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1.
J Environ Manage ; 284: 112024, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33548751

RESUMO

The presence of moderate concentrations of impurities in the nickel-plating baths generates failures on the coated pieces. This situation entails the necessity of replacing the electroplating bath, which implies the generation of large volumes of wastewater with metallic species and high quantity of sludge. For this reason, the adsorption of the principal impurities of nickel-plating baths of an industry was analyzed in this work. Particularly, the removal of Zn2+ was studied in more detail since the presence of this metal in the baths generates black spots on the coated pieces. Different commercial materials were used as adsorbents and Zn2+ adsorption studies were carried out using both standard solutions and industrial water from the nickel-plating baths. All the adsorption tests were performed in batch systems under constant agitation and the quantification of the impurities was made by ICP-MS analysis. The bone char (BC) was an efficient adsorbent for the removal of the principal impurities of nickel-plating baths. The use of molecular simulation tools helped to understand the preferences of the hydroxyapatite (the principal component of bone char) for different metallic ions present in the industrial waters. According to both the experimental adsorption and molecular simulation results, hydroxyl and phosphate groups of bone char are responsible of the adsorption of impurities of nickel-plating baths.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Adsorção , Banhos , Galvanoplastia , Níquel/análise , Poluentes Químicos da Água/análise
2.
Ecotoxicol Environ Saf ; 208: 111735, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396064

RESUMO

The transformation between hexavalent chromium (Cr6+) and trivalent chromium (Cr3+) has a significant impact on ecosystems, as Cr6+ has higher levels of toxicity than Cr3+. In this regard, a variety of Cr6+ reduction processes occurring in natural environments have been studied extensively. In this work, we investigate the reductive transformation of Cr6+ by ferrous ions (Fe2+) in ice at -20 °C, and compare the same process in water at 25 °C. The Fe2+-mediated reduction of Cr6+ occurred much faster in ice than it did in water. The accelerated reduction of Cr6+ in ice is primarily ascribed to the accumulation of Cr6+, Fe2+, and protons in the grain boundaries formed during freezing, which constitutes favorable conditions for redox reactions between Cr6+ and Fe2+. This freeze concentration phenomenon was verified using UV-visible spectroscopy with o-cresolsulfonephthalein (as a pH indicator) and confocal Raman spectroscopy. The reductive transformation of Cr6+ (20 µM) by Fe2+ in ice proceeded rapidly under various Fe2+ concentrations (20-140 µM), pH values (2.0-5.0), and freezing temperatures (-10 to -30 °C) with a constant molar ratio of oxidized Fe2+ to reduced Cr6+ (3:1). This result implies that the proposed mechanism (i.e., the redox reaction between Cr6+ and Fe2+ in ice) can significantly contribute to the natural conversion of Cr6+ in cold regions. The Fe2+-mediated Cr6+ reduction kinetics in frozen Cr6+-contaminated wastewater was similar to that in frozen Cr6+ solution. This indicates that the variety of substrates typically present in electroplating wastewater have a negligible effect on the redox reaction between Cr6+ and Fe2+ in ice; it also proposes that the Fe2+/freezing process can be used for the treatment of Cr6+-contaminated wastewater.


Assuntos
Cromo/química , Congelamento , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Cromo/análise , Ecossistema , Galvanoplastia , Ferro/química , Cinética , Oxirredução , Águas Residuárias/química , Água/química , Poluentes Químicos da Água/análise
3.
J Environ Manage ; 277: 111370, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32979751

