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1.
Cells ; 10(12)2021 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-34943904

RESUMO

BACKGROUND: Boron neutron capture therapy (BNCT) is a nuclear reaction-based tumor cell-selective particle irradiation method. High-dose methotrexate and whole-brain radiation therapy (WBRT) are the recommended treatments for primary central nervous system lymphoma (PCNSL). This tumor responds well to initial treatment but relapses even after successful treatment, and the prognosis is poor as there is no safe and effective treatment for relapse. In this study, we aimed to conduct basic research to explore the possibility of using BNCT as a treatment for PCNSL. METHODS: The boron concentration in human lymphoma cells was measured. Subsequently, neutron irradiation experiments on lymphoma cells were conducted. A mouse central nervous system (CNS) lymphoma model was created to evaluate the biodistribution of boron after the administration of borono-phenylalanine as a capture agent. In the neutron irradiation study of a mouse PCNSL model, the therapeutic effect of BNCT on PCNSL was evaluated in terms of survival. RESULTS: The boron uptake capability of human lymphoma cells was sufficiently high both in vitro and in vivo. In the neutron irradiation study, the BNCT group showed a higher cell killing effect and prolonged survival compared with the control group. CONCLUSIONS: A new therapeutic approach for PCNSL is urgently required, and BNCT may be a promising treatment for PCNSL. The results of this study, including those of neutron irradiation, suggest success in the conduct of future clinical trials to explore the possibility of BNCT as a new treatment option for PCNSL.


Assuntos
Terapia por Captura de Nêutron de Boro , Encéfalo/efeitos da radiação , Neoplasias do Sistema Nervoso Central/radioterapia , Linfoma/radioterapia , Animais , Apoptose/efeitos da radiação , Boro/química , Boro/isolamento & purificação , Boro/farmacologia , Encéfalo/patologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Neoplasias do Sistema Nervoso Central/tratamento farmacológico , Neoplasias do Sistema Nervoso Central/patologia , Irradiação Craniana , Modelos Animais de Doenças , Humanos , Linfoma/tratamento farmacológico , Linfoma/patologia , Metotrexato/farmacologia , Camundongos , Fenilalanina/química , Fenilalanina/isolamento & purificação , Fenilalanina/farmacologia , Distribuição Tecidual/efeitos dos fármacos
2.
Int J Mol Sci ; 20(7)2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-30925788

RESUMO

In this study, a chitosan hydrogel supported with ceria (labelled Ce-CTS) was prepared by an encapsulation technique and used for the efficient removal of excess B(III) from aqueous solutions. The functionalisation of chitosan with Ce(IV) and the improvement in the adsorptive behaviour of the hydrogel were determined by SEM-EDS, FTIR, XRD, and inductively coupled plasma optical emission spectrometer (ICP-OES) analyses and discussed. The results demonstrate that Ce-CTS removes boric acid from aqueous solutions more efficiently than either cerium dioxide hydrate or raw chitosan beads, the precursors of the Ce-CTS biosorbent. The maximum adsorption capacity of 13.5 ± 0.9 mg/g was achieved at pH 7 after 24 h. The equilibrium data of boron adsorption on Ce-CTS fitted the Freundlich isotherm model, while the kinetic data followed the Elovich pseudo-second-order model, which indicated that the process was non-homogeneous. The dominant mechanism of removal was the reaction between boric acid molecules and hydroxyl groups bound to the ceria chelated by chitosan active centres. Due to its high efficiency in removing boron, good regeneration capacity and convenient form, Ce-CTS may be considered a promising biosorbent in water purification.


