O-containing Functional Groups Research Articles

Comparative analysis of Cr(VI) oxyanions adsorption on aged polyamide microplastics: Evaluating UV irradiation versus chemical aging

Microplastics (MPs) commonly undergo aging in various environmental media, affecting both their environmental behavior and Trojan-horse effect for contaminants. However, the mechanisms underlying the different impact of various aging processes on the Trojan-horse effect of polyamide (PA) MPs towards metal oxyanions remain unclear. This study explored how chemical aging and UV irradiation impact the structural characteristics and Cr(VI) adsorption of PA MPs under various influencing factors. Results showed that both aging processes enhanced the negative surface charge, surface oxygen content, and roughness of PA MPs, with FTIR correlation spectroscopy confirming an increase in O-containing functional groups. Cr(VI) adsorption onto aged PA sharply increased by 17.4 % (14 days of UV irradiation), 39.4 % (42 days of UV irradiation), and 21.7 % (chemical aging) compared to original PA. Salinity and natural organic matter had adverse effects on Cr(VI) adsorption. Spectroscopic analyses highlighted the crucial role of hydrophilic amide groups in controlling Cr(VI) adsorption onto aged PA, involving hydrogen bonding, electrostatic interactions, and reduction. Aged PA exhibited higher adsorption capacities but also greater desorption under simulated seawater and intestinal fluid, suggesting increased migration potential for Cr(VI). This study provides helpful insights into assessing the environmental risk of co-existing PA MPs and metal oxyanions, particularly considering the effect of aging processes.

Characteristics of chemical aged biochars and their adsorption behaviors for norfloxacin

The biochar after long-term application will inevitably undergo ageing, thus promoting or inhibiting its remediation efficiency for antibiotics due to the differences in feedstocks and ageing process. To elucidate the adsorption performance and mechanisms of norfloxacin (NOR) by the different aged biochars, a batch of fresh biochars (BCs) prepared from Platanus orientalis Linn. leaf at 400 and 700 ℃ were aged by H2O2 (HBCs) and KMnO4 (MBCs) to simulate the natural ageing process. Compared with BCs, HBCs and MBCs showed larger specific surface area, richer micropores and O-containing functional groups. The maximum adsorption capacities of MBCs (43.96–49.32 mg g−1) and HBCs (18.38–19.79 mg g−1) were generally greater than those of BCs (16.44–20.01 mg g−1), which was resulted from the enhanced pore filling and hydrogen bonds. Furthermore, MBCs introduced with MnOx showed higher adsorption performances than those of HBCs, mainly due to the surface complexation. Na+ and Ca2+ inhibited the NOR adsorption by all the aged biochars. Humic acid and citric acid enhanced NOR adsorption at pH 3.0 but weakened the adsorption at pH 7.0. Furthermore, the NOR removal efficiency of BCs and aged biochars in the natural waters were reduced by 20–25 % and 6–17 %, respectively, showing the excellent sorption performance of the aged biochars. Our findings clarified the enhanced adsorption capacities of NOR by the aged biochar and the potential adsorption mechanism, providing the evidence for predicting the environmental fate of antibiotics in water environment and designing the functional biochars for controlling antibiotic pollution.

Evaluation of chemical properties and humification process during co-composting of spent mushroom substrate (Pleurotus ostreatus) and pig manure under different mass ratios

