BC Surface Research Articles

Adsorption properties and mechanism of Cr(VI) by Fe2(SO4)3 modified biochar derived from Egeria najas

The aquatic plant Egeria najas based biochar was innovatively constructed by modifying it with Fe2(SO4)3 (Fe2(SO4)3 @EN-BC) for Cr(VI) removal. The characterizations of Fe2(SO4)3 @EN-BC confirmed that Fe2(SO4)3 was attached to biochar in form of Fe2O3 after hydrolysis and calcination under high temperature. The results showed that Fe2(SO4)3 @EN-BC had a high removal efficiency of Cr(VI) with approaching 99.88%, which was about 7 times higher compared to unmodified biochar (EN-BC). Batch experiments of Cr(VI) removal included initial concentration, reaction temperature, solution pH and kinetics were conducted. The adsorption kinetics could be more accurately explained using pseudo-second order kinetics model, indicating the chemical adsorption controlled the reaction process. According to the Langmuir model, the maximum adsorption capacities for Cr(VI) were 138.79, 159.36 and 190.91 mg/g at 298, 313 and 333 K, respectively. Moreover, based on FTIR and XPS results, the Fe2(SO4)3 @EN-BC surface was loaded with many functional groups conducive to Cr(VI) adsorption. The main removal mechanisms of Cr(VI) by Fe2(SO4)3 @EN-BC included adsorption and reduction, and the percentage of Cr(VI) removed by adsorption and reduction were 19.1% and 80.9%, respectively.

A Comparative Study of Re-Referencing EEGs With Non-Unipolar to Unipolar Reference by REST

The combination of biological and electrochemical techniques enhances the bioremediation efficiency of treating oil-contaminated water. In this study a non-growing fungal whole cell biocatalyst (BC; Aspergillus brasiliensis attached to perlite) pretreated with an electric field (EF), was used to degrade a hydrocarbon blend (hexadecane-phenanthrene-pyrene; 100:1:1 w/w) in an airlift bioreactor (ALB). During hydrocarbon degradation, all mass transfer resistances (internal and external) and sorption capacity were experimentally quantified. Internal mass transfer resistances were evaluated through BC effectiveness factor analysis as a function of the Thiele modulus (using first order reaction kinetics, assuming a spherical BC, five particle diameters). External (interfacial) mass transfer resistances were evaluated by kLa determination. EF pretreatment during BC production promoted surface changes in BC and production of an emulsifier protein in the ALB. The BC surface modifications enhanced the affinity for hydrocarbons, improving hydrocarbon uptake by direct contact. The resulting emulsion was associated with decreased internal and external mass transfer resistances. EF pretreatment effects can be summarized as: a combined uptake mechanism (direct contact dominant followed by emulsified form dominant) diminishing mass transfer limitations, resulting in a non-specific hydrocarbon degradation in blend. The pretreated BC is a good applicant for oil-contaminated water remediation.

In situ growth of hydrophilic nickel-cobalt layered double hydroxides nanosheets on biomass waste-derived porous carbon for high-performance hybrid supercapacitors

Rational design and cost-effective fabrication of layered double hydroxides (LDHs) nanosheets with extraordinary electrochemical performance is a key challenge for hybrid supercapacitors (HSCs). Herein, we report a facile in situ growth methodology to eco-friendly synthesize hydrophilic NiCo-LDHs nanosheets on biomass waste-derived porous carbon (BC) for robust high-performance HSC cathode. The in situ growth process under ultrasonication realizes the rational arrangement of NiCo-LDHs nanosheets on the surface of BC, which effectively increases the specific surface area, promotes the electronic conductivity and enhances the wettability of NiCo-LDHs nanosheets without affecting their thickness values. With the beneficial effects of ultrathin thickness of LDHs nanosheets (6.20 nm), large specific surface area (2324.1 m2 g−1), low charge transfer resistance (1.65 Ω), and high wettability with electrolyte (34°–35°), the obtained Ni2Co1-LDHs/BC50 electrode possesses an ultra-high specific capacitance of 2390 F g−1 (956 C g−1) at 1 A g−1, which is superior to most reported values. Furthermore, an assembled Ni2Co1-LDHs/BC50//YP-80F HSC delivers a maximum specific energy of 52.47 Wh kg−1 at 375 W kg−1, and maintains a high capacitance retention of 75.9% even after 4000 cycles. This work provides a facile approach to fabricate LDHs nanosheets based cathode materials for high-performance HSCs.

