[Preparation of Narrow Pore Diameter Phosphorus Containing Cotton Stalk Carbon and Its Adsorption Mechanism for Tetracycline].

Using cotton stalk as biomass raw material and phosphoric acid as a modifier, narrow pore distribution phosphorus-containing cotton stalk biochar (CSP) with a high surface area (1916 m2·g-1) and pore volume (1.3982 mL·g-1) was prepared through one-step carbonization, and the adsorption characteristics and mechanisms for tetracycline (TC) were investigated. The results showed that the TC adsorption capacity of CSP was up to 669 mg·g-1, which was 43.6 times that of unmodified cotton stalk carbon. FTIR, XPS, and isothermal adsorption studies showed that the high adsorption capacity of CSP for TC resulted from the joint action of complexation, hydrogen bonding, pore filling, and π-π dispersion forces, and the highly active phosphate ester group (P-O-C) endowed by phosphoric acid modification greatly enhanced the chemical interaction with TC molecules, which was the key factor for the significant increase in adsorption capacity. Isotherm and thermodynamic study further confirmed that chemical adsorption played a major role in the adsorption process, the adsorption process was spontaneous and endothermic, and the material had good regeneration performance. This study provides theoretical guidance for the preparation of modified biomass carbon with high adsorption performance to remove tetracycline antibiotic pollution.

[Preparation of High Specific Surface Thiourea Modified Peanut Shell Carbon and Adsorption of Tetracycline and Copper].

High activity nitrogen and sulfur co-doping high specific surface-modified peanut shell carbon PBC-NS was prepared through one-step carbonization using thiourea and phosphoric acid as modifiers. The TC/Cu(Ⅱ) adsorption characteristics of peanut shell carbon in single and mixed-adsorption systems were discussed, and the enhancement effect and mechanism of modification on TC/Cu(Ⅱ) adsorption were studied. The results showed that the modified peanut shell carbon PBC-NS successfully introduced nitrogen-sulfur functional groups such as Pyridinic N, Graphitic N, C- S-C, and -SH, and the modified specific surface area was as high as 1437 m2·g-1, which was 2.6 times higher than that before modification. The maximum adsorption capacities of modified peanut shell carbon PBC-NS for single-system TC and Cu(Ⅱ) were 585 mg·g-1 and 21.2 mg·g-1, respectively, which were 2.6 times and 2.7 times higher than those before modification. The saturated adsorption capacities of TC and Cu(Ⅱ) in the system were increased by 13 mg·g-1 and 6.8 mg·g-1 compared with that in the single system. The adsorption capacity of PBC-NS for TC and Cu(Ⅱ) could still reach 66% and 70% of the initial adsorption capacity after four times of repeated use. Isotherm fitting and modern spectroscopic analysis indicated that the substantial increase in the adsorption capacity of TC/Cu(Ⅱ) on PBC-NS by modification was mainly attributed to the combined effect of chemical chelation of nitrogen-sulfur active functional sites and pore filling caused by high specific surface area. These results indicated that thiourea/phosphoric acid chemical modification could effectively improve the adsorption capacity of peanut shell carbon for TC/Cu(Ⅱ), which can provide a new idea for the structural regulation of mixed-pollution biochar with high adsorption capacity and adsorption treatment of TC/Cu(Ⅱ) water pollution.

Efficiently catalytic degradation of tetracycline via persulfate activation with plant-based biochars: Insight into endogenous mineral self-template effect and pyrolysis catalysis.

