Many metal-ferrite-based adsorbents are reported, encouraging this work. We investigated Fe3O4 formation during attempted CaFe2O4 deposition by a published method on pinecone biochar. Fe3O4@PCBC was formed without any confirmed evidence of CaFe2O4 formation. The resulting composite was magnetically recoverable after Malachite Green (MG) dye uptake. This adsorbent was characterized using XRD, FTIR, SEM-EDX, BET surface area, pHpzc, CHNS combustion, EDX surface, and bulk Ca and Fe analyses. MG adsorption parameters were evaluated. Crystalline CaFe2O4, neat Fe3O4, and Fe3O4@PCBC could not be distinguished by XRD, requiring elemental analysis for confirmation of all synthesized samples. Importantly, the identification of CaFe2O4 and other ferrites on supports in the literature sometimes depends only on XRD. Thus, the example we report is a warning to not depend exclusively on XRD. MG uptake data on Fe3O4@PCBC at 278, 298, 308, and 323 K fit the Langmuir isotherm (R2= 0.97) with maximum capacities of 22.3, 32.0, 39.6, and 34.2 mg/g, respectively, at pH 5. Adsorption was spontaneous (Delta Go278 - 323K = -23.5, - 27.3, - 29.2, - 32.0kJ/mol), endothermic (Delta H degrees 278-323 K = 28.9 kJ/mol), and caused enhanced randomness (Delta So278 - 323K = 188.5J/mol center dot K). Uptake followed both pseudo-first and pseudo-second order kinetics. Neat-PCBC has smaller maximum Langmuir MG capacities (278-323 K) of 7.88, 9.50, 20.02, and 3.40 mg/g. Magnetic separations were demonstrated.

In situ formed nanoscale zero-valent Cu assists the solid-state rearrangement of lignin-derived aromatic carbon rings, producing few-layer turbostratic graphene under inert thermal treatment.

The Ca/Mg-biochar hybrids have outstanding phosphate adsorption abilities over most modified adsorbents when applied in stoichiometric amounts; recent MgO-functionalized lignin-based bio-charcoal reported the highest phosphate uptake (906.8 mg/g). Apart from large phosphate uptake, Ca/Mg-rich biochars offer a variety of advantages like non-renewable phosphate recovery, soil amendment, resource utilization, waste management and conversion, etc. However, complex preparation methods, expensive metallic reagents, and/or the need for energy-intensive equipment limit the economic interest for these composites. Therefore, in this review, the latest Mg/Ca-biochar synthesis methods are evaluated, emphasizing the value of utilizing green/ waste materials and reagent-free fabrication methods leading to sustainable development. Among the loaded elements, Ca and Mg are employed to provide a prospect of high phosphate uptake as well as increased phosphate recovery. The spent Ca/Mg-biochar hybrids with large phosphate loadings can be implemented as safe slow-release phosphate fertilizers or can be recycled using practical methods; a recent study found that basification followed by tap water addition recovered over 82% phosphate, after reusing the absorbent for 4 cycles, without affecting its stability. At the end of the review, the real-time applications, and limitations of these biochars, important knowledge gaps in the literature, and future directions are summarized, aiming to promote the sustainable utilization of Ca/Mg-modified biochar in various environmental applications.

This study presents a sustainable strategy for developing water, oil, and grease-resistant fiber sheet and molded fiber products using metal ions and cellulose nanofibrils (CNF). Water resistance was achieved through direct fiber treatment with Zr4+ and Fe3+ ions, with Zr4+ demonstrating superior performance by reducing the water Cobb₆₀ value from 464 to below 30 g/m2 at just 4 mg/g fiber loading. In contrast, Fe3+ required 10 mg/g to achieve similar results. Both metal ions exhibited high stability with minimal leaching across acidic (pH 3), neutral (pH 7), and basic (pH 10) conditions. Enhanced water resistance also contributed to improved wet strength. Oil and grease resistance was imparted using CNF through both coating and blending methods. The coating method applied 3-32 wt% CNF, with ≥6 wt% (13 g/m2) loading achieving oil Cobb₆₀ values of ∼25-50 g/m2, kit value of 12, and oil hold-up time exceeding 2 h. The blending method incorporated 5-35 wt% CNF, with ≥20 wt% (40 g/m2) resulting in oil Cobb₆₀ values of ∼10-30 g/m2, kit values of 4-5, and similar oil hold-up times. These results demonstrate an effective PFAS-free and biodegradable approach to enhancing barrier properties in fiber-based packaging materials.