Graphene-like BC3 and NC3 flakes as promising drug delivery systems

In recent years, two-dimensional nanostructures have become some of the most interesting to be studied for application in the drug delivery. Novel two-dimensional layers, denoted by BC 3 and NC 3 flakes, have been previously synthesized. Motivated by these interesting nanomaterials, in the present study, we have investigated the pristine graphene as well as BC 3 and NC 3 flakes as versatile drug delivery systems. The main objective of the present work is to study the interaction of graphene, BC 3 , and NC 3 flakes with 5-fluorouracil (FU) anticancer drug using the density functional theory (DFT). We found that the more negative values of adsorption energies in the solvent phase reveal that the considered flakes can improve their solubility and modify their interaction with the drug in the aqueous phase. Also, our ultraviolet–visible analysis shows that the electronic spectra of the drug/sheet complexes show a blue shift toward lower wavelengths. To gain insight into the binding features of considered systems with FU drug, the Atoms in Molecules analysis was also performed. Our results determine the electrostatic features of the drug/BC 3 flake bonding. Therefore, ore calculations demonstrated that the graphene-like BC 3 flake could be used as potential carrier for the delivery of the 5-fluorouracil anticancer drug. Graphene-like BC3 flake as versatile drug delivery system. • The stability and electronic properties of graphene-like BC 3 and NC 3 flakes were studied. • The 5-fluorouracil adsorption on the surface of BC 3 is more favorable than the NC 3 . • Electronic spectra of drug/flake complexes exhibit a blue shift toward lower wavelengths. • BC 3 flake could be used as potential carrier for delivery of 5-fluorouracil in the nanomedicine domain.

Micro-computed tomographic evaluation of single-cone obturation with three sealers.

ObjectivesThis study used micro-computed tomography (µCT) to compare voids and interfaces in single-cone obturation among AH Plus, EndoSequence BC, and prototype surface pre-reacted glass ionomer (S-PRG) sealers and to determine the percentage of sealer contact at the dentin and gutta-percha (GP) interfaces.Materials and MethodsFifteen single-rooted human teeth were shaped using ProTaper NEXT size X5 rotary files using 2.5% NaOCl irrigation. Roots were obturated with a single-cone ProTaper NEXT GP point X5 with AH Plus, EndoSequence BC, or prototype S-PRG sealer (n = 5/group).ResultsThe volumes of GP, sealer, and voids were measured in the region of 0–2, 2–4, 4–6, and 6–8 mm from the apex, using image analysis of sagittal µCT scans. GP volume percentages were: AH Plus (75.5%), EndoSequence BC (87.3%), and prototype S-PRG (94.4%). Sealer volume percentages were less: AH Plus (14.3%), EndoSequence BC (6.8%), and prototype S-PRG (4.6%). Void percentages were AH Plus (10.1%), EndoSequence BC (5.9%), and prototype S-PRG (1.0%). Dentin-sealer contact ratios of AH Plus, EndoSequence BC, and prototype S-PRG groups were 82.4% ± 6.8%, 71.6% ± 25.3%, and 70.2% ± 9.4%, respectively. GP-sealer contact ratios of AH Plus, EndoSequence BC, and prototype S-PRG groups were 65.6% ± 29.1%, 80.7% ± 25.8%, and 87.0% ± 8.6%, respectively.ConclusionsPrototype S-PRG sealer created a low-void obturation, similar to EndoSequence BC sealer with similar dentin-sealer contact (> 70%) and GP-sealer contact (> 80%). Prototype S-PRG sealer presented comparable filling quality to EndoSequence BC sealer.

