Single-step Pyrolysis Research Articles

Preparation of N-doped biochar from sewage sludge and melamine for peroxymonosulfate activation: N-functionality and catalytic mechanisms

In this study, a group of nitrogen-doped sludge biochar were prepared by a single-step pyrolysis method and employed as catalysts for the activation of peroxymonosulfate (PMS). The N content of as-synthesized biochar composites was altered by adding a different ratio of melamine with the precursors. The sample characterization results indicated that the N content of sludge-melamine-blended biochar named SM-(0.5:1) significantly increased from 1.91 to 9.93% compared with that of raw sludge biochar. Consequently, the surface area and mesoporosity also enhanced. SM-(0.5:1) exhibited excellent degradation ability of reluctant organic pollutants in PMS/acidic media, which outperformed many previously reported carbocatalysts. Complete color removal of a mixture solution of seven cationic and anionic dyes (10 mg L−1 of each) was achieved within 50 min by using 200 mg L−1 of SM-(0.5:1) and 350 mg L−1 of PMS. A mechanism study indicated that the non-radical process performed by the pyridine N dominated the oxidative degradation of pollutants rather than that of SO4− and OH radical process governed by graphitic N, CO, and surface metal oxides. This study concurrently provides a facile route of enhancing N functionality of sludge-based carbocatalysts and an efficient way of sludge valorization.

Single-step pyrolysis for producing magnetic activated carbon from tucumã (Astrocaryum aculeatum) seed and nickel(II) chloride and zinc(II) chloride. Application for removal of nicotinamide and propanolol

The present research describes the synthesis of new nanomagnetic activated carbon material with high magnetization, and high surface area prepared in a single pyrolysis step that is used for the carbonization, activation, and magnetization of the produced material. The pyrolysis step of tucumã seed was carried out in a conventional tubular oven at 600 °C under N2-flow. It was prepared three magnetic carbons MT-1.5, MT-2.0, MT-2.5, that corresponds to the proportion of biomass: ZnCl2 always 1:1 and varying the proportion of NiCl2 of 1.5, 2.0, and 2.5, respectively. These magnetic nanocomposites were characterized by Vibrating Sample Magnetometer (VSM), X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, hydrophobic/hydrophilic balance, CHN/O elemental analysis, modified Boehm titration, N2 adsorption-desorption isotherms; and pHpzc. All the materials obtained presented Ni particles with an average crystallite size of less than 33 nm. The MT-2.0 was employed for the removal of nicotinamide and propranolol from aqueous solutions. Based on Liu isotherm, the Qmax was 199.3 and 335.4 mg g−1 for nicotinamide and propranolol, respectively. MT-2.0 was used to treat simulated pharmaceutical industry effluents attaining removal of all organic compounds attaining up to 99.1 % of removal.

Biopolymer Derived Thin Carbon Film As a Novel Sensing Material for Low-Cost Resistive and Fast-Response Humidity Sensors

