Thermochemical behavior of tris(2-butoxyethyl) phosphate (TBEP) during co-pyrolysis with biomass

Phosphorus Footprint in the Whole Biowaste-Biochar-Soil-Plant System: Reservation, Replenishment, and Reception

Two phosphorus (P)-rich biowastes, sewage sludge (SS) and bone dreg (BD), were selected to clarify P footprints among biowaste, biochar, soil, and plants by introducing a novel "3R" concept model. Results showed that pyrolysis resulted in P transformation from an unstable-organic amorphous phase to a stable-inorganic crystalline phase with a P retention rate of 70-90% in biochar (P reservation). In soil, SSBC released more P in acid red soil and alkaline yellow soil than BDBC, while the opposite result appeared in neutral paddy soil. The P released from SSBC formed AlPO4 by combining with Al in soil, whereas P from BDBC transformed into Ca5(PO4)3F(or Cl) in conjunction with Ca in the soil (P replenishment). Various plants exhibited an uptake of approximately 2-6 times more P from biochar-amended soil than from the original soil (P reception). This study can guide the application of biochar in various soil-plant systems for effective nutrient reclamation.

Calcium enhances phosphorus reclamation during biochar formation: Mechanisms and potential application as a phosphorus fertilizer in a paddy soil

Transformation of phosphorus (P) species during pyrolytic production of biochar from P-rich biowastes with a subsequent soil amendment is important to P reclamation. Aiming at increasing the content of plant-available P and restraining the formation of easily mobile P in pyrolysis product, this study used exogenous calcium ions (20 wt% CaCl₂) addition prior to pyrolysis to regulate the pyrolytic transformation of P chemical fractions from sewage sludge and bone dreg. Results showed that active Ca catalyzed the decomposition of organic P to transform into inorganic orthophosphate. Based on Hedley's sequential extraction method, this study found that addition of Ca ions remarkably reduced the content of soluble P, exchange P, Fe/Al bound P, and occluded P in biochar, while increased Ca bound P from 78 to 85% to 85-96%. Liquid ³¹P NMR indicated that exogenous Ca induced the crack of the P-O-P bond in pyrophosphate to become orthophosphates. It also explained why new orthophosphates including chlorapatite (Ca₅(PO₄)₃Cl) and calcium hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) appeared in the Ca-composite biochar compared to pristine biochar. Combined with rapid P-release test in paddy soil (pH 6.27) and 30-days rice seedling growth test under flooded condition (10 wt% biochar addition ratio), it was confirmed that compared to pristine biochar, Ca-composite biochar released more P in paddy soil, but also promoted more P to be taken in by rice root and stalk. These results suggested that pretreating biowaste with Ca ion was a friendly approach to enhance P reclamation during biochar formation, making it a promising P fertilizer.

Online TG-FTIR-MS analysis of the catalytic pyrolysis of polyethylene and polyvinyl chloride microplastics

Microplastics (MPs) are frequently detected in urban waters, which would pose a threat to human health through the food chain. Thus, efficient approaches to the elimination of MPs are urgently required. Pyrolysis is a powerful technique for the potential treatment of MPs. The online thermogravimetry-Fourier transform infrared reflection-Mass spectrometry (TG-FTIR-MS) is applied for tracking the pyrolysis process of representative polyethylene (PE) and polyvinyl chloride (PVC) MPs in urban waters, together with or without the FeAlO_x catalyst. TG could quantitatively determine the decomposition behavior and kinetics of MPs while FTIR and MS spectra would be capable of characterizing the pyrolysis products. The results revealed that FeAlO_x is an excellent carbon support, and the deposited carbon can be gasified to CO at higher pyrolysis temperatures. Moreover, more aromatic compounds were generated from the pyrolysis of PE MPs with the catalyzation of FeAlO_x. Large quantities of benzene were also produced in the PVC MPs pyrolysis with or without FeAlO_x. Also, FeAlO_x largely decreased the concentrations of chlorine-containing compounds in the liquid products of PVC MPs pyrolysis. This study provides a efficient technique for the online observation of the MPs' catalytic pyrolysis process, which would guide future upcycling of MPs into value-added products.