Pyrogenic carbon for decontamination of low-level radioactive effluents: Simultaneous separation of 137Cs and 60Co

Radiocesium (137Cs) and radiocobalt (60Co) represent main dose-significant radionuclides in low-level radioactive liquid effluents released from commercial nuclear power plants (NPPs). Although pyrogenic carbon-based adsorbents (biochars, BC) have been studied for toxic metal removal, the reports of their use in the adsorption of radionuclides are rare. This article focuses on the competitive removal of Cs+ and Co2+ ions from radioactive solutions to waste biomass derived biochar and the multi-component isotherms. BC exhibited a good affinity to both Cs and Co, and in single-component systems the maximal adsorption capacity Qmaxexp reached 97.4 ± 5.0 (Cs+) and 74.5 ± 0.4 μmol g−1 (Co2+). 3D adsorption surfaces obtained by Sheindorf-Rebuhn-Steintuch (SRS) and extended Freundlich models indicate that the sorption of Cs+ ions from the Cs–Co binary system is significantly affected by Co2+ ions and during the adsorption competitive and interaction effects between Cs+ and Co2+ ions occur. Moreover, mono- and divalent cations present in the solution acted as competing ions, decreasing the Kd values. SEM-EDX maps, FTIR and XPS spectra confirmed that both biochar mineral and carbon fraction participated in Cs and Co immobilization. Beside interactions of Cs+ and Co2+ ions with O-containing moieties on the biochar surface (chemisorption), mineral components and porosity of BC (physisorption) were involved in both Cs and Co removal. Finally, the adsorption loading and fast kinetics for both Cs and Co indicate suitability of biochar to decontaminate low-level radioactive effluents contaminated by 137Cs and 60Co.

Fe/Al (hydr)oxides engineered biochar for reducing phosphorus leaching from a fertile calcareous soil

Excessive input of phosphate fertilizer into agricultural soils has caused critical environmental concerns due to high phosphorus (P) accumulation in farmland and P leaching into subsurface drainage. In this study, an Fe/Al (hydr)oxides modified biochar (FA-BC) was fabricated from corn straw via a wet-precipitation method and utilized to reduce P leaching from a fertile calcareous soil. Spectroscopic techniques demonstrated that the FA-BC exhibited a higher oxidation resistance than the raw BC due to oxide impregnation on the BC surface. The maximum Langmuir P adsorption capacities (393 and 528 mg kg−1) of the BC (4%, w/w) and FA-BC (4%, w/w) treated soils demonstrated a more efficient P adsorption capacity of the FA-BC. Application of the 2% (w/w) FA-BC also significantly reduced the leaching of total P (81.3%) from the soil column, while maintained an appropriate level of bioavailable P in the soil for sustaining plant growth. The chemical sequestration test and in-situ P k-edge XANES analyses of the FA-BC incubated soils revealed that the labile Ca–P fractions were transformed into stabilized Fe/Al–P complexes. The increased soil pH, a higher degree of soil P saturation, and intensive interaction between P and Fe/Al (hydr)oxides also contributed to the superior ability of the FA-BC amended soils towards P retention. This study provided field-relevant implications for the design and application of engineered biochar for green and sustainable improvement of agricultural soils.

Reduce graphene oxide-manganese oxide-black cumin based hybrid composite (rGO-MnO2/BC): A novel material for water remediation

Herein, the synthesis, characterization, and water treatment application of reduced graphene oxide-manganese oxide-black cumin hybrid composite, rGO-MnO2/BC, has been reported. The rGO-MnO2/BC was synthesized by incorporating MnO2 particles into reduced graphene oxide functionalized with functional groups of black cumin seeds. The prepared rGO-MnO2/BC was highly amorphous, having large numbers of functional sites, and was evaluated for adsorptive removal of arsenic and methylene blue from their respective aqueous solutions. Adsorption capacities of rGO-MnO2/BC for methylene blue and arsenite were evaluated in batch manner under optimum conditions. 1.0 g/L dosage of rGO-MnO2/BC could remove approximately 99 % of methylene blue and arsenite from initial concentration of 10.0 and 1.0 mg/L, respectively, after 75 min at 7.0 pH, and 27 °C temperature. The sorption data was evaluated to propose the adsorption mechanism by fitting into isotherm and kinetic models. The process of methylene blue and arsenite sorption was proved to be exothermic and feasible based on thermodynamic parameters. The Freundlich isotherm was most suitable for arsenite sorption and both Langmuir and Freundlich isotherms were suitable for methylene blue sorption data. The sorption kinetics followed pseudo-second order relationship for both adsorbates. The exploration of thermodynamics, isotherms, and kinetics parameters revealed physicochemical sorption mechanisms for both adsorbates onto rGO-MnO2/BC surface. The Langmuir sorption capacity of rGO-MnO2/BC for methylene blue and arsenite were found to be 232.5 and 14.7 mg/g, respectively, at 27 °C. The rGO-MnO2/BC is easy to prepare and is low-cost material, and showed high adsorption capacity as compared to the other reported adsorbents. Therefore, the application of rGO-MnO2/BC will be beneficial for upcoming research on water treatment technologies.