Assuntos
Ácidos Bóricos/isolamento & purificação , Boro/isolamento & purificação , Cério/química , Quitosana/química , Hidrogéis/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Água/análise , Purificação da Água/métodos
3.
J Environ Manage ; 228: 20-31, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30212671

RESUMO

Boron removal from water environment is a critical issue for scientific spotlight because its removal from wastewater is difficult and costly with conventional treatment method. Herein, an innovative, cost effective and attractive method which depends on duckweed-based wastewater treatment systems coupled with microbial fuel cell reactor (DWWT-MFC) was investigated for B-polluted domestic wastewater treatment and simultaneous electricity generation for the first time in an eco-technological study. Lemna gibba L. was selected as a model duckweed species, and different reactors were also designed to identify which mechanisms are dominant for B removal in a DWWT-MFC reactor matrix. DWWT-MFC reactor achieved 71% B removal in experiment period, and the plant effect on B removal mechanisms in the reactor matrix was recorded as 37.7 ±â€¯4.92% (F = 2.543, p < 0.05). However, supplementary aeration and microbial effects on B removal were determined as negligible. Average maximum voltage output was found as 1.47 V, and maximum power density was 34.8 mW/m2 at a current density of 43.9 mA/m2 with supplementary aeration. Moreover, DWWT-MFC reactor achieved 84%, 81% and 76% of COD, NH4+ and PO43- removal efficiencies, respectively. Moreover, L. gibba grew well in the anode chamber of DWWT-MFC with an average biomass yield of 218 ±â€¯43 g/m2 and a total chlorophyll (a+b) concentration of 30.2 mg g-1, which indicates that anolyte environment was not toxic for L. gibba growth. Consequently, it can be suggested that environmental experts may use DWWT-MFC as an efficient removal method to treat B from domestic wastewater and to produce bioelectricity.


Assuntos
Araceae/química , Fontes de Energia Bioelétrica , Boro/isolamento & purificação , Águas Residuárias/química , Biomassa , Eletricidade
4.
Chemosphere ; 194: 722-736, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29247932

RESUMO

Boron (B) pollution is an expanding environmental problem throughout the world due to intensive mining practices and extensive usage of B in agricultural chemicals and industrial products in recent years. The purpose of this study was to investigate B removal performance of four poplar and four willow species in small scale Constructed Wetland (CW). Rooted cuttings of tested species were treated with simulated wastewater having five elevated B concentrations (0.5, 5, 10, 20 and 40 ppm). All the tested species could resist up to 20 ppm wastewater B supply and could regrow from their roots in the soil having maximum 15 mg/kg B content. The result of the study indicated that 65% ± 5.3 of B was removed from the wastewater in 5 ppm B treatment while the same efficiency decreased to 45% ± 4.6 at 40 ppm B supply. The average effect of sediment on B removal was found to be approximately 20% for all B treatments while the remaining part of the loaded B was removed from the CW within effluent (35-54%). Therefore, actual effects of plant species on B removal was ranged from 45% to 25% between 5 and 40 ppm B treatments. Mass B removal within plant body (phytextraction) comprised the 13-10% of total loaded B in CW while the remaining part of the loaded B (31-15%) was stabilized into the sediment with the effects of poplar and willow roots. These results presented clear understanding of effective B purification mechanisms in CWs. Boron phytextraction capacity of a plant species was less effective than its phytstabilization efficiency which increase filtering capacity of the sediment and stabilization of more B around the rhizosphere. In terms of their B removal ability, P.nigra and S.anatolica had the highest B removal capacities with phytextraction (20-11%) while S.alba, P.alba and S.babylonica had more phytstabilizaiton performance (40-15%) in CW. Disposal of B loaded plant material create another environmental costs for CW applications. Therefore, B loaded wood and leaf tissues were mixed and used for production of wooden panels in the study. Then a combustion test was applied on these panels to test their fire resistance. The results of the tests revealed much higher burning tolerance of the B loaded panels (5-20%) compared to controls. Annual harvesting, fast growing and deep rooting ability of the poplar and willow species with their high phytstabilization and phytextraction efficiencies make these species excellent tools to remove B from the polluted waters. Utilization of these species for B removal in large scale CWs is quite possible which should be also investigated in further studies.