Traditional and novel organophosphate esters (OPEs) in PM2.5 of a megacity, southern China: Spatioseasonal variations, sources, and influencing factors

Organophosphate esters (OPEs) are ubiquitous contaminants in the environment, whereas their atmospheric processes and fate are poorly understood. The present study revealed the spatial heterogeneity and seasonal variations of traditional and novel OPEs in PM_2.5 (particulate matter with diameters < 2.5 μm) across a megacity (including residential areas and potential source sites) in South China. Potential influencing factors on the contamination levels of OPEs were addressed. The total concentrations of 11 traditional OPEs ranging from 262 to 42,194 pg/m³ (median = 1872 pg/m³) were substantially higher than those of 10 novel OPEs (33.5-3835 pg/m³, median = 318 pg/m³). Significant spatial and temporal variations in the concentrations of most OPEs were observed. The overall district-specific contamination levels in this city showed dependence on the secondary industry sector for non-predominant OPEs and on the tertiary industry for predominant OPEs. The seasonal variations of the OPE concentrations suggest difference in their sources or influence of meteorological conditions. The correlations between the individual OPEs in PM_2.5 are determined largely by either their applications or physicochemical properties (in particular vapor pressure). The correlations between OPE concentrations and each meteorological factor (temperature, relative humidity, wind speed, and surface solar radiation) were inconsistent (positive and negative). Wind speed had the greatest effect on the OPE levels; While most OPEs bound to PM_2.5 were not efficiently scavenged by below-cloud rainfall. The results suggest that atmospheric half-life and Henry's Law Constant of OPEs are also determining factors for the wind speed and rainfall influence, respectively. However, mechanisms underlying the influence of meteorological conditions on atmospheric OPEs still need further research.

CO2 dual roles in food scraps-derived biochar activation to enhance lead adsorption capacity

Driven by China's waste classification system, the recycling of food scraps is a work of great importance. The carbonate (CO₃^2-) and phosphate (PO₄^3-) in food scraps indicate that its derived biochar can be a good candidate for Pb immobilization. In the current study, Pb²⁺ adsorption sites (CO₃^2- and PO₄^3-) of biochar were adjusted by carrier gas atmosphere and activation temperature. Results indicate that CO₂ has dual roles in activation of food scraps-derived biochar. CO₂ can not only inhibit the decomposition of CO₃^2- but also increase the content of PO₄^3- via consuming aromatic carbon combined with phosphorus at high temperature (>600 °C). Thus, the biochar prepared at 700 °C and CO₂ atmosphere has more adsorption sites, resulting in an outstanding Pb adsorption capacity (up to 555.6 mg/g) via coprecipitation mechanisms. As-prepared biochar sample also can be prepared to a hydrogel with a remarkable mechanic strength. But biochar hydrogel decreases Pb adsorption capacity to 104.2 mg/g due to the pore blocking effect. Life cycle assessment illustrates that the scene of food scraps activated by CO₂ has lower Global Warming Potential (GWP) and Primary Energy Demand (PED). Therefore, current research provides a high-efficiency method for treatment of food scraps.

Effects of phosphorus modified nZVI-biochar composite on emission of greenhouse gases and changes of microbial community in soil

The effect of modified biochar on the greenhouse gas emission in soil is not clear until now. In this study, biochar (BC) was modified by phosphoric acid (P) and further combined with nano-zero-valent iron (nZVI) to form nZVI-P-BC composite. The P modified biochar could significantly increase the available phosphorus in soil. The release of CO₂ and N₂O in soil was inhibited during the initial stage of the experiment, with inhibition becoming more obvious over time. On the contrary, CH₄ and N₂O emission in soil was enhanced by nZVI-P-BC composite. The proportion of Sphingomonas and Gemmatimonas were the most abundant bacterial species, which were related to the metabolism and transformation of nitrogen. The community structure of the fungus was also affected by nZVI-P-BC composite with Fusarium as the main species. PCoA analysis result suggested that bacterial community was more affected by the incubation time while fungal community was more related to the addition of different biochar and modified biochars.

Phosphorus and nitrogen transformation in antibiotic mycelial residue derived hydrochar and activated pyrolyzed samples: Effect on Pb (II) immobilization

In this study, lincomycin residue (LR, a type of antibiotic mycelial residue) derived hydrochar samples (LR-HCs) were obtained from hydrothermal carbonization (HTC), and pyrolysis applied to these LR-HCs to produce activated pyrolyzed samples (LR-APs). Transformation of phosphorus (P) and nitrogen (N) species during HTC and pyrolysis was of primary interest and characterized by several techniques. Nitrogen content of dry LR was calculated by elemental analysis, being 7.91 wt. %, decreasing to 2.51 after HTC and 1.12 wt. % after concesutive HTC and pyrolysis. FT-IR analysis provided evidence for amine groups in LR samples. XPS analysis described N species (Pyridinic-N, Amine-N, Protein-N, Pyrrolic-N, and Quaternary-N) and P species (ortho-P/pyro-P and Ar-P) in LR samples, effectively. Sequential extraction showed that the HTC and pyrolysis changed the proportion of the P species from labile (P-NaHCO₃ and P-NaOH) to stable ones (P-residue). Utilization and suitability of as-prepared LR-HCs and LR-APs for heavy metal Pb (II) immobilization show promising results. To help understand immobilization process, kinetic (pseudo-1st-order and pseudo-2nd-order) and isotherm (Freundlich) models were tested and verified. Results confirmed that P and N species were transformed during HTC and pyrolysis and that these processes lead to an advantageous effect on Pb (II) removal from solution.