Endogenous mineral of plant such as potassium, calcium and iron may play a crucial role in boosting the physicochemical structure and catalytic activity of high temperature pyrolyzed plant-based biochar while it is often neglected owing to its relative less content. Herein, self-template pyrolyzed plant-based biochars were prepared from two different ash-contained agricultural wastes of peanut hull (PH, 3.2% ash) and cotton straw (CS, 0.8% ash), and aimed at investigating the relationship among the endogenous mineral fractions of plant-based biomass, physicochemical active structure and persulfate (PS) catalytic degradation activity for tetracycline (TC). The results of energy/spectral characterization showed that under the self-template effect and pyrolysis catalysis of endogenous minerals, PH biochar (PBC) possessed much more specific surface area, conjugated graphite domain, C=O and pyrrolic-N surface active functional sites than CS biochar (CBC), enhancing TC removal rate of PBC/PS to 88.37%, twice that of CBC/PS (44.16%). Meanwhile, reactive oxygen quenching and electrochemical experiments showed that electrons transfer and non-free radical pathways based on singlet oxygen contributed 92% of TC removal in PBC/PS system. Remarkably, by comparing the differences in structure and TC removal performance of pre-deashing and non-deashing prepared plant-based biochars, a possible mechanism for endogenous mineral components' self-template effect and pyrolysis catalysis role of plant-based biomass was proposed. This study provides a new insight for revealing the intrinsic mechanism of mineral elements enhancing the active surface structures and catalytic properties of plant-based biochars derived from distinct feedstocks.

Multifunctional cellulose-based aerogel for intelligent fire fighting.

Multifunctional biomass-based aerogels with mechanically robust and high fire safety are urgently needed for the development of environmentally-friendly intelligent fire fighting but challenging. Herein, a novel polymethylsilsesquioxane (PMSQ)/cellulose/MXene composite aerogel (PCM) with superior comprehensive performance was fabricated by ice-induced assembly and in-situ mineralization. It exhibited light weight (16.2 mg·cm-3), excellent mechanical resilience, and rapidly recovered after being subjected to the pressure of 9000 times of its own weight. Moreover, PCM demonstrated outstanding thermal insulation, hydrophobicity and sensitive piezoresistive sensing. In addition, benefiting from the synergism of PMSQ and MXene, PCM displayed good flame retardancy and improved thermostability. The limiting oxygen index of PCM was higher than 45.0 %, and it quickly self-extinguished after being removed away from fire. More importantly, the rapid electrical resistance reduction of MXene at high temperature endowed PCM with sensitive fire-warning capability (trigger time was less than 1.8 s), which provided valuable time for people to evacuate and relief. This work provides new insights for the preparation and application of the next-generation high performance biomass-based aerogels.

Magnetic, self-heating and superhydrophobic sponge for solar-driven high-viscosity oil-water separation.

In this work, a novel oil-adsorption sponge with superhydrophobicity was fabricated using polymer-assisted electroless deposition and dip-coating techniques for depositing a rough polydopamine layer, magnetic particles, and low surface energy polydimethylsiloxane onto the surface of a sponge skeleton. The as-prepared superhydrophobic sponge (WCA > 150° and SA < 5°) exhibited rapid adsorption behavior, large adsorption capacity (up to 50.6 times its own dry weight or above 90% of its own volume), excellent durability (above 80% of the adsorption capacity after 80 recycles), and a self-cleaning property owing to sufficient open-cell pores and superelasticity provided by the melamine-formaldehyde host as well as the hierarchical roughness and convenient magnetic recovery enabled by the polymer-assisted electroless deposition approach. The pump-, gravity-, and solar-driven oil-water separation devices based on the fabricated cubic composites were also demonstrated, particularly the separation of high-viscosity oil-water mixtures via the solar-driven mode, demonstrating the broad prospects of such modified sponges in actual applications. This study provides a new avenue for rationally designing novel oil adsorption and separation materials.

The transmission mode of Legionella from water.

The transmission mode of Legionella from its source was analyzed by microscope and fluorescence Quantitative Polymerase Chain Reaction (qPCR). The Legionella removal efficiency by water surface was 94.5%, and Legionella had difficulty in penetrating through the surface of the water membrane. A deflection point at the interface between water and air indicated a cluster of Legionella that was bonded to the contact surface by some unknown emplastic media. The emplastic media could stick firmly on glass and Legionella like glue. Force analysis showed that the surface tension of water is 106 orders of magnitude larger than the net force from the sum of the buoyancy and the weight of Legionella, and revealed that the surface tension of water is so large that a Legionella bacterium cannot break away from the water surface membrane and escape. The qPCR results showed that no Legionella was found in the air from a Legionella incubator or the Legionella laboratory. The results demonstrate that Legionella cannot be transmitted to people through water vapour or aerosol. The experimental results also indicate that water was able to remove most Legionella bacteria.