Introduction Recently, fast response humidity sensors are an active area of research for applications such as industrial, agricultural and point of care devices. Among various types of humidity sensor materials, thin film based resistive humidity sensors have been actively studied because those exhibit high surface area and the sensor configuration is simple. However, most of these sensors are relatively slow with long response time (over 60 seconds) and narrow detection limits (30-50 RH%), making them difficult to use in many applications [1-2]. Besides, the need of an external heater for fast response increases power consumption and complicates the manufacturing process of the sensor. Functionalized graphene, the most popular humidity sensor material, offers significant advantages due to its unique 2D structure and oxygen-containing functional groups, providing a large surface reaction site. However, it also has limitations such as poor stability in a moist environment due to its hydrophilic nature and weak adhesion with the substrate, complex synthesis procedure, makes it difficult to develop practical sensing devices.Here, we developed the low-cost and fast-response humidity sensors by integration of thermally decomposed carbon (TDC) thin film and carbon nano-sized interdigitated electrodes (IDEs). Carbon IDEs were used as a sensor platform due to its excellent thermal compatibility with TDC films and it provides low-cost wafer-level fabrication of three-dimensional nanoelectrodes [3], resulting in the miniaturized sensor configuration at a wafer level. Shellac, a low-cost biopolymer, was used as a precursor for synthesizing TDC films via single-step pyrolysis. The obtained film showed conformal coating with no grain boundaries or defects and formed high sp2 hybridized carbon network on the carbon nano-sized IDEs, thus providing excellent stability, rapid response/recovery and low power consumption as a room temperature humidity sensor. Our results demonstrate the potential application of TDC film as an alternative sensing material for environmental humidity, instant calibration for gas sensing measurements and human respiration in real time. Methods We integrated a nanometer-thick TDC film onto the carbon nano-IDEs, using two-step process, to facilitate a simple and cost-effective humidity sensor. Firstly, microscale interdigitated polymer patterns were fabricated using photolithography and then pyrolyzed into nanoscale carbon IDEs due to volume reduction in pyrolysis. The interdigitated carbon nanoelectrodes were annealed at 1000 °C using a rapid thermal annealing process to enhance the electrical conductivity. The next step is the integration of a TDC film on the carbon IDEs. For that, shellac solution (4 wt.%) was uniformly spray-coated on the carbon IDEs and air-dried (1 hour). This shellac film was pyrolyzed at 600 °C to obtain a uniform TDC thin film. Results and Conclusions Figure a shows a scanning electron microscopy (SEM) image of the TDC coated nano-sized carbon IDEs (width = 800 nm, height = 300 nm, gap = 2.5 μm). The film displays a conformal coating with no signature of defects or grain boundaries. The electrical properties of TDC film were evaluated using a two-probe I-V technique (Figure b), which indicated the excellent ohmic contact with carbon IDEs. Raman spectra of the TDC film (Figure c) indicated the presence of local intrinsic defects and disorder (intense D band) due to the presence of oxygen functional groups, especially at the edges and basal plane of the TDC film. X-ray photoelectron spectroscopy (XPS) for carbon (Figure d) also confirmed the presence of oxygen-containing functional groups (C-OH and C=O) and a high sp2 hybridized carbon network. Higher dynamic response (40 %) is attributed to the presence of oxygen functional groups (Figure e), whereas sp2 carbon network induce hydrophobicity, which lowers the condensation of water molecules without using any external heating source, resulted in fast response (37s) and recovery time (8s) (Figure f), compared to previously reported rGO-based sensors [4]. The obtained thin film humidity sensor also displayed the linear response over the wide humidity range (10-90 RH%), with high sensitivity > 0.7/RH%. The dynamic response of the sensor revealed that the protonic conduction mechanism is dominant in TDC film.

Highly propylene equilibrium selective carbon molecular sieve adsorbent

Propylene-propane separation is one of the most challenging and relevant industrial separations. Since this separation is very energy demanding, the research for new processes and/or materials able to separate these components efficiently with lower energy is encouraged. The present work reports a new carbon molecular sieve adsorbent highly equilibrium selective towards propylene – GLE800. This adsorbent was prepared in a single-step pyrolysis under nitrogen atmosphere. The pore size distribution, obtained based on the CO2 adsorption equilibrium isotherm at 0 °C, reveals a well-developed pore structure in the micropore range. Adsorption equilibrium isotherms were obtained at 25 °C, 35 °C and 45 °C. GLE800 adsorbent displayed a very high propylene/propane adsorbed concentration ratio of ca.140 at 1 bar and 25 °C. The breakthrough curves, mono- and multicomponent, confirmed the high adsorption selectivity obtained from the adsorption equilibrium isotherms.

Engineered biochar via microwave CO2 and steam pyrolysis to treat carcinogenic Congo red dye

We developed an innovative single-step pyrolysis approach that combines microwave heating and activation by CO2 or steam to transform orange peel waste (OPW) into microwave activated biochar (MAB). This involves carbonization and activation simultaneously under an inert environment. Using CO2 demonstrates dual functions in this approach, acting as purging gas to provide an inert environment for pyrolysis while activating highly porous MAB. This approach demonstrates rapid heating rate (15–120 °C/min), higher temperature (> 800 °C) and shorter process time (15 min) compared to conventional method using furnace (> 1 h). The MAB shows higher mass yield (31–44 wt %), high content of fixed carbon (58.6–61.2 wt %), Brunauer Emmett Teller (BET) surface area (158.5–305.1 m2/g), low ratio of H/C (0.3) and O/C (0.2). Activation with CO2 produces more micropores than using steam that generates more mesopores. Steam-activated MAB records a higher adsorption efficiency (136 mg/g) compared to CO2 activation (91 mg/g), achieving 89–93 % removal of Congo Red dye. The microwave pyrolysis coupled with steam or CO2 activation thereby represents a promising approach to transform fruit-peel waste to microwave-activated biochar that remove hazardous dye.