Tomato is a major crop, and efforts are ongoing to enhance its resilience to biotic and abiotic stresses. Weed management remains a key challenge, prompting the search for sustainable alternatives to reduce the impact of excessive herbicide use. Biochar is a promising alternative, as it enriches the soil, improves its water retention capacity, promotes its regeneration and increased fertility, delays nutrient leaching, and improves fertilizer use efficiency. This study aimed to investigate the efficiency of biochar use in mitigating stress caused by different herbicides. Two different biochar materials, Douglas fir and rice husk, were used. Tomato seeds were sown in pots and arranged in a randomized design. At the 4V stage (28 days after sowing), the herbicides S-metolachlor, metribuzin, and halosulfuron were applied. Plant length, injury, antioxidant enzyme activity, ascorbate peroxidase (APX), catalase (CAT), guaiacol peroxidase (GPOD), glutathione reductase (GR), and hydrogen peroxide content (H2O2) were assessed 7 and 14 days after herbicide application. Plants treated with biochar and submitted to herbicide treatments showed significantly higher growth parameters and fewer injuries when compared to plants treated with herbicides without biochar. The antioxidant response of the plants followed the same trend; smaller plants with more injuries showed greater H2O2 accumulation and significantly higher antioxidant enzyme activity. These findings highlight the protective effect of biochar, particularly Douglas fir biochar, as it effectively mitigated herbicide-induced oxidative stress and helped maintain plant growth and structural integrity under treatment conditions.

Magnetite nanoparticles were deposited on Douglas fir biochar (Fe3O4/DFBC) using aqueous, NaOH-induced chemical co-precipitation from Fe2+/Fe3+ salt solutions. Fe3O4/DFBC was used to remediate As(V)-contaminated water. Kinetics and isotherms were studied. pH 5 was selected as the optimized pH due to low iron leaching and closeness to groundwater pH. Adsorption equilibrium was reached after 3 h, 2 h, and 1 h for 0.5, 5, and 50 mg/L initial As(V) concentrations, respectively. Adsorption was exothermic, and the Langmuir capacity was 6.33 mg/g at 25 oC. Ionic strength, impacts of Fe3O4/DFBC particle size, and competitive ion/ molecule effects during As(V) adsorption were studied. Continuous-flow fixed-bed column breakthrough studies performed at 0.5, 5, and 50 mg/L of As(V) at pH 5 exhibited maximum capacities of 3.47, 3.99, and 3.72 mg/g, respectively. Aqueous potassium phosphate was used successfully for column regeneration. Fe3O4/DFBC was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Mössbauer spectroscopy before and after As(III) and As(V) adsorption. Mössbauer found the “Fe3O4” was composed of several phases. A key target was the study of simultaneous toxic As(III) adsorption and its transformation to As(V) from pH 1-13. The highest removal of As(III) and oxidized As(V) was obtained at pH 3. The relationship between iron leaching and pH was investigated and the pH-dependent surface adsorption was monitored using X-ray photoelectron spectroscopy (XPS) from pH 1 to 13. Readsorption of leached iron occurred via the formation of insoluble iron-arsenate and arsenites at concentrations exceeding their Ksp values at the pHs. One goal of this study was to enhance the understanding of the adsorption characteristics needed for initial scaling of a treatment facility that can efficiently remediate arsenic-contaminated wastewater. Experiments were conducted using batch and fixed bed continuous flow columns to optimize adsorption process parameters under various circumstances and solution matrices. Another goal was to further establish the surface structures of the chemisorbed arsenates versus pH.

