Recycle Times Research Articles

Chelation‐activated multiple‐site reversible chemical absorption of ammonia in ionic liquids

AbstractDeveloping new and facile strategies for multiple‐site reversible chemical absorption of pollutant gases is of wide interests in chemical engineering research. Herein, a series of lithium (Li)‐triethylene glycol (TEG)–chelated ionic liquids (ILs) with crown‐ether‐like cation and different anions were designed. The Li‐TEG–chelated ILs were prepared in quantitative yields by simply mixing equimolar TEG and Li salts. It is found that the chelation of TEG with Li+ activates the hydroxyl sites in TEG for strong interaction with ammonia (NH3). Thus, the hydroxyl sites chelated with Li+, as well as the chelation‐unsaturated Li+, provide the multiple sites for chemical absorption of NH3 in Li‐TEG–chelated ILs. Moreover, the absorption of NH3 in Li‐TEG–chelated ILs is totally reversible, with the NH3 solubilities remaining unchanged after eight times of recycling. The results obtained herein can provide useful guidance for the construction of gas absorbents with high capacity and excellent reversibility.

The impact of packaging recyclable ability on environment: Case and scenario analysis of polypropylene express boxes and corrugated cartons

With the push for sustainable design strategies, recyclable packaging is widely favored by the public in the express delivery industry due to its potential for lowering environmental burden and solving climatic challenges. The goal of this paper was to quantify and integrate the environmental footprints of polypropylene hollow board express box (PPH-EB) and establish evaluation model between the recyclable ability and environment performance (EMRE) based on life cycle assessment. This work was carried out by multiple indicators to avoid environmental problem-shifting, and corrugated cartons express box (C-EB) was taken as control objects. The results show that integrated index of PPH-EB is 94.42% lower than that of C-EB. Industrial Water Use (IWU), Primary Energy Demand (PED) and SO2 are major factors affecting results of PPH-EB, which mainly come from polypropylene particles and water resource consumption from recycle process. The most obvious advantage of PPH-EB compared with C-EB is the nearly 1700 times difference in normalized COD index caused by direct emission of paper preparation process. Scenario analysis showed that integrated index of PPH-EB was lower than that of traditional corrugated cartons after more than twice of use, but if the recycling times of PPH-EB continued to increase, the effect on reducing environmental burden was no longer significant. Therefore, although the recyclable times plays a role in decreasing the environmental impact, it is not a permanent strategy. In the design stage of the recyclable express box, the recyclable ability should be reasonably designed through EMRE, so as to minimize the environmental burden.

Novel and Green Fe3O4@Sio2-L-Cys Magnetic Absorbent for Efficient Removal of Pb (II) from Aqueous Solution

In this study, Fe3O4@Sio2-NH2 was synthesized by the modification of Fe3O4 particles with tetraethyl orthosilicate(TEOS) and 3-aminopropyl-Triethoxysilane (APTES), and then the cysteine was grafted with glutaraldehyde as cross-linking agent.The material was characterized by XRD,FIIR and TEM. The effects of temperature, time, initial concentration of Pb(II) and pH value on the adsorption rate of Pb(II) were investigated, and the adsorption mechanism and the regeneration performance of the adsorbent were discussed.The results indicated that when the amount of adsorbent was 0.4g/L, the temperature was 303K, the adsorption time was 2.5h and the pH was 5.02, the adsorption rate of Pb(II) in water can reach up to 98.25%.The adsorption kinetics of Pb(II) on the material accorded with Lagergren quasi-second-order kinetic equation, which belonged to the chemisorption process.Adsorption isothermal curve studies showed that the adsorption of Pb(II) on the material complied with the Langmuir isothermal adsorption model and was a monolayer adsorption.The maximum adsorption capacity of Pb(II) is 120.77mg/g. Adsorption thermodynamics studies showed that the whole system was endothermic reaction,and warming was conducive to the adsorption,which happens spontaneously.After 4 times of the adsorption recycling,the adsorption rate can still reach 92.7%.

