酸改性泥炭对含亚甲基蓝废水的吸附净化作用

采用稀硝酸对泥炭进行改性处理获得酸改性泥炭,并将其用于处理亚甲基蓝废水。考察初始溶液pH、接触时间、酸改性泥炭投加量和亚甲基蓝溶液初始浓度等因素对酸改性泥炭吸附效果影响。结果表明,初始溶液pH、接触时间、酸改性泥炭投加量和亚甲基蓝溶液初始浓度对酸改性泥炭吸附性能都有一定的影响。在最佳的反应条件下(接触时间为60 min,反应温度为35℃,初始溶液pH为7.12,酸改性泥炭投加量为2 g),亚甲基蓝去除率可达90.88%,其吸附较好地符合Freundlich和Langmuir等温方程,拟合相关系数均大于0.9。通过热力学计算发现,ΔG<0、ΔS>0,表明该吸附反应是自发的、吸热反应。且该吸附过程符合准二级动力学方程(R2=0.98)。     

葛根去除水溶液中亚甲基蓝的生物吸附机理和特性

对农副产品葛根吸附水溶液中亚甲基蓝的特性和机理进行了一系列的研究。考察了不同条件对吸附效果的影响;采用2种等温线模型和3种动力学模型对吸附机理和动力学特性进行了模拟分析,并计算了相关的热力学函数。结果发现,溶液pH值等实验条件对吸附效果有较大的影响;Langmuir方程能很好地描述其吸附等温线,吸附是一个符合二级动力学过程的物理吸附;热力学函数计算结果显示,此吸附是一个自发的放热过程。在3种不同温度下,由Langmuir方程计算的最大吸附量为98.23、91.04和87.28 mg/g,表明葛根是一种良好的,具有一定发展潜力的染料吸附剂。     

Green synthesis of silver nanoparticles by microorganism using organic pollutant: its antimicrobial and catalytic application

A novel approach for the green synthesis of silver nanoparticles (AgNPs) from aqueous solution of AgNO₃ using culture supernatant of phenol degraded broth is reported in this work. The synthesis was observed within 10 h, and AgNPs showed characteristic surface plasmon resonance around 410 nm. Spherical nanoparticles of size less than 30 nm were observed in transmission electron microscopy. X-ray diffraction pattern corresponding to 111, 200, 220, and 311 revealed the crystalline nature of the as-formed nanoparticles. It was found that the colloidal solution of AgNP suspensions exhibited excellent stability over a wide range of ionic strength, pH, and temperature. The effect of pH and ionic strength indicated that stabilization is due to electrostatic repulsion arising from the negative charge of the conjugate proteins. The AgNPs showed highly potent antimicrobial activity against Gram-positive, Gram-negative, and fungal microorganisms. The as-prepared AgNPs showed excellent catalytic activity in reduction of 4-nitrophenol to 4-aminophenol by NaBH₄. By manufacturing magnetic alginate beads, the reusability of the AgNPs for the catalytic reaction has been demonstrated.     

Assessing the effectiveness of green synthetized silver nanoparticles with Cryptocarya alba extracts for remotion of the organic pollutant methylene blue dye

Environmental Science and Pollution Research - In the present work, silver nanoparticles (AgNPs) synthetized with Cryptocarya alba (Peumo) leaf extract were studied. The fabrication method was...     

Photodegradation of gaseous acetaldehyde and methylene blue in aqueous solution with titanium dioxide-loaded activated carbon fiber polymer materials and aquatic plant ecotoxicity tests

TiO₂-supported activated carbon felts (TiO₂–ACFTs) were prepared by dip coating of felts composed of activated carbon fibers (ACFs) with either polyester fibers (PS-A20) and/or a polyethylene pulp (PE-W15) in a TiO₂ aqueous suspension followed by calcination at 250 °C for 1 h. The as-prepared TiO₂–ACFTs with 29–35 wt.% TiO₂ were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and N₂ adsorption. The TiO₂–ACFT(PS-A20) samples with 0 and 29 wt.% TiO₂ were microporous with specific surface areas (S _BET) of 996 and 738 m²/g, respectively, whereas the TiO₂–ACFT(PE-W15) samples with 0 and 35 wt.% TiO₂ were mesoporous with S _BET of 826 and 586 m²/g, respectively. Adsorption and photocatalytic activity of the as-prepared samples were evaluated by measuring adsorption in the dark and photodegradation of gaseous acetaldehyde (AcH) and methylene blue (MB) in aqueous solution under UV light. The TiO₂ loading caused a considerable decrease in the S _BET and MB adsorption capacity along with an increase in MB photodegradation and AcH mineralization. Lemna minor was chosen as a representative aquatic plant for ecotoxicity tests measuring detoxification of water obtained from the MB photodegradation reaction with the TiO₂–ACFT samples under UV light.     

