Magnetic Fe3O4@poly(m-phenylenediamine) particles (Fe3O4@PmPDs) with well-defined core–shell structure were first designed for high performance Cr(VI) removal by taking advantages of the easy ...separation property of magnetic nanoparticles (MNPs) and the satisfactory adsorption property of polymers. Through controlling the polymerization on MNPs, directly coating was realized without the complicated premodification procedures. The particle property and adsorption mechanism were analyzed in details. Fe3O4@PmPDs exhibited tunable PmPD shell thickness from 10 to 100 nm, high magnetic (∼150 to ∼73 emu g–1) and facile separation property by magnet. The coating of PmPD significantly enhanced Cr(VI) adsorption capacity from 46.79 (bare MNPs) to 246.09 mg g–1 (71.55% PmPD loading proportion), much higher than many reported composite adsorbents. The high Cr(VI) removal performance was attributed to the adsorption of Cr(VI) on protonated imino groups and the efficient reduction of Cr(VI) to Cr(III) by amine, followed by Cr(III) chelated on imino groups, which are spontaneous and endothermic. The Fe3O4@PmPDs have great potential in treating Cr(VI)-contaminated water.
•Lowering oxidation state of poly(m-phenylenediamine) (PmPD) facilitates Cr(VI) sorption.•PmPD with low oxidation state bears removal of 500mgg−1 and excellent Cr(VI) selectivity.•Redox reaction, ...doping adsorption and chelation are the main mechanism for Cr(VI) adsorption.
Poly(m-phenylenediamine) (PmPD) with different oxidation state was successfully synthesized by the improved chemically oxidative polymerization. The function of oxidation state on Cr(VI) adsorption was systematically examined through adsorption experiments. Results showed that the Cr(VI) adsorptivity of all PmPD increased with decreasing the initial pH. When the oxidation state of PmPD was dropped, the equilibrium time for Cr(VI) adsorption was obviously shortened and its Cr(VI) removal and adsorption selectivity were profoundly obviously increased. Typically, PmPD with the lowest oxidation state in this research possesses the highest Cr(VI) removal of 500mgg−1. Moreover, PmPD with lower oxidation state displays a potentially superior prospect in Cr(VI) treatment through preliminary experiments on 5 cycles of adsorption, column adsorption and practical wastewater treatment. The possible adsorption mechanism was discussed mainly according to characterizations (FTIR, XPS) and experiments, which together suggests that the Cr(VI) adsorption most possibly involve redox reaction, chelation and doping adsorption.
The conversion of low-cost renewable lignin could enable the economic fabrication of carbon materials for energy storage devices. However, the traditional activation methods for the production of a ...lignin-derived porous carbon with a large specific surface area are complex and expensive, and some activators can cause pollution. In this paper, we propose a novel green bacterial activation method for the synthesis of a carbon material with a large surface area of up to 1831 m
2
g
−1
and abundant micropores and mesopores through a conventional carbonization procedure with a simple bacterial culture process. The transformation of the lignin structure by the bacteria optimizes the pore structure of the derived carbon and promotes graphitization. Consequently, as an electrode in a supercapacitor, the obtained material exhibits a very high specific capacitance (428 F g
−1
at 1 A g
−1
), high cycling stability (capacitance retention of 96.7% after 10 000 cycles at 5 A g
−1
), and superior rate performance in an aqueous electrolyte. In addition, the symmetric supercapacitor based on the bacteria-activated lignin-derived carbon exhibits a superior energy density of 66.18 W h kg
−1
at 312 W kg
−1
in an ionic liquid electrolyte system. These excellent features demonstrate the large potential of the developed material for applications in high-performance supercapacitors. Furthermore, the proposed bacteria-activation method can guide a novel bio-modification for material syntheses.
A novel green bacterial activation method for the synthesis of a lignin derived carbon material with excellent electrochemical performances.