Nitrogen and Phosphorus Doped Activated Carbon Catalyst Prepared from Shrimp Shell and its Application in MFC Air Cathode

AbstractCathode design and cost is one of the major challenges for microbial fuel cell (MFC) large scale operation due to the adoption of precious Pt/C catalyst. In this work, shrimp shells were chosen to prepare a cheap and sustainable ORR catalyst and applied it in MFC air cathode. Single step pyrolysis and activation at 700 °C with H3PO4 was used to introduce phosphorus atom in the carbon. Three types of catalysts, named shrimp shells activated carbon (SS‐AC), commercial activated carbon (C‐AC) and Pt/C were compared for their performance in MFC system. The results showed that SS‐AC had high porous surface that contained nitrogenous and phosphorous functionalities at a significant percentage with high surface area of about 448.96 m2 g−2. The maximum power density achieved by the MFC that used SS‐AC catalyst was 1207±15 mW m−2 at 3.14 A m−2, 12 % less than Pt/C and 44 % higher than those of the C‐AC. The coulombic efficiency of 67 % was also achieved with this MFC slightly lower than those by Pt/C and higher than those by C‐AC. The good performance of this material was mainly due to the double doped heteroatoms which increases the oxygen reduction sites on the surface of the carbon.

Enhancement of CO2 adsorption on biochar sorbent modified by metal incorporation.

This work is scrutinizing the development of metallized biochar as a low-cost bio-sorbent for low temperature CO2 capture with high adsorption capacity. Accordingly, single-step pyrolysis process was carried out in order to synthesize biochar from rambutan peel (RP) at different temperatures. The biochar product was then subjected to wet impregnation with several magnesium salts including magnesium nitrate, magnesium sulphate, magnesium chloride and magnesium acetate which then subsequently heat-treated with N2. The impregnation of magnesium into the biochar structure improved the CO2 capture performance in the sequence of magnesium nitrate > magnesium sulphate > magnesium chloride > magnesium acetate. There is an enhancement in CO2 adsorption capacity of metallized biochar (76.80mgg-1) compare with pristine biochar (68.74mgg-1). It can be justified by the synergetic influences of physicochemical characteristics. Gas selectivity study verified the high affinity of biochar for CO2 capture compared with other gases such as air, methane, and nitrogen. This investigation also revealed a stable performance of the metallized biochar in 25cycles of CO2 adsorption and desorption. Avrami kinetic model accurately predicted the dynamic CO2 adsorption performance for pristine and metallized biochar.

Engineering magnetic N-doped porous carbon with super-high ciprofloxacin adsorption capacity and wide pH adaptability

We report a high performance magnetic N-doped nanoporous carbon (MNPC) adsorbent synthesized by a simple single-step pyrolysis protocol. Grinding the mixture of ZnO nanoparticles, cobalt hydroxide and 2-methylimidazole produced Zn/Co-ZIFs that were converted into MNPC following subsequent pyrolysis in N2 atmosphere. The optimized MNPC-700-0.4 adsorbent, obtained at 700 °C with Co/(Zn + Co) molar ratio of 0.4, is featured with super-high ciprofloxacin (CIP) adsorption capacity of 1563.7 mg g−1 at 25 °C, fast adsorption dynamics (1.5 h of adsorption equilibrium time), wide pH adaptability (almost unchanged CIP adsorption capacity in pH 4–10), and good magnetic property. The magnetic property and CIP adsorption performance can be easily regulated by modulating the molar ratio of Co/(Zn + Co) and the pyrolysis temperature. The optimal MNPC-700-0.4 was chosen to explore adsorption kinetics and isotherm. The effects of pH, ionic strength and humic acid on CIP adsorption were investigated. CIP adsorption obeyed pseudo-second-order kinetics and well fitted the Langmuir adsorption model. The favorable textural properties (high surface area and pore volume), riched nitrogen structure and large amounts of defects endow the MNPC-700-0.4 lots of sites for CIP adsorption. The CIP adsorption onto MNPC-700-0.4 was mainly controlled by the electrostatic interaction, hydrophobic interaction, π-π stacking and hydrogen bond.

Carbon quantum dots as fluorescence sensors for label-free detection of folic acid in biological samples.

Carbon quantum dots (CQDs) have been fabricated by a facile single-step pyrolysis method from citric acid and ethylene imine polymer. When excited at 359nm, CQDs show intense blue fluorescence at 434nm. The fluorescence can be effectively quenched by folic acid (FA), which is attributed to the combination of static quenching and inner filter effect. Thus, the CQDs are developed as an efficient fluorescent sensing platform for label-free sensitive and selective detection of FA. Key parameters influencing the detection were investigated, such as incubation time, salt concentration, selectivity and potential interferences. Under the optimal conditions, a good linearity was observed for the emission intensity against 1.14-47.57μM with a correlation coefficient of 0.99. The limit of detection was found to be 0.38μM. The practical application of the sensing system was demonstrated by analyzing FA in human urine samples. The sample recoveries fell in the range of 82.0%-113.1% with RSDs≤10.9%, which presented its reliable and feasible application in real samples.