Protonated cross-linkable nanocomposite coatings with outstanding underwater superoleophobic and anti-viscous oil-fouling properties for crude oil/water separation.

Superhydrophilic/underwater superoleophobic coatings that effectively prevent viscous oil contamination have been of considerable interest for the great potential in oil spill remediation and oilfield wastewater treatment. In the present work, a protonated cross-linkable nanocomposite coating with robust underwater superoleophobicity and intensified hydration capability is proposed through the synthesis of active polymeric nanocomplex (PNC), cross-linking reaction between PNC and hydrophilic chitosan (CS), and final protonation to further improve water affinity. Benefiting from the hierarchical structure and strong hydration capability induced by electrostatic interactions and hydrogen bondings, the nanocomposite coating coated textile exhibits excellent superhydrophilicity (within 0.28 s with water contact angle reaching 0°), underwater superoleophobicity (underwater crude oil contact angle at 160°), and ultralow oil adhesion even to highly viscous silicone oil. Moreover, the nanocomposite coating presents a robust chemical resistance, mechanical tolerance, and storage stability. Simultaneously, the nanocomposite coating adapts well to various porous substrates (e.g., stainless steel mesh and Ni sponge) with great anti-oil-fouling and self-cleaning performances. Importantly, the coating coated textile is successfully applied in crude oil/water separation with excellent efficiency and repeatability. The findings conceivably stand out as a new methodology to fabricate superhydrophilic/underwater superoleophobic materials with outstanding anti-viscous oil-fouling property for practically treating oily wastewater.

Degradable and stretchable bio-based strain sensor for human motion detection.

In recent years, flexible strain sensors have attracted considerable attention for the great application potential in the emerging fields of wearable devices, electronic skin and health monitoring. However, most of flexible strain sensors are nondegradable, and the produced numerous electronic wastes after uselessness will seriously threaten environment and ecology. Herein, we propose a new strategy to fabricate degradable and stretchable bio-based strain sensor using candle soot (CS) particles to construct conductive pathways and chitosan, potato starch (PS), and polyvinyl alcohol (PVA) to form stretchable matrix in the presence of Fe3+ ions. Owing to the formation of multiple hydrogen bonding constructed by chitosan, PS and PVA as well as coordination bonding by Fe3+ ions, the obtained strain sensor showed high elongation at break up to 200% and good fatigue resistance. Furthermore, the firm embedding of the CS particles into the surface of the stretchable matrix endowed the strain sensor with steady sensitivity (gauge factors of 1.49 at 0-60% strain and 2.71 at 60-100% strain), fast response (0.22 s) and good repeatability even after 1000 stretching-releasing cycles. In addition, the strain sensor was successfully applied to detect various human motions including finger and wrist bending, swallowing and pronunciation. Interestingly, after connecting to an Arduino microcontroller circuit with a Bluetooth module, the strain sensor was able to wirelessly detect real-time movements of index finger joints. Different from most previously reported sensors, the prepared strain sensor in this work was completely degraded in 2 wt% CH3COOH solution at 90 °C only within 10 min, thus effectively avoiding the production of electrical waste after the updating and upgrading of the sensors. The findings conceivably stand out as a new methodology to prepare environmental-friendly sensors in the field of flexible electronics, which is very beneficial for the sustainable development of environment and society.

The neuroprotective effect of dexmedetomidine and its mechanism.

Dexmedetomidine (DEX) is a highly selective α2 receptor agonist that is routinely used in the clinic for sedation and anesthesia. Recently, an increasing number of studies have shown that DEX has a protective effect against brain injury caused by traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), cerebral ischemia and ischemia-reperfusion (I/R), suggesting its potential as a neuroprotective agent. Here, we summarized the neuroprotective effects of DEX in several models of neurological damage and examined its mechanism based on the current literature. Ultimately, we found that the neuroprotective effect of DEX mainly involved inhibition of inflammatory reactions, reduction of apoptosis and autophagy, and protection of the blood-brain barrier and enhancement of stable cell structures in five way. Therefore, DEX can provide a crucial advantage in neurological recovery for patients with brain injury. The purpose of this study was to further clarify the neuroprotective mechanisms of DEX therefore suggesting its potential in the clinical management of the neurological injuries.