Hematite-facilitated pyrolysis: An innovative method for remediating soils contaminated with heavy hydrocarbons

As a recalcitrant fraction of petroleum, heavy hydrocarbons (including aromatics, resins, and asphaltenes) can remain in contaminated soils even after decades of weathering, thereby causing serious harm to the soil ecosystem and human health. Pyrolysis is a promising technique for remediating petroleum-contaminated soil. However, this technique still presents some drawbacks, such as high energy consumption and damage to soil properties. Therefore, an innovative method using hematite (Fe₂O₃) for the catalytic pyrolysis of weathered petroleum-contaminated soil was developed in this study. Compared with soil pyrolyzed without Fe₂O₃ at 400 °C for 30 min, the residual concentrations of aromatics, resins, and asphaltenes in soil pyrolyzed with 5.0% Fe₂O₃ were reduced by 67.8%, 52.3%, and 67.9%, respectively. After pyrolysis with 5.0% Fe₂O₃, the water-holding capacity of soil was considerably increased and the soil became darker and rougher. Scanning electron microscopy analysis showed that many small holes occurred on the surface of the pyrolytic soil. X-ray photoelectron spectrometer analysis showed that a thin layer of graphitic C was formed and deposited on the surface of the pyrolytic soil. We also observed that the wheat germination percentage and biomass yield in the soil pyrolyzed with 5.0% Fe₂O₃ were even higher than those in clean soil.

Understanding the Impact of Relative Humidity and Coexisting Soluble Iron on the OH-Initiated Heterogeneous Oxidation of Organophosphate Flame Retardants

The current uncertainties in the reactivity and atmospheric persistence of particle-associated chemicals present a challenge for the prediction of long-range transport and deposition of emerging chemicals such as organophosphate flame retardants, which are ubiquitous in the global environment. Here, the OH-initiated heterogeneous oxidation kinetics of organophosphate flame retardants (OPFRs) coated on inert (NH₄)₂SO₄ and redox-active FeSO₄ particles were systematically determined as a function of relative humidity (RH). The derived reaction rate constants for the heterogeneous loss of tricresyl phosphate (TCP; k_TCP) and tris(2-butoxyethyl) phosphate (TBEP; k_TBEP) were in the range of (2.69-3.57) × 10^-12 and (3.06-5.55) × 10^-12 cm³ molecules^-1 s^-1, respectively, depending on the RH and coexisting Fe(II) content. The k_TCP (coated on (NH₄)₂SO₄) was relatively constant over the investigated RH range while k_TBEP was enhanced by up to 19% with increasing RH. For both OPFRs, the presence of Fe(II) enhanced their k by up to 53% over inert (NH₄)₂SO₄. These enhancement effects (RH and Fe(II)) were attributed to fundamental changes in the organic phase state (higher RH lowered particle viscosity) and Fenton-type chemistry which resulted in the formation of reactive oxygen species, respectively. Such findings serve to emphasize the importance of ambient RH, the phase state of particle-bound organics in general, and the presence of coexisting metallic species for an accurate description of the degradation kinetics and aging of particulate OPFRs in models used to evaluate their atmospheric persistence.

Remediation of Petroleum-Contaminated Soil and Simultaneous Recovery of Oil by Fast Pyrolysis

Petroleum-contaminated soil (PCS) caused by the accidental release of crude oil into the environment, which occurs frequently during oil exploitation worldwide, needs efficient and cost-effective remediation. In this study, a fast pyrolysis technology was implemented to remediate the PCS and concurrently recover the oil. The remediation effect related to pyrolytic parameters, the recovery rate of oil and its possible formation pathway, and the physicochemical properties of the remediated PCS and its suitability for planting were systematically investigated. The results show that 50.9% carbon was recovered in oil, whose quality even exceeds that of crude oil. Both extractable total petroleum hydrocarbon (TPH) and water-soluble organic matter (SOM) in PCS were completely removed at 500 °C within 30 min. The remaining carbon in remediated PCS was determined to be in a stable and innocuous state, which has no adverse effect on wheat growth. On the basis of the systematically characterizations of initial PCS and pyrolytic products, a possible thermochemical mechanism was proposed which involves evaporation, cracking and polymerization. In addition, the energy consumption analysis and remediation effect of various PCSs indicate that fast pyrolysis is a viable and cost-effective method for PCS remediation.