Spent mushroom substrate (SMS) from Pleurotus ostreatus is high in salinity, susceptible to deterioration caused by mold, and not suitable for direct application in soil. Its high C/N ratio and low pH inhibit the humification process during composting. Pig manure (PM) possesses high density and low porosity, impeding microbial metabolism. Co-composting SMS and PM can overcome these challenges. A 120-day composting experiment was conducted with varying mass ratios of SMS and PM, supplemented with calcium bentonite and microbial inoculum. After composting, there was observed a significant rise in the N and K2O contents, ranging from 11.1% to 84.1% and 55.1%–296.8%, respectively. Additionally, there was a decrease in the C/N ratio by a range of 18.9%–60.1%. The total nutrient content of SMS post-composting solely was a mere 4.9%, failing to meet the 5% required by China's Professional Standard outlined for organic fertilizers (NY/T525-2021). Composting PM alone simplified the molecular structure of humic-extracted acid (HE) and reduced the C content of humic acid (HA) by up to 18.1%. In contrast, co-composting SMS and PM in equal proportions stimulated microbial consumption of water-soluble substances, resulting in increase in C contents of HE and HA by 11.5% and 18.7%, respectively, along with a 15.4% rise in the polymerization level of the composted materials. Furthermore, this combination facilitated the conversion of inert humic component, reducing C content of humin by 79.3%, lowering the electrical conductivity (EC) value by 23.0%, and boosting GI value by 154.1%. Increasing the proportion of SMS in co-compost proved advantageous in enriching its organic matter content. The composting process involved bio-degradation of O-containing functional groups like phenols and alcohols, utilization of polysaccharides by microorganisms, and development of carboxyl groups in the HA. Based on the above index analysis, the most effective compost ratio to achieve higher humification level and compost quality was determined to be a mass ratio of SMS to PM of 5:5, followed by 6:4.

A comprehensive investigation of thermal coke formation during rapid non-catalytic pyrolysis of rubber seed oil

Due to coking deposits, catalyst deactivation severely affects the upgrading of triglyceride biomass. Understanding the chemical nature and development of coke species is essential for mitigating the degree of coking and for the regeneration process of the catalysts. In this study, SEM, XRD, FT-IR, Raman and XPS are employed to gain insights into the coking behavior of RSO during the rapid pyrolysis process. The results show that pyrolysis of RSO produces high quality syngas with 98.72 % H2 and CO. The unstable O-containing functional groups in the cokes continue to be lost, which indirectly promotes the condensation reaction of aromatic hydrocarbons. The hydroxyl group is the main functional group that affects the reactivity of cokes, and it is one of its more active groups. Although the crystal size of the cokes is growing, its degree of graphitization is decreasing with the temperature increases. The size of the aromatic ring system in the cokes gradually increases with increasing temperature. The cross-linking structure in the coke is constantly being destroyed. Resulting in some O-containing functional groups entering the cokes. Based on this work, the coke evolutionary route of rapid pyrolysis of RSO is proposed.

Effect of citric acid modification on the properties of hydrochar and pyrochar and their adsorption performance toward methylene blue: crucial roles of minerals and oxygen functional groups.

Modification is widely used to enhance the adsorption performance of pristine hydrochar (HBC) and pyrochar (BC). However, comparisons between modified HBC and BC toward pollutant removal have rarely been reported. In this study, pristine HBC and BC derived from rice straw were first produced, and then citric acid (CA) was used as a modifier to synthesize CA-modified HBC (CAHBC) and CA-modified BC (CABC). Furthermore, the adsorption performance of biochars toward methylene blue (MB) was investigated. The results showed that BC exhibits relatively rough surfaces and contains more minerals (ash), whereas HBC has plentiful O-containing functional groups and fewer minerals. CA modification partially removed minerals from the surface of BC, which weakened the ion exchange, surface complexation, and n-π interaction, resulting in a lower adsorption ability toward MB. By contrast, CA produced more O-containing functional groups on the surface of HBC, which strengthened the hydrogen bonding and electrostatic interaction, thus increasing the adsorption capacity toward MB. The two-compartment model showed a good fit to the adsorption process of MB on CAHBC, and the isotherm data for MB adsorption by HBC and CAHBC are suitable for the Freundlich model. The highest adsorption amount of MB using CAHBC was 80.13mg·g-1, which was 27.66% higher than that for CABC. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis indicated that the carboxyl groups in the surface functional groups of CAHBC played a crucial role in the MB adsorption process. In addition, CAHBC showed a good performance for a wide range of pH values (4.0-10.0) and under the interference of coexisting ions, and also presented a recycling ability. Furthermore, the adsorption of MB on CAHBC biochar was a spontaneous, exothermic, degree-of-randomness-increasing process. Consequently, CA modification of HBC is a promising strategy and could be used for MB removal from aquatic environments.