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•A new strategy for bio-converting Kraft lignin (KL) into polyhydroxyalkanoate by bacteria was presented.•KL was depolymerized into aromatic compounds and then converted into ...polyhydroxyalkanoate.•Great productivity of polyhydroxyalkanoate was obtained from KL by Cupriavidus basilensis B-8 without any pretreatment.
This work presents here a new fundamental strategy for bio-converting Kraft lignin (KL) into useful products. Cupriavidus basilensis B-8 (here after B-8) was able to use KL as the sole carbon source. Fully 41.5% of lignin, 37.7% of total carbon (TC) and 43.0% of color were removed after 7days of incubation. At the same time, lignin was depolymerized into small fragments, which was confirmed by scanning electron microscopy (SEM) and gel permeation chromatography (GPC). Bacterial biomass accumulated to 735.6mg/L at the initial KL concentration of 5gL−1, and the corresponding volumetric productivity of polyhydroxyalkanoate (PHA) was 128mg/L. PHA productivity was significantly improved through fed batch fermentation and reached to 319.4mg/L. GC–MS analysis showed that PHA polymer was composed of three basic monomers: 98.3mol% of (S)-3-hydroxy-butanoic acid (S3HB), 1.3mol% of ®-3-hydroxybutyric acid (R3HB) and 0.4mol% of 3-hydroxy-butanoic acid (3HB).
Cu–m-phenylenediamine (Cu–mPD) complex was firstly exploited to efficiently synthesize poly(m-phenylenediamine)/reduced graphene oxide (PmPD/rGO) hydrogel. Cu–mPD complex shows high gelation and ...redox reaction activity with GO, which is ascribed to the joint and mediation effect of Cu2+. The green and efficient route realized high monomer polymerization (>99%) and decreased hydrothermal reaction time (1h) without additional polymerization process. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transformed infrared spectroscopy, and Raman spectroscopy were conducted to characterize the morphology and structure of PmPD/rGO hydrogel. The macroscopic hydrogels exhibit high porosity, good mechanical strength, superior adsorption performance (with methylene blue adsorbance of 615mgg−1), and readily recycle properties.
•Mesoporous carbon stabilized alumina was prepared by one-pot hard-templating method.•MC/Al2O3 showed excellent performance for Cd(II) and Pb(II) adsorption.•Enhanced adsorption was due to the high ...surface area and special functional groups.
A novel adsorbent of mesoporous carbon stabilized alumina (MC/Al2O3) was synthesized through one-pot hard-templating method. The adsorption potential of MC/Al2O3 for Cd(II) and Pb(II) from aqueous solution was investigated compared with the mesoporous carbon. The results indicated the MC/Al2O3 showed excellent performance for Cd(II) and Pb(II) removal, the adsorption capacity reached 49.98mgg−1 for Cd(II) with initial concentration of 50mgL−1 and reached 235.57mgg−1 for Pb(II) with initial concentration of 250mgL−1, respectively. The kinetics data of Cd(II) adsorption demonstrated that the Cd(II) adsorption rate was fast, and the removal efficiencies with initial concentration of 10 and 50mgL−1 can reach up 99% within 5 and 20min, respectively. The pseudo-second-order kinetic model could describe the kinetics of Cd(II) adsorption well, indicating the chemical reaction was the rate-controlling step. The mechanism for Cd(II) and Pb(II) adsorption by MC/Al2O3 was investigated by X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared spectroscopy (FTIR), and the results indicated that the excellent performance for Cd(II) and Pb(II) adsorption of MC/Al2O3 was mainly attributed to its high surface area and the special functional groups of hydroxy-aluminum, hydroxyl, carboxylic through the formation of strong surface complexation or ion-exchange. It was concluded that MC/Al2O3 can be recognized as an effective adsorbent for removal of Cd(II) and Pb(II) in aqueous solution.
Heavy metals and ammonia are difficult to remove from wastewater,as they easily combine into refractory complexes.The struvite formation method（SFM） was applied for the complex decomposition and ...simultaneous removal of heavy metal and ammonia.The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion.Ammonia was separated from solution as crystalline struvite,and the copper mainly co-precipitated as copper hydroxide together with struvite.Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide.Hydrogen bonding was concluded to be the key factor leading to the co-precipitation.In addition,incorporation of copper ions into the struvite crystal also occurred during the treatment process.
