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•Pyridinic-N, pyrrolic-N, and quaternary-N dominate biochar N-functional groups.•N-functional groups of biochar can be analyzed by FTIR, XPS, NMR and XANES.•N-functional groups are ...mainly results of biomass, pyrolysis temperature & N-doping.•Biochar N-functional groups favor pollutant removal, redox reaction & energy storage.
Biochar is a carbonaceous material produced by thermal treatment, e.g., pyrolysis, of biomass in oxygen-deficient or oxygen-free environment. Nitrogen containing functional groups of biochar have a wide range of applications, such as adsorption of pollutants, catalysis, and energy storage. To date, many methods have been developed and used to strengthen the function of N-containing biochar to promote its application and commercialization. However, there is no review available specifically on the development of biochar technologies concerning nitrogen-containing functional groups. This paper aims to present a review on fractionation, analysis, formation, engineering, and application of N-functional groups of biochar. The effect of influencing factors on biochar N-functional groups, including biomass feedstock, pyrolysis parameters (e.g., temperature), and additional treatment (e.g., N-doping) were discussed in detail to reveal the formation mechanisms and performance of the N-functional groups. Future prospective investigation directions on the analysis and engineering of biochar N-functional groups were also proposed.
Abstract Objective Treatment of acetabular fractures remains one of the most challenging tasks that orthopedic surgeons face. An accurate assessment of the injuries and preoperative planning are ...essential for an excellent reduction. The purpose of this study was to evaluate the feasibility, accuracy and effectiveness of performing 3D Printing technology and Computer-assisted virtual surgical procedures for preoperative planning in acetabular fractures. We hypothesized that more accurate preoperative planning using 3D printing models will reduce the operation time and significantly improve the outcome of acetabular fracture repair. Methods Ten patients with acetabular fractures were recruited prospectively and examined by CT scanning. A 3-D model of each acetabular fracture was reconstructed with MIMICS14.0 software from the DICOM file of the CT data. Bone fragmentswere moved and rotated to simulate fracture reduction and restore the pelvic integrity with virtual fixation. The computer-assisted 3D image of the reduced acetabula was printed for surgery simulation and plate pre-bending. The postoperative CT scan was performed to compare the consistency of the preoperative planning with the surgical implants by 3D-superimposition in MIMICS14.0, and evaluated by Matta's method. Results Computer-basedpre-operations were precisely mimicked and consistent with the actual operations in all cases. The pre-bent fixation plates had an anatomical shape specifically fit to the individual pelvis without further bending or adjustment at the time of surgery and fracture reductions were significantly improved. Seven out of 10 patients had a displacement of fracture reduction of less than 1 mm; 3 cases had a displacement of fracture reduction between 1 and 2 mm. Conclusions The 3D printing technology combined with virtual surgery for acetabular fractures is feasible, accurate, and effective leading to improved patient-specific preoperative planningand outcome of real surgery. The results provide useful technical tips in planning pelvic surgeries.
•Graphene oxide was synthesized by a modified Hummers’ method.•The Zn(II) removal by adsorption was directly dependent on the pH.•The Zn(II) adsorption process can be explained by pseudo-second-order ...kinetic model.•Adsorption of Zn(II) fitted well with Langmuir model at different temperatures.•The maximum adsorption capacity of Zn(II) on graphene oxide was up to 245.70mg/g.
In this study, graphene oxide (GO) was synthesized via modified Hummers’ method, and characterized by scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), and Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS). The adsorption of Zn(II) on GO as a function of pH, adsorbent dosage, foreign ions, contact time, and temperature was investigated using batch technique. Results showed that the suitable pH for Zn(II) removal was about 7.0, and the optimal dosage was 2mg. The adsorption of Zn(II) onto GO increased sharply within 20min and obtained equilibrium gradually. Meanwhile, foreign ion and temperature also affected the adsorption performance of GO. The adsorption process was found to be well described by the pseudo-second-order rate model. Equilibrium studies indicated that the data of Zn(II) adsorption followed the Langmuir model. The maximum adsorption capacity for Zn(II) was up to 246mg/g with a Langmuir adsorption equilibrium constant of 5.7L/g at 20°C. The thermodynamic parameters calculated from temperature-dependent sorption isotherms suggested that Zn(II) sorption on GO was an exothermic and spontaneous process in nature. The possibility of Zn(II) recovery was investigated and the result revealed that the maximum Zn(II) recovery yield was achieved with hydrochloric acid.