Surface Coordination Modulated Morphological Anisotropic Engineering of Iron-Benzoquinone Frameworks for Lithium-Ion Batteries.

Morphological anisotropic engineering is powerful to synthesize metal-organic frameworks (MOFs) with versatile physicochemical properties for diverse applications ranging from gas storage/separation to electrocatalysis and batteries, etc. Herein, we developed a carbon substrate guided strategy to manipulate the facet-dependent coordination for morphology engineering of Fe-THBQ (tetrahydroxy-1,4-benzoquinone) frameworks, which is built with cubic Fe octamer bridged by two parallel THBQ ligands along three orthogonal axes, extending to a three-dimensional (3D) framework with pcu-e network topology. The electronegative O-containing functional groups on carbon surfaces compete with THBQ linkers to selectively interact with the unsaturated coordinated Fe cations on the {111} facets and inhibit crystal growth along the <111> direction. The morphology of Fe-THBQ evolves from thermodynamically favored truncated cube to cuboctahedron depending on the content of O-containing functional groups on the carbon substrate. The Fe-THBQ with varied morphologies exhibits facet-dependent performances for electrochemical lithium storage. This work will shed light on the morphology modulation of MOFs for promising applications.

Decoupling the Ca release characteristics induced by O-containing functional groups during volatile-char interaction based on model compounds

Alkali metals and alkaline earth metals (AAEM) are important factors to be considered in coal gasification process, and understanding the release behavior of AAEM under the interaction of volatile-char is the key to realize efficient thermal conversion of coal. In this study, four typical O-containing functional groups (—COOH,—OH, CO,—OCH3) were used to react with coal char in a fixed-bed reactor, the reaction temperature was set up at 750，800，850，900 ℃ to survey the release characteristics of Ca by different oxygen functional groups during the interaction of volatile-char at different temperatures from a quantitative point of view. The result show that the Ca release rate of coal char is not high in the whole reaction temperature range, and the interaction of O-containing compounds-coal char at lower temperature will increase the O content (C—O and CO) of coal char, the content of Ca in interactive coal chars was higher than that of the coal char. At lower temperature, the order of compounds inhibiting Ca release ability is: C6H5CHO≈C6H5COOH > C10H8O2 > C6H5OCH3. In addition, it also seems that O-containing compounds (except C6H5COOH) can obviously promote the conversion of ammonium acetate-soluble Ca to water-soluble Ca during the interaction with char. As the temperature increases, the change trend of O-containing functional groups on the surface of sample after interaction is completely opposite to that at lower temperature, the O-containing model compounds undergo de-oxidation, cracking and polymerization in the effect of coal char and AAEM, causing the formation of polycyclic aromatic hydrocarbon on the surface of the char, which hinders the diffusion of Ca from the char to the gas phase. This work is good for enriching and developing the study on the release characteristics of alkali earth metals during the interaction of volatile-char, and provides a theoretical basis for the development of related industries.

Effective strategy for alleviation of oil contamination in marine via the superhydrophobic biochar: Performances, mechanisms and environmental recalcitrance