Influence of activation conditions on the physicochemical properties of activated biochar: a review

The biochar produced from agricultural crop residues through thermochemical processes helps in crop waste management. Biochar has paid more attention due to its distinctive features such as high organic carbon content, stable structure, large surface area, and cation exchange capacity. The biochar obtained from crop residues can be readily converted into activated biochar. This review paper systematically summarised the preparation of activated biochar, characterisation, and analytical techniques of activated biochar based on more than 150 literatures published in the last 10 years. The physicochemical properties of activated biochar varies according to the type of feedstock, pyrolysis condition, and mode of activation. The selection of the activation method mainly depends on its further end environmental application. Physical activation or steam purging at high temperature creates pores inside biochar. Gas purging increases the surface area and pore volume, although steam activation is not much suitable to improve the BC surface functionality as compared to chemical and impregnation activation. Sulphuric and oxalic acid–modified biochar was found to be most suitable for the soil amendment. Alkaline activation enhances the surface area and oxygen-containing functional group in activated biochar. Metal oxide–modified biochar had better surface functionalities than did physical- and chemical-activated biochar and better sorption of organic and inorganic contaminants from potable water and waste water. In summary, activated biochar has a wide environmental prospect in remediation.

Black carbon enriches short-range-order ferrihydrite in Amazonian Dark Earth: Interplay mechanism and environmental implications

Our study underpins the mechanism of organo-mineral interaction between black carbon (BC, biochar) and associated minerals in the historical BC-rich Amazonian Dark Earth (ADE) by using synchrotron-based microscopic (TXM), microspectroscopic (μFTIR) and spectroscopic (XAS and μ-diffraction) approaches. The BC-rich ADE contained over 100% more poorly crystalline minerals than the adjacent tropical soil. Linear combination fitting of k-spacing in the X-ray Absorption Spectra (XAS) revealed that ferrihydrite contributed to 81.1% of the Fe-minerals in BC. A small but distinct peak was observed at 5.7 Å−1 in the extended X-ray absorption fine structure k oscillation of BC, revealing the presence of FeC (including Fe-O-C) covalent bonds. No FeC path was yielded by the XAS fitting when an obvious peak downshift of the first (FeFe1) shell was observed, suggesting that the availability of inner-sphere FeC complexation was limited to the BC surface and interphase region. The main minerals for organo-mineral complexation were short-range-order (SRO) ferrihydrite on BC instead of corner-sharing FeO6 octahedra. Compared to ADE, the coordination number of the first (FeFe1) and second (FeFe2) shell was higher in BC, revealing a higher degree of order in coordination between the neighboring Fe mineral crystals. Black C limited the progressive aging of amorphous Fe phases and greatly enriched SRO ferrihydrite in the redox-fluctuating and high-leaching environment. The transformation of SRO ferrihydrite into the more crystalline Fe oxides was controlled by the local pH environment. A strong signal from the complexed phenolic group (aryl-OH, 1241 cm−1) and a distinct band of inner-sphere complexation (Fe-aryl C, 1380–1384 cm−1) were identified in the FTIR spectra. The enrichment of poorly crystalline minerals can have positive feedback on the long-term stabilization of BC. The scale-up application of biochar to agricultural and ecological systems may have a long-lasting impact on the enrichment and transformation of the SRO minerals in the soil.