Performance of nitrogen removal in an alternating activated sludge reactor for full-scale applications.

A novel wastewater treatment process, known as an alternating activated sludge reactor (AASR), is proposed to treat wastewater in full-scale operations. The AASR is a technical development based on the sequencing batch reactor (SBR) and cyclic activated sludge technology (CAST). The performance of AASR was evaluated in this study and found to be effective for the removal of pollutants. The average effluent NH4+-N, TN, TP, and COD concentrations were 0.5, 17, 0.8, and 40 mgL-1, respectively. The corresponding average removal efficiencies were 97%, 59%, 83%, and 83%, respectively, indicating that the AASR was also a successful operating system for the removal of organic matter. The AASR has many advantages, such as successive filling, high removal efficiency, high stability and reliability, low area requirement, no sludge circulation reflux, and low construction costs. The operation mode of the alternating anoxic, anaerobic, and aerobic conditions displayed a higher efficiency for nitrification than that of conventional SBR. The effective mode for denitrification was a step-feed. The control program of the AASR is highly flexible and can easily be modified by a plant manager to meet various loading requirements.

Effect of nitric acid pre-oxidation concentration on pore structure and nitrogen/oxygen active decoration sites of ethylenediamine -modified biochar for mercury(II) adsorption and the possible mechanism.

Controlling of pre-oxidation conditions can effectively enhance the aimed active functional groups via promoting the oxidation and grafting reaction on biochar's surface. Here, the effect of different nitric acid pre-oxidation concentration (NAPOC) was investigated on the type and content of active oxygen-containing functional sites during the pre-oxidation stage, as well as the active nitrogen-containing binding sites for the following grafting process. And the possible reaction mechanisms for introducing nitrogen/oxygen-containing functional groups such as amide, pyridinic, carbonyl, carboxyl, etc., into the surface by ethylenediamine (EDA) were proposed. The samples were characterized by various analyses including N2 adsorption/desorption, Boehm titration, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Results showed that the NAPOC played a crucial role in promoting the formation of oxygen-containing initiators, and difference of NAPOC resulted in different reaction principles. At higher NAPOC, more carbonyl, carboxyl and hydroxyl functional groups were formed, which facilitated the decoration of nitrogen binding active sites of amide and pyridinic for mercury ions adsorption into the carbon lattice of mesoporous biomass-derived biochar (MBB). The proportions of micropore and mesopore remained basically unchanged, indicating that the decorated nitrogen/oxygen sites were highly uniformly dispersed in MBB's frame and thus resulted in high activity. The comparison of adsorption properties of MBB showed that MBB-25-EDA had the highest adsorption capacity of 153 mg g-1 at pH 6, confirming that the 25% was the optimum NAPOC for introducing nitrogen/oxygen functional binding sites for effectively anchoring mercury.

Preparation of Biomass-based Mesoporous Carbon with Higher Nitrogen-/Oxygen-chelating Adsorption for Cu(II) Through Microwave Pre-Pyrolysis.

An environment-friendly technique for synthesizing biomass-based mesoporous activated carbon with high nitrogen-/oxygen-chelating adsorption for Cu(II) is proposed. Bagasse impregnated with phosphoric acid is utilized as the precursor. To pyrolyze the precursor, two separate heating modes are used: microwave pyrolysis and conventional electric-heating pyrolysis. The resulting bagasse-derived carbon samples are modified with nitrification and reduction modification. Nitrogen (N)/oxygen (O) functional groups are simultaneously introduced to the surface of activated carbon, enhancing its adsorption of Cu(II) by complexing and ion-exchange. Characterization and copper adsorption experiments are performed to investigate the physicochemical properties of four prepared carbon samples and determine which heating method favors the subsequent modification for doping of N/O functional groups. In this technique, based on analyzing data of nitrogen adsorption, Fourier transform infrared spectroscopy, and batch adsorption experiments, it is proven that microwave-pyrolyzed carbon has more defect sites and, therefore, time-saving effective microwave pyrolysis contributes more N/O species to the carbon, although it leads to a lower specific surface area. This technique offers a promising route to synthesis adsorbents with higher nitrogen and oxygen content and a higher adsorption capacity of heavy-metal ions in wastewater remediation applications.