Study on catalytic properties of graphene/molybdenum sulfide under near-infrared light irradiation

Graphene/MoS2 hybrid material was prepared by the hydrothermal method. The hybrid material was characterized by X-ray diffraction spectrum, Raman spectra, transmission electron microscope and UV-vis-NIRS. It was used as a near-infrared photocatalyst to catalyze and degrade Rhodamine B (RhB). The results showed that when the concentration of the RhB solution was 50.0 mg·L–1, the pH value of the solution was 7, the volume of the solution was 50.0 mL, the amount of G/MoS2 catalyst was 0.05 g and near-infrared radiation was carried out for 3 h, the degradation rate of RhB in the 50 mL solution reached 96.5%. When MoS2 was used as the photocatalyst, the degradation rate of RhB was only 75.5%. After 5 times of recycling, the catalytic efficiency of the hybrid photocatalyst was still more than 90%, indicating that the catalyst is very stable.

Ultra-robust, self-healable and recyclable polyurethane elastomer via a combination of hydrogen bonds, dynamic chemistry, and microphase separation

Flexibility, robustness, transparency, and recyclability are critical to the application of self-healing polymer materials in the field of flexible electronics. However, integrating all the above properties remains a huge challenge to date. In this work, we put forward a facile strategy to prepare polyurethane (PU) elastomer with ultra-high strength and self-healing performance based on hydrogen bonds, disulfide dynamic chemistry, and microphase separation at the same time. Three different self-healing PUs were obtained by introducing disulfide bonds and different types of hydrogen bonds. A robust, transparent, and recyclable PU with amino-terminated chain extender (PUA) with fast and efficient self-healing performance was prepared. The mechanical and self-healing properties of the PUA were effectively balanced by the synergistic effect of reversible interaction of disulfide bonds and the formation of microphase separated structure. The results indicated that the PUA exhibited high transparency up to 90% and excellent mechanical property, e.g. the tensile strength and elongation at break can reach 37.10 MPa and 1080%, respectively. Meanwhile, it can achieve a high self-healing efficiency of 96.8% at 80 °C for 4 h and maintain 84% of the initial mechanical strength even after four times of recycling. Moreover, the colloid graphite/PUA flexible strain sensor was prepared by the combination of colloid graphite and PUA, which can accurately detect both large and tiny scale deformations.

Facile synthesis of Poly(epichlorohydrin-diethylenetriamine) hydrogel for highly selective diclofenac sodium removal

Diclofenac sodium (DS), which remains in natural aqueous environments, is eco-toxic. To remove DS in aqueous solutions, a new adsorbent, poly(epichlorohydrin-diethylenetriamine) [P(ECH-DETA)] hydrogel, was simply synthesized by crosslinking copolymerization. In this work, the newly prepared P(ECH-DETA) hydrogel has the advantages of the simple synthesis method, certain anti-interference ability for DS adsorption, the relatively high adsorption capacity, and the obvious selective adsorption performance for DS in mixed-pharmaceuticals solutions. The adsorption inhibitory effects were acceptable within a range of wide pH (pH = 3–10), interfering ions concentration (0.1–10 mmol/L) and coexisting humic acid (1–15 mg/L). Besides, the adsorption capacity can reach 540.3 mg/g according to the Langmuir fitting model, much higher than that of DS adsorbents reported in most studies. After 5 times of recycle, the adsorption capacity still maintained 80.32%, indicating high sustainability. In addition, the selective adsorption capacity was evaluated by testing the adsorption performance on 6 different pharmaceuticals besides DS. The results indicated that P(ECH-DETA) hydrogel could selectively adsorb DS from DS/quinolones and DS/tetracyclines. The adsorption mechanisms of DS were studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), indicating that the adsorption mechanisms are mainly amine groups (electrostatic attraction) and hydroxyl groups (hydrogen bonding). P(ECH-DETA) hydrogel prepared in this study is a hopeful adsorbent for DS removal.