Hierarchical growth of nickel oxyhydroxide on bacterial cellulose hydrogel: role of water channels in hydrogel to form hierarchical structure

AbstractBacterial cellulose (BC) hydrogel was used as a three‐dimensional scaffold for the hierarchical formation of nickel oxyhydroxide (NiOOH). The formation was completed, without the need of any external energy utilization, special apparatus, and surface modification at room temperature. A solution‐process method is utilized through controlled reaction conditions. The proposed mechanism ascribed that the abundant water channels in the BC hydrogel play a pivotal role in the formation of hierarchical NiOOH nanocoating on individual fiber while preserving the open three‐dimensional structures of BC. The composite structures in both hydrogel and freeze‐dried forms were compared using optical microscopy, scanning electron microscopy, and powder X‐ray diffractions. Furthermore, the formation mechanism was explained on the basis of spectroscopy analysis. As a final step, the formed aerogels (BC‐NiOOH) were annealed at 300°C for a particular time to transform NiOOH to hierarchical nickel oxide (NiO) on the surface of BC without any structural deformation.

Sustainable removal of Hg(II) by sulfur-modified pine-needle biochar

Sulfur-modified pine-needle biochar (BC–S) was produced for the removal of Hg(II) in aqueous media via post-pyrolysis S stream exposure. Fourier-transform infrared spectroscopy, elemental analysis, and X-ray photoelectron spectroscopy confirmed the addition of S(0) groups on the surface of BC–S. Hg(II) adsorption on BC–S was best described by the Freundlich isotherm with a KF of 21.0 mg L g−1 and a pseudo-second-order adsorption kinetics model with a rate of 0.35 g mg−1 min−1. Hg(II) removal on BC–S was found to be an endothermic process that relied on C-Hg and S-Hg interactions rather than reduction by S(0) groups. The adsorption increased with increasing solution pH and decreased with increasing dissolved organic matter concentration, but was unaffected by increasing salt concentrations. BC–S showed a maximum of 3 % S leaching in aqueous media after 28-d exposure time, and exposure to aqueous media did not convert Hg(II) to elemental Hg. Overall, BC–S exhibited superior Hg(II) removal performance over unmodified BC, thus having potential applications in natural water and wastewater treatment with no significant threat of secondary pollution.

Nano-manganese oxides-modified biochar for efficient chelated copper citrate removal from water by oxidation-assisted adsorption process

Removal of chelated copper from wastewater is more difficult than that of copper ions owing to its stable structure, wide range of pH tolerance, and stronger mobility. Copper citrate (CuCA) widely exists in the water system and inevitably poses serious hazards to human health and environment. Biochar as economic functional material has been widely used for environmental applications, especially in wastewater treatment. This study focused on the performance of manganese oxide-modified biochar (BC-MnOx) toward uptake and removal of CuCA and to understand the related mechanism. The result indicated that the CuCA removal efficiency reached up to 99%. High removal efficiency and low concentration of dissolved Mn over a wide pH range proved that the BC-MnOx is efficient and chemically stable. Furthermore, the removal mechanism may involve the following processes: First, CuCA was removed via the chemical bonds formed between CuCA and MnOx on the surface of BC. Second, chemisorption due to the oxygen-containing functional groups or physisorption of porous structure in BC worked synergistically on CuCA. Third, CuCA was partially oxidized into low molecular weight acids by means of MnOx, while the released Cu ions were retained on the adsorbent surface. This study demonstrates that BC-MnOx is a promising material for the removal of CuCA from wastewater.

Removal of phosphate from aqueous solution using MgO-modified magnetic biochar derived from anaerobic digestion residue

A novel MgO-modified magnetic biochar (MgO@MBC) was made by chemical co-precipitation of Mg2+/Fe3+ on anaerobic digestion residue (ADR) and subsequently pyrolyzing at different temperatures. MgO@MBC was used for phosphate recovery from aqueous solution. The physicochemical properties of MgO@MBC were comprehensively investigated using TEM-EDS, FT-IR, XRD, VSM, N2 adsorption-desorption and TGA. Results showed that MgO/γ-Fe2O3 nanoparticles were successfully deposited onto the surface of BC. The effects of reaction temperature, initial solution pH, MgO@MBC dosage, coexisting anions and phosphate concentration on the removal of phosphate by MgO@MBC were researched. Additionally, the adsorption process of phosphate onto MgO@MBC was well described by the pseudo second-order and pseudo first-order models, which indicated a chemisorption and physisorption process. Besides, the maximum adsorption capacity of MgO@MBC for phosphate by the Langmuir model were 149.25 mg/g at 25 °C. Moreover, the thermodynamic study suggested that the adsorption of phosphate onto MgO@MBC was a spontaneous and endothermic process. The adsorption mechanisms including physical absorption, surface electrostatic attraction, surface complexation and precipitation were revealed. It could be concluded that MgO@MBC exhibited high removal efficiency of phosphate and excellent magnetic property for the recovery. MgO@MBC could be utilized as a magnetically recoverable adsorbent to realize phosphate recovery and MgO@MBC after the adsorpion of phosphate could be applied in agricultural production as a fertilizer.