Effect of pre-pyrolysis mode on simultaneous introduction of nitrogen/oxygen-containing functional groups into the structure of bagasse-based mesoporous carbon and its influence on Cu(II) adsorption.

A convenient effective microwave pre-pyrolysis treatment to synthesize biomass-based mesoporous carbon with higher nitrogen/oxygen-chelating adsorption for Cu(II) is reported here, in which phosphoric acid impregnated bagasse was used as a microwave absorber and porogen. For comparison, conventional electric-heating pyrolyzed carbon was prepared and doped with nitrogen/oxygen groups. Nitrogen adsorption, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS) and batch adsorption were employed to investigate the effects of the two pre-pyrolysis modes on the sample physicochemical and Cu(II) adsorptive properties. The 22-min-microwave-pyrolyzed bagasse mesoporous activated carbon (MBAC, 85.32% mesoporosity) contained 10.52% O, which is 3.94% more than electric-heating pyrolyzed mesoporous activated carbon (89.52% mesoporosity). After electrophilic aromatic substitutions of N/O doping, the former possessed more N (5.83%) and more O (21.40%), confirming that time-saving energy-efficient microwave pyrolysis favors the formation of defective C/O atoms in or at the edges of the graphite layer of MBAC, which are highly active and tend to act as preferred reactive positions for the doping of N/O-containing groups simultaneously compared with conventional electric-heating pyrolysis. These N and O species existed mainly as COOH, OH, NH and NH2 functional groups, and were confirmed by XPS to be active sites for metal binding via electrostatic attraction, hydrogen bonding, a chelate effect and complexation, resulting in the great enhancement of Cu(II) adsorption. Langmuir isotherm and pseudo-second-order kinetic fitting further proved that Cu(II) adsorption by N/O-doped MBAC is ascribed mainly to chemisorption. Therefore, rapid microwave pre-pyrolysis provides a promising route to prepare excellent-performance N/O-doped carbon adsorbents.

Effects of N mono- and N/P dual-doping on H2O2, OH generation, and MB electrochemical degradation efficiency of activated carbon fiber electrodes.

Pure N mono- and N/P dual-doped cotton-stalk-derived activated carbon fibers (CSCFs) were synthesized by steam, HNO3(CSCF-N), NH3(CSCF-A), and (NH4)3PO4(CSCF-N/P) treatments. This study investigated how three different N/P modifiers affected the pore structure, chemical property, H2O2 generation ability, and electrocatalytic activity of methylene blue (MB) degradation of CSCFs in an electric-Fenton system. Results confirmed that the three employed treatments effectively doped N/P in the carbon lattice and slightly changed the pore structures. NH3 and (NH4)3PO4 were the most effective modifiers for the N mono-doping and N/P dual-doping of CSCFs, respectively. Among the fabricated CSCFs, the N/P dual-doped CSCF-N/P demonstrated the highest electrochemical activity in an electro-Fenton system, followed by the N mono-doped CSCF-A, the CSCF-N, and the raw CSCF. In contrast to the CSCF electrode, the CSCF-N/P electrode exhibited enhanced H2O2, OH generation, and MB degradation efficiency by 42%, 41%, and 35%, respectively. Under optimum conditions, the electrochemical decolorization efficiency of MB (initial concentration, 100 mg L-1) of the CSCF-N/P reached 93% after 150 min and was 24.1% higher than that of the CSCF. By the tenth cycle, 82.2% of the MB could still be decomposed, suggesting the excellent stability and reusability of the N/P co-doped CSCF electrode. The outstanding electrocatalytic performance of the CSCF-N/P electrode is primarily due to the simultaneous doping of active N/P sites with low activation energy and introduction of mesopores with strong trapping forces for MB. The MB reduction catalyzed by CSCF electrodes followed pseudo-first-order kinetics, and the reaction rate depended on the modifiers.

Plasmas ozone inactivation of Legionella in deionized water and wastewater.