RESUMO

Present study investigated the Cu2+ removal potential of Trichoderma lixii CR700, isolated from enormously heavy metal polluted electroplating wastewater. In the batch study, actively growing CR700 was able to remove 84.6% of Cu2+ at the concentration 10 mg/L of Cu2+ within 120 h after incubation and the accumulated and surface adsorbed amount of Cu was 0.51 and 0.47 mg/g of dry biomass respectively. T. lixii CR700 also showed efficient Cu2+ removal potential in the pH ranges from 5.0 to 8.0, in the presence of other co-occurring contaminant such as heavy metal, anions and metabolic inhibitor as well from real tannery wastewater. Alteration on cell surface of Cu2+ treated mycelia of T. lixii CR700 was analyzed using scanning electron microscope. Fourier transform infrared spectroscopic analysis was performed to identify the role of surface functional group in Cu2+ adsorption which revealed that COO─ functional group lead Cu2+ adsorption onto the surface of T. lixii CR700. Thus, T. lixii CR700 uses simultaneous surface sorption and accumulation mechanism in Cu2+ removal and can be potentially applied for bioremediation of Cu2+ contaminated wastewater in ecofriendly, safe and sustainable way.


Assuntos
Trichoderma , Poluentes Químicos da Água , Adsorção , Biodegradação Ambiental , Cobre , Galvanoplastia , Concentração de Íons de Hidrogênio , Águas Residuárias
4.
Chemosphere ; 263: 128208, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33297167

RESUMO

The low concentration of nickel in electroplating wastewater is difficult to treat to meet the discharge standard. In this study, a commercial cation exchange membrane was used to combine the electrodialysis on a titanium plate anode sintered ruthenium-iridium and the electrodeposition on a stainless steel cathode to reduce the nickel concentration to less 0.1 mg L-1. The electrolytic properties of the electrodialysis combined with the electrodeposition were investigated at different cell voltages, electrolysis time, initial electrolyte pH, electrolyte flow rates and initial Ni2+ concentrations. The results indicated that the Ni2+ concentration in the anolyte and the catholyte could be reduced to 0.015 and 0.085 mg L-1, respectively, with the initial Ni2+ concentration of 1.0 mg L-1, which could meet the most strict Ni2+ discharge standard of 0.1 mg L-1. The electrodeposition of Ni2+ on the cathode enhanced the migration of the Ni2+ in the electrolytes, which was beneficial to decrease the energy consumption. Therefore, the combination of electrodialysis and electrodeposition was promising to reduce the low concentration of Ni2+ in the electroplating wastewater.


Assuntos
Galvanoplastia , Águas Residuárias , Eletrólise , Íons , Níquel/análise , Águas Residuárias/análise
5.
Chemosphere ; 262: 128031, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182077

RESUMO

In this research, raw jujube seeds (RJS) treated with sulphuric acid followed by ultrasonic treatment such as ultrasonic assisted jujube seeds (UAJS) based biochar have been experimented as a viable material for treating Zn(II) and Pb(II) contaminated water. The adsorption ability of UAJS was compared with RJS through Langmuir adsorption capacity. The produced adsorbents were analysed by using BET surface area and thermogravimetric analyses. The removal kinetics, isotherms and thermodynamic behaviours of metal ions adsorption by UAJS were studied. Adsorption equilibrium data were analysed using various equilibrium models and Freundlich isotherm was appropriate towards explain the adsorption characteristics. UAJS Langmuir capacity of 221.1 mg/g and 119.8 mg/g were obtained for Zn(II) ions and Pb(II) ions, respectively. The results observed that UAJS holds higher capacity as compared with RJS. The pseudo-first order model was relevant to address adsorption behaviour. The mechanism on the separation of metal ions by UAJS was tested using diffusion and Boyd models. The mechanism outcomes observed that the internal and external diffusion controlled the separation process. The thermodynamic results explain the separation process was viable, exothermic and natural. The electroplating industrial wastewater was also treated with UAJS biochar to remove the metal ions such as copper, nickel, chromium and zinc ions from wastewater. Desorption process showed that 0.1 N HCl provide the good results as compared with other desorbing agents. The adsorbent property is not lost till the maximum of 5 adsorption/desorption cycles. The produced UAJS can be a better adsorbent for treating the heavy metal polluted wastewater.