Preparation of polyethersulfone/magnesium silicate membranes via casting and electrospinning and their application in the removal of free fatty acids from biodiesel

Due to the reversible nature of reactions in biodiesel production, a purification process is necessary for the biodiesel to meet international standards. As an effective method, dry washing has been applied in biodiesel purification for years, but it still faces limitations and challenges. In this work, a magnesium silicate (MS) was synthesized using the hydrothermal method. Two types of composite membranes were prepared by doping the prepared magnesium silicate into polyethersulfone (PES) via casting and electrospinning, respectively. Structural and physical properties of the composite membranes were characterized. The composite membranes were applied as adsorbents to remove free fatty acids (FFAs) from crude biodiesel. Adsorption isotherm and kinetic studies were performed at different temperatures (20, 40 and 60 °C). For both membranes, the obtained adsorption capacity was higher at low temperature (20 °C). Maximum adsorption capacity was found with the electrospun membrane to be 852 mg g-1, calculated from the Langmuir model. Adsorption kinetics for both membranes can be well described using the pseudo-second-order model. In addition, the internal diffusion was not negligible during the adsorption process based on the intraparticle diffusion analysis. As revealed by thermodynamic study, the adsorption processes were all exothermic with a spontaneous nature. Reusability of the membrane adsorbents was evaluated, in which the electrospun membrane showed a promising performance with 94% adsorption capacity remaining over 8 cycles of adsorption and desorption.

Catalytic oxygen evolution from hydrogen peroxide by trans-[Co(en)2Cl2]@InBTB metal-organic framework catalytic system.

The diethylammonium counter-cations of the [Et2NH2]3[In3(BTB)4] metal–organic framework (InBTB MOF, BTB = 1,3,5-benzenetribenzoate) with an anionic framework can be effectively exchanged with cationic trans-[Co(en)2Cl2]+ complex ions through a simple cation-exchange process. The heterogenized trans-[Co(en)2Cl2]+-encapsulated InBTB MOF (trans-[Co(en)2Cl2]@InBTB) catalytic system maintained the activity of the captured trans-[Co(en)2Cl2]+ complex ion for hydrogen peroxide decomposition in aqueous solution under mild reaction conditions. The captured trans-[Co(en)2Cl2]+ complex also exhibited trans–cis isomerization to produce either cis-[Co(en)2Cl2]@InBTB or cis-[Co(en)2(H2O)Cl]@InBTB based on IR spectroscopic investigation. The trans-[Co(en)2Cl2]@InBTB catalytic system showed high recyclability for oxygen evolution from hydrogen peroxide. The catalytic ability of trans-[Co(en)2Cl2]@InBTB was maintained up to seven times of recycling.

Application effect of centralized management combined with Information system application management in recycling, cleaning, disinfection and packaging of radiology instruments and reusable medical devices

To conduct centralized management combined with Information system application management in radiology instruments and reusable medical devices, and explore the promotion value of cleaning quality and work efficiency. The recycling time, cleaning quality, packaging quality and distribution errors of the devices with which centralized management combined with Information system application management (June 2019) was implemented half a year before and after in the radiology department of our hospital were collected and compared. With implementation of centralized management combined with Information system application management, the average recycling time (25.33 ± 5.64) of devices was remarkably shorter than that before implementation (42.37 ± 6.77) (P < 0.05). The yield of cleaning (94.57%) and packaging (98.91%) in the observation group were significantly higher than those in the control group (86.05%) and (87.21%) (P < 0.05). The probability of distribution error (8.70%) and recycling error (5.43%) of devices in the observation group were significantly lower than those in the control group (19.77% and 18.60%) (P < 0.05). Centralized management combined with Information system application management effectively improves the cleaning quality and work efficiency of radiology instruments and reusable instruments, indicating long-term application value.

Structural and Optical Properties of Ni-Cu Doped TiO2 Synthesized by Sol-Gel Method

Ni-Cu doped TiO2 nanoparticles as photocatalyst were synthesized by simple sol-gel method. The effect of Ni and Cu doping on TiO2 and their structural and optical properties were analyzed by XRD, FT-IR, SEM-EDS, TEM and UV-DRS techniques. The XRD patterns of calcined nanoparticles showed a monophasic anatase structure with average diameter around 8 nm, which is in close agreement with the TEM results. The surface morphology of the prepared Ni-Cu doped TiO2 nanoparticles were also analyzed by SEM-EDS technique. From UV-DRS analysis, the band-gap energy value of Ni-Cu doped TiO2 nanoparticles was found to be 2.72 eV. The photocatalytic effect of Ni-Cu doped TiO2 nanoparticles as photocatalyst was studied under visible light irradiation through the degradation of Congo red azo dye. The photocatalytic results revealed that Ni-Cu doped TiO2 showed 99.6% degradation efficiency towards Congo red dye, whereas TOC analysis showed a complete mineralization of Congo red dye with minimum degradated byproducts. These results clearly elucidated that the synthesized photocatalyst is practically effective and is recovered easily, thus minimizing the operating costs. Due to the stability of Ni-Cu doped TiO2 nanoparticles, the prepared photocatalyst exhibit high degrading efficiency even after recycled several times.