Rapid and efficient removal of Ni2+ from aqueous solution by the one-pot synthesized EDTA-modified magnetic nanoparticles

A facile one-pot process has been proposed to prepare the novel ethylenediaminetetraacetic acid (EDTA)-modified magnetite nanoparticles (EDTA-MNPs). The bared Fe₃O₄ magnetite nanoparticles and EDTA-MNPs were characterized using FTIR spectroscopy, TEM, VSM, and X-ray diffraction. The application of the modified magnetite nanoparticles for metal ion uptake was studied using Ni²⁺ as a model. The adsorption was fast and the equilibrium was established within 5 min, and the adsorption kinetics of Ni²⁺ onto EDTA-MNPs followed the pseudo second-order chemisorption mechanism. Maximum adsorption capacity for Ni²⁺ reached as high as 41.3 mg/g at pH 6. The successive adsorption–desorption studies indicated that the EDTA-MNPs kept the adsorption and desorption efficiencies constant over ten cycles. Importantly, EDTA-MNPs were able to remove nearly 100 % of Ni²⁺ from real water.     

Porous material based on modified carbon and the effect of pore size distribution on the adsorption of methylene blue dye from an aqueous solution

Environmental Science and Pollution Research - Carbon porous materials obtained through KOH activation of a furfural?+?hydroquinone?+?urotropine mixture were applied as...     

纳米钯?铝双金属对水中3-氯酚的脱氯降解研究

采用置换沉积法制备了纳米钯/铝双金属催化剂,氢解还原去除水相中难降解有毒有机物3-氯酚(3-CP),考察了溶液pH、钯负载量、纳米钯/铝双金属投加量、反应温度对脱氯效果的影响并解析相关反应机制。结果表明:(1)初始pH 3.0时,沉积液中93.25%(质量分数,下同)～96.67%的钯可有效负载于铝材上。(2)在pH为3.0、纳米钯/铝双金属投加量为2g/L、钯负载量为1.16%(质量分数)、反应温度为25℃下降解初始摩尔浓度为0.389mmol/L的3-CP,反应终了时脱氯率在99%以上。利用纳米钯/铝双金属降解氯代有机污染物具有高效低耗的优势,在实际应用上具有较好的前景。     

Gadolinium nanoparticle-decorated multiwalled carbon nanotube/titania nanocomposites for degradation of methylene blue in water under simulated solar light

Gadolinium oxide nanoparticles of diameters <5 nm were uniformly decorated on the surfaces of multiwalled carbon nanotubes which were subsequently used as templates to fabricate gadolinium oxide nanoparticle-decorated multiwalled carbon nanotube/titania nanocomposites. The prepared nanocomposites were evaluated for the photocatalytic degradation of methylene blue under simulated solar light irradiation. Higher photocatalytic activity was observed for the gadolinium oxide-decorated multiwalled carbon nanotube-based nanocomposites compared to the neat multiwalled carbon nanotube/titania nanocomposite and commercial titania. This improvement in photocatalytic activity was ascribed to the gadolinium oxide nanoparticles supported at the interface of the carbon nanotubes and titania resulting in efficient electron transfer between the two components of the composite. Total organic carbon (TOC) analysis revealed a higher degree of complete mineralisation of methylene blue (80.0 % TOC removal) which minimise the possible formation of toxic by-products. The photocatalyst could be re-used for five times, reaching a maximum degradation efficiency of 85.9 % after the five cycles. The proposed photocatalytic degradation mechanism is outlined herein.     