Assuntos
Carvão Vegetal/química , Galvanoplastia , Metais Pesados/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Difusão , Íons , Cinética , Sementes/química , Termodinâmica , Ziziphus/química
6.
Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi ; 38(10): 782-786, 2020 Oct 20.
Artigo em Chinês | MEDLINE | ID: mdl-33142389

RESUMO

Objective: To explore the applicability of different exposure assessment methods in occupational health risk assessment of trichloroethylene (TCE) occupation posts in electroplating enterprise. Methods: In November 2018, the occupational health risk assessments are conducted in trichloroethylene (TCE) occupation posts of 6 metal plating enterprises in a street in Shenzhen by using the qualitative risk assessment, semi-quantitative risk assessment (including contact ratio method, contact index method and synthesis index method) and quantitative risk assessment method (including non-carcinogenic and carcinogenic risk assessment methods) , and the results of different methods are compared. Results: The results of qualitative assessment method are all level 4 (high risk) ; the results of contact ratio method show that the risk level is level 5 (very high risk) ; the results of contact index method and Synthesis index method show that the risk level is level 3 and level 4, 66.7% and 33.3% respectively; Non-carcinogenic risk assessment results show that TCE jobs are "unacceptable"; carcinogenic risk assessment results in carcinogenic inhalation excess risk of 50% each being "unacceptable" and "acceptable". The results of the six risk assessment methods showed that there were 3 "substantially consistent", 1 "partially consistent", and 2 "inconsistent" among the 6 companies. Conclusion: Synthesis index method and the carcinogenic risk assessment method are more suitable for occupational health risks of TCE occupation posts.


Assuntos
Exposição Ocupacional , Saúde do Trabalhador , Tricloroetileno , Galvanoplastia , Medição de Risco
7.
Chemosphere ; 261: 128157, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33113652

RESUMO

Porous titanium-based PbO2 electrodes were successfully fabricated by pulse electrodeposition method. The primary pulse electrodeposition parameters, including pulse frequency (f), duty ratio (γ), average current density (Ja) and electrodeposition time (t) were considered in this study. An orthogonal experiment was designed based on those four factors and in three levels. SEM images and XRD results suggest that the surface morphology and structure of PbO2 electrodes could be easily changed by varying pulse electrodeposition parameters. Orthogonal analysis reveals that the increase of f and Ja could decrease the average grain size of PbO2 electrodes, which is conducive to create more active sites and promote the generation of hydroxide radicals. The electrochemical degradation of Azophloxine was carried out to evaluate the electrochemical oxidation performance of pulse electrodeposited electrodes. The results indicate that the influences of four factors can be ranked as follow: Ja >γ≈ t > f. The higher f, larger Ja and longer t could facilitate the optimization of the integrated electrochemical degradation performance of prepared PbO2 electrode. The accelerated life time is dominated by Ja and t, coincident with the average weight increase of ß-PbO2 layer. The optimal parameters of pulse electrodeposition turn out to be: f = 50 Hz, γ = 30%, Ja = 25 mA cm-2, t = 60 min. Together, the consequences of the experiments give assistance to uncover and roughly conclude the mechanism of pulse electrodeposition.


Assuntos
Galvanoplastia/métodos , Chumbo/química , Modelos Teóricos , Óxidos/química , Titânio/química , Compostos Azo/análise , Eletrodos , Naftalenossulfonatos/análise , Oxirredução , Porosidade , Propriedades de Superfície , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos
8.
J Environ Manage ; 276: 111357, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32932072

RESUMO

A Cu/GO/Ti electrode was prepared by electrodeposition for removal of nitrate by means of the electrochemical reduction. The structure, morphology and characteristics of the electrode were characterized by scanning electron microscopy (SEM), Raman spectroscopy (RS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical workstation, and Cu/GO/Ti was used as the cathode to remove nitrate in water by electrochemical process. Characterization results indicated that GO was successfully deposited on the Ti plate and it was partially reduced to reduced graphene. Dendritic and granular Cu particles are agglomerated on the surface of GO layer by chemical interaction in the form of metallic Cu, Cu2O and CuO, and the dendrite Cu layer increased the specific surface area of Cu layer. The addition of GO layer increases the electroreduction activity for nitrate. Furthermore, through comparison with Cu/Ti electrode, Cu/GO/Ti electrode improved the percentage of nitrate removal from 78.8% to 91.5%, and energy consumption decreased from 0.82 to 0.47 kW h/g NO3--N. The present results showed the promising application of GO-based electrodes with Cu in electrocatalytic nitrate removal.