A method of pH manipulation has been used to improve chemically oxidative polymerization of m-phenylenediamine (mPD) through concurrent addition of NaOH when adding oxidant (NH4)2S2O8. pH detection ...and open-circuit potential technique were adopted to monitor the polymerization process of mPD and to explain the oxidation state–pH and yield–pH relationships. Results from Fourier transformed infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies indicate that a low oxidation state is under control by regulating NaOH concentration. At 2.5 M NaOH, the oxidation state of poly(m-phenylenediamine) (PmPD) is 64.7 mol % (measured by molar content of quinoid imine from XPS), while the yield is 84%. The synthesized PmPD possesses better Ag+ adsorption performance when lowering its oxidation state. Moreover, the Ag+ adsorbance of PmPD can reach 1693 mg g–1. Meanwhile, Ag+ adsorption mechanism was studied by pH tracking, X-ray diffraction (XRD) patterns, and X-ray photoelectron spectroscopy. The adsorption process includes redox reaction, chelation, and physical adsorption.
► We use Penicillium chrysogenum growth experiment data to fit Gompertz model. ► We compared the removal efficiencies of bioleaching with chemical bioleaching. ► The morphology and resistant ...mechanism of P. chrysogenum were preliminary examined. ► Glucose oxidase activity produced by P. chrysogenum during bioleaching was studied.
The ability and bioleaching mechanism of heavy metals by Penicillium chrysogenum in soils contaminated with smelting slag were examined in this study. Batch experiments were performed to investigate the growth kinetics of P. chrysogenum, organic acids production and to compare the removal efficiencies of heavy metals between bioleaching with P. chrysogenum and chemical organic acids. The results showed that the bioleaching had higher removals than chemical leaching, and the removal percentages of Cd, Cu, Pb, Zn, Mn and Cr reached up to 74%, 59%, 24%, 55%, 57% and 25%, respectively. Removal efficiencies of heavy metals (15.41mg/50mL) by bioleaching were higher than chemical leaching with 0.5% of citric acid (15.15mg/50mL), oxalic acid (8.46mg/50mL), malic acid (11.35mg/50mL) and succinic acid (10.85mg/50mL). The results of transmission electron microscope (TEM) showed that no damage was obviously observed on the surface of the living cell except for thinner cell wall, discontinuous plasma membrane, compartmentalized lumen and concentrated cytoplasm during bioleaching process. The activity of extracellular glucose oxidase (GOD) produced by P. chrysogenum is influenced severely by the multi-heavy metal ions. The result implied that P. chrysogenum can be used to remove heavy metals from polluted soil and smeltery slag.
► Esterified spent grain (ESG) is efficient for Cd(II) adsorption. ► The maximum Cd(II) adsorption capacity is 473.93mgg−1. ► The adsorption equilibrium can be established in 15min. ► ESG shows good ...reusability during nine cycles of sorption–desorption. ► Most of Cd(II) is directly attached to the oxygen atom of CO in carboxyl group.
A novel adsorbent—esterified spent grain (ESG) was used to remove Cadmium(II) from aqueous solution. Cd(II) adsorption behavior and mechanisms were investigated in this paper. The sorption process was very fast and the equilibrium was established in 15min. The maximum Cd(II) adsorption capacity of ESG calculated from Langmuir isotherm was 473.93mgg−1 that was higher than other adsorbents reported. The sorption kinetics was well described by the pseudo-second order kinetic model. The calculated activation energy (Ea) implied that adsorption of Cd(II) on ESG was a chemical adsorption. The thermodynamic parameters of sorption systems indicated a spontaneous and endothermic process. More importantly, Cd(II) binding mechanisms on ESG were discussed by FT-IR and XPS studies. The results showed that the carbon–oxygen (CO) in carboxyl group of ESG directly attached to the cadmium ion that led to most of the adsorption.