Assuntos
Boro/isolamento & purificação , Poluição Ambiental/análise , Populus/metabolismo , Salix/metabolismo , Áreas Alagadas , Biodegradação Ambiental , Boro/farmacocinética , Poluição Ambiental/prevenção & controle , Raízes de Plantas/química , Raízes de Plantas/crescimento & desenvolvimento , Solo/química , Águas Residuárias/química , Poluentes Químicos da Água/isolamento & purificação
5.
J Environ Manage ; 207: 405-416, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-29190483

RESUMO

This study investigated the use of eggshell membrane (ESM) as a bio-sorbent and the effect of temperature, pH, and initial concentration on its efficiency. Furthermore, by altering the chemical composition, modified eggshell membrane (MESM) was prepared, and its efficiency was compared with the ESM. Results showed that the adsorption of boron preferred an acidic condition; pH 6 at 35 °C. In addition, the positive value of ΔH° suggested that the reaction favored endothermic pathway, while the negative value for ΔG° further suggested that the adsorption process was spontaneous. Furthermore, the ESM could adsorb 97% of boron, while MESM was able to adsorb 95%. From the Fourier transform infrared (FTIR), different functional groups were recorded on the surface of the ESM and MESM, and they played key role in the boron adsorption mechanisms. Linear Freundlich model was suggested to best describe the experimental data with 99.4% correlation coefficient.


Assuntos
Boro/isolamento & purificação , Casca de Ovo , Adsorção , Animais , Boro/química , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Água , Poluentes Químicos da Água
6.
Int J Phytoremediation ; 20(2): 175-183, 2018 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-28692304

RESUMO

The metalloid boron (B) and its compounds widely exist in the environment, and boron can have hazardous effects on plants, animals, and human beings when it is found in high concentrations in water bodies. It is difficult and costly to remove B with conventional treatment methods from drinking water. Therefore, alternative and cost-effective treatment techniques are necessary. In this study, for the first time, a novel and environmentally friendly method based on the phytoremediation ability of chitosan and duckweed (Lemna gibba L.) combination was evaluated for B removal from drinking water. Our results from batch adsorption experiment indicated that the highest B uptake capacity of chitosan bead was found as 3.18 mg/g, and we determined the optimal B sorption occurs at pH value of 7. The Langmuir isotherm and pseudo-second-order kinetic model better fitted the equilibrium obtained for B removal. B in drinking water could be reduced to less than 2.4 mg L -1 when 0.05 g of plant-based chitosan beads and 12 L. gibba fronds were used in the 4-day treatment period.


Assuntos
Araceae , Biodegradação Ambiental , Boro , Água Potável , Poluentes Químicos da Água , Purificação da Água , Adsorção , Boro/isolamento & purificação , Quitosana , Concentração de Íons de Hidrogênio , Cinética , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos
7.
Water Res ; 126: 481-487, 2017 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-29028491

RESUMO

One promising water management strategy during hydraulic fracturing is treatment and reuse of flowback/produced water. In particular, the saline flowback water contains many of the chemicals employed for fracking, which need to be removed before possible reuse as "frac water." This manuscript targets turbidity along with one of the additives; borate-based cross-linkers used to adjust the rheological characteristics of the frac-fluid. Alum and ferric chloride were evaluated as coagulants for clarification and boron removal from saline flowback water obtained from a well in the Eagle Ford shale. Extremely high dosages (> 9000 mg/L or 333 mM Al and 160 mM Fe) corresponding to Al/B and Fe/B mass ratios of ∼70 and molar ratios of ∼28 and 13 respectively were necessary to remove ∼80% boron. Hence, coagulation does not appear to be feasible for boron removal from high-strength waste streams. X-ray photoelectron spectroscopy revealed BO bonding on surfaces of freshly precipitated Al(OH)3(am) and Fe(OH)3(am) suggesting boron uptake was predominantly via ligand exchange. Attenuated total reflection-Fourier transform infrared spectroscopy provided direct evidence of inner-sphere boron complexation with surface hydroxyl groups on both amorphous aluminum and iron hydroxides. Only trigonal boron was detected on aluminum flocs since possible presence of tetrahedral boron was masked by severe AlO interferences. Both trigonal and tetrahedral conformation of boron complexes were identified on Fe(OH)3 surfaces.