The performance of layered double hydroxides (LDH)-biochar composite on alleviating oil spill pollution is poorly understood. A superhydrophobic biochar (NCY) was synthesized from the pristine wood chips biochar (WCB) after the surface deposition of NiCo-LDH (NCB) and hydrophobic modification with stearate. The oil removal potential of the designed biochars was investigated via the diesel oil/crude oil adsorption experiments and the environmental recalcitrance evaluation. The compared characterization results revealed that NiCo-LDH was successfully deposited onto biochar matrix via the electrostatic attraction and pore filling effect, which facilitated a special flower-like hierarchical architecture rough surface for biochar and hinder the multi-layer stacking of LDH. Benefit from the constructed hierarchical architecture, the occupancy of oxygen-containing functional groups and hydrophobic modification of stearate, the water contact angle of NCY (156°) was remarkably larger than NCB (117°) and WCB (50.1°), which exhibit a superhydrophobic. The maximum diesel oil sorption capacities of biochars increased from 3.28 g/g in WCB to 5.64 g/g in NCB and 11.6 g/g in NCY, as well as the maximum crude oil sorption capacities of biochars showed a similar trend (WCB: 4.64 g/g, NCB: 8.74 g/g, NCY: 18.6 g/g). Accordingly, NCY showed higher oil adsorption capacity than NCB and WCB mainly due to the enhanced hydrophobic forces and the π-π electron donor-acceptor interaction resulted from lower amount of O-containing functional groups and superhydrophobic surface wettability. Furthermore, the application of LDH remarkably improved the environmental recalcitrance of biochar (resist to the chemical oxidation and thermal decomposition in marine) due to the coating of NiCo-LDH could enhance the bulk stability of biochar and increase the liable carbon content in biochar. This study proved that the application of NiCo-LDH and stearate could be an effective approach for improve the oil pollution remediation capacity and the environmental recalcitrance of biochar.

Study on the adsorption mechanism of polar and non-polar VOCs by the activated carbon with surface oxygen

In this study, CO2 was converted to activated carbon by the molten salt CO2 capture and electrochemical conversion (MSCC-EC) method, and the surface oxygen content of the activated carbon was further modified for the adsorption of polar molecules (chlorobenzene) and nonpolar molecules (toluene), the role of the pore structure and surface O-containing functional groups of the adsorbents in contributing to the adsorption process was systematically investigated. The results showed that MS-AC500-10, MS-AC500-15, and MS-AC550-15 have rich pore structures with specific surface areas of 811.56 m2/g, 835.35 m2/g, 1249.104 m2/g, and surface oxygen contents of about 10 %, 15 %, 15 %, respectively. The toluene adsorption capacity of MS-AC500-10, MS-AC500-15, and MS-AC550-15 was 203.82 mg/g, 229.72 mg/g, and 358.97 mg/g, respectively, and was dominated by pore adsorption, which was positively proportional to the specific surface areas and pore volumes, the adsorption process belonged to the pseudo-first-order kinetic model. The adsorption amounts of chlorobenzene by MS-AC500-10, MS-AC500-15, and MS-AC550-15 were 287.98 mg/g, 363.11 mg/g, and 495.41 mg/g, respectively. In addition to the pore adsorption, the oxygen content on the surface of the adsorbents had a non-negligible promotion effect on the adsorption of chlorobenzene, mainly because chlorobenzene is a polar molecule, and the asymmetric electrons on its surface have strong interactions with the O-containing functional groups on the surface of the adsorbents. Moreover, the prepared adsorbents were thermally stable, and the decay rate of adsorption performance was less than 5 % after five adsorption–desorption cycles.

Untapped potential of food waste derived biochar for the removal of heavy metals from wastewater