Biomass derived functional carbon from Sargassum Wightii seaweed for supercapacitors

In this present work, microporous functional carbon is prepared by a single step pyrolysis method of dried SargassumWightiiseaweeds (SW) as crushed powder without activation and tested for supercapacitors. Although the complete study presented here on seaweeds of SargassumWightii(SW), the synthesis technique is standard and relevant to most forms of dried biomass. The morphological studies were characterized by X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy (RAMAN), field emission scanning microscopy (FE-SEM) and Fourier-transform infrared spectroscopy (FTIR). The behaviour of the functional carbon were performed by using cyclic voltammetry (CV), galvanostatic charge and discharge (CD) and Impedance analysis. In aqueous electrolyte (1M H2SO4), by using three-electrode system shows highest capacitance of 354 F/g. Furthermore, it was observed that the carbonized temperature has significant role in the electrochemical performance, as the carbonized sample at 700°C showed best activity compared to the samples carbonized at 800°C and 900°C without any external activation. The electrochemical act obviously shows that the carbon produced from dried SW seaweeds can be used as a favourable material for electrodes in the application of supercapacitors.

Synthesis of carbon nanospheres and piezoresistive study of carbon nanospheres-PEDOT:PSS nanocomposite flexible thin film for strain sensing applications

Microporous carbon nanospheres were synthesized using the single step pyrolysis method with oil palm leaves as a precursor. Non-hazardous bio-wastes from oil palm leaves were used for pyrolysis which was carried out at 700 °C in the nitrogen atmosphere. Nanocomposites consisting of different concentrations of carbon nanospheres(0.025 wt%, 0.05 wt%, 0.075 wt%, 0.1 wt%) and poly(3, 4-ethylenedioxythiophene) polymerized with poly(4-styrenesulfonate) polymer were prepared and were spin coated on flexible polyethylene terephthalate substrates to form nanocomposite thin films. These nanocomposite thin films were characterized for their nanostructure and elemental composition. The films were subjected to incremental strain from 0 to 6% at the speed of 0.2 mm min−1 and subsequently evaluated for their piezoresistive response. The carbon nanospheres-poly(3, 4-ethylenedioxythiophene) poly(4-styrenesulfonate) thin film with 0.05 wt% of carbon nanospheres(which is the wt% of carbon nanospheres close to the percolation threshold) in poly(3, 4-ethylene dioxythiophene) poly(4-styrene sulfonate) exhibited highest gauge factor of 34.57 with correlation coefficient 0.869 96 at 6% strain and the highest conductivity of 39.27 S m−1 for 0.1 wt% of carbon nanospheres was achieved. Hence, the fabricated thin film was found to be suitable in piezoresistive flexible strain sensing applications.

The behavior of heteroatom compounds during the pyrolysis of waste computer casing plastic under various heating conditions

Single step and two-step pyrolysis of waste computer casing plastic were conducted to optimize both the product distribution and characteristics of liquid products. The single step pyrolysis was performed under various final temperatures ranging from 350 to 600 °C. The two-step pyrolysis was undertaken by initially increasing the temperatures to 350–380 °C and holding for 15 min, followed by a further increase to a peak temperature of 500 °C. The pyrolysis kinetic studies showed the activation energy of the two stages against conversion and revealed the synergistic reactions between BFR additives and plastic matrix. In the single step pyrolysis, fixed bed experiments showed that the final pyrolysis temperature had a significant influence on the product yield. The highest yield of 45.3 wt% oil was produced at 500 °C. The oil products mainly consisted of aromatic compounds, phenolic compounds, nitrogen-containing compounds, and approximately 11.3–15.9 wt% of toxic bromine. For the two-step pyrolysis, the impurities of O-, N- and Br-containing compounds were mainly enriched in the pyrolytic oils from the first step. Comparatively, more than 57% of single aromatic compounds was obtained in the pyrolytic oils from the second step, with less than 2.0 wt% of bromine. Meanwhile, the depolymerization of the plastic for the formation of styrene was promoted at the second step. The results suggested that in the two stage pyrolysis, bromine can be transferred into the liquid phase in the first stage, thus producing bromine containing compounds deficient oil in the second stage.

