PDS) activation were systematically investigated. Characterization results demonstrate that the prepared SBC exhibited a typical lamellar structure with abundant pores and fissures on its surface. XPS analysis confirmed the successful incorporation of sulfur into the biochar matrix, primarily in the form of thiophene. Under the optimized condition of a 20% sulfur doping ratio, the SBC exhibited high efficiency in activating PDS, achieving a phenol degradation rate of 97%. Remarkably, the removal rate remained at 81% even after the fifth cycle, indicating excellent cyclic stability. Density functional theory (DFT) calculations and electrochemical impedance spectroscopy (EIS) measurements further revealed that sulfur doping significantly modified the electron density distribution of the biochar, reducing its surface electrochemical impedance from 32.88 Ω to 13.64 Ω. This reduction facilitated efficient electron transfer during the catalytic process. This study provides both experimental and theoretical insights into the charge distribution characteristics of sulfur-doped biochar, offering valuable references for understanding the mechanism of PDS activation by SBC. Full article

This paper presents the results of an investigation into the effect of the physicochemical properties of carbon chars (biochars) on the performance of direct carbon solid oxide fuel cells (DC-SOFCs). Biochars were obtained from walnut, coconut, pistachio, hazelnut and peanut shells by pyrolysis at a temperature of 850 °C. The results of structural studies conducted using X-ray diffraction and Raman spectroscopy reflected a low degree of graphitisation of carbon particles. Biochar derived from walnut shells is characterised by a relatively uniform content of alkali elements, such as sodium, potassium, calcium, magnesium and iron, which are natural components of the mineral residue and act as catalysts for the Boudouard reaction. This study of gasification of biochar samples in a CO₂ atmosphere recorded that the highest conversion rate from solid phase to gaseous phase was for the biochar sample produced from walnut shells. The superior properties of this sample are directly connected to structural features, as well as to the random distribution of alkali elements. DC-SOFCs involving 10 mol% of Sc₂O₃, 1 mol% of CeO₂, 89 mol% of ZrO₂ (10S1CeZ) or 8 mol% of Y₂O₃ in ZrO₂ (8YSZ) were used as both solid oxide electrolytes and components of the anode electrode. It was found that the highest electrochemical power output (P_max) was achieved for DC-SOFCs fuelled by biochar from walnut shells, with around 103 mW/cm² obtained for such DC-SOFCs involving 10S1CeZ electrolytes. Full article

Biochar is an eco-friendly material that influences heavy metals adsorption. Three kinds of bean shell biochar, namely, peanut, pea, and soybean biochar, were prepared at pyrolysis temperatures of 400 °C, 500 °C, and 600 °C. The characteristics of these biochars and the physicochemical properties of the biochars were analyzed. The capacities of the different biochars to adsorb Pb and Cd from aqueous solution were determined. With increasing pyrolysis temperature, the relative content of carbon in the biochar increased and that of hydrogen decreased, the porosity decreased, and the specific surface area increased; accordingly, the adsorption capacity of the biochar for Pb and Cd increased. The Pb adsorption capacity of the peanut shell biochar prepared at 400 °C was lower than that of the other shell biochars when the initial Pb concentration was at a low concentration. Three adsorption isotherm models were used to fit the adsorption processes of Pb or Cd on the three different biochars. The Freundlich curves better fit the adsorption capacity of biochar for Cd, and the Freundlich and Langmuir curves better fit the adsorption capacity of biochar for Pb. This work provides a scientific basis for the rational selection of bean shell biochar used in metal-contaminated water. Full article

To investigate the effects of biochar on the availability of trace elements (Fe, Mn, Cu, and Zn) in soils with different properties, biochar derived from wheat straw (WSBC) and peanut shells (PSBC) was added to red and yellow-brown soils for pot experiments. The results showed that WSBC and PSBC significantly increased the red and yellow-brown soils’ organic matter (SOM) and available potassium (AK), C, and C/N, especially with WSBC in red soil. The total and available amounts of trace elements in red and yellow-brown soil decreased after biochar was applied, where the effect of WSBC on the available of Fe, Mn, and Zn was greater than that of PSBC and the effect on the available contents of Fe, Mn, and Zn was less than that of PSBC. WSBC and PSBC decreased the contents of Fe, Mn, and Zn in the grains in both soils, while they increased the content of Cu in the grains. According to the results of a canonical correlation analysis, there was a competitive relationship between Mn and Cu in the grains. Fe and Zn in the grains were negatively correlated with AP in red soil and positively correlated with AP in yellow-brown soil. This study evaluates the effect of biochar on soil nutrient cycles, ultimately maximizing the application of biochar in the field of agriculture. Full article