Novel aspects of uptake patterns, metabolite formation and toxicological responses in Salmon exposed to the organophosphate esters-Tris(2-butoxyethyl)- and tris(2-chloroethyl) phosphate

Given the compound differences between tris(2-butoxyethyl)- and tris(2-cloroethyl) phosphate (TBOEP and TCEP, respectively), we hypothesized that exposure of juvenile salmon to TBOEP and TCEP will produce compound-specific differences in uptake and bioaccumulation patterns, resulting in potential formation of OH-metabolites. Juvenile salmon were exposed to waterborne TCEP or TBOEP (0.04, 0.2 and 1 mg/L) for 7 days. The muscle accumulation was measured and bioconcentration factor (BCF) was calculated, showing that TCEP was less accumulative and resistant to metabolism in salmon than TBOEP. Metabolite formations were only detected in TBOEP-exposed fish, showing seven phase I biotransformation metabolites with hydroxylation, ether cleavage or combination of both reactions as important metabolic pathways. In vitro incubation of trout S9 liver fraction with TBOEP was performed showing that the generated metabolite patterns were similar to those found in muscle tissue exposed in vivo. However, another OH-TBOEP isomer and an unidentified metabolite not present in in vivo exposure were observed with the trout S9 incubation. Overall, some of the observed metabolic products were similar to those in a previous in vitro report using human liver microsomes and some metabolites were identified for the first time in the present study. Toxicological analysis indicated that TBOEP produced less effect, although it was taken up faster and accumulated more in fish muscle than TCEP. TCEP produced more severe toxicological responses in multiple fish organs. However, liver biotransformation responses did not parallel the metabolite formation observed in TBOEP-exposed fish.

Transformation of Phosphorus during (Hydro)thermal Treatments of Solid Biowastes: Reaction Mechanisms and Implications for P Reclamation and Recycling

Phosphorus (P) is an essential nutrient for all organisms, thus playing unique and critical roles at the food-energy-water nexus. Most P utilized by human activities eventually converges into various solid biowastes, such as crop biomass, animal manures, and sewage sludges. Therefore, integration of efficient P recovery practices into solid biowaste management will not only significantly reduce the dependence on limited geological P resources but also reduce P runoff and related water contamination issues associated with traditional waste management strategies. This study reviews the applications of (hydro)thermal techniques for the treatment of solid biowastes, which can greatly facilitate P recovery in addition to waste volume reduction, decontamination, and energy recovery. Research showed that P speciation (including molecular moiety, complexation state, and mineralogy) can experience significant changes during (hydro)thermal treatments, and are impacted by treatment techniques and conditions. Changes in P speciation and overall properties of the products can alter the mobility and bioavailability of P, and subsequent P reclamation and recycling efficiency of the treatment products. This review summarizes recent progresses in this direction, identifies the challenges and knowledge gaps, and provides a foundation for future research efforts targeting at sustainable management of nutrient-rich biowastes.

Multifold enhanced synergistic removal of nickel and phosphate by a (N,Fe)-dual-functional bio-sorbent: Mechanism and application

A novel (N,Fe)-dual-functional biosorbent (N/Fe-DB) capable of efficient synergistic removal of Ni(II) and H₂PO₄^- from aqueous solution was synthesized. The adsorption capacities of Ni(II) and H₂PO₄^- were both remarkably enhanced over 3 times compared with those in single systems. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed that complexation of amino groups and ligand exchange of hydrous ferric oxide in N/Fe-DB played dominant roles. The electric double layer compressing and chelating ligand of deprotonated H₂PO₄^- accounted for the enhanced removal of Ni(II) in binary system, while cation bridge interaction promoted uptake of H₂PO₄^-. Furthermore, the coadsorbates were sequentially recovered, with the ratios of more than 99.0%. Besides, the recovered N/Fe-DB remained stable and applicable to the treatment of real electroplating wastewater even after six adsorption-regeneration cycles. Since the electroplating industry is springing up, effective control of heavy metals and phosphate has attracted global concerns. Based on the enhanced coremoval properties and superb regenerability, N/Fe-DB is potentially applicable to practical production.