Lignites are widely available and cost-effective in many countries. Sustainable methods for their utilization drive innovation, potentially advancing environmental sustainability and resource efficiency. In the present study, Fe3O4 ( 25.1 nm) supported on KOH-activated lignite (A-L) displayed 8 times higher phosphate removal than pristine A-L (67.6 mg/g vs. 8.5 mg/g at pH 5, 50 mg of absorbent in 25 mL of 1500 ppm [phosphate]), owing to its abundant Fe3O4 (10 wt% of Fe) nanoparticle content. The removal occurred within 2 h, following a pseudosecond-order kinetic model. Across pH levels ranging from 5.0 to 9.0, Fe3O4- A- L's phosphate removal occurs via both chemisorption and precipitation, as evident by kinetic, pH, and XPS analyses. The phosphate adsorption fits better with the Freundlich isotherm. The combined benefits of facile recovery, rapid phosphate uptake, straightforward regeneration, and attractive post-adsorption benefits (e.g., possibly use as a Fe, P-rich fertilizer) make magnetic Fe3O4-A-L a promising candidate for real-world applications. Artificial Neural Network (ANN) modeling indicates an excellent accuracy (R2 = 0.99) in predicting the amount of phosphate removed by Fe3O4- A- L. Sensitivity analysis revealed both temperature and initial concentration as the most influencing factors. Leveraging lignite in environmentally friendly applications not only addresses immediate challenges but also aligns with sustainability goals. The study clearly articulates the potential benefits of utilizing lignite for sustainable phosphate removal and recovery, offering avenues for mitigating environmental concerns while utilizing resources efficiently.

As coffee constitutes a global cultural phenomenon consumed at 9 million tons annually across 167 countries, its scientific studies attract widespread attention. Accordingly, the present study investigates trace elements in coffee samples available in the US market, spanning sensory, health, environmental, and toxicological dimensions. Specifically, the study employs Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for the analysis of 14 elements in 12 diverse coffee brands. Geographical variations, sustainability implications, and a leaching experiment further enrich our understanding. The findings contribute insights for consumers, producers, and regulators, shaping the evolving landscape of the coffee industry.

Copper is a non-biodegradable heavy metal, and high levels in water bodies cause serious environmental and health issues. Douglas fir biochar has a higher number of carboxylic, phenolic, and lactonic groups, which provide suitable active sites for copper removal. Douglas fir biochar (BC) was modified using 20% solutions of KOH (KOH/BC), H2SO4, (H2SO4/BC), and Na2CO3 (Na2CO3/BC). All materials were characterized using SEM, SEM-EDS, FTIR, TGA, XRD, BET, and elemental analysis. These modifications were done to compare the activations of those sites by measuring copper removal efficiencies. KOH/BC, H2SO4/BC, and Na2CO3/BC materials gave surface areas of 389.3, 326.7, and 367.9 m2 g−1, respectively, compared with pristine biochar with a surface area of 578.9 m2 g−1. The maximum Langmuir adsorption capacities for Na2CO3/BC, KOH/BC, BC, and H2SO4/BC were 24.79, 18.31, 17.38, and 9.17 mg g−1, respectively. All three modifications gave faster kinetics at 2 mg/L initial copper concentrations (pH 5) compared with pristine BC. The copper removal efficiency was demonstrated in four different spiked real water matrices. The copper removals of all four water matrices were above 90% at 2 mg/L initial concentration with a 2 g/L biochar dosage. The competitive effects of Pb2+, Zn2+, Cd2+, and Mg2+ were studied at equimolar concentrations of Cu2+ and competitive ions for all four materials.