Seasonal freeze–thaw cycles compromise soil structure, thereby increasing hydraulic conductivity but diminishing water retention capacity—both of which are essential for sustaining crop health and nutrient retention in agricultural soils. Prior research has suggested that biochar may alleviate these detrimental effects; however; further investigation into its influence on soil hydraulic properties through freeze–thaw cycles is essential. This study explores the impact of freeze–thaw cycles on the soil water retention and hydraulic conductivity and evaluates the potential of peanut shell biochar to mitigate these effects. Peanut shell biochar was used, and its effects on soil water retention and unsaturated hydraulic conductivity were evaluated through evaporation tests. The findings indicate that freeze–thaw cycles predominantly affect clay’s ability to retain water and control hydraulic conductivity by generating macropores and fissures; with a notable increase in conductivity at high matric potentials. The impact lessens as matric potential decreases below −30 kPa, resulting in smaller differences in conductivity. Introducing biochar helps mitigate these effects by converting large pores into smaller micro- or meso-pores, effectively increasing water retention, especially at higher content of biochar. While biochar’s impact is more pronounced at higher matric potentials, it also significantly reduces conductivity at lower potentials. The total porosity of the soil increased under low biochar application rates (0% and 1%) but declined at higher application rates (2% and 3%) as the number of freeze–thaw cycles increased. Furthermore, the characteristics of soil deformation during freeze–thaw cycles shifted from frost heaving to thaw settlement with increasing biochar application rates. Notably, an optimal biochar application rate was observed to mitigate soil deformation induced by freeze–thaw processes. These findings contribute to the scientific understanding necessary for the development and management of sustainable agricultural soil systems. Full article

This study investigated the phytotoxicity of agro-industrial wastes (almond, walnut, pistachio and peanut shells, asparagus spears, and brewer’s spent grain) and their biochar through germination bioassays in several horticultural species: green pea, lettuce, radish, and arugula. Biowaste was pyrolyzed under controlled conditions to produce biochar, and both biowaste and biochar were characterized. Germination bioassay was conducted using seeds exposed to different dilutions of aqueous extract of biowaste and their biochar (0, 50, and 100%). Germination percentage, seed vigor, germination index, and root and aerial lengths were evaluated. The results showed that the phytotoxicity of the biowaste was significantly different to that of its biochar. The biochar obtained demonstrated changing effects on germination and seedling growth. In particular, biochar extracts from spent brewers grains, walnut shells, and pistachio shells showed 5–14% increases in seed vigor and root and aerial length. Furthermore, the response of different species to both agro-industrial waste and biochar revealed species-specific sensitivity. Seeds of lettuce and arugula species were more sensitive to aqueous extracts than radish and green peas. This knowledge not only elucidates the behavior of agro-industrial waste-based biochar in the early stage of plant development but also provides valuable insights regarding phytotoxicity, seed sensitivity, and the variables involved in germination. Full article

Five different biomass wastes—orange peel, coffee grounds, cork, almond shell, and peanut shell—were transformed into biochars (BCs) or activated carbons (ACs) to serve as adsorbents and/or ozone catalysts for the removal of recalcitrant water treatment products. Oxalic acid (OXL) was used as a model pollutant due to its known refractory character towards ozone. The obtained materials were characterized by different techniques, namely thermogravimetric analysis, specific surface area measurement by nitrogen adsorption, and elemental analysis. In adsorption experiments, BCs generally outperformed ACs, except for cork-derived materials. Orange peel BC revealed the highest adsorption capacity (Qe = 40 mg g⁻¹), while almond shell BC showed the best cost–benefit ratio at €0.0096 per mg of OXL adsorbed. In terms of catalytic ozonation, only ACs made from cork and coffee grounds presented significant catalytic activity, achieving pollutant removal rates of 72 and 64%, respectively. Among these materials, ACs made from coffee grounds reveal the best cost/benefit ratio with €0.02 per mg of OXL degraded. Despite the cost analysis showing that these materials are not the cheapest options, other aspects rather than the price alone must be considered in the decision-making process for implementation. This study highlights the promising role of biomass wastes as precursors for efficient and eco-friendly water treatment processes, whether as adsorbents following ozone water treatment or as catalysts in the ozonation reaction itself. Full article