Assuntos
Galvanoplastia , Titânio , Eletrodos , Nitratos , Óxidos de Nitrogênio
9.
J Environ Manage ; 274: 111153, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32784081

RESUMO

In this study, cellulose sulfate was synthesized through sulfonation of cotton, and polypyrrole was coated on the surface of fibers. Then, the optimum ratio of pyrrole to cellulose sulfate was evaluated, and the physical, chemical, and morphological properties of the composite were assessed by using FESEM, EDS, FTIR, BET, and TGA analysis. Furthermore, adsorption of hexavalent chromium using the composite adsorbent was studied by the results of designed experiments with the Box-Behnken technique to assess the effect of pH, contact time, adsorbent dose and the initial concentration of hexavalent chromium and optimize the adsorption process. The removal percentage was 99.9% under the optimum conditions (adsorbent dose, 4 g L-1; initial concentration of Cr(VI), 200 mg L-1; pH value, 2; contact time, 200 min). The results of adsorption isotherms illustrated that the adsorption process followed Redlich-Peterson, Freundlich, Radke-Prausnitz, and UT models, and the calculated maximum adsorption capacity by the Langmuir model was 198 mg g-1. Based on the kinetic and thermodynamic studies, the adsorption process followed the intraparticle diffusion model and showed the endothermic and spontaneous adsorption with an increase in entropy on the adsorbent surface. The presence of copper, nickel and zinc cations had no adverse effect on the removal percentage of hexavalent chromium significantly. The adsorbent was reused successfully in four sequential treatments. Consequently, the synthesized adsorbent is efficient due to the high efficiency of hexavalent chromium removal percentage from electroplating effluent (99.87%).


Assuntos
Águas Residuárias , Poluentes Químicos da Água/análise , Adsorção , Celulose/análogos & derivados , Cromo/análise , Galvanoplastia , Concentração de Íons de Hidrogênio , Cinética , Polímeros , Pirróis , Termodinâmica
10.
J Chromatogr A ; 1628: 461486, 2020 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-32822970

RESUMO

In this work, an inexpensive, fast, and selective ionic liquid modified graphene oxide (GO-IL) was synthesized and electrochemically deposited on the inner surface of a stainless-steel tube. Then, it was applied for circulated headspace in-tube solid-phase microextraction (CHS-IT-SPME) of naphthalene from honey samples. Next, the coated tube was replaced with the sample loop of a six-port injection valve for on-line desorption and further HPLC-UV analysis of naphthalene. The sorbent was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDX). Different parameters affecting the procedure efficiency, including extraction temperature, extraction time, salt concentration, and sample volume were optimized by central composite design and response surface methodology. Under the optimum conditions, the calibration curve was linear within the range of 0.3-200 ng mL-1, with a regression coefficient of 0.9972. The limits of detection (LOD) and quantification (LOQ) were found to be 0.1 ng mL-1 and 0.3 ng mL-1, respectively. Intra-day and inter-day RSDs% for three replicate measurements of naphthalene at the concentration of 10 ng mL-1 were obtained 3.9% and 5.0%, respectively. Also, good tube-to-tube reproducibility of 5.3% was achieved. Finally, the method was successfully applied for measuring trace amounts of naphthalene in honey samples. Relative recoveries were calculated within the range of 90.0-106.5%, indicating excellent efficiency of the proposed method.