Assuntos
Hidróxido de Alumínio/química , Boro/isolamento & purificação , Compostos Férricos/química , Fraturamento Hidráulico , Purificação da Água/métodos , Compostos de Alúmen , Alumínio , Cloretos , Hidróxidos , Ferro , Nefelometria e Turbidimetria , Águas Residuárias/química , Água , Poluentes Químicos da Água/isolamento & purificação
8.
J Hazard Mater ; 333: 319-328, 2017 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-28376360

RESUMO

Wetland mesocosms were constructed to assess two hybrid poplar clones (Populustrichocarpa×P. deltoides×P. nigra '345-1' and '347-14') for treating saline water high in boron (B) and selenium (Se), and a hydroponic experiment was performed to test the B tolerance and B accumulation in both clones. In the mesocosm experiment, clone 345-1 exhibited no toxic symptoms at an EC of 10mScm-1, while clone 347-14 showed slight toxic symptoms at 7.5mScm-1. The removal percentages of B, Se, sodium (Na), and chloride (Cl) ranged from 26.7-45.6%, 50-69.4%, 18.4-24.0%, and 15.8-23.2%, respectively, by clone 345-1, and from 22.9-29.4%, 31.7-43.8%, 16.5-24.2%, and 14.9-23.9%, respectively, by clone 347-1. In the hydroponic experiment, B toxic symptoms were observed at treatments of 150 and 200mg B L-1 for clones 345-1 and 347-14, respectively. The greatest leaf B concentrations of 3699 and 1913mgkg-1 were found in clone 345-1 and clone 347-14, respectively. The translocation factor (TF) of clone 347-14 was less than clone 345-1. Clone 345-1 only showed significantly greater (P<0.05) B removal percentages than clone 347-14 when B treatment was <20mg B L-1. In conclusion, both tested poplar clones competitively accumulated and removed B and Se in constructed wetlands.


Assuntos
Biodegradação Ambiental , Boro/isolamento & purificação , Populus/metabolismo , Águas Salinas/química , Selênio/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Áreas Alagadas , Biomassa , Boro/análise , Boro/metabolismo , Cloretos/isolamento & purificação , Hibridização Genética , Hidroponia , Populus/genética , Selênio/análise , Selênio/metabolismo , Sódio/isolamento & purificação , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo
9.
Carbohydr Polym ; 166: 209-218, 2017 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-28385225

RESUMO

Boron exists in various types of water environments, and it is difficult and costly to remove B with conventional treatment methods from drinking water. Clearly, alternative and cost effective treatment techniques are imperative. In the present study, an innovative and environment friendly method based on hybrid systems consisting of various chitosan composite beads and Lemna gibba were evaluated for removal of B from drinking water. Our results from batch adsorption experiment indicated that a plant-based chitosan composite bead has a higher capacity of B removal than mineral-based chitosan composite beads. Almost 50% of total B removal was achieved using the hybrid system based on dried Lemna-chitosan composite beads and Lemna gibba combination in 4 days. Even at the high B concentration (8mgBL-1), B in drinking water could be reduced to less than 2.4mgL -1 when 0.05g plant-based chitosan composite beads and 12 Lemna fronds were used for 50mL test solution.


Assuntos
Araceae , Boro/isolamento & purificação , Quitosana/química , Água Potável/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Concentração de Íons de Hidrogênio , Cinética
10.
Chemosphere ; 166: 184-191, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27697706