Microwave hydrothermal synthesis of a Bi2SiO5/Bi12SiO20 heterojunction with oxygen vacancies and multiple charge transfer for enhanced photocatalytic activity

A novel Bi2SiO5/Bi12SiO20 heterojunction photocatalyst was synthesized by microwave hydrothermal synthesis using Bi(NO3)3 and nano-SiO2 as precursors. The as-prepared Bi2SiO5/Bi12SiO20 heterojunction exhibited more efficient charge separation and higher ultraviolet (UV) light photocatalytic activity in the degradation of rhodamine B (Rh-B) and methylene blue (MB). The optimal reaction rate constant of the Bi2SiO5/Bi12SiO20 heterojunction photocatalyst is 3 and 4.3 times higher than that of Bi12SiO20, respectively. Experimental results reveal that the high photocatalytic performance of Bi2SiO5/Bi12SiO20 could be attributed to its larger specific surface area, good crystallinity, smaller particle morphology, and remarkable improvement of charge separation ability via the heterojunctions. The influence of Bi2SiO5/Bi12SiO20 on the charge separation efficiency and optical properties was investigated by electrochemical impedance spectroscopy and photocurrent analysis. Basis on DMPO-ESR spin trapping and radical scavenger experiments, the active species produced from the Bi2SiO5/Bi12SiO20 heterojunction under UV light irradiation were superoxide radicals (O2−) and holes (h+). Additionally, the possible photocatalytic mechanism of the Bi2SiO5/Bi12SiO20 heterojunction was discussed, and finally, a photocatalytic degradation mechanism based on multiple charge transfer channels was proposed. Furthermore, the Bi2SiO5/Bi12SiO20 heterojunction sample still displayed a high photochemical stability even after 5 times of recycling.

Artificial naringinase system for cooperative enzymatic synthesis of naringenin

Naringinase is a kind of glycosidase that catalyzes the biotransformation of naringin into naringenin. It is a multi-compound enzyme that provides the activity of α-L-rhamnosidase and β-glucosidase. In this study, an artificial naringinase system was constructed by co-immobilizing α-L-rhamnosidase (Aspergillus oryzae FJ0123, Ao-rha) and β-glucosidase (Thermotoga maritima MSB8, Tm-glu) on magnetic silica-based chitosan microspheres (MSC). The molar ratio of enzymes and the preparation conditions were optimized for improving synergistic effect and immobilization efficiency. Under optimized conditions (the molar ratio of Ao-rha and Tm-glu, 3:1; temperature, 25 °C; glutaraldehyde concentration, 2.0%; pH, 3.0; time, 9 h), the immobilization yield and activity recovery were 61.4% and 37.3% for Ao-rha and 90.1% and 56.3% for Tm-glu, respectively. Biochemical characterization indicated that MSC-naringinase had better adaptability and stability than free enzymes. The activity of MSC-naringinase was maintained at 58.7% after 10 times of recycling. The catalytic conditions were also investigated. The cascade reactions of naringin to prunin and prunin to naringenin by using MSC-naringinase resulted in a yield of 0.62 mg/mL and a conversion rate of 96.9%, respectively, without prunin accumulation. These results indicated the great potential of MSC-naringinase as an efficient artificial naringinase system for cooperative enzymatic synthesis of naringenin.