Poly(N-vinyl-2-pyrrolidone)-stabilized ruthenium supported on bamboo leaf-derived porous carbon for NH3BH3 hydrolysis

In this work, poly(N-vinyl-2-pyrrolidone) (PVP)-stabilized ruthenium nanoparticles (NPs) supported on bamboo leaf-derived porous carbon (Ru/BC) has been synthesized via a one-step procedure. The structure and morphology of the as-synthesized samples were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM). As a catalyst for hydrogen generation from the hydrolysis of ammonia-borane (AB, NH3BH3) at room temperature, Ru/BC stabilized with 1 mg of PVP exhibited high activity (TOF = 718 molH2·molRu−1·min−1) and low activation energy (Ea = 22.8 kJ mol−1). In addition, the catalyst could be easily recovered and showed fairly good recyclability with 55.6% of the initial catalytic activity retained after ten experimental cycles, which confirmed that PVP could stabilize the Ru NPs and prevent their agglomeration on BC surface. Our results suggest that PVP-stabilized Ru/BC is a highly efficient catalyst for the hydrolysis of AB.

Multifunctional iron-biochar composites for the removal of potentially toxic elements, inherent cations, and hetero-chloride from hydraulic fracturing wastewater

This paper evaluates a novel sorbent for the removal of potentially toxic elements, inherent cations, and hetero-chloride from hydraulic fracturing wastewater (FWW). A series of iron-biochar (Fe-BC) composites with different Fe/BC impregnation mass ratios (0.5:1, 1:1, and 2:1) were prepared by mixing forestry wood waste-derived BC powder with an aqueous FeCl3 solution and subsequently pyrolyzing them at 1000 °C in a N2-purged tubular furnace. The porosity, surface morphology, crystalline structure, and interfacial chemical behavior of the Fe-BC composites were characterized, revealing that Fe chelated with CO bonds as COFe moieties on the BC surface, which were subsequently reduced to a CC bond and nanoscale zerovalent Fe (nZVI) during pyrolysis. The performance of the Fe-BC composites was evaluated for simultaneous removal of potentially toxic elements (Cu(II), Cr(VI), Zn(II), and As(V)), inherent cations (K, Na, Ca, Mg, Ba, and Sr), hetero-chloride (1,1,2-trichlorethane (1,1,2-TCA)), and total organic carbon (TOC) from high-salinity (233 g L−1 total dissolved solids (TDS)) model FWW. By elucidating the removal mechanisms of different contaminants, we demonstrated that Fe-BC (1:1) had an optimal reducing/charge-transfer reactivity owing to the homogenous distribution of nZVI with the highest Fe0/Fe2+ ratio. A lower Fe content in Fe-BC (0.5:1) resulted in a rapid exhaustion of Fe0, while a higher Fe content in Fe-BC (2:1) caused severe aggregation and oxidization of Fe0, contributing to its complexation/(co-)precipitation with Fe2+/Fe3+. All of the synthesized Fe-BC composites exhibited a high removal capacity for inherent cations (3.2–7.2 g g−1) in FWW through bridging with the CO bonds and cation-π interactions. Overall, this study illustrated the potential efficacy and mechanistic roles of Fe-BC composites for (pre-)treatment of high-salinity and complex FWW.