RESUMO

The electrocoagulation (EC) using metallic Ni foam as electrodes was studied for the removal of boron from solution. The electrolytic parameters were pH (4-12), current density (0.6-2.5 mA cm-2), and initial concentration of boron (10-100 mg L-1). Experimental results revealed that removal efficiency was maximized at pH 8-9, and decreased as the pH increased beyond that range. At particular onset potentials (0.5-0.8 V vs. Hg/HgO), the micro-granular nickel oxide that was created on the surface of the nickel metal substrate depended on pH, as determined by cyclic voltammetry. Most of the crystallites of the precipitates comprised a mixed phase of ß-Ni(OH)2, a theophrastite phase, and NiOOH, as revealed by XRD and SEM analyses. A current density of 1.25 mA cm-2 was effective in the EC of boron, and increasing the concentration of boric acid from 10 to 100 mg L-1 did not greatly impair removal efficiency. A kinetic investigation revealed that the reaction followed a pseudo-second order rate model. The optimal conditions under which 99.2% of boron was removed from treated wastewater with 10 mg L-1-B, leaving less than 0.1 mg L-1-B in the electrolyte, were pH 8 and 1.25 mA cm-2 for 120 min.


Assuntos
Boro/química , Boro/isolamento & purificação , Eletroquímica/instrumentação , Níquel/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Eletrodos , Concentração de Íons de Hidrogênio , Cinética , Oxirredução , Águas Residuárias/química
11.
J Environ Manage ; 188: 58-63, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-27930956

RESUMO

Mg-Al layered double hydroxide intercalated with NO3- and Mg-Al oxide were found to remove hazardous materials such as B and As, as well as Cl- and SO42-, from artificial and real hot spring wastewater. However, compared with the mixture of Al2(SO4)3 and Ca(OH)2, both adsorbents were inferior for the removal of B from real hot spring wastewater. Both adsorbents were also found to remove F- and PO43- from artificial semiconductor plant wastewater. Both adsorbents have the same ability to remove B from landfill wastewater as the mixture of Al2(SO4)3 and Ca(OH)2; furthermore, both remove Cl-, Br-, and SO42-. The benefit of Mg-Al layered double hydroxide intercalated with NO3- is that it does not require neutralization after the treatment. Overall, it can be stated that among the materials tested, Mg-Al layered double hydroxide intercalated with NO3- is the most suitable adsorbent for the treatment of hot spring and landfill wastewater.


Assuntos
Boro/isolamento & purificação , Fluoretos/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Hidróxido de Alumínio/química , Óxido de Alumínio/química , Boro/química , Fluoretos/química , Óxido de Magnésio/química , Instalações de Eliminação de Resíduos , Águas Residuárias/química , Poluentes Químicos da Água/química , Purificação da Água/métodos
12.
J Environ Manage ; 183(Pt 3): 917-924, 2016 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-27671009

RESUMO

Porous magnetic hybrids were synthesized and functionalized with glycidol to produce boron-selective adsorbent. The magnetic hybrid (MH) comparatively out-performed the existing expensive adsorbents. MH had a saturation magnetisation of 63.48 emu/g and average pore diameter ranging from meso to macropores. The magnetic hybrids showed excellent selectivity towards boron and resulted in 79-93% boron removal even in the presence of competing metal ions (Na+ and Cr2+). Experiments were performed in a column system, and breakthrough time was observed to increase with bed depths and decreased with flow rates. The batch experiments revealed that 60 min was enough to achieve equilibrium, and the level of boron sorption was 108.5 mg/g from a synthetic solution. Several adsorption-desorption cycles were performed using a simple acid-water treatment and evaluated using various kinetic models. The spent adsorbents could be separated easily from the mixture by an external magnetic field. The cost-benefit analysis was performed for the treatment of 72 m3/year boron effluent, including five years straight line depreciation charges of equipment. The net profit and standard percentage confirmed that the recovery process is economically feasible.


Assuntos
Boro/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/economia , Purificação da Água/métodos , Adsorção , Ácidos Bóricos/isolamento & purificação , Precipitação Química , Cromo/química , Análise Custo-Benefício , Compostos Férricos/química , Concentração de Íons de Hidrogênio , Cinética , Magnetismo/métodos , Modelos Teóricos , Níquel/química , Porosidade , Sódio/química , Poluentes Químicos da Água/química , Purificação da Água/instrumentação
13.
Talanta ; 150: 240-52, 2016 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-26838405