微波辐射回用活性炭对水中亚甲基蓝和Cd~(2+)去除效果的研究

考察了微波-活性炭联合处理技术对模拟染料废水中亚甲基蓝和Cd2+的去除效果。对于100 mL浓度为1 000 mg/L的亚甲基蓝溶液、活性炭用量为10 g时,新活性炭对亚甲基蓝的去除率为99.99%;采用700 W微波对吸附亚甲基蓝的活性炭辐射10 min进行再生并回用,经微波辐射再生10次后活性炭对亚甲基蓝的去除率为99.68%,未经微波作用反复使用10次的活性炭对亚甲基蓝的去除率为85.41%。结果表明:微波处理有效地减缓了活性炭吸附能力的下降速率,实现了活性炭再生和反复使用。在吸附过程中,Cd2+使活性炭对亚甲基蓝的吸附能力略有下降,而共存的亚甲基蓝则促进了活性炭对Cd2+的吸附,对新炭和再生后活性炭物理化学特性的表征证明了活性炭对亚甲基蓝的吸附为物理吸附,对Cd2+的吸附为化学吸附。     

Green synthesis of zinc oxide nanoparticles loaded on activated carbon prepared from walnut peel extract for the removal of Eosin Y and Erythrosine B dyes from aqueous solution: experimental approaches,kinetics models,and thermodynamic studies

Environmental Science and Pollution Research - Water contamination due to release of dye containing effluents is one of the environmental problems of serious concern today. The present study...     

微波诱导改性活性炭催化降解邻苯二甲酸二甲酯

通过HNO3、H2O2、NaOH对活性炭进行浸渍改性,采用BET、SEM、Boehm、FT-IR对改性前后的活性炭进行表征,研究了改性前后的活性炭在不同反应体系对DMP的降解效果和动力学,探讨了微波诱导改性前后的活性炭催化降解DMP的机理。结果表明,3种改性活性炭的BET比表面积、总孔容、微孔孔容和平均孔径均有所增加。HNO3、H2O2改性后表面酸性基团增加、碱性基团减少,而NaOH改性呈现相反的理化特征变化。活性炭理化特征的变化可能与化学改性剂溶液的酸碱性、氧化还原性有关。微波诱导改性前后的活性炭催化体系对DMP的降解率大于单独吸附或单纯微波辐射体系,且均符合一级反应动力学。在微波诱导改性前后的活性炭催化体系中,改性前后的活性炭通过表面吸附-微波诱导氧化协同作用极大地提高了对DMP的降解率。     

4A沸石去除水中Pb~(2+)的研究

在静态条件下,研究了4A沸石对废水中Pb2+的吸附性能,并探讨了影响吸附的因素。实验表明:当温度为30℃,废水pH为5~6,0.01 g4A沸石对100 mg/LPb2+溶液10 mL吸附20 min,Pb2+的去除率可达到99%以上。在实验研究条件下,4A沸石对Pb2+的吸附符合Langmuir和Freundlich等温吸附方程,相关系数为0.9819和0.9998。经计算,4A沸石对Pb2+的饱和吸附量为125 mg/g。4A沸石吸附水中Pb2+,达到吸附平衡的时间较短;溶液pH值的变化对吸附效果影响不显著;温度从室温略微升高,Pb2+的去除率略有增大。吸附在4 A沸石上的Pb2+可回收利用,处理后的4A沸石可以再生,且重复使用性能较好。     

Synergistic effect and degradation mechanism on Fe-Ni/CNTs for removal of 2,4-dichlorophenol in aqueous solution

Environmental Science and Pollution Research - Fe-Ni bimetallic nanoparticles supported on CNTs (Fe-Ni/CNTs) were synthesized, characterized, and applied for removal of 2,4-dichlorophenol (2,4-DCP)...     

Temperature-responsive graphene oxide/N-isopropylacrylamide/2-allylphenol nanocomposite for the removal of phenol and 2,4-dichlorophenol from aqueous solution

In this study, a novel thermo-responsive polymer was synthesized with efficient grafting of N-isopropylacrylamide as a thermosensitive polymer onto the graphene oxide surface for the efficient removal of phenol and 2,4-dichlorophenol from aqueous solutions. The synthesized polymer was conjugated with 2-allylphenol. Phenol and 2,4-dichlorophenol were monitored by ultra-performance liquid chromatography system equipped with a photodiode array detector. The nanoadsorbent was characterized by different techniques. The nanoadsorbent revealed high adsorption capacity where the removal percentages of 91 and 99% were found under optimal conditions for phenol and 2,4-dichlorophenol, respectively (for phenol; adsorbent dosage = 0.005 g, pH = 8, temperature= 25 °C, contact time = 60 min; for 2,4-dichlorophenol; adsorbent dosage = 0.005 g, pH = 5, temperature = 25 °C, contact time = 10 min). Adsorption of phenol and 2,4-dichlorophenol onto nanoadsorbent followed pseudo-second-order kinetic and Langmuir isotherm models, respectively. The values of ΔG (average value = ? 11.39 kJ mol^?1 for phenol and 13.42 kJ mol^?1 for 2,4-dichlorophenol), ΔH (? 431.72 J mol^?1 for phenol and ? 15,721.8 J mol^?1 for 2,4-dichlorophenol), and ΔS (35.39 J mol^?1 K^?1 for phenol and ? 7.40 J mol^?1 K^?1 for 2,4-dichlorophenol) confirmed spontaneous and exothermic adsorption. The reusability study indicated that the adsorbent can be reused in the wastewater treatment application. Thermosensitive nanoadsorbent could be used as a low-cost and efficient sorbent for phenol and 2,4-dichlorophenol removal from wastewater samples.