The results show that ozone concentration determination using ultraviolet spectrophotometry (UV-2450) at 258 nm is easier than using indigo method at 600 nm. A strong linear relationship was found between purge time and O3 concentration in deionized water. Ozone concentration can be predicted in deionized water. A higher O3 flow rate or lower temperature led to a higher O3 concentration. Ozone concentration was stable in 60 min, so that ozone self-decomposition could be ignored at ozone concentrations below 0.4 mg L-1. A higher temperature led to a higher inactivation efficiency and rate, and that a lower temperature led to a lower ozone decay rate and inactivation efficiency even if ozone solubility increased when temperature decreased. The fastest inactivation rate occurred before c0t = 165 µg L-1 s, but the inactivation rate decreased after c0t = 165 µg L-1 s with tail phenomena. The tail phenomena were clearly observed and may be caused by oxidization of lipopolysaccharides (LPS), cell membrane, etc. The activation energy Ea = 55,404 ± 0.3 J mol-1 were obtained for Legionella inactivation with ozone in deionized water. Ozone maximum decay rate was positively proportional to COD concentration. COD impacted on ozone concentration seriously. Higher COD concentration resulted in higher ozone decay rate. COD could result in ozone concentration decrement rapidly to a steady value in 5 s. Higher initial ozone concentration resulted in higher germ inactivation rate. Higher initial COD concentration resulted in lower Legionella inactivation efficiency. COD was easier to react with ozone than Legionella. The relationship among the initial COD concentrations COD0, the initial O3 concentration c0, and the O3 contact time t necessary for a 99.999% reduction of Legionella in wastewater can be expressed in some equations. O3 disinfection time t necessary for a 99.999% reduction of Legionella can be predicted by Eqs. (10) and (11). Graphical abstract ᅟ.

Chemical modification of bagasse-based mesoporous carbons for chromium(III) ion adsorption.

AIMS: Modified bagasse-based mesoporous carbons were prepared for the efficient chromium(III) ion adsorption and removal from aqueous solutions. METHODS: Mesoporous carbons were prepared from bagasse with H3PO4 activation and subsequently oxidized with nitric acid and modified with ethylenediamine. RESULTS: The results showed that the modified carbon was rich in mesopores, oxygen and nitrogen-containing groups, and the Cr(III) adsorption capacity was greatly improved after modification, which was found to be higher than both pristine and oxidized carbons. The Cr(III) adsorption capacity on modified carbon was significantly influenced by the solution pH, and the optimum pH was 6 with the maximum Cr(III) adsorption capacity up to 24.61mg/g, which was almost 3 times higher than that for pristine carbon. Thermodynamic results manifested the adsorption was spontaneous and endothermic. Kinetic rates fitted the pseudo-second-order model very well. XPS study indicated the amino group was a key factor of the high efficient adsorption.

Kinetic analysis of Legionella inactivation using ozone in wastewater.

Legionella inactivation using ozone was studied in wastewater using kinetic analysis and modeling. The experimental results indicate that the relationship between the ozone concentration, germ concentration, and chemical oxygen demand (COD) can be used to predict variations in germ and COD concentrations. The ozone reaction with COD and inactivation of Legionella occurred simultaneously, but the reaction with COD likely occurred at a higher rate than the inactivation, as COD is more easily oxidized by ozone than Legionella. Higher initial COD concentrations resulted in a lower inactivation rate and higher lnN/N0. Higher temperature led to a higher inactivation efficiency. The relationship of the initial O3 concentration and Legionella inactivation rate was not linear, and thus, the Ct value required for a 99.99% reduction was not constant. The initial O3 concentration was more important than the contact time, and a reduction of the initial O3 concentration could not be compensated by increasing the contact time. The Ct values were compared over a narrow range of initial concentrations; the Ct values could only be contrasted when the initial O3 concentrations were very similar. A higher initial O3 concentration led to a higher inflection point value for the lnN/N0 vs C0t curve. Energy consumption using a plasma corona was lower than when using boron-doped diamond electrodes.

[Adsorption kinetics and mechanism of lead (II) on polyamine-functionalized mesoporous activated carbon].