RESUMO

Using the carminic acid assay, we determined the concentration of boron in oilfield waters. We investigated the effect of high concentrations of salts and dissolved metals on the assay performance. The influence of temperature, development time, reagent concentration, and water volume was studied. Ten produced and flowback water samples of different origins were measured, and the method was successfully validated against ICP-MS measurements. In water-stressed regions, produced water is a potential source of fresh water for irrigation, industrial applications, or consumption. Therefore, boron concentration must be determined and controlled to match the envisaged waste water reuse. Fast, precise, and onsite measurements are needed to minimize errors introduced by sample transportation to laboratories. We found that the optimum conditions for our application were a 5:1 mixing volume ratio (reagent to sample), a 1 g L(-1) carminic acid concentration in 99.99% sulfuric acid, and a 30 min reaction time at ambient temperature (20 °C to 23 °C). Absorption values were best measured at 610 nm and 630 nm and baseline corrected at 865 nm. Under these conditions, the sensitivity of the assay to boron was maximized while its cross-sensitivity to dissolved titanium, iron, barium and zirconium was minimized, alleviating the need for masking agents and extraction methods.


Assuntos
Boro/análise , Carmim/química , Técnicas de Química Analítica/métodos , Águas Residuárias/química , Métodos Analíticos de Preparação de Amostras , Boro/isolamento & purificação , Calibragem , Colorimetria , Resíduos Industriais/análise , Metais/química , Sais/química , Temperatura , Fatores de Tempo
14.
Water Sci Technol ; 72(10): 1832-9, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26540546

RESUMO

In this study boron removal capacities of different microorganisms were tested. Candida tropicalis, Rhodotorula mucilaginosa, Micrococcus luteus, Bacillus thuringiensis, Bacillus cereus, Bacillus megaterium, Bacillus pumilus, Pseudomonas aeruginosa and Aspergillus versicolor were examined for their boron bioaccumulation capacities in simulated municipal wastewater. A. versicolor and B. cereus were found as the most boron-tolerant microorganisms in the experiments. Also boron bioaccumulation yield of A. versicolor was 49.25% at 15 mg/L boron concentration. On the other hand biosorption experiments revealed that A. versicolor was more capable of boron removal in inactive form at the highest boron concentrations. In this paper maximum boron bioaccumulation yield was detected as 39.08% at 24.17 mg/L and the maximum boron biosorption yield was detected as 41.36% at 24.01 mg/L boron concentrations.


Assuntos
Aspergillus/metabolismo , Boro/isolamento & purificação , Águas Residuárias , Bacillus cereus/metabolismo , Bactérias/metabolismo , Eliminação de Resíduos Líquidos/métodos
15.
Environ Sci Technol ; 49(20): 12441-9, 2015 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-26351732

RESUMO

Recovery of resources, in particular, metals, from waste flows is widely seen as a prioritized option to reduce their potential supply constraints in the future. The current waste electrical and electronic equipment (WEEE) treatment system is more focused on bulk metals, where the recycling rate of specialty metals, such as rare earths, is negligible compared to their increasing use in modern products, such as electronics. This study investigates the challenges in recovering these resources in the existing WEEE treatment system. It is illustrated by following the material flows of resources in a conventional WEEE treatment plant in Denmark. Computer hard disk drives (HDDs) containing neodymium-iron-boron (NdFeB) magnets were selected as the case product for this experiment. The resulting output fractions were tracked until their final treatment in order to estimate the recovery potential of rare earth elements (REEs) and other resources contained in HDDs. The results further show that out of the 244 kg of HDDs treated, 212 kg comprising mainly of aluminum and steel can be finally recovered from the metallurgic process. The results further demonstrate the complete loss of REEs in the existing shredding-based WEEE treatment processes. Dismantling and separate processing of NdFeB magnets from their end-use products can be a more preferred option over shredding. However, it remains a technological and logistic challenge for the existing system.