Assuntos
Cromatografia Líquida/métodos , Galvanoplastia/métodos , Grafite/química , Mel/análise , Líquidos Iônicos/química , Naftalenos/isolamento & purificação , Sistemas On-Line , Microextração em Fase Sólida/métodos , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Reprodutibilidade dos Testes
11.
Chemosphere ; 260: 127546, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32758765

RESUMO

Hexavalent chromium [Cr (Ⅵ)] has extensive applications in industries, and long-term occupational exposure to Cr (Ⅵ) may lead to lung carcinoma and other cancers. While microRNA (miRNA) can take part in carcinogenesis, little is known about its expression profile in the population with Cr (Ⅵ) exposure. Thus, this study aimed to explore miRNA expression profiles in Cr (Ⅵ) exposed workers and to identify the potential biological function of differentially expressed miRNAs. A total of 45 significant differentially expressed miRNAs were identified by the miRNA array. The results of validation showed that miR-19a-3p, miR-19b-3p, and miR-142-3p were downregulated and miR-590-3p and miR-941 were upregulated in the exposure group. Multivariate analysis demonstrated that age, exposure duration and urinary chromium level were associated with one or more miRNAs expression. Target gene analysis indicated that these miRNAs might participate in the regulation of DNA damage-related signaling pathways. Taken together, Cr (Ⅵ) exposure can result in differential expression of miRNAs in occupational workers, and the expression of these miRNAs is correlated with the level and duration of Cr (Ⅵ) exposure, and the differentially expressed miRNAs may participate in DNA damage response.


Assuntos
Cromo/toxicidade , Galvanoplastia , Exposição Ocupacional/análise , Carcinogênese , Estudos de Casos e Controles , Cromo/análise , Dano ao DNA , Regulação para Baixo , Perfilação da Expressão Gênica , Humanos , Neoplasias Pulmonares , Masculino , MicroRNAs/genética , Pessoa de Meia-Idade , Transdução de Sinais , Regulação para Cima
12.
Chemosphere ; 259: 127488, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32640376

RESUMO

A Ce-doped Ti/PbO2 electrode was prepared in a deposition solution containing Ce3+ and Pb2+ ions by electrodeposition, and the surface morphology, crystal structure and elemental states were characterized by SEM, XRD and XPS. The electrode was used to investigate the simultaneous degradation of three phthalate esters (PAEs), i.e., dimethyl phthalate (DMP), diethyl phthalate (DEP) and dibutyl phthalate (DBP) in synthetic wastewaters. The results showed that the electrode exhibited excellent electrocatalytic activity and good reusability and stability, and the removal efficiencies of 5 mg L-1 DBP, DMP and DEP in 0.05 M Na2SO4 (pH 7) reached 98.2%, 95.8% and 81.1% at current density of 25 mA cm-2 after 10 h degradation, respectively. The degradation processes followed pseudo first-order kinetic model very well, and the observed rate constants of DBP, DEP and DMP were 0.42, 0.40 and 0.29 h-1, respectively. The energy consumption in three PAEs degradation was also assessed. The main degradation products of the three PAEs were identified by using liquid chromatography-tandem mass spectrometry, and the possible degradation pathways mainly included dealkylation, hydroxyl addition, decarboxylation and benzene ring cleavage. This work is a promising candidate for efficient treatment of multiple PAEs in wastewater and protection of the aquatic ecological environment.


Assuntos
Cério/química , Galvanoplastia/métodos , Recuperação e Remediação Ambiental/métodos , Ácidos Ftálicos/química , Águas Residuárias/química , Poluentes Químicos da Água/química , Dibutilftalato/química , Eletrodos , Ésteres/química , Chumbo/química , Óxidos/química , Titânio/química
13.
Water Sci Technol ; 81(7): 1471-1478, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32616699

RESUMO

SiO2 gel was formed on the grain surface of silica sand by hydrolysis and condensation of tetraethyl orthosilicate in water with the addition of 1-butylamine. The resultant product was a composite consisting of sand grains with mesoporous silica coating containing alkylamine inside. This composite exhibited basicity in the wastewater from copper electroplating due to its release of amine. As a result, the strongly acidic wastewater was neutralized and the co-precipitation of complex metal ions occurred. It was shown that up to 12 major metal ions in the wastewater could be simultaneously removed under static condition at room temperature by using the sand composite. The Fe and Cu in the wastewater could be removed completely, while the concentrations of Al, Cd, Ti, V, and Zn in the wastewater were reduced by two to three orders of magnitude. After the removal of multiple metal ions from the electroplating wastewater, the used sand was further applied as a raw material for making a silicate glass. The glass was chemically stable and thus the heavy metal ions from the wastewater were immobilized.