The presence of heavy metals in water pose a serious threat to both public and environmental health. However, the advances in the application of low cost biochar based adsorbent synthesize from various feedstocks plays an effective role in the of removal heavy metals from water. This study implies the introduction of novel method of converting food waste (FW) to biochar through pyrolysis, examine its physiochemical characteristics, and investigate its adsorption potential for the removal of heavy metals from water. The results revealed that biochar yield decreased from 18.4 % to 14.31 % with increase in pyrolysis temperature from 350 to 550 °C. Likewise, increase in the pyrolysis temperature also resulted in the increase in the ash content from 39.87 % to 42.05 % thus transforming the biochar into alkaline nature (pH 10.17). The structural and chemical compositions of biochar produced at various temperatures (350, 450, and 550 °C) showed a wide range of mineralogical composition, and changes in the concentration of surface functional groups. Similarly, the adsorption potential showed that all the produced biochar effectively removed the selected heavy metals from wastewater. However a slightly high removal capacity was observed for biochar produced at 550 °C that was credited to the alkaline nature, negatively charged biochar active sites due to O-containing functional groups and swelling behavior. The results also showed that the maximum adsorption was recorded at pH 8 at adsorbent dose of 2.5 g L−1 with the contact time of 120 min. To express the adsorption equilibrium, the results were subjected to Langmuir and Freundlich isotherms and correlation coefficient implies that the adsorption process follows the Freundlich adsorption isotherm. The findings of this study suggest the suitability of the novel FW derived biochar as an effective and low cost adsorbent for the removal of heavy metals form wastewater.

Synthesis and characteristics of carbon-based synfuel from biomass and coal powder by synergistic co-carbonization technology

A synergistic co-carbonization method based on the use of corn stalk (CS), wood shavings (WS) and bituminous coal (BC) is proposed as a green and low-cost technology. The preparation parameters included a co-carbonization temperature of 600 °C, a co-carbonization time of 30 min, and a biomass/coal ratio of 4/6. The high calorific value (HCV) and bulk density of the CS/BC synfuel were 29.81 MJ kg−1 and 495 kg m−3, respectively, and those of the WS/BC synfuel were 30.11 MJ kg−1 and 485 kg m−3, respectively. The results indicated that the microcrystalline structure was ordered and that the proportion of the graphitic structure increased during the synergistic co-carbonization process. In addition, the co-carbonization process changed the contents of the functional groups on the surface. The amount of aromatic C–O increased during the synergistic co-carbonization process. Decreases in the O-containing functional groups and increases in the graphitic carbon content in the synfuel demonstrated that the interactions of the biomass volatiles with the bituminous coal generated a more regular structure for the carbon-based synfuel and changed the carbon type of the synfuel. This work provides a mechanism for the biomass and coal interactions occurring during the preparation of carbon-based synfuels.

Effect of oxygen-containing functional group contents on sorption of lead ions by acrylate-functionalized hydrochar

The surface functional groups of hydrochar are crucial to its surface properties, and their contents are strongly positively correlated with the adsorption performance. In this study, acrylate-functionalized hydrochar (AHC) with varying contents of O-containing functional groups (OFGs) was synthesized via hydrothermal carbonization (HTC) of bamboo, acrylic acid and an initiator, and then deprotonated with NaOH. The AHCs were analyzed by various characterization techniques. During HTC, the higher amount of acrylic acid added led to higher carbon, oxygen and carboxyl contents, and to the larger specific surface area and pore volume of AHC. The adsorption kinetics, isotherms, thermodynamic, ionic strength and pH effects of Pb(II) on AHC were studied. Adsorption isotherms and kinetics obeyed Langmuir and pseudo-second-order models, respectively, indicating adsorption is monolayer chemical process. The adsorptive ability was well linearly related to the OFG contents of AHC. When acrylic acid was added to 25 mL during HTC, the adsorbing ability of AHC over Pb(II) reached 193.90 mg g−1. Hence, direct HTC of acrylic acid, biomass and an initiator can prepare hydrochar with controllable OFG contents, which is a prospective adsorbent for treating metal cations.

Multifaceted Characterization for the Hepatic Clearance of Graphene Oxide and Size-Related Hepatic Toxicity.