     

Rapid biological synthesis of silver nanoparticles using <Emphasis Type="Italic">Leucas martinicensis</Emphasis> leaf extract for catalytic and antibacterial activity

A novel green approach for the synthesis and stabilization of silver nanoparticles (AgNPs) using water extract of Leucas martinicensis leaf has been developed. As obtained, the nanoparticles are characterized by UV-visible (UV-Vis), transmission electron microscope (TEM), and X-ray diffraction (XRD). The crystalline nature of the AgNPs is confirmed by the prominent peaks in the XRD pattern. FTIR spectra suggest that the possible biomolecules are responsible for the efficient stabilization of the sample. The effects of leaf quantity on the biosynthesis of AgNPs are investigated by UV-Vis spectrophotometer. The synthesized AgNPs are observed to have a good catalytic activity on the reduction of methylene blue by L. martinicensis leaf. This is confirmed by the decrease in absorbance maximum values of methylene blue with respect to time through UV-Vis spectrophotometer. Moreover, the antibacterial activity of synthesized AgNPs against Staphylococcus aureus, Bacillus subtilis, Salmonella typhi, and Escherichia coli are screened.     

Cyclodextrin inclusion: catalytic effects on the degradation of organophosphorus pesticides in neutral aqueous solution.

alpha-, beta and gamma-Cyclodextrins were found to have promotive inclusion-catalytic effects on the degradation of organophosphorus pesticides solubilized in neutral aqueous media. Pesticide degradations were especially accelerated in such systems as alpha-cyclodextrin plus diazinon and beta-cyclodextrin plus chloropyrifos. The above findings are in contrast with the inhibitive catalytic effects of cyclodextrins on pesticide degradations in alkaline media. Cyclodextrin catalytic effects found here were considerably affected by differences in the substitutional and hetero-cyclic properties of the aromatic rings of pesticides and also by the sizes of cyclodextrin cavities.     

The interaction "light, Fe(III)" as a tool for pollutant removal in aqueous solution: degradation of alcohol ethoxylates

The photoinduced degradation of an alcohol ethoxylate (AE) (Brij 30) by Fe(III) in aqueous solution has been investigated. The study was carried out with the major fraction of ethoxymers having an alkyl chain length of 12 carbon atoms and n ethoxy units E (C12En). The Fe(III) sensitised degradation of this fraction occurs efficiently at 365 nm. The rate of degradation depends on the concentration of Fe(OH)2+, the most photoreactive species in terms of .OH radical formation. Formate ethoxylates were identified as photoproducts and shortening of the ethoxylated chain all along the degradation process was observed. The mechanism of Brij 30 degradation implies a major .OH radicals attack on the polyethoxylated chain. For prolonged irradiations, the total degradation of Brij 30 and of the photoproducts is obtained. Consequently, the degradation photoinduced by iron (III) could be an efficient method of AEs removal in water.     

Catalytic activity of Ru/Al2O3 for ozonation of dimethyl phthalate in aqueous solution

With dimethyl phthalate as the model pollutant and Ru/Al(2)O(3) as catalyst, this paper systemically investigates the removal of total organic carbon (TOC) of system. Our results have confirmed that Ru/Al(2)O(3) can significantly increase the effect of ozonation. TOC removal in 120 min can reach 72% while only 24% with ozone alone. The optimal catalyst preparing condition was 0.1 wt% Ru content, 600 degrees C calcination temperature, 0.5-1.0mm particle diameter, which is characterized by a high surface area and a large population of surface active sites. The contrasting experiments of ozone alone, catalyst adsorption after ozonation, and catalytic ozonation confirmed that catalytic reaction was the most important process to TOC removal in system with Ru/Al(2)O(3) as catalyst.