This study aimed to investigate the efficacy of biochar, produced from different agricultural residues varying in lignin and cellulose content and subjected to different pyrolysis temperatures, in removing cadmium ions (Cd (II)) from an aqueous solution. This removal process is crucial for protecting human health and the environment. Specifically, the study focused on the adsorption behaviors of Cd (II) by the biochars made from rice husk biochar (RHB), maize straw biochar (MSB), peanut shell biochar (PSB), cottonseed shell biochar (CHB), and mulberry leaf biochar (MLB), which were prepared at 300 °C and 600 °C. The results indicated that the type of agricultural residue used to produce biochar significantly influenced the adsorption of Cd (II). Notably, mulberry leaf biochar prepared at 300 °C (MLB-300) demonstrated the highest adsorption efficiency, achieving a maximum adsorption capacity of 42.2 mg g⁻¹. Batch adsorption experiments assessed the impact of various factors, including system pH, NO₃⁻ concentration, and adsorption duration. The adsorption kinetics were better described by the pseudo-second-order model than the pseudo-first-order model. Moreover, the study found that the lignin content of the biochar plays a major role in determining the adsorption capacity. The surface characteristics of biochar, influenced by the types of agricultural residues and preparation temperature, directly impact its adsorption mechanism and capacity. While biochar produced at 300 °C showed optimal Cd(II) adsorption, those processed at 600 °C were less effective, likely due to the loss of functional groups at higher temperatures. Full article

Three successive vegetable pot experiments were conducted to assess the effects on the long-term immobilization of heavy metals in soil and crop yield improvement after the addition of peanut shell biochar and an alkaline mineral to an acidic soil contaminated with lead and cadmium. Compared with the CK treatment, the change rates of biomass in the edible parts of the three types of vegetables treated with B0.3, B1, B3, B9, R0.2 and B1R0.2 were −15.43%~123.30%, 35.10%~269.09%, 40.77%~929.31%, −26.08%~711.99%, 44.14%~1067.12% and 53.09%~1139.06%, respectively. The cadmium contents in the edible parts of the three vegetables treated with these six additives reduced by 2.08%~13.21%, 9.56%~24.78%, 9.96%~35.61%, 41.96%~78.42%, −4.19%~57.07% and 12.43%~65.92%, respectively, while the lead contents in the edible parts reduced by −15.70%~59.47%, 6.55%~70.75%, 3.40%~80.10%, 55.26%~89.79%, 11.05%~70.15% and 50.35%~79.25%, respectively. Due to the increases in soil pH, soil cation-exchange capacity and soil organic carbon content, the accumulation of Cd and Pb in the vegetables was most notably reduced with a high dosage of 9% peanut shell biochar alone, followed by the addition of a low dosage of 1% peanut shell biochar blended with 0.2% alkaline mineral. Therefore, the addition of a low dosage of 1% peanut shell biochar blended with 0.2% alkaline mineral was the best additive in increasing the vegetable biomass, whereas the addition of 9% peanut shell biochar alone was the worst. Evidently, the addition of 0.2% alkaline mineral can significantly reduce the amount of peanut shell needed for passivating heavy metals in soil, while it also achieves the effect of increasing the vegetable yield. Full article

The doping of porous carbon materials with nitrogen is an effective approach to enhance the electrochemical performance of electrode materials. In this study, nitrogen-doped porous carbon derived from peanut shells was prepared as an electrode for supercapacitors. Melamine, urea, urea phosphate, and ammonium dihydrogen phosphate were employed as different nitrogen dopants. The optimized electrode material PA-1-1 prepared by peanut shells, with ammonium dihydrogen phosphate as a nitrogen dopant, exhibited a N content of 3.11% and a specific surface area of 602.7 m²/g. In 6 M KOH, the PA-1-1 electrode delivered a high specific capacitance of 208.3 F/g at a current density of 1 A/g. Furthermore, the PA-1-1 electrode demonstrated an excellent rate performance with a specific capacitance of 170.0 F/g (retention rate of 81.6%) maintained at 20 A/g. It delivered a capacitance of PA-1-1 with a specific capacitance retention of 98.8% at 20 A/g after 5000 cycles, indicating excellent cycling stability. The PA-1-1//PA-1-1 symmetric supercapacitor exhibited an energy density of 17.7 Wh/kg at a power density of 2467.0 W/kg. This work not only presents attractive N-doped porous carbon materials for supercapacitors but also offers a novel insight into the rational design of biochar carbon derived from waste peelings. Full article