Understanding the final fate of nanomaterials (NMs) in the liver is crucial for their safer application. As a representative two-dimensional (2D) soft nanomaterial, graphene oxide (GO) has shown to have high potential for applications in the biomedical field, including in biosensing, drug delivery, tissue engineering, therapeutics, etc. GO has been shown to accumulate in the liver after entering the body, and thus, understanding the GO-liver interaction will facilitate the development of safer bio-applications. In this study, the hepatic clearance of two types of PEGylated GOs with different lateral sizes (s-GOs: ~70 nm and l-GOs: ~300 nm) was carefully investigated. We found that GO sheets across the hepatic sinusoidal endothelium, which then may be taken up by the hepatocytes via the Disse space. The hepatocytes may degrade GO into dot-like particles, which may be excreted via the hepatobiliary route. In combination with ICP-MS, LA-ICP-MS, and synchrotron radiation FTIR techniques, we found that more s-GO sheets in the liver were prone to be cleared via hepatobiliary excretion than l-GO sheets. A Raman imaging analysis of ID/IG ratios further indicated that both s-GO and l-GO generated more defects in the liver. The liver microsomes may contribute to GO biotransformation into O-containing functional groups, which plays an important role in GO degradation and excretion. In particular, more small-sized GO sheets in the liver were more likely to be cleared via hepatobiliary excretion than l-GO sheets, and a greater clearance of s-GO will mitigate their hepatotoxicity. These results provide a better understanding of the hepatic clearance of soft NMs, which is important in the safer-by-design of GO.

Effect of chlorination and ultraviolet on the adsorption of pefloxacin on polystyrene and polyvinyl chloride

During the water treatment process, chlorination and ultraviolet (UV) sterilization can modify microplastics (MPs) and alter their physicochemical properties, causing various changes between MPs and other pollutants. In this study, the impact of chlorination and UV modification on the physicochemical properties of polystyrene (PS) and polyvinyl chloride (PVC) were investigated, and the adsorption behavior of pefloxacin (PEF) before and after modification was examined. The effect of pH, ionic strength, dissolved organic matter, heavy metal ions and other water environmental conditions on adsorption behavior was revealed. The results showed that PS had a higher adsorption capacity of PEF than PVC, and the modification increased the presence of O-containing functional groups in the MPs, thereby enhancing the adsorption capacity of both materials. Chlorination had a more significant impact on the physicochemical properties of MPs compared to UV irradiation within the same time period, leading to better adsorption performance of chlorination. The optimal pH for adsorption was found to be 6, and NaCl, sodium alginate and Cu2+ would inhibit adsorption to varying degrees, among which the inhibition caused by pH was the strongest. Chlorination and UV modification would weaken the inhibitory effect of environmental factors on the adsorption of PEF by MPs. The main mechanisms of adsorption involved electrostatic interaction and hydrogen bonding. The study clarified the effects of modification on the physicochemical properties of MPs, providing reference for subsequent biotoxicity analysis and environmental protection studies.

Hydrochars as slow-release phosphorus fertilizers for enhancing corn and soybean growth in an agricultural soil