Single-step pyrolysis of phosphoric acid-activated chitin for efficient adsorption of cephalexin antibiotic

Cephalexin (CFX) antibiotic, a potent pharmaceutical water pollutant, was efficiently removed by activated carbon (AC) derived from a single-step pyrolysis of phosphoric acid-activated chitin. Experimental conditions such as temperature, CFX initial concentration, and solution pH were screened in batch adsorption. Phosphoric acid activation of chitin and subsequent pyrolysis tailored the Brunauer–Emmett–Teller surface area, total pore volume, and average pore diameter to 1199.02 m2/g, 0.641 cm3/g, and 21.37 Å, respectively. The Langmuir isotherm adequately described the equilibrium data for CFX adsorption on chitin–AC, with an R2 of 0.99 and a monolayer capacity of 245.19 mg/g at 50 °C. Chitin–AC showed higher adsorption capacity compared with other ACs derived from industrial and agricultural precursors. When activated by phosphoric acid, chitin–AC featured functional multi-sites for vast antibiotic adsorption treatment. Overall, chitin–AC could be a promising adsorbent for removal of CFX.

Ternary MnO/CoMn alloy@N-doped graphitic composites derived from a bi-metallic pigment as bi-functional electrocatalysts

A composite comprising a CoMn alloy coated with N-doped graphitic carbon (CoMn@NC) and MnO was fabricated by a single-step pyrolysis of a Prussian blue analogue, showing superior activity and stability for both the ORR and OER.

Fully-resolved simulations of coal particle combustion using a detailed multi-step approach for heterogeneous kinetics

Fully-resolved simulations of the heating, ignition, volatile flame combustion and char conversion of single coal particles in convective gas environments are conducted and compared to experimental data (Molina and Shaddix, 2007). This work extends a previous computational study (Tufano et al., 2016) by adding a significant level of model fidelity and generality, in particular with regard to the particle interior description and heterogeneous kinetics. The model considers the elemental analysis of the given coal and interpolates its properties by linear superposition of a set of reference coals. The improved model description alleviates previously made assumptions of single-step pyrolysis, fixed volatile composition and simplified particle interior properties, and it allows for the consideration of char conversion. The results show that the burning behavior is affected by the oxygen concentration, i.e. for enhanced oxygen levels ignition occurs in a single step, whereas decreasing the oxygen content leads to a two-stage ignition process. Char conversion becomes dominant once the volatiles have been depleted, but also causes noticeable deviations of temperature, released mass, and overall particle conversion during devolatilization already, indicating an overlap of the two stages of coal conversion which are usually considered to be consecutive. The complex pyrolysis model leads to non-monotonous profiles of the combustion quantities which introduce a minor dependency of the ignition delay time τign on its definition. Regardless of the chosen extraction method, the simulations capture the measured values of τign very well.

One-step synthesis of N-doped metal/biochar composite using NH3-ambiance pyrolysis for efficient degradation and mineralization of Methylene Blue

A series of new biochar-supported composite based on the combination of biochar and metallic nanoparticles (NPs) were produced through single-step pyrolysis of FeCl3–Ti(OBu)4 laden agar biomass under NH3 environment. The physiochemical properties of composites were characterized thoroughly. It has found that heating temperature and N-doping through NH3-ambiance pyrolysis significantly influence the visible-light sensitivity and bandgap energy of composites. The catalytic activities of composites were measured by degradation of Methylene Blue (MB) in the presence or absence of H2O2 and visible-light irradiation. Our best catalyst (N–TiO2–Fe3O4-biochar) exhibits rapid and high MB removal competency (99.99%) via synergism of adsorption, photodegradation, and Fenton-like reaction. Continuous production of O2− and OH radicles performs MB degradation and mineralization, confirmed by scavenging experiments and degradation product analysis. The local trap state Ti3+, Fe3O4, and N-carbon of the catalyst acted as active sites. It has suggested that the Ti3+ and N-doped dense carbon layer improve charge separation and shuttle that prolonged photo-Fenton like reaction. Moreover, the catalyst is highly stable, collectible, and recyclable up to 5 cycles with high MB degradation efficiency. This work provides a new insight into the synthesis of highly visible-light sensitized biochar-supported photocatalyst through NH3-ambiance pyrolysis of NPs-laden biomass.