Graphene, as an ideal two-dimensional material and single-atom layer of graphite, has attracted exploding interests in multidisciplinary research because of its unique structure and exceptional ...physicochemical properties. Especially, graphene-based materials offer a wide range of potentialities for environmental remediation and energy applications. This review shows an extensive overview of the main principles and the recent synthetic technologies about designing and fabricating various innovative graphene-based materials. Furthermore, an extensive list of graphene-based sorbents and catalysts from vast literature has been compiled. The adsorptive and catalytic properties of graphene-based materials for the removal of various pollutants and hydrogen storage/production as available in the literature are presented. Tremendous adsorption capacity, excellent catalytic performance and abundant availability are the significant factors making these materials suitable alternatives for environmental pollutant control and energy-related system, especially in terms of the removal of pollutants in water, gas cleanup and purification, and hydrogen generation and storage. Meanwhile, a brief discussion is also included on the influence of graphene materials on the environment, and its toxicological effects. Lastly, some unsolved subjects together with major challenges in this germinating area of research are highlighted and discussed. Conclusively, the expanding of graphene-based materials in the field of adsorption and catalysis science represents a viable and powerful tool, resulting in the superior improvement of environmental pollution control and energy development.
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•Recent studies on synthetic pathways of graphene-based materials are reviewed.•Applications of graphene-based sorbents and catalysts are discussed and summarized.•Opportunities and outlook about graphene-based materials are presented.
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•Sewage sludge was liquefied under different temperatures with different solvents.•Heavy metals distributed mainly into the bio-chars with a few into the bio-oils.•The environmental ...risk of HMs in bio-chars was mitigated compared to SS.•The environmental risk of Zn and Ni in bio-oils was undesirably high.•Liquefaction temperature and solvent would effect on HM redistribution.
Bio-oils and bio-chars were obtained from sewage sludge (SS) by liquefaction with ethanol (or acetone) as the solvent at the temperature of 280, 320 and 360°C. The migration and transformation of HMs as Pb, Zn, Cu and Ni during liquefaction were thoroughly investigated. Meanwhile, the environmental risk of HMs in the bio-oils and bio-chars was assessed according to the risk assessment code (RAC). The results showed that the liquefaction solvent and temperature significantly affected the redistribution of HMs. HMs distributed mainly into the bio-chars, with less than 10% into the bio-oils. Increasing liquefaction temperature would promote a higher HM content in bio-oils. The environmental risk of HMs in bio-chars was mitigated compared to SS, especially for Ni. However, the environmental risk of Zn and Ni in bio-oils was undesirably high in comparison with bio-chars. It was suggested that the bio-oil should be pretreated before utilization.
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•Pyrolysis temperature is the dominant processing parameter to biochar stability.•High temperature, long residence time and slow heating rate are preferable.•Biomass feedstock of high ...lignin content with large particle size are favorable.•Both biochar yield and stability are decisive to carbon sequestration potential.
Biochar produced from biomass pyrolysis is becoming a powerful tool for carbon sequestration and greenhouse gas (GHG) emission reduction. Biochar C recalcitrance or biochar stability is the decisive property determining its carbon sequestration potential. The effect of pyrolysis process parameters on biochar stability is becoming a frontier of biochar study. This review discussed comprehensively how and why biomass compositions and physicochemical properties and biomass processing conditions such as pyrolysis temperature and reaction residence time affect the stability of biochar. The review found that relative high temperature (400–700 °C), long reaction residence time, slow heating rate, high pressure, the presence of some minerals and biomass feedstock of high-lignin content with large particle size are preferable to biochar stability. However, challenges exist to mediate the trade-offs between biochar stability and other potential wins. Strategies were then proposed to promote the utilization of biochar as a climate change mitigation tool.
•Co-pelletization of sludge and biomass was investigated.•Effect of process parameters on pellet properties was examined.•The mechanisms of inter-particular adhesion bonding were studied.•Higher ...quality pellets can be produced at lower pressure and temperature.•Synergies of protein and lignin could be the mechanism of the co-pelletization.
In the present study, the effects of process parameters on pellet properties were investigated for the co-pelletization of sludge and biomass materials. The relaxed pellet density and Meyer hardness of pellets were identified. Scanning electron microscopy, FT-IR spectra and chemical analysis were conducted to investigate the mechanisms of inter-particular adhesion bonding. Thermogravimetric analysis was applied to investigate the combustion characteristics. Results showed that the pellet density was increased with the parameters increasing, such as pressure, sludge ratio and temperature. High hardness pellets could be obtained at low pressure, temperature and biomass size. The optimal moisture content for co-pelletization was 10–15%. Moreover, the addition of sludge can reduce the diversity of pellet hardness caused by the heterogeneity of biomass. Increasing ratio of sludge in the pellet would slow down the release of volatile. Synergistic effects of protein and lignin can be the mechanism in the co-pelletization of sludge and biomass.