Hydrochars as carbonaceous amendments rich in porous structures and nutrients can be used as promising slow-release fertilizers and soil health amendments. Yet, the performance of hydrochars derived from different feedstocks in improving crop plant growth and soil phosphorus (P) availability is not well understood. Here, a batch of sewage sludge (SS) and chicken manure (CM) derived hydrochars (SSCs and CMCs) were produced at 125 and 225 °C (SS125/225 and CM125/225) to investigate their characteristics and performances in improving the seedling growth of two representative crops, soybean (Glycine max) and corn (Zea mays), as well as the P availability in an acidic agricultural soil in comparison with triple super phosphate (TSP), a conventional P fertilizer. Compared with CMCs, SSCs with more porous and rougher surfaces contained relatively lower contents of carbon (C; 32.3–33.3%), hydrogen (H; 3.9–4.69%), and potassium (K; 29.2–51 mg g−1), but higher contents of P (37.4–85.4%) and nitrogen (N; 2.26–4.9%), as well as more O-containing and N-containing functional groups. The impacts of hydrochars on soybean and corn growth showed distinct variations. The application of SSCs showed little effect on soybean growth (i.e., biomass, chlorophyl contents, and number of leaves), while CMCs significantly increased its total dry biomass by 23.2–66.2%. For corn, both SSCs and CMCs increased the total dry biomass by 32.8–92.4% and 21.8–69.7%, respectively, compared to those in the un-amended soils. In addition, compared with the higher temperature hydrochars (SS225 and CM225), the lower temperature ones (SS125 and CM125) increased the total dry biomass by 24.6% and 34.9% for soybean and 44.8% and 39.3% for corn, respectively. The significant improvement in crop growth by hydrochars was mainly due to the direct nutrient supply (particularly P) by the hydrochars, which was supported by the increased soil and shoot P concentrations. Moreover, hydrochar application led to a rise in soil water soluble P (WSP) levels. However, as time progressed, these levels fell due to the fixation and adsorption of P via precipitation, electrostatic attraction, and ion exchange on the hydrochars. Contrarily, TSP maintained persistently high soil WSP levels, increasing the leaching risk of P through the soil profile. Our results provide direct evidence for hydrochars as slow-release P fertilizers to enhance crop growth and production and give better insights for producing functionalized P-rich chars as an alternative to chemical P fertilizers to maintain sustainable agricultural production.Graphical

Low temperature and facile synthesis of nitrogen-doped hierarchical porous carbon derived from waste polyethylene terephthalate for efficient CO2 capture

Waste polyethylene terephthalate (PET) with high carbon content (>60 wt%) has shown great potential in the field of synthesizing carbon materials for CO2 capture, attracting increasing attention. Herein, an innovative strategy was proposed to synthesize nitrogen-doped hierarchical porous carbon (PC) for CO2 capture using PET as precursor and sodium amide (NaNH2) as both nitrogen dopant and low-temperature activator. As-synthesized N-doped PC exhibited a significantly high micropore volume of 0.755 cm3/g and a rich content of N- and O-containing functional groups, offering ample active sites for CO2 molecules. Further, the adsorbents demonstrated excellent CO2 capture capacity, achieving 5.7 mmol/g (0 °C) and 3.3 mmol/g (25 °C) at 1 bar, respectively. This was primarily attributed to the synergistic effect of narrow micropores filling and electrostatic interactions. Moreover, as-synthesized PC exhibited rapid CO2 adsorption capability, and its dynamic adsorption process was effectively described using a pseudo-second-order kinetic model. After five consecutive cycles, PET-derived PC still maintained ~100 % of adsorption capacity. They also possessed good CO2/N2 selectivity and reasonable isosteric heat of adsorption. Therefore, as-synthesized nitrogen-doped PC is a promising CO2 adsorbent through low-temperature activation of carbonized PET with NaNH2. Such findings have substantial implications for waste plastic recycling and mitigating the greenhouse effect.

Using waste to treat waste: facile synthesis of hollow carbon nanospheres from lignin for water decontamination.

Lignin, the most abundant natural material, is considered as a low-value commercial biomass waste from paper mills and wineries. In an effort to turn biomass waste into a highly valuable material, herein, a new-type of hollow carbon nanospheres (HCNs) is designed and synthesized by pyrolysis of biomass dealkali lignin, as an efficient nanocatalyst for the elimination of antibiotics in complex water matrices. Detailed characterization shows that HCNs possess a hollow nanosphere structure, with abundant graphitic C/N and surface N and O-containing functional groups favorable for peroxydisulfate (PDS) activation. Among them, HCN-500 provides the maximum degradation rate (95.0%) and mineralization efficiency (74.4%) surpassing those of most metal-based advanced oxidation processes (AOPs) in the elimination of oxytetracycline (OTC). Density functional theory (DFT) calculations and high-resolution mass spectroscopy (HR-MS) were employed to reveal the possible degradation pathway of OTC elimination. In addition, the HCN-500/PDS system is also successfully applied to real antibiotics removal in complex water matrices (e.g. river water and tap water), with excellent catalytic performances.