Ion release and biocompatibility of Co-Cr alloy fabricated by selective laser melting from recycled Co-Cr powder: An in vitro study

Statement of problemAs the cobalt chromium (Co-Cr) powder used in selective laser melting (SLM) is costly, reusing the remaining powder after multiple cycles provides an economic and environmental benefit. However, knowledge of the cytotoxic effect of the alloy fabricated from recycled powder is lacking. PurposeThe purpose of this in vitro study was to evaluate the biological effects of the Co-Cr ions released from the alloy fabricated from the recycled powder on the human gingival fibroblasts (HGFs) and normal oral keratinocytes (NOKs). Material and methodsDisk-shaped Co-Cr specimens were fabricated by using the SLM technique from powders with different proportions of recycled to unused and from different recycling times. Co and Cr ions released from the disks immersed in the Dulbecco Modified Eagle Medium (DMEM) for 24 hours or 7 days were measured by inductively coupled plasma mass spectrometry (ICP-MS). Biocompatibility of Co-Cr alloy was detected by incubation of HGFs and NOKs in DMEM containing Co and Cr ions for 24 hours. The ANOVA test was used to evaluate statistically significant differences among different groups (α=.05). ResultsCompared with the alloy fabricated from 100% unused powder, the concentrations of Co and Cr ions increased with the increase of recycled to unused powder ratio or with the increase in the recycling times. HGFs and NOKs showed an increase in apoptosis, intracellular oxidative stress (ROS), hypoxia-inducing factor1α (HIF-1α), and proinflammatory cytokines (tumor necrosis factor alpha [TNF- α], interleukin 6 [IL-6], interleukin 8 [IL-8], and vascular endothelial growth factor [VEGF]) with the increase of Co-Cr ions in a concentration-dependent manner. A significant reduction in cell proliferation was found with the increase in the concentrations of Co and Cr ions (P<.05). ConclusionsThe results of this study indicated that Co-Cr alloy fabricated from partially recycled powder or powder with different recycling times released significantly more Co and Cr ions and showed higher cytotoxicity to HGFs and NOKs than the alloy fabricated from unused powder.

One-pot, green and surfactant-less synthesis of polyhedral PdNPs anchored on GO as superior catalyst for reduction of 4-nitrophenol

An aqueous-based, green, one-pot, and surfactant-less method to synthesize highly dispersed Pd nanoparticles (PdNPs) on graphene oxide (GO) nanosheets at room temperature was reported. The Pd/GO nanocomposites display an even distribution of highly-dispersed polyhedral PdNPs at high density onto GO sheets. The number density and size of deposited PdNPs are facilely adjusted by controlling the quantity of GO in the growth solution. The Pd/GO nanocomposites demonstrate a superior catalytic activity with apparent rate constant kapp of 1.057 min−1 and an excellent stability of up to 15 recycle times toward the reduction of 4-nitrophenol (4-NP) without any loss in efficiency. In addition, different factors including the amount of nanocatalysts, GO, ascorbic acid, and the molar ratio of 4-NP vs. NaBH4 also play crucial roles in manipulating the catalytic activities of the as-synthesized Pd/GO nanocomposites. This facile and green synthetic approach combined with their remarkable catalytic activity and durability highlight the potential of the Pd/GO nanocomposites in removal of recalcitrant organic compounds.

Selective removal and recovery of La(III) using a phosphonic-based ion imprinted polymer: Adsorption performance, regeneration, and mechanism

It is significant and difficult to selective removal and recovery rare earth elements in wastewater. A novel La(III) imprinted polymer (La-IIP) was synthesized by taking advantage of the strong interaction between Lanthanum and phosphorus combined the adsorption selectively of ion imprinted technology. The adsorption capacity of La-IIP is 62.8 mg g–1 and the selectivity coefficient kLa/Cu is 54.57. La-IIP can reach adsorption equilibrium within 0.5 h, the adsorption process was well revealed by the Intra-particle diffusion model. The regeneration properties (desorption rate, extent, and recycle times) of La-IIP were investigated. About 88% of the adsorbed La(III) was desorbed in the first 10 min. The high desorption rate was further confirmed in a fixed-bed column experiment. More significantly, the removal efficiency of the La-IIP remained about 100% after five regeneration cycles. Results of FT-IR, XPS, and DFT calculation indicated that the La(III) adsorption by La-IIP involves the reaction between La and O in the phosphonic group. This study not only demonstrated a high adsorption capacity, acid-stable, quick-desorption, and reusable adsorbent for La(III) recovery, but also developed a more comprehensive strategy for the design and testing of adsorbents with practical application prospects.