Feedstock characteristics impact biochar physicochemical properties, and reproducible biochar properties are essential for any potential application. However, in most articles, feedstock aspects (i.e., taxonomic name of the species, part of the plant, and phenological phase) are scarcely reported. This research aimed at studying the effect of species and phenological stage of the feedstock on the properties of the derived biochars and, thus, adsorption capacities in water treatment. In this study, we analysed the anatomical characteristics of three different woody bamboo species [Guadua chacoensis (GC), Phyllostachys aurea (PA), and Bambusa tuldoides (BT)] in culms harvested at two different phenological phases (young and mature), and statistically correlated them with the characteristics of the six derived biochars, including their adsorption performance in aqueous media. Sclerenchyma fibres and parenchyma cells diameter and cell-wall width significantly differed among species. Additionally, sclerenchyma fibres and parenchyma cell-wall width as well as sclerenchyma fibre cell diameters are dependent on the phenological phase of the culms.Consequently, differences in biochar characteristics (i.e., yield and average pore diameter) were also observed, leading to differential methylene blue (MB) adsorption capacities between individuals at different phenological phases. MB adsorption capacities were higher for biochar produced from young culms compared to those obtained from matures ones (i.e., GC: 628.66 vs. 507.79; BT: 537.45 vs. 477.53; PA: 477.52 vs. 462.82 mg/g), which had smaller cell wall widths leading to a lower percentage of biochar yield. The feedstock anatomical properties determined biochar characteristics which modulated adsorption capacities.

Phosphorus-rich materials (PRMs) are widely used soil remediation agents because they are biocompatible, abundant, non-toxic, and have a high affinity for heavy metals in soil. However, PRMs tend to aggregate at the nanoscale and are susceptible to phosphorus leaching, which limit their application in soil remediation. Dispersing PRMs on porous biochar (BC) is a promising solution to the aggregation and phosphorus leaching issues. The resulting phosphorus-enriched BC (PBC) has excellent adsorption capabilities for heavy metals. This review focuses on recent advances in PBC synthesis and their application in soil remediation. A thorough evaluation of the biomass and phosphorus precursors used for PBC synthesis and a summarization of the common approaches in the synthesis of PBC are carried out in this review. Advantages of PBC for soil remediation are surveyed and reviewed in brief. Thereafter, heavy metal immobilization mechanisms (e.g., precipitation, ion exchange, sorption, etc.) of PBC in soil is highlighted. Finally, the preparation of engineered PBC (ePBC) composites by incorporating auxiliary components (e.g., iron, microorganisms, layered double hydroxides, etc.) with PBC is discussed along with the advantages of ePBC over PBC in soil. This review aims to convene disseminated knowledge and provide a detailed array of information required to gain a thorough understanding of PBC.

Global plastic production and usage has increased annually for decades and microplastic pollutants (≤5 mm) are a growing concern. Microplastics in surface waters can adsorb and desorb harmful chemicals such as per- and polyfluoroalkyl substances (PFAS). Microplastics can accumulate across all tropic levels in the marine food web. The purpose of this research was to analyze the stomach and intestinal contents of stranded (Mississippi coast) bottlenose dolphins and sea turtles for the presence of microplastics and commonly found PFAS, PFOS, PFOA, and GenX. Gut contents were digested (10% KOH in 50% MeOH) and then analyzed for microplastics using pyrolysis gas chromatography-mass spectrometry (Pyro-GC-MS), Nile red microscopy, X-ray photo electron spectroscopy (XPS), and Raman spectroscopy. Digested sample filtrate was pre-concentrated using solid-phase extraction (SPE) before PFAS liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The PFOS extraction and analysis had 98.6% recovery when validated with certified pike‒perch fish reference material. The Nile red testing on most samples revealed the presence of microplastics (Table S1). The Pyro-GC-MS results from two samples confirmed the presence of the plasticizer acetamide. The Raman spectroscopy analysis indicated characteristic plastic peaks corresponding to polystyrene in one sample. PFOS (95.5 to 1,934.5 µg/kg) was detected in three dolphin stomach samples. This project is part of a long-term study with the goal of a better understanding of microplastics and PFAS environmental contamination and their impact on bottlenose dolphins and sea turtles.