Assuntos
Metais Pesados/análise , Poluentes Químicos da Água/análise , Cobre , Galvanoplastia , Íons , Areia , Dióxido de Silício , Águas Residuárias
14.
Chemosphere ; 260: 127587, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32663673

RESUMO

In this work, a three-dimension grapnene-PbO2 (3DG-PbO2) composite anode was prepared using coelectrodeposition technology for electrocatalytic oxidation of perfluorooctane sulfonate (PFOS). The effect of 3DG on the surface morphology, structure and electrocatalytic activity of PbO2 electrode was investigated. The results indicated that the 3DG-PbO2-0.08 anode (3DG concentration in electrodeposition solution was 0.08 g L-1) possessed the best electrocatalytic activity due to its stronger ·OH radicals generation capacity, more active sites and smaller charge-transfer resistance. The degradation rate constant of PFOS on 3DG-PbO2-0.08 anode was 2.33 times than that of pure PbO2 anode. Additionally, the by-products formed in electrocatalytic degradation of PFOS were identified and a PFOS degradation pathway was proposed accordingly, which was dominated by the dissociation of -CF2- groups via the attack of ·OH radicals. Finally, the toxicity evolution of degradation solution was examined to evaluate the ecological risk of electrocatalytic oxidation of PFOS by acute toxicity assays to zebrafish embryos.


Assuntos
Ácidos Alcanossulfônicos/análise , Técnicas Eletroquímicas/métodos , Fluorcarbonetos/análise , Grafite/química , Chumbo/química , Nanocompostos/química , Óxidos/química , Titânio/química , Poluentes Químicos da Água/análise , Ácidos Alcanossulfônicos/toxicidade , Animais , Eletrodos , Galvanoplastia , Embrião não Mamífero/efeitos dos fármacos , Fluorcarbonetos/toxicidade , Oxirredução , Poluentes Químicos da Água/toxicidade , Peixe-Zebra
15.
J Environ Manage ; 271: 110963, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32579522

RESUMO

Heavy metals, which commonly occur in complex forms, are difficult to remove in alkali electroplating wastewater effluent, and their resource recycling is rarely reported. Here, a Cu-bearing alkali wastewater effluent was effectively treated through Fenton oxidation, and the generated Fenton sludge was recycled into highly pure tenorite and hematite particles. The effluent contained 1.51 mg/L Cu and was subjected to Fenton oxidation, pH adjustment and coagulation. Amongst the three methods, Fenton oxidation showed superior efficiency to Cu removal, and the residual Cu in the effluent was 0.06 mg/L, thereby meeting the discharge standard for electroplating wastewater. However, Cu removal achieved less than 20% after pH adjustment and coagulation. Cu-bearing sludge, which was generated through the Fenton process, was dissolved in a mixture of hydrochloric and nitric acids. The dissolved solution contained 1.92 g/L Cu and 73.6 g/L Fe impurity. Impure Fe (67.4%) was removed as hematite aggregates after the solution was directly treated via a hydrometallurgy route, whilst 99.2% Cu was kept. When 0.5 mL of methanol was introduced to the hydrometallurgy system, nearly 100% Fe was removed as hematite nanoparticles with 94.8% purity, whilst more than 98% Cu was kept. The residual Cu was 1.88 g/L and precipitated as a tenorite block with a CuO content of 91.1% by adjusting the treated solution to pH 9. This study presented an environment-friendly method for enriching Cu from electroplating wastewater effluent without generating any waste.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Galvanoplastia , Peróxido de Hidrogênio , Oxirredução , Reciclagem , Eliminação de Resíduos Líquidos
16.
Environ Sci Pollut Res Int ; 27(27): 34541-34556, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32557073