Many inspiring achievements have been made in inducing chiral amplification in helical polymers; however, the induction of helical chirality in random coil polymers by the intermolecular noncovalent ...force in solutions so far is still an intractable task, which is almost only accomplishable in biopolymer systems. In this contribution, we found that a random coil poly(N-propargylamide) with an l- or d-alanine residue as the pendant (P-l(or -d)-ala-NH2) can be induced to form a predominantly one-handed helical structure in an aqueous solution by complexing with metal ions, including Cu2+ and Ag+. The random coil to predominantly one-handed helix transformation and the chiral amplification therein were clearly evidenced by the remarkable red-shift of the UV–vis absorption peak, the occurrence of strong circular dichroism (CD), and the sharp increase in the absolute value of specific rotation. When Cu2+ was used as an inducer, the CD and UV–vis absorptions of P-l-ala-NH2 were barely affected by heating and changing anions, demonstrating the high stability of the induced helical structure. The results obtained from CD, UV–vis, resonance Raman, Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopies and differential scanning calorimetry indicate that a contracted cis-cisoidal helical structure was formed in the polymer main chain through the generation of cis nearly square-planar complexes between each Cu2+ ion and the four nitrogens of two pendants. The metal ion coordination concurrently provided appropriate linkage among the pendants and reduced the pendant flexibility, thus endowing the main chain with helicity and triggering chiral amplification. Inspired by this mechanism, a universal and convenient methodology for preparing helical polymer/metal ion complexes and the corresponding chiral materials from random coil polymers may be established.
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•MnCuSAPO-34 catalysts were synthesized by one-pot hydrothermal method.•MnCuSAPO-34 catalysts exhibited high LT SCR activity.•The addition of Cu to MnSAPO-34 could enhance the H2O ...resistance significantly.•Isolated Cu2+ and Mn4+ play a crucial role in LT SCR reaction.
A one-pot synthetic method was used to prepare copper (Cu)-modified manganese (Mn)-rich MnSAPO-34 catalysts, which were then used for NOx removal from stationary-source flue gas. The addition of Cu to these Mn-rich MnSAPO-34 catalysts significantly enhanced their low temperature (LT) selective catalytic reduction (SCR) activity and H2O resistance. The Mn0.4Cu0.05SAPO-34 catalysts demonstrated excellent LT NH3-SCR activity, with NOx removal being >90% from 160 to 300°C. In addition, Mn0.4Cu0.05SAPO-34 catalysts exhibited high H2O resistance. This excellent performance was ascribed to strong synergistic effects between Mn4+ and isolated Cu2+ species in Mn0.4Cu0.05SAPO-34 catalysts, leading to suitable redox ability. The results of in situ FT-IR analysis indicated that LT-SCR reactions mainly proceeded by an Eley–Rideal reaction pathway at 200°C in Cu-modified manganese-rich MnSAPO-34 catalysts. Thus, Mn0.4Cu0.05SAPO-34 was considered as a promising candidate for NOx removal from flue gas of stationary sources at low temperatures.
Natural iron minerals and zero-valent metals have been widely tested as catalysts for the Fenton-like process, but the systematical comparison study about their catalytic performance was rarely ...conducted, and the risk of the secondary pollution of toxic heavy metals was still not uncertain. In this paper, a comparison study of applying pyrite, ilmenite, vanadium titano-magnetite (VTM), zero-valent iron (ZVI), and zero-valent copper (ZVC) as Fenton-like catalysts for the removal of imidacloprid was performed. The results showed that ZVI exhibited the highest activity among the recyclable solid catalysts with a removal rate of 96.8% at initial pH 3 using 10.78 mmol/L H
2
O
2
, due to iron corrosive dissolution. Vanadium titano-magnetite (VTM) exhibited the best activity at first use among tested minerals but with low reusability. Pyrite with stable morphology showed a medium but sustainable ability to degrade imidacloprid, achieving a removal rate of 10.5% in the fifth use. The reaction much favored the acidic condition of initial pH around 2 or 3. Meanwhile, there was a significant positive correlation between removal efficiency and dissolved Fe or Cu concentration. Pyrite was considered to be a promising catalyst in Fenton-like reaction. It was suggested that the system proceeded predominantly through a homogeneous route via dissolved Fe or Cu ions. Except ZVC and VTM, other tested catalysts showed the low possibility of causing secondary pollution of toxic metals in the application of Fenton-like process.