Nitrates and phosphates, found in fertilizers, are the most common eutrophication-causing agents. Douglas fir biochar (BC), a syngas byproduct, was treated with different Al/Mg ratios of sulfate (5% w/w metal loading) followed by an NaOH treatment. The greatest phosphate uptake at 25 °C and pH 7 was attributed to the composite with a Mg/Al 2:1 ratio prepared at pH 13 (AMBC). Batch AMBC phosphate uptake was optimized for initial pH, equilibrium time, temperature, and initial phosphate concentration. Phosphate removal following pseudo-2nd-order kinetics and increases gradually before reaching a max at pH 11, with 95% phosphate uptake in 15 mins. The Sips isotherm model provided the best sorption data fit resulting in a 42.1 mg/g capacity at 25 °C and pH 11. Endothermic and spontaneous adsorption were determined using van ’t Hoff’s plots. BET, XRD, XPS, SEM, TEM, and EDS were used to characterize the biochar before and after phosphate sorption. Used AMBC has the potential to be exploited as a phosphate fertilizer as a key part of an environmentally friendly agricultural management plan.

Carbothermal reduction using biochar (BC) is a green and effective method of synthesizing BC-supported nanoscale zero-valent iron (nanoFe 0 ) composites. However, the effect of BC surface area on the structure, distribution, and performance such as the heavy metal uptake capacity of nanoFe0 particles remains unclear. Soybean stover-based BCs with different surface areas (1.7 - 1 472 m 2 /g) were prepared in this study. They have been used for in-situ synthesis BCs-supported nanoFe0 particles through carbothermal reduction of ferrous chloride. The BCs-supported nanoFe0 particles were found to be covered with graphene shells and dispersed onto BC surfaces, forming the BC-supported graphene-encapsulated nanoFe0 (BC-G@Fe 0 ) composite. These graphene shells covering the nanoFe0 particles were formed because of gaseous carbon evolved from biomass car-bonization reacting with iron oxides/iron salts. Increasing BC surface area decreased the average diameters of nanoFe0 particles, indicating a higher BC surface area alleviated the aggregation of nanoFe0 particles, which resulted in higher heavy metal uptake capacity. At the optimized condi-tion, BC-G@Fe0 composite exhibited uptake capacities of 124.4, 121.8, 254.5, and 48.0 mg/g for Cu2 +, Pb2 +, Ag +, and As3 +, respectively (pH 5, 25 degrees C). Moreover, the BC-G@Fe0 composite also demonstrated high stability for Cu2 + removal from the fixed-bed continuous flow, in which 1 g of BC-G@Fe0 can work for 120 h in a 4 mg/L Cu2 + flow continually and clean 28.6 L Cu2 + contami-nated water. Furthermore, the BC-G@Fe0 composite can effectively immobilize the bioavailable As3 + from the contaminated soil, i.e., 5% ( w ) of BC-G@Fe0 composite addition can immobilize up to 92.2% bioavailable As3 + from the contaminated soil.