RESUMO

A waste material known as palm oil empty fruit bunch (EFB) is used as a source of cellulose for the development of polymeric materials for the removal of metal ions from industrial wastewater. A poly(acrylonitrile)-grafted palm cellulose copolymer was synthesized by a conventional free radical initiating process followed by synthesis of a poly(amidoxime) ligand by oximation reaction. The resulting products were characterized by FT-IR, FE-SEM, EDX, TGA, DSC, and XPS. The poly(amidoxime) ligand was used to coordinate with and extract a series of transition metal ions from water samples. The binding capacity (qe) of the ligand with the metal ions such as copper, iron, cobalt, nickel, and lead were 260, 210, 168, 172, and 272 mg g-1, respectively at pH 6. The adsorption process followed the pseudo-first-order kinetic model (R2 > 0.99) and as well as the Freundlich isotherm model (R2 > 0.99) indicating the occurrence of a multi-layer adsorption process in the amidoxime ligand adsorbent. Results from reusability studies show that the ligand can be recycled for at least 10 cycles without any significant losses to its initial adsorption capacity. The synthesized polymeric ligand was shown to absorb heavy metals from electroplating wastewater with up to 95% efficiency.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Purificação da Água , Adsorção , Galvanoplastia , Concentração de Íons de Hidrogênio , Cinética , Oximas , Espectroscopia de Infravermelho com Transformada de Fourier , Águas Residuárias
17.
Chemosphere ; 255: 126973, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32402889

RESUMO

Ti/SnO2-Sb is a promising anode for electrochemical advanced oxidation process with advantages of low cost and no secondary pollution, while suffers from low work economy due to the short service life. In this study, a facile strategy was proposed to fabricate Ti/SnO2-Sb electrode with high oxidation ability and long service life based on novelly sealing electrodeposited Sn-Sb coating with stannous citrate complex. The treated Ti/SnO2-Sb electrode exhibited an accelerated service life of 41.5 h (100 mA cm-2; 0.5 M H2SO4) and a degradation rate constant for methylene blue dye of 1.02 h-1 which were respectively 11.9 and 2.5 times as that of the untreated electrode. It was found out that the complex could well repair the coating defects inside or outside and form a covering film to tighten the coating, and was then mineralized during the following calcination process to achieve a uniform, rough and highly active SnO2-Sb catalytic layer. The distinctive structure was confirmed by XRD, SEM, XPS and FT-IR. The sealing treatment could be achieved by in situ electrodepositing Sn-Sb coating from or ex situ dipping Sn-Sb coating in solution containing stannous citrate complex followed by drying in air. This study provided a novel, facile and effective strategy to enhance performance of Ti/SnO2-Sb electrode that could be easily achieved in both laboratory and industrial scales and combined with other strategies.


Assuntos
Citratos/química , Modelos Químicos , Compostos de Estanho/química , Catálise , Ácido Cítrico , Eletrodos , Galvanoplastia , Azul de Metileno , Oxirredução , Espectroscopia de Infravermelho com Transformada de Fourier , Titânio/química
18.
Waste Manag ; 108: 172-182, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32360998

RESUMO

The coordinated treatment for two kinds of waste is an effective way to save energy and improve the recovery efficiency of resource. In worldwide, more than half of palladium is used to produce catalysts in automobile. However, with the increasing consumption of palladium, the scarcity of palladium resource is becoming prominent. This paper proposed an integrated process based on capture of copper scrap and electrodeposition process to recycle palladium in spent catalysis from automobile. The technological process mainly consisted of two procedures: capture of copper scrap with the purposes of enriching palladium and electrodeposition process with the purposes of separating and purifying palladium. Several highlights were summarized as follows: (i) a capture mechanism of palladium by copper scrap was studied by the calculation of surface thermodynamics and first principles. (ii) Optimum designs, parameter and product analysis were developed to guide industrial recycling. The appropriate parameters for capture of copper scrap are the melting temperature reached 1400 °C, adding 20% dosage of copper scrap and 2 of mass ratio of SiO2/Al2O3 and for the electrodeposition process, nearly 100% of palladium was deposited on the cathode under 0.1 M concentration of HNO3, -0.042 V of electrodeposition potential and 25 °C reaction temperature with 9 h. (iii) This process overcame the shortages of traditional process and showed its efficiency and environmental performance. This study is significant for high-efficient, low-cost and environment-friendly recycling of valuable resource in spent catalysis from automobile.