Interaction between the Black Carbon Aerosol Warming Effect and East Asian Monsoon Using RegCM4

AbstractBlack carbon aerosol (BC) has a significant influence on regional climate changes because of its warming effect. Such changes will feed back to BC loadings. Here, the interactions between the BC warming effect and the East Asian monsoon (EAM) in both winter (EAWM) and summer (EASM) are investigated using a regional climate model, RegCM4, that essentially captures the EAM features and the BC variations in China. The seasonal mean BC optical depth is 0.021 over East Asia during winter, which is 10.5% higher than that during summer. Nevertheless, the BC direct radiative forcing is 32% stronger during summer (+1.85 W m−2). The BC direct effect would induce lower air to warm by 0.11–0.12 K, which causes a meridional circulation anomaly associated with a cyclone at 20°–30°N and southerly anomalies at 850 hPa over East Asia. Consequently, the EAM circulation is weakened during winter but enhanced during summer. Precipitation is likely increased, especially in southern China during summer (by 3.73%). Relative to BC changes that result from EAM interannual variations, BC changes from its warming effect are as important but are weaker. BC surface concentrations are decreased by 1%–3% during both winter and summer, whereas the columnar BC is increased in south China during winter. During the strongest monsoon years, the BC loadings are higher at lower latitudes than those during the weakest years, resulting in more southerly meridional circulation anomalies and BC feedbacks during both winter and summer. However, the interactions between the BC warming effect and EAWM/EASM are more intense during the weakest monsoon years.

Adsorption of phosphorus by calcium-flour biochar: Isotherm, kinetic and transformation studies

Discharging phosphorus (P)-contaminated water directly into the aquatic environment leads to resource loss and eutrophication. Thus, removing P from waste streams is imperative. In this study, calcium-decorated biochar (Ca-BC) in different mass ratios of Ca to BC was designed to effectively adsorb P from solution. Ca-BC was characterized through X-ray diffraction (XRD) analysis, followed by isotherm and kinetic adsorption experiments. The decorated Ca on the BC surface was found to have preferred P adsorption ability. A design of calcium hydroxide (Ca(OH)2) to flour in a mass ratio of 2:1 was found to have a maximum adsorption capacity of 314.22 mg g−1 for P. The Langmuir and pseudo-second-order models fit the sorption process adequately. XRD analysis indicated that the preferable adsorption ability to P was due to the reaction of Ca(OH)2 and PO43−, forming the hydroxylapatite (Ca5(PO4)3(OH)) crystal. The P in solution was transformed to the crystal. Thus, Ca-BC is an environmental friendly and low-cost sorbent for P removal.

Chemical sputtering of boronized and oxidized carbon surfaces irradiated by low-energy deuterium atoms

We use molecular dynamics to study the chemical sputtering of boronized and oxidized amorphous carbon surfaces by deuterium irradiation in the range of impact energies of 5–30 eV. We report the sputtering yield as well as mass, energy, and angular spectra of ejected atoms and molecules of both virgin and deuterium saturated BCO surfaces and compare them with our data for a deuterated BC surface and existing theoretical and experimental results for amorphous C:D surfaces. Boron significantly suppresses the erosion of carbon, while the presence of oxygen results in further suppression.

Fungal biocatalyst activated by an electric field: Improved mass transfer and non-specificity for hydrocarbon degradation in an airlift bioreactor

The combination of biological and electrochemical techniques enhances the bioremediation efficiency of treating oil-contaminated water. In this study a non-growing fungal whole cell biocatalyst (BC; Aspergillus brasiliensis attached to perlite) pretreated with an electric field (EF), was used to degrade a hydrocarbon blend (hexadecane-phenanthrene-pyrene; 100:1:1w/w) in an airlift bioreactor (ALB). During hydrocarbon degradation, all mass transfer resistances (internal and external) and sorption capacity were experimentally quantified. Internal mass transfer resistances were evaluated through BC effectiveness factor analysis as a function of the Thiele modulus (using first order reaction kinetics, assuming a spherical BC, five particle diameters). External (interfacial) mass transfer resistances were evaluated by kLa determination. EF pretreatment during BC production promoted surface changes in BC and production of an emulsifier protein in the ALB. The BC surface modifications enhanced the affinity for hydrocarbons, improving hydrocarbon uptake by direct contact. The resulting emulsion was associated with decreased internal and external mass transfer resistances. EF pretreatment effects can be summarized as: a combined uptake mechanism (direct contact dominant followed by emulsified form dominant) diminishing mass transfer limitations, resulting in a non-specific hydrocarbon degradation in blend. The pretreated BC is a good applicant for oil-contaminated water remediation.