Assuntos
Computadores , Resíduo Eletrônico/análise , Metais Terras Raras/isolamento & purificação , Reciclagem/métodos , Alumínio , Boro/isolamento & purificação , Dinamarca , Resíduo Eletrônico/estatística & dados numéricos , Monitoramento Ambiental/métodos , Ferro/isolamento & purificação , Imãs , Metalurgia/métodos , Metais Terras Raras/análise , Neodímio/isolamento & purificação , Aço
16.
Chemosphere ; 111: 232-7, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24997923

RESUMO

Chemical oxo-precipitation (COP), which combines treatment with an oxidant and precipitation using metal salts, was developed for treating boron-containing water under milder conditions (room temperature, pH 10) than those of conventional coagulation processes. The concentration of boron compounds was 1000mg-BL(-1). They included boric acid (H3BO3) and perborate (NaBO3). Precipitation using calcium chloride eliminated 80% of the boron from the perborate solution, but was unable to treat boric acid. COP uses hydrogen peroxide (H2O2) to pretreat boric acid, substantially increasing the removal of boron from boric acid solution by chemical precipitation from less than 5% to 80%. Furthermore, of alkaline earth metals, barium ions are the most efficient precipitant, and can increase the 80% boron removal to 98.5% at [H2O2]/[B] and [Ba]/[B] molar ratios of 2 and 1, respectively. The residual boron in the end water of COP contained 15ppm-B: this value cannot be achieved using conventional coagulation processes.


Assuntos
Boro/química , Águas Residuárias/química , Poluentes Químicos da Água/química , Ácidos Bóricos/química , Ácidos Bóricos/isolamento & purificação , Boro/isolamento & purificação , Precipitação Química , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Metais/química , Sais/química , Temperatura , Poluentes Químicos da Água/isolamento & purificação
17.
Environ Toxicol Chem ; 33(10): 2172-80, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24619924

RESUMO

Various chemical models of ion adsorption are presented and discussed. Chemical models, such as surface complexation models, provide a molecular description of anion adsorption reactions using an equilibrium approach. Two such models, the constant capacitance model and the triple layer model, are described in the present study. Characteristics common to all the surface complexation models are equilibrium constant expressions, mass and charge balances, and surface activity coefficient electrostatic potential terms. Methods for determining parameter values for surface site density, capacitances, and surface complexation constants also are discussed. Spectroscopic experimental methods of establishing ion adsorption mechanisms include vibrational spectroscopy, nuclear magnetic resonance spectroscopy, electron spin resonance spectroscopy, X-ray absorption spectroscopy, and X-ray reflectivity. Experimental determinations of point of zero charge shifts and ionic strength dependence of adsorption results and molecular modeling calculations also can be used to deduce adsorption mechanisms. Applications of the surface complexation models to heterogeneous natural materials, such as soils, using the component additivity and the generalized composite approaches are described. Emphasis is on the generalized composite approach for predicting anion adsorption by soils. Continuing research is needed to develop consistent and realistic protocols for describing ion adsorption reactions on soil minerals and soils. The availability of standardized model parameter databases for use in chemical speciation-transport models is critical.


Assuntos
Ânions/química , Boro/química , Minerais/química , Modelos Químicos , Molibdênio/química , Solo/química , Adsorção , Ânions/isolamento & purificação , Boro/isolamento & purificação , Molibdênio/isolamento & purificação , Concentração Osmolar , Análise Espectral , Eletricidade Estática , Propriedades de Superfície
18.
Water Res ; 51: 113-23, 2014 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-24412846

RESUMO

This work investigated the removal of boron from wastewater and its recovery by electrocoagulation and hydrothermal mineralization methods respectively. The experimental design was developed using Box-Behnken Model. An initial study was performed based on four preselected variables (pH, current density, concentration and time) using synthetic wastewater. Response surface methodology (RSM) was used to evaluate the effect of process variables and their interaction on boron removal. The optimum conditions were obtained as pH 6.3, current density 17.4 mA/cm(2), and time 89 min. At these applied optimum conditions, 99.7% boron removal from an initial concentration of 10.4 mg/L was achieved. The process was effectively optimized by RSM with a desirability value of 1.0. The results showed that boron removal efficiency enhanced with increase in current density and treatment time. Removal efficiency also increased when pH was increased from 4 to 7 and subsequently decreased at pH 10. Adsorption kinetics study revealed that the reaction followed pseudo second order kinetic model; evidenced by high correlation and goodness of fit. Thermodynamics study showed that mechanism of boron adsorption was chemisorption and the reaction was endothermic in nature. Furthermore, the adsorption process was spontaneous as indicated by negative values of the adsorption free energy. Treatment of real produced water using electrocoagulation resulted in 98% boron removal. The hydrothermal mineralization study showed that borate minerals (Inyoite, Takadaite and Nifontovite) can be recovered as recyclable precipitate from electrocoagulation flocs of produced water.