Preparation and application of embedded and immobilized Achromobacter sp. agent for effective removal of ammonia nitrogen from water.

A novel wastewater-quality-improver, Sodium Alginate Embedded Microbe-treated Zeolite (SAEMZ), was proposed. The strains used are screened from black-odorous water and have high-efficiency NH4+-N degradation performance. The Gram-positive bacteria, belonging to Achromobacter sp., was determined through the screening and identification for this strain, whose removal rate of NH4+-N can reach 88.06%, to decrease the NH4+-N concentration from 61.83 mg/L to 7.80 mg/L, and its optimal growth conditions are pH 7-8, rotation speed 150-210 r/min, temperature 25-35 °C. The SAEMZ's removal effect on NH4+-N was considered in this research from aspects of reusability, storage stability, and the effects of dosage, coexisting ions, and wastewater's concentration. The increase of the SAEMZ's dosage effectively improved the NH4+-N removal rate; Ca2+ in the solution promoted the NH4+-N removal rate, while Mg2+ and Mn2+ inhibited it. Also, the NH4+-N removal rate improved slightly with Fe2+ concentration's increase and then decreased significantly; with the increase of the wastewater dilution factor, the NH4+-N removal rate showed an upward trend and with the increase of the SAEMZ's reuse times, it decreased. Therefore, recycle times should be controlled to less than 3 times in practical application; the SAEMZ still maintains its physiological stability, high mechanical strength, and good storage stability after being stored at 4 °C for 120 days.

The effect of dopped Al3+-Gd3+- Cr3+ on the chemical structure of M−type strontium hexaferrite and investigation on their photocatalysis properties

M−type strontium hexaferrite and substituted derivatives were synthesized via sol–gel auto combustion method with the formula of SrGdx Alx Crx Fe(12-3x) O19 ((x = 0, 0.2, 0.4, 0.6, 0.8)(B0, B1, B2, B3, B4)). The findings of the Fourier-transform infrared spectroscopy (FTIR) spectrum revealed that characteristic peaks between 400 and 560 cm−1 were related to Fe-O bonds at octahedral and tetrahedral sites confirmed the hexaferrite bonding. Moreover, the X-ray diffractometer (XRD) represented that magnetoplumbite hexagonal structure had formed with little impurities. The crystallite sizes of the synthesized nanoparticles (NPs) were also around 42.6–75.4 nm and there is an increase in a lattice parameter from 5.79 to 5.87. The surfaces of the prepared samples were subsequently analyzed through field emission scanning electron microscopy (FESEM) surface images and micrographs illuminated the prepared ferrites have hexagonal structures and EDX spectra represent that all elements are belonging to the prepared composition. Hysteresis loops of SrGdx Alx Crx Fe(12-3x)O19 ((x = 0, 0.2, 0.4, 0.6, 0.8)(B0, B1, B2, B3, B4)) depicted that Ms had decreased in a dramatic manner (from 68.36 to 27.66) as the number of dopants had increased (from 0.0 to 0.8).The c/a confirmed the formation of the hexaferrite. Also, the photocatalysis capability of prepared samples was studied under Visible light and the results declare that Sr Fe12O19 without any dopant shown 60% degradation while SrGd0.8 Al0.8 Cr0.8Fe11.2 O19 has shown the best ability under visible light with a 90% degradation rate. By contrast, SrGd0.8 Al0.8 Cr0.8 Fe11.2 O19 represented the highest photodegradation even after 3 times of recycling.

