RESUMO
Polymeric metal coagulants are increasingly being used to improve coagulation efficiency, yet the research on the development of titanium and particularly polytitanium salts remains limited. This study is the first attempt in the synthesis, characterization, and application of polytitanium salts as coagulants. Polytitanium tetrachloride (PTC) solutions with different basicity values B (OH/Ti molar ratio) were prepared using a slow alkaline titration method. Jar tests were conducted to assess coagulation performance using both synthetic and real raw water samples, and the floc characteristics were monitored online using a laser diffraction particle size analyzer. Electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) was utilized to identify various Ti species, with the results providing strong evidence of the presence of various hydrolyzed Ti species in the titanium aqueous phase. Compared to titanium tetrachloride (TiCl4), higher or comparable turbidity and organic matter removal efficiency could be achieved by PTC with improved floc characteristics in terms of size, growth rate, and structure. Besides, the water pH after PTC coagulation was significantly improved toward neutral pH. This study indicates that PTC is an effective and promising coagulant for water purification. Besides, the PTC flocculated sludge was able to recycle and produce functional TiO2 photocatalyst.
Assuntos
Titânio/química , Purificação da Água/métodos , Floculação , Fractais , Polímeros/química , Rios/química , Esgotos/química , Soluções , Espectrometria de Massas por Ionização por Electrospray , Água/química , Difração de Raios XRESUMO
OBJECTIVE: To explore the role of phospholipase C epsilon 1 (PLCE1) in regulating cell apoptosis of non-small cell lung cancer (NSCLC) and its underlying mechanism. PATIENTS AND METHODS: The mRNA and protein levels of PLCE1 in NSCLC tissues, adjacent normal tissues and NSCLC cell lines (A549 and H1299) were detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) and Western blot, respectively. Methylation status in the promoter region of PTEN in NSCLC cells was accessed using the relative commercial kit. Cell apoptosis after transfection of PLCE1 siRNA in NSCLC cells was detected by flow cytometry. Protein expressions of apoptosis-related genes in NSCLC cells after altering PLCE1 expression were detected by Western blot. RESULTS: PLCE1 was highly expressed in NSCLC tissues and cell lines than that of controls. PLCE1 knockdown promoted PTEN expression and inhibited methylation in H1299 cells. Transfection of PLCE1 siRNA in NSCLC cells remarkably induced cell apoptosis. CONCLUSIONS: PLCE1 inhibits cell apoptosis of NSCLC by promoting PTEN methylation.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/genética , Neoplasias Pulmonares/genética , PTEN Fosfo-Hidrolase/genética , Fosfoinositídeo Fosfolipase C/genética , Fosfoinositídeo Fosfolipase C/metabolismo , Células A549 , Apoptose , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Linhagem Celular Tumoral , Metilação de DNA , Células HEK293 , Humanos , Neoplasias Pulmonares/metabolismo , Regiões Promotoras Genéticas , Regulação para CimaRESUMO
Polyamine flocculants were synthesized by the polycondensation of dimethylamine and epichlorohydrin, in which organic amines, e.g. 1,2-diaminoethane, were used as modifying agents. Different products were obtained by varying the reaction parameters, such as the molar ratio of epichlorohydrin to dimethylamine, the amount of 1,2-diaminoethane and reaction temperature. The polyamine flocculants were characterized by transmission electron microscope (TEM). Their flocculation performance was evaluated with simulated dye liquor and actual printing and dyeing wastewater. The behavior of the flocculants was compared with that of inorganic coagulant, polyaluminum chloride (PAC). The experimental results show that polyamine with the highest viscosity and cationicity could be prepared under following conditions: an epichlorohydrin to dimethylamine molar ratio of 1.5, a reaction temperature of 70 degrees C, a 3% content of 1,2-diaminoethane in the total reaction monomers and a reaction time of 7h. Polyamine polymers can, as flocculants for treating simulated and actual dye wastewater, remove color and COD efficiently. The rate of color removal from reactive red liquor, reactive blue liquor and reductive yellow liquor reached as high as 96%, 97% and 96%, respectively. The highest efficiency of color removal and COD removal from polyamine for treating dye wastewater was 90% and 89%, respectively.