Using peanut shells, a sustainable agricultural waste product, as its raw material, the acid group-modified biochar (AMBC) was prepared through phosphoric acid activation, partial carbonization, and concentrated sulfuric acid sulfonation for efficient removal of lead ion from aqueous solutions. Characterization techniques such as N₂ isothermal adsorption–desorption, SEM, XRD, FT-IR, TG-DTA, and acid–base titration were utilized to fully understand the properties of the AMBC. It was found that there were high densities of acidic oxygen-containing functional groups (-SO₃H, -COOH, Ph-OH) on the surface of the AMBC. The optimal adsorption performance of the AMBC for Pb(II) in water occurred when the initial concentration of Pb(II) was 100 mg/L, the pH was 5, the dosage of the adsorbent was 0.5 g/L, and the contact time was 120 min. Under the optimal conditions, the removal ratio of Pb(II) was 76.0%, with an adsorption capacity of 148.6 mg/g. This performance far surpassed that of its activated carbon precursor, which achieved a removal ratio of 39.7% and an adsorption capacity of 83.1 mg/g. The superior adsorption performance of AMBC can be caused by the high content of acidic oxygen-containing functional groups on its surface. These functional groups facilitate the strong binding between AMBC and Pb(II), enabling effective removal from water solutions. Full article

Pollution caused by antibiotics has brought significant challenges to the ecological environment. To improve the efficiency of the removal of tetracycline (TC) from aqueous solutions, a composite material consisting of TiO₂ and phosphoric acid-treated peanut shell biochar (p-BC) has been successfully synthesized in the present study by the sol-gel method. In addition, the composite material was characterized using various techniques, including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) spectroscopy, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, and ultraviolet–visible diffuse reflectance spectroscopy (UV-vis DRS). The XPS and FTIR analyses revealed the formation of a new Ti–O–C bond, while the XRD analysis confirmed the presence of TiO₂ (with an anatase phase) in the composite material. Also, the PL analyses showed a notable decrease in the recombination efficiency of electrons and holes, which was due to the formation of a composite. This was further supported by the UV-vis DRS analyses, which revealed a decrease in bandgap (to 2.73 eV) of the composite material and led to enhanced light utilization and improved photocatalytic activity. Furthermore, the effects of pH, composite dosage, and initial concentration on the removal of TC were thoroughly examined, which resulted in a maximum removal efficiency of 95.3% under optimal conditions. Additionally, five consecutive cycle tests demonstrated an exceptional reusability and stability of the composite material. As a result of the experiments, the active species verified that ·O₂⁻ played a key role in the photodegradation of TC. Four possible degradation pathways of TC were then proposed. As a general conclusion, the TiO_2/p–BC composite can be used as an efficient photocatalyst in the removal of TC from aqueous solutions. Full article

This study examined using peanut shells, rice husks, and cocoa husks as soil conditioners to boost yields in Allium cepa var. Alvara onions. Three types of biochar and four application rates (1%, 1.5%, 3%, and 5%) were compared to a control with no biochar. The biochars had different nutrient makeups, with cocoa husk biochar (CHB) containing the most essential elements. While overall plant growth (height, leaves, and roots) was not significantly affected (p > 0.05) by any biochar type compared to the control, some plant parts responded differently. CHB (5%) and peanut husk biochar (PHB) (1%) yielded the tallest onion plants (71 and 65 cm), while 1% rice and cocoa biochar resulted in the shortest (below 42 cm). PHB (3% and 5%) produced the longest roots (9 cm), while 1.5% rice husk biochar (RHB) had the shortest. Biochar application had no significant effect on leaf count. However, specific application rates of RHB and PHB increased the harvest index (HI), indicating more efficient yield allocation. HI values > 0.85 were obtained with specific biochar rates (e.g., 1.0–1.5% PHB, 1.5–5% RHB, or 5.0% CHB). Full article