Assuntos
Cobre , Paládio , Automóveis , Catálise , Galvanoplastia , Reciclagem , Dióxido de Silício
19.
Chemosphere ; 256: 127139, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32470737

RESUMO

The existence of ß-naphthoxyacetic acid (BNOA) pesticide in water system has aroused serious environmental problem because of its potential toxicity for humans and organisms. Therefore, exploiting an efficient method without secondary pollution is extremely urgent. Herein, a promising Ti/PbO2-Co-Pr composite electrode has been successfully fabricated through simple one-step electrodeposition for efficiently electrocatalytic degradation of BNOA. Compared with Ti/PbO2, Ti/PbO2-Co and Ti/PbO2-Pr electrodes, Ti/PbO2-Co-Pr electrode with smaller pyramidal particles possesses higher oxygen evolution potential, excellent electrochemical stability and outstanding electrocatalytic activity. The optimal degradation condition is assessed by major parameters including temperature, initial pH, current density and Na2SO4 concentration. The degradation efficiency and chemical oxygen demand removal efficiency of BNOA reach up to 94.6% and 84.6%, respectively, under optimal condition (temperature 35 °C, initial pH 5, current density 12 mA cm-2, Na2SO4 concentration 8.0 g L-1 and electrolysis time 3 h). Furthermore, Ti/PbO2-Co-Pr electrode presents economic energy consumption and superior repeatability. Finally, the possible degradation mechanism of BNOA is put forward according to the main intermediate products identified by liquid chromatography-mass spectrometer. The present research paves a new path to degrade BNOA pesticide wastewater with Ti/PbO2-Co-Pr electrode.


Assuntos
Eletrólise/métodos , Glicolatos/química , Chumbo/química , Praguicidas/química , Titânio/química , Águas Residuárias/análise , Poluentes Químicos da Água/química , Análise da Demanda Biológica de Oxigênio , Eletrodos , Eletrólise/instrumentação , Galvanoplastia , Oxirredução , Óxidos/química , Sulfatos/química
20.
Chemosphere ; 251: 126309, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32443244

RESUMO

Conventional techniques used for reduction of Cr(VI) in wastewater product great amounts of metal sludge due to the use of reducing chemicals. Since in electrochemical process, the reducing agent is the electron, so the main advantage of this method is its adaptability to the environment. The aim of the current study is to reduce Cr(VI) from electroplating wastewater by the electrochemical method and to adsorb Cr(III) by cellulose sulfate adsorbent. Furthermore, to enhance the reduction efficiency of Cr(VI), the cathode was modified with Pd nanoparticles. In the present study, recovery in the electrochemical column was conducted continuously and semi-continuously. In addition, the effect of pH, amperage, flow rate, and initial concentration of Cr(VI) was investigated. To remove Cr(III) from the wastewater, the cellulose sulfate adsorbent was provided from modification of cotton health wastes. The highest recovery rate (99.63%) was witnessed at pH = 1.5, 1 A amperage, flow rate of 4.24 mL min-1, and initial concentration of 50 mg L-1. The sewage was removed from the system after several consecutive cycles and during 20-55 min reached recovery efficiency of 99.99%. Based on the results, pH had the highest effect on the process. The optimum removal percentage was 85.74% occurred at a pH of 5.6, chromium concentration of 150 mg L-1, and adsorbent concentration of 400 mg L-1. The removal rate of the pollutant was 97.32%, done by cellulose sulfate adsorbent.


Assuntos
Cromo/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Adsorção , Celulose/análogos & derivados , Cromo/química , Cobre , Eletrodos , Galvanoplastia , Concentração de Íons de Hidrogênio , Nanopartículas Metálicas , Paládio , Esgotos , Poluentes Químicos da Água/química
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