Assuntos
Corantes/isolamento & purificação , Floculação , Resíduos Industriais , Poliaminas/síntese química , Poluentes Químicos da Água/isolamento & purificação , Microscopia Eletrônica de TransmissãoRESUMO
OBJECTIVE: To detect the relative expression of long intergenic non-protein coding RNA 460 (linc00460) in non-small cell lung cancer (NSCLC) tissues and cells, to investigate the effects of linc00460 on proliferation, migration and invasion of NSCLC and to preliminarily explore its potential molecular action mechanisms. PATIENTS AND METHODS: The relative expression of cancer tissues from 52 patients with NSCLC compared with that of para-carcinoma normal tissues was detected through Real-time quantitative polymerase chain reaction (qRT-PCR). qRT-PCR was also used to test the relative expressions of linc00460 in 4 strains of NSCLC cells. Effects of knockdown of linc00460 expression on the cell proliferation ability were detected by cell counting kit-8 (CCK-8) assay through transfection of small interfering linc00460 (si-linc00460) interference sequence in A549 cells and PC-9 cells. Transwell assay was used to detect the effects of lic00460 on the migration and invasion abilities of NSCLC cells. Western blot was applied to observe the changes of epithelial-mesenchymal transition (EMT)-related proteins. The expression changes of EMT-related proteins were detected by immunofluorescence assay. RESULTS: qRT-PCR results showed that there were 40 cases (76.9%) with up-regulated linc00460 expressions in tissues from 52 patients with NSCLC. The linc00460 expressions in 5 strains of NSCLC cells were higher than those of human bronchial epithelial (16HBE) cells. Interference in linc00460 expression could inhibit the proliferation, invasion and migration of NSCLC cells. Results of Western blot and immunofluorescence found that interfering with the linc00460 expression could affect the expression changes of EMT-related proteins. CONCLUSIONS: The relative expression of linc00460 is upregulated in NSCLC tissues. Cells and linc00460 can promote the tumor invasion and migration through affecting EMT.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/metabolismo , Movimento Celular/fisiologia , Transição Epitelial-Mesenquimal/fisiologia , Neoplasias Pulmonares/metabolismo , RNA Longo não Codificante/biossíntese , Células A549 , Carcinoma Pulmonar de Células não Pequenas/genética , Linhagem Celular Tumoral , Proliferação de Células/fisiologia , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias Pulmonares/genética , MicroRNAs/biossíntese , MicroRNAs/genética , Invasividade Neoplásica/genética , RNA Longo não Codificante/genéticaRESUMO
Fly ash modification by polydimethydiallylammonium chloride (PDMDAAC) in laboratory scale was explored in this work and the adsorption performance of modified fly ash and its application in dyeing wastewater treatment were also studied. The key factors (concentration and temperature) for PDMDAAC to affect the adsorption properties of fly ash (FA) were revealed using the orthogonal test with four factors. The results indicated that the adsorption magnitude of fly ash to PDMDAAC increased due to its favorable specific surface causing the change of the surface charge nature. Hence, adsorption performance of modified fly ash on organic molecules and its ion exchange capacity are strengthened. The maximum color removal efficiency was obtained as 88.2% by modified fly ash with 2.0 g/100 mL dosage in dyeing wastewater, which is much higher than 12.5% color removal efficiency by raw fly ash with the same dosage. And, the used modified fly ash could be used for cement production as additive agent. The intensity of cement produced with 15% the modified fly ash in weight reached the Chinese Cement Standard (GB/T17671-1999), blazing a promising novel way in fly ash utilization.