Assuntos
Boro/isolamento & purificação , Eletrocoagulação/métodos , Águas Residuárias/análise , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Cinética , Modelos Químicos , Reciclagem/métodos
19.
Environ Technol ; 34(9-12): 1369-76, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24191469

RESUMO

A new adsorbent based on natural clinoptilolite and amorphous zirconium dioxide (ZrO2) was prepared for the uptake of boron from fresh water. The sorption behaviour of this adsorbent for boron was investigated using a batch system and found to obey Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The ZrO2 loading level, pH, temperature, contact time, initial boron concentration and adsorbent dose, on the removal of boron were studied. It was found that the removal of boron increased while the adsorbent dose increased and the temperature decreased at an optimum pH (pH = 8) and a contact time of 30 min. At optimum conditions, the maximum boron percentage removal was 75%. According to the D-R model, the maximum capacity was estimated to be > 3 mg B/g of the adsorbent. The adsorption energy value (calculated as 9.13 kJ/mol) indicated that the adsorption of boron on clinoptilolite modified with ZrO2 was physical in nature. The parameters of the adsorption models and the pH investigations pointed to the possibility of a chemisorption process. The thermodynamic parameters (standard entropy deltaS degrees, enthalpy deltaH degrees , and free energy deltaG degrees changes) of boron adsorption were also calculated. The negative value of deltaS degrees indicated a decreased randomness at the solid-solution interface during the boron adsorption. Negative values of deltaH degrees showed the exothermic nature of the process. The negative values of deltaG degrees implied that the adsorption of boron on clinoptilolite modified with amorphous ZrO2 at 25 degrees C was spontaneous. It was considered that boron dissolved in water had been adsorbed both physically and chemically on clinoptilolite modified with 30% ZrO2.


Assuntos
Boro/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Boro/análise , Boro/química , Concentração de Íons de Hidrogênio , Termodinâmica , Água/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Zeolitas/química , Zircônio/química
20.
Anal Chim Acta ; 740: 66-73, 2012 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-22840652

RESUMO

Glucaminium-based ionic liquids are a new class of solvents capable of extracting boron-species from water with high efficiency. The complexation behavior of these ILs with borate was thoroughly studied using (11)B NMR. Two different complexes, namely, monochelate complex and bischelate complex, were observed. (11)B NMR was used extensively to determine the formation constants for monochelate and bischelate complexes. The IL concentration was observed to have a significant effect on the IL-borate complexes. Using an in situ dispersive liquid-liquid microextraction (in situ DLLME) method, the extraction efficiency for boron species was increased dramatically when lithium bis[(trifluoromethyl)sulfonyl]imide (LiNTf(2)) was used as the metathesis salt in an aqueous solution containing 0.1M sodium chloride. IL regeneration after extraction was achieved using 0.1M hydrochloric acid. The extraction efficiency of boron species was consistent when the IL was employed after three regeneration cycles. The selectivity of the IL for boron species in synthetic seawater samples was similar to performing the same extraction from Milli-Q water samples.


Assuntos
Boro/isolamento & purificação , Quelantes/química , Líquidos Iônicos/química , Microextração em Fase Líquida , Meglumina/química , Boro/química , Cromatografia Líquida de Alta Pressão , Líquidos Iônicos/síntese química , Espectroscopia de Ressonância Magnética , Meglumina/análogos & derivados , Meglumina/síntese química , Solventes/síntese química , Solventes/química
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