Electrochemical Dechlorination of 3-chlorophenol with Palladium-Loaded Carbon Felt Electrode

Electrochemical dechlorination with Pd-loaded electrodes offers an effective method for detoxification of wastewater. Electro-reductive dechlorination of 3-chlorophenol (3-CP) with Pd loaded on carbon felt (Pd/CF) was investigated. Pd was loaded on carbon felt by electrolytic method. The prepared electrodes were characterized by XRD, SEM, EDS, S-TEM and CV. The sizes of the Pd particles loaded on CF were found in the range of 100–400 nm. The preparing conditions including loading amount of Pd and loading currents were investigated. Moreover, the reduction conditions including electrolytes, reductive currents and recycle times were also studied. The Pd/CF cathodes with Pd loading of 0.5 mg/cm2, preparing current of 5 mA, electrolyte concentration of 30 mmol/L NaCl and 30 mmol/L CH3COONa were used to reduce 3-CP for dechlorination. When CH3COONa was used as the electrolyte, the current was 5 mA, the initial pH was 7.5, the initial 3-CP concentration was 1 mmol/L and the degradation rate of 3-CP could reach 95.81% after reduction of 150 min under an argon atmosphere. The electrochemical reduction of 3-CP was confirmed to follow the first-order rate law. 3-CP was qualitatively dechlorinated to phenol on electrodes with Pd. The fact that active hydrogen formed on palladium during preliminary electrolysis could be proved by the dechlorinated 3-CP in non-electroreduction after preliminary electrolysis. A possible reduction pathway was proposed based on the results.

Deep desulfurization of model oil using green amino acid ionic liquids combined with H2O2

The sulfur compounds in diesel can cause environmental pollution. As the main component of the sulfide compounds in diesel, dibenzothiophene (DBT) must be removed previously. In this study, 1-alkyl-3-methyl imidazole ionic liquids (ILs) bromic [C n mim]Br (n = 4, 6, 8, 12) were prepared. The phenylalanine, histidine, glycine, tryptophan were used as anions to displace the Br−1 of [C n mim]Br through ion exchange resin to get the amino acid ionic liquids for deep removal of DBT from model oil in the presence of H2O2. The results show that the desulfurization of 1-octyl-3-methyl phenylalanine imidazole ionic liquid [C8mim]Phe is higher than that of [C8mim]His, [C8mim]Gly, and [C8mim]Trp. The effect of temperature, the volume ratio of H2O2/model oil, and time on desulfurization of [C8mim]Phe combined with H2O2 was studied. The response surface analysis was used to seek the optimal desulfurization process parameters of the [C8mim]Phe combined with H2O2. Repeated experiments of DBT removal by [C8mim]Phe combined with H2O2 from model oil were conducted under the optimized conditions. The desulfurization of [C8mim]Phe combined with H2O2 was declined from 97.4% to 93.4% after 8 recycle times. Meanwhile, the oxidation-extraction desulfurization mechanism of [C8mim]Phe combined with H2O2 was confirmed by Fourier transform infrared spectroscopy (FT-IR) and liquid chromatography-mass spectrometry (LC-MS).

Amidoxime-functionalized covalent organic framework as simultaneous luminescent sensor and adsorbent for organic arsenic from water

Organoarsenic compounds are widely used as feed additives in the poultry industry. However, the release of organoarsenic-containing wastewater can cause serious poisoning to the ecosystem. For this reason, detection and adsorption of organic arsenic from wastewater is crucial but also very challenging. Here, the use of covalent organic frameworks (COFs) as fluorescence sensors and adsorbents for the detection and adsorption of organic arsenic from water has been investigated for the first time. Two isoreticular crystalline and highly porous sp2 carbon-conjugated COFs were synthesized, and amidoxime-functionalized via post-synthetic modification (PSM). The long-range order and π-conjugated system ensure that both COFs act as fluorescent sensors for detecting the representative organic arsenic, roxarsone (ROX). The fluorescence quenching efficiencies of ROX on both COFs are over 98%. The limits of detection (LOD) for ROX by both COFs are estimated to be 6.5 and 12.3 nM. Additionally, the regular pores and the abundantly decorated amidoxime moiety exhibit extraordinary accessibility, which facilitates the adsorption of ROX. High adsorption capacities were obtained for both materials which amounts are up to 732 and 787 mg g−1. After five times of recycling, a negligible decrease in the adsorption capacity was noted, which reveals the excellent regeneration ability of those two amidoxime-functionalized COFs. These results indicate that the state-of-the-art sp2 carbon-conjugated amidoxime-functionalized COFs exhibit a high potential for the practical detection and adsorption of organoarsenic compounds from wastewater.