Biochar and soil properties affect remediation of Zn contamination by biochar: A global meta-analysis

Zinc (Zn) is one of the most common heavy metals that pollute soils and can threaten both environmental and human health. Biochar is a potential solution for remediating soil Zn contamination. This meta-analysis investigates the effect of biochar application on the remediation of Zn-contaminated soils and the factors affecting the remediation efficiency. We found that biochar application in Zn-contaminated soils reduced Zn bioavailability by up to 77.2% in urban soils, 55.1% in acidic soils, and 50.8% in coarse textured soils. Moreover, the remediation efficiency depends on the biochar production condition, with crop straw and sewage sludge feedstocks, high pyrolysis temperature (450–550 °C), low heating rate (<10 °C min−1), and short residence time (<180 min) producing high performing biochars. Biochar affects soil Zn bioavailability by changing soil pH and organic carbon, as well as through its high surface area, ash content, and O-containing surface functional groups. Our findings highlight the role of biochar as a promising and environmentally friendly material for remediating Zn contamination in acidic and/or coarse textured soils. We conclude that soil properties must be considered when selecting biochars for remediating soil Zn contamination.

Hydrogenation of Acetylene over Pd–Ag/Sibunit Catalysts: Effect of the Deposition Sequence of Active Component Precursors

The study investigates interactions between palladium and silver in Pd–Ag bimetallic catalysts supported on a mesoporous carbon material Sibunit and, in particular, the dependence of these interactions on the deposition sequence of the metal precursors. Using XRD and TEM results, it was shown that impregnating the support with an aqueous solution that contained nitrate salts of both metals, followed by hydrogen treatment at 500°C, generates uniformly sized Pd0.6Ag0.4 particles (dav = 5.6 nm). These particles exhibit high selectivity (79%) in the reaction of acetylene hydrogenation to ethylene. The catalysts synthesized by sequential impregnation of the support with solutions of Pd and Ag nitrates interleaved with heat treatment in H2 exhibited a lower selectivity (68–73%) due to the formation of particles non-uniform both in composition and size (about 4 to 60 nm). The IR spectroscopy data suggest this effect is presumably associated with the removal of O-containing functional groups from the carbon surface during the reduction of the supported precursor. Given that O-groups act as anchoring sites for the precursors of active components and suppress the ability of Sibunit to reduce metals from their salt solutions, the subsequent deposition of the second metal salt causes a non-uniform distribution of this metal on the surface and the generation of larger particles.

New insights into the fate and interaction mechanisms of hydrolyzed aluminum-titanium species in the removal of aged polystyrene

Polyaluminum-titanium chloride composite coagulant (PATC) has been demonstrated to be a promising coagulant in microplastics (MPs) treatment. However, the interaction process between the dominant species of PATC and MPs remains unclear, which will hinder our understanding of the coagulation mechanisms. Here, the species transformation of PATC during its interaction with aged polystyrene powder (APSp) was studied. The results showed that the rise of O-containing functional groups in APSp increased the possibility of forming C-O-M coordination bonds and hydrogen bonds between APSp and PATC, which improved the removal of PSp. Furthermore, Al13(OH)53Ti13O17(H2O)204+ (Al13Ti13) was considered to be the most effective species of PATC. At pH 4, electrostatic attraction brought Al13Ti13 approached APSp first, followed by hydrogen bonding and complexation occurred, respectively. However, the Al13Ti13-APSp complexes were easily converted to monomers and dimers during coagulation, which influenced the coagulation efficiency. With the increase of pH, OH- in the solution would further polymerize the depolymerized Al2Ti into oligomers and mesomers. Under weakly acid conditions, the diversity of PATC hydrolysates and the increase in APSp binding sites correspondingly led to the maximum APSp removal of 75%. When the pH further increased to 10, PATC interacted with APSp mainly by hydrogen bonding and sweeping effect.