Bagasse mesoporous carbon was prepared by microwave assisted H3 PO4 activation. Amido and imido groups were modified with ethanediamine on the channels' surface of mesoporous carbon through nitric oxidation and amide reaction. The influence of Pb(II) concentration, adsorption time on Pb(II) adsorption on the ethanediamine-modified mesoporous carbon (AC-EDA) was investigated. The adsorption kinetics and mechanism were also discussed. The results showed that AC-EDA had a great performance for Pb(II) adsorption, and more than 70% of Pb(II) was adsorbed in 5 minutes. The adsorption amount of Pb(II) on the carbon increased with the increase of solution pH in acidic conditions. It was found that AC-EDA had different binding energies on different adsorption sites for Pb(II) separation. The Pb(II) adsorption process on AC-EDA was controlled by intra-particle diffusion in the first 3 min, and then film diffusion played the important pole on the adsorption. The adsorption amount increased with the increase of temperature, indicating the adsorption was an endothermic reaction. The high adsorption energy (> 11 kJ x mol(-1)) implied that the) adsorption was a chemical adsorption. The XPS of AC-EDA before and after Pb(II) adsorption showed that the polyamine group was involved in the adsorption, and should be a main factor of the high efficient adsorption.

[Preparation, characterization and adsorption performance of mesoporous activated carbon with acidic groups].

Mesoporous activated carbons containing acidic groups were prepared with cotton stalk based fiber as raw materials and H3PO4 as activating agent by one step carbonization method. Effects of impregnation ratio, carbonization temperature and heat preservation time on the yield, elemental composition, oxygen-containing acid functional groups and adsorptive capacity of activated carbon were studied. The adsorption capacity of the prepared activated carbon AC-01 for p-nitroaniline and Pb(II) was studied, and the adsorption mechanism was also suggested according to the equilibrium experimental results. The maximum yield of activated carbons prepared from cotton stalk fiber reached 35.5% when the maximum mesoporous volume and BET surface area were 1.39 cm3 x g(-1) and 1 731 m2 x g(-1), respectively. The activated carbon AC-01 prepared under a H3 PO4/precursor ratio of 3:2 and activated at 900 degrees C for 90 min had a total pore volume of 1.02 cm3 x g(-1), a micoporous ratio of 31%, and a mesoporous ratio of 65%. The pore diameter of the mesoporous activated carbon was mainly distributed in the range of 2-5 nm. The Langmuir maximum adsorption capacities of Pb(II) and p-nitroaniline on cotton stalk fiber activated carbon were 123 mg x g(-1) and 427 mg x g(-1), respectively, which were both higher than those for commercial activated carbon fiber ACF-CK. The equilibrium adsorption experimental data showed that mesopore and oxygen-containing acid functional groups played an important role in the adsorption.

[Preparation, characterization and adsorption performance of high surface area biomass-based activated carbons].

High surface area activated carbons were prepared with Spartina alterniflora and cotton stalk as raw materials and KOH as activating agent. Effects of materials type, impregnation ratio, activation temperature and heat preservation time on the yield, elemental composition and adsorptive capacity of activated carbon were studied. The properties and pore structure of the carbons were characterized with nitrogen adsorption, powder X-ray diffractometry (XRD), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Main pore characteristics of activated carbons were analyzed by BET equation, Horvath-Kawazoe BET method and DFT method. The considerable preparation conditions are obtained as follows: impregnation ratio of 3: 1, an activation temperature of 800 degrees C and an activation time of 1.5 h. The BET surface area of activated carbon prepared from Spartina alterniflora reached 2 825 m2 x g(-1) when its total pore volume, yield, iodine number and methylene blue adsorption were 1.374 cm3 x g(-1), 16.36%, 1797 mg x g(-1) and 495 mg x g(-1) respectively under above conditions. The activated carbon from cotton stalk was prepared with BET surface area of 2 135 m2 x g(-1), total pore volume of 1.038 cm3 x g(-1), yield of 11.22%, methylene blue adsorption of 1 251 mg x g(-1), and iodine number of 478 mg x g(-1), respectively. The methylene blue adsorption and iodine number are much higher than the national first level for activated carbon. The Langmuir maximum adsorption capacities of 2,4-dinitrophenol on the two carbons were 932 mg x g(-1) and 747 mg x g(-1), respectively, which are superior to ordinary activated carbon and activated carbon fiber.