Fates of Chemical Elements in Biomass during Its Pyrolysis

Biomass is increasingly perceived as a renewable resource rather than as an organic solid waste today, as it can be converted to various chemicals, biofuels, and solid biochar using modern processes. In the past few years, pyrolysis has attracted growing interest as a promising versatile platform to convert biomass into valuable resources. However, an efficient and selective conversion process is still difficult to be realized due to the complex nature of biomass, which usually makes the products complicated. Furthermore, various contaminants and inorganic elements (e.g., heavy metals, nitrogen, phosphorus, sulfur, and chlorine) embodied in biomass may be transferred into pyrolysis products or released into the environment, arousing environmental pollution concerns. Understanding their behaviors in biomass pyrolysis is essential to optimizing the pyrolysis process for efficient resource recovery and less environmental pollution. However, there is no comprehensive review so far about the fates of chemical elements in biomass during its pyrolysis. Here, we provide a critical review about the fates of main chemical elements (C, H, O, N, P, Cl, S, and metals) in biomass during its pyrolysis. We overview the research advances about the emission, transformation, and distribution of elements in biomass pyrolysis, discuss the present challenges for resource-oriented conversion and pollution abatement, highlight the importance and significance of understanding the fate of elements during pyrolysis, and outlook the future development directions for process control. The review provides useful information for developing sustainable biomass pyrolysis processes with an improved efficiency and selectivity as well as minimized environmental impacts, and encourages more research efforts from the scientific communities of chemistry, the environment, and energy.

Lifestyle chemistries from phones for individual profiling

Imagine a scenario where personal belongings such as pens, keys, phones, or handbags are found at an investigative site. It is often valuable to the investigative team that is trying to trace back the belongings to an individual to understand their personal habits, even when DNA evidence is also available. Here, we develop an approach to translate chemistries recovered from personal objects such as phones into a lifestyle sketch of the owner, using mass spectrometry and informatics approaches. Our results show that phones' chemistries reflect a personalized lifestyle profile. The collective repertoire of molecules found on these objects provides a sketch of the lifestyle of an individual by highlighting the type of hygiene/beauty products the person uses, diet, medical status, and even the location where this person may have been. These findings introduce an additional form of trace evidence from skin-associated lifestyle chemicals found on personal belongings. Such information could help a criminal investigator narrowing down the owner of an object found at a crime scene, such as a suspect or missing person.

Pyrolytic Temperature Dependent and Ash Catalyzed Formation of Sludge Char with Ultra-High Adsorption to 1-Naphthol

Massively produced sewage sludge brings a serious problem to environment. Pyrolysis is a promising and bifunctional technology to dispose the sewage sludge and recover energy, in which a large amount of pyrolytic sludge char is also produced. In this study, we proposed a value-added utilization of sludge char. We prepared an adsorbent with ultrahigh capacity for hydrophobic organic pollutant (1-naphthol) by pyrolysis of sludge and removal of the ash moiety from the sludge char. The adsorptive behavior of the adsorbent is strongly dependent on the pyrolytic temperature of sludge, and the maximum adsorption capacity of 666 mg g(-1) was achieved at 800 °C, which is comparable to deliberately modified graphene. Further exploration indicated that the robust adsorption to 1-naphthol is attributed to the catalytic effect of ash in sludge which facilitated the formation of more orderly graphitic structures and aromaticity at high pyrolytic temperatures.

Phosphorus-assisted biomass thermal conversion: reducing carbon loss and improving biochar stability

There is often over 50% carbon loss during the thermal conversion of biomass into biochar, leading to it controversy for the biochar formation as a carbon sequestration strategy. Sometimes the biochar also seems not to be stable enough due to physical, chemical, and biological reactions in soils. In this study, three phosphorus-bearing materials, H₃PO₄, phosphate rock tailing (PRT), and triple superphosphate (TSP), were used as additives to wheat straw with a ratio of 1: 0.4–0.8 for biochar production at 500°C, aiming to alleviate carbon loss during pyrolysis and to increase biochar-C stabilization. All these additives remarkably increased the biochar yield from 31.7% (unmodified biochar) to 46.9%–56.9% (modified biochars). Carbon loss during pyrolysis was reduced from 51.7% to 35.5%–47.7%. Thermogravimetric analysis curves showed that the additives had no effect on thermal stability of biochar but did enhance its oxidative stability. Microbial mineralization was obviously reduced in the modified biochar, especially in the TSP-BC, in which the total CO₂ emission during 60-d incubation was reduced by 67.8%, compared to the unmodified biochar. Enhancement of carbon retention and biochar stability was probably due to the formation of meta-phosphate or C-O-PO₃, which could either form a physical layer to hinder the contact of C with O₂ and bacteria, or occupy the active sites of the C band. Our results indicate that pre-treating biomass with phosphors-bearing materials is effective for reducing carbon loss during pyrolysis and for increasing biochar stabilization, which provides a novel method by which biochar can be designed to improve the carbon sequestration capacity.