Development of low-cost and safe IONPs-based biochar hybrids with efficient multiple pollutant removal abilities is critical. In the present study, we studied the potential of an Fe3O4-modified wood-based biochar (FDBC) composite to remove an aqueous anionic dye, bromophenol blue (BPB) via simple magnets. Smaller surface area (1.5 times) and a smaller pore volume (similar to 2 times) of FDBC over the original biochar (DBC) does not impede the BPB uptake by FDBC. The Langmuir monolayer BPB adsorption capacities of FDBC and DBC are 448.0 and 451.0 mg/g (removal percentages, 89.8 % vs. 90.3 %) (adsorbent dose 50 mg, 25 mL of 1000 mg/L BPB concentration, 2 h, pH 5.0). The larger surface area (248 m(2)/g) and abundant nano Fe3O4 (11.0 nm) sites account for FDBC's excellent BPB removal compared to recent IONPs-based adsorbents. At pH 5.0-8.0, the BPB is bound to the FDBC (points of zero charge = 8.2) via H-bonding and pi-pi stacking, as confirmed by pH, desorption, and thermodynamic studies. Compared to NaOH and H2O2, methanol desorbs more BPB from the spent adsorbent at pH 7.0. Moreover, this composite removes even the BPB residuals from real wastewater, becoming an ideal adsorbent for BPB removal. A limited life cycle assessment of FDBC's synthesis revealed a higher impact for global warming (2.38 kg CO(2)eq) per kg of the adsorbent, whereas the lower impacts for ozone depletion, particulate matter emissions, and air quality. The FDBC is more economical because of its green and facile synthesis, excellent dye removal capacity, easy and fast recovery. Efficient multiple dye uptake of FDBC produces large concentration of recovered dyes, which can be possibly reused in various economic applications.

Eutrophication, a major environmental and economic issue, stems from the increased nutrient levels in water bodies, notably phosphorus, and demands focused attention. On the other hand, investigating phosphate recovery options receive immediate attention, as phosphate sources are limited. Many studies have been dedicated to the development of tailored biochars as effective agents for phosphate adsorption and recovery from aqueous environments. This review explores the multifaceted advantages of Ca/Mg-rich biochars, with a primary focus on their exceptional phosphate uptake capabilities. Beyond their remarkable phosphate sequestration potential, these biochars offer diverse benefits, including non-renewable phosphate recovery, soil enhancement, resource utilization, waste management, and conversion. Nevertheless, the complex preparation methods, reliance on expensive metallic reagents, and energy-intensive equipment pose significant limitations to the mass production of these composites. In response to these challenges, this review critically evaluates the latest Mg/Ca-biochar synthesis strategies, highlighting the need for sustainable materials and fabrication methods to enhance economic and environmental viability. Furthermore, the potential of spent Ca/Mg-biochar hybrids, enriched with substantial phosphate loadings, is examined, offering insights into their utilization as safe slow-release phosphate fertilizers or their recycling through practical methods. The review also delves into the development of easy, cost-effective, and environmentally friendly regeneration and reuse strategies, which can be implemented for Ca/Mg biochars. Finally, the article summarizes the real-time applications, and limitations, identifies crucial knowledge gaps, and outlines future directions, to advance the use of Ca/Mg-modified biochars in various sustainable environmental applications.

The goal of this work was to evaluate the immobilization of uranium (U) through crystallization of calcium phosphate minerals (phosphates), which have a strong ability to absorb and retain dissolved uranyl, and therefore, are useful in various geological and environmental applications. To date, most of the experimental studies have been conducted at room temperature and high temperature assessments on uranium immobilization rely on the extrapolation procedure, which is not always accurate. To evaluate uranium partition coefficients between phosphates and hydrothermal fluid, we performed a series of crystallization experiments at 25-350 degrees C and various aqueous uranium concentrations.Crystallization occurred through the transformation of brushite to monetite or/and apatite in aqueous solutions doped with uranium aliquots. Solid products were extracted and characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The local bonding environment and valence state of uranium in apatite were determined via X-ray absorption spectroscopy (XAS). Uranium concentration in crystals and coexisting solutions were measured with inductively coupled plasma mass spectrometry (ICP-MS). Apparent partition coefficients were calculated as Nernst partition coefficients (DU) and Doener-Hoskins partition coefficients (KU/Ca D  H ) (to account for closed reservoir effect). Experimental DU values were compared with those calculated using the lattice strain model. Results showed that >92% of U added to solutions was extracted via this crystallization method and KU/Ca D H decreases with increasing phosphate crystallization temperature. Thus, phosphates, especially apatite, has a strong potential to immobilize uranium under hydrothermal conditions and can be used in the development of engineering barriers to further improve the efficiency of existing backfill materials in the disposal of nuclear waste.