Metal incorporated biochar as a potential adsorbent for high capacity CO2 capture at ambient condition

This work investigates the development of metal incorporated biochar as a low-cost and robust adsorbent for high capacity CO2 capture at ambient condition. For this purpose, biochars were prepared through single-step pyrolysis of walnut shell (WS) at different temperatures (500, 700 and 900 °C). The biochar with larger specific surface area and higher microporosity fraction (WS900) was then subjected to metal impregnation followed by N2 heat treatment. The incorporation of basic metal sites into the biochar skeleton enhanced the adsorption of acidic CO2 gas onto the metalized-biochar in the sequence of Mg > Al > Fe > Ni > Ca > raw-biochar > Na. The enhanced CO2 uptake of Mg-loaded biochar (82.0 mg/g) compared to the pristine biochar (72.6 mg/g) at 25 °C and 1 atm, could be explained by the synergistic effects of physical and chemical interactions, yet kinetic studies showed that physisorption was the main governing mechanism controlling the adsorption of CO2 onto the metalized-biochar. Cyclic CO2 capture studies indicated the great stability of Mg-loaded biochar upon several cycles of adsorption-desorption, with no loss in its CO2 capture capacity. It also showed easy regeneration and fast desorption kinetic which makes it a promising inexpensive candidate for real-world CO2 capture systems. Moreover, the adsorbent showed a superior capture performance towards CO2 over N2, O2 and CH4.

One-step pyrolytic synthesis and growth mechanism of core–shell type Fe/Fe[formula omitted]C-graphite nanoparticles-embedded carbon globules

We report the synthesis and detailed characterization of amorphous carbon globules containing Fe/Fe3C-graphite core–shell type nanoparticles. The samples were synthesized via a low-cost chemical vapour deposition (CVD) method by the single-step pyrolysis of precursors (benzene and ferrocene). The amount of precursors and the reaction temperature were found to control the morphology of the carbon globules, and the shape, size, composition and distribution of Fe/Fe–C based nanoparticles inside the carbon globules. At the CVD tube wall deposition of Fe derived from the decomposed-ferrocene forms Fe3C particles at high temperature, which are unstable in carbon rich environment and transforms to γ-Fe and carbon-product (graphite). Furthermore, γ-Fe is also unstable at RT and transforms to α-Fe and Fe3C phases while cooling. A fraction of γ-Fe is, however, kinetically arrested during the cooling process. This leads to the formation of ‘Fe/Fe3C (core)-graphite (shell)’ nanoparticles-embedded amorphous carbon globules.

OPAC (orange peel activated carbon) derived from waste orange peel for the adsorption of chlorophenoxyacetic acid herbicides from water: Adsorption isotherm, kinetic modelling and thermodynamic studies

This study presents the orange peel activated carbon (OPAC), derived from biowaste precursor (orange peel) by single step pyrolysis method and its application for the adsorption of chlorophenoxyacetic acid herbicides from the water. The OPAC exhibited the surface area of 592.471 m2 g−1, pore volume and pore diameter of 0.242 cc g−1 and 1.301 nm respectively. The adsorption kinetics and thermodynamic equilibrium modelling for all chlorophenoxyacetic acid herbicides were investigated. The various parametric effects such as pH and temperature were evaluated. A pseudo-second-order kinetic model was well fitted for all the herbicides. The Langmuir isotherm was obeyed for all the herbicides and the maximum Langmuir capacity of 574.71 mg g−1 was achieved. The thermodynamic studies revealed that the adsorption increases with increase in temperature. The results shows that the orange peel derived carbon (OPAC) as effective and efficient adsorbent material for the removal of chlorophenoxyacid herbicides from the water.

Facile synthesis of porous nitrogen-doped carbon for aerobic oxidation of amines to imines

A nitrogen-doped carbon material with developed porous structure was prepared by the simple single-step pyrolysis of sodium alginate and 1, 6-hexanediamine. Nitrogen-doped carbon catalysts were optimized and characterized, and their catalytic activities were investigated using the self-oxidative coupling of amine as model reaction. N2 adsorption-desorption exhibited that the introduction of 1, 6-hexanediamine could observably increase the specific surface area and pore volume of the carbon material. X-ray photoelectron spectroscopy confirmed N was incorporated successfully into the carbon. Benefiting from these, nitrogen-doped carbon material exhibited high catalytic performance for the oxidation of amines to imines under solvent-free, air atmospheric conditions. And the nitrogen-doped carbon possessed good reusability and applicability. Meanwhile, the nitrogen-doped carbon material was available, low cost and environment-friendly owing to the use of cheap, renewable natural starting materials and simple synthetic procedure.