Assuntos
Carbono , Materiais de Construção , Resíduos Industriais/prevenção & controle , Material Particulado , Polietilenos , Compostos de Amônio Quaternário , Poluentes da Água/isolamento & purificação , Adsorção , Cinza de Carvão , Corantes , Propriedades de SuperfícieRESUMO
In this study, the decolorization of textile wastewater using composite flocculants was examined. It was composed of Fe(III) flocculants and polydimethyldiallylammonium chloride (PDMDAAC). The color removal efficiency of the composite flocculants was compared with that of individual flocculants, ferric chloride (FeCl3), polyferric chloride (PFC) and PDMDAAC, respectively. The results showed that the composite flocculants were more efficient than individual ones in color removal. The color removal efficiency of the composite flocculants was found to be related to the weight percentage of PDMDAAC (Wp), basicity (B) of PFC and molecular weight (MW) of PDMDAAC. The removal rate is higher at a larger Wp and MW value and lower B value. Chemical oxygen demand (COD) removal from textile wastewater was also investigated in this study. During color removal by the composite flocculants, only up to 20% COD could be removed from the textile wastewater. FeCl3 was then used to further remove the remaining COD from the decolorized wastewater. This two-step treatment of textile wastewater could achieve a 91.6% reduction in COD and an 88.9% reduction in color.
Assuntos
Cor , Floculação , Resíduos Industriais , Indústria Têxtil , Poluentes Químicos da Água/isolamento & purificação , Recuperação e Remediação Ambiental/instrumentação , Recuperação e Remediação Ambiental/métodosRESUMO
The inducibility of codeine metabolism by carbamazepine (CBZ) and cigarette smoking has been investigated. A single oral dose of 25 mg of codeine was given to seven epileptic patients before and after 3 weeks' regular CBZ treatment (400-600 mg per day). Codeine was also given to nine volunteers who were heavy smokers (20 cigarettes per day) and to nine non-smokers as controls. All subjects were found to be extensive metabolizers of codeine by O-demethylation. Urine was collected over 8 h following codeine intake. Codeine and the metabolites were analysed with HPLC. CBZ significantly increased the urinary excretion of the N-demethylated metabolite, norcodeine (NC) which led to a significant decrease in the metabolic ratio (MR) for N-demethylation. The O-demethylation was not significantly altered. The excretion of normorphine, an active metabolite formed through both O- and N-demethylation of codeine increased by almost three-fold after CBZ treatment. Contrary to CBZ treatment, cigarette smoking slightly but significantly induced the glucuronidation of codeine as shown by a decreased MR for glucuronidation in the smokers, while the O- and N-demethylations were not significantly changed as indicated by the similar MRs in smokers and in non-smokers. These results suggest that CBZ and cigarette smoking selectively induce different metabolizing enzymes. The polymorphic O-demethylation is relatively stable to these factors.
Assuntos
Carbamazepina/farmacologia , Codeína/metabolismo , Fumar , Adolescente , Adulto , Codeína/análogos & derivados , Codeína/urina , Sinergismo Farmacológico , Feminino , Glucuronatos/urina , Humanos , Masculino , Pessoa de Meia-Idade , Plantas Tóxicas , NicotianaRESUMO
The cytochromes P450 participate in the metabolic activation of precarcinogens. Recent results reveal that many P450 genes are polymorphically distributed. Different investigators have tried to link polymorphic variants of the CYP1A1, CYP2D6 and CYP2E1 genes to the incidence of cancer, particularly lung cancer, in Asian and Caucasian populations. In the current overview we briefly summarize this research. It appears that interesting functionally linked interindividual differences in the CYP1A1 gene have been found and could be of importance in understanding differences in susceptibility to lung cancer. On the other hand, the data presented regarding CYP2D6 and CYP2E1 are less promising. We also describe interethnic differences in the P450 gene structures as a major obstacle for extrapolation of results between different ethnic groups.
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Neoplasias Pulmonares/enzimologia , Neoplasias Pulmonares/genética , Citocromo P-450 CYP1A1 , Citocromo P-450 CYP2D6 , Sistema Enzimático do Citocromo P-450/metabolismo , Análise Mutacional de DNA , Humanos , Oxigenases de Função Mista/genética , Oxigenases de Função Mista/metabolismo , Oxirredutases/genética , Oxirredutases/metabolismo , Mutação Puntual , Polimorfismo Genético , Grupos Raciais/genéticaRESUMO
The CYP2D6 genotype and the debrisoquine and mephenytoin hydroxylation phenotypes were studied in 63 Oriental subjects including 21 Chinese, 21 Japanese and 21 Koreans. All subjects were extensive metabolizers of debrisoquine. The incidence of the S-mephenytoin poor metabolizer phenotype was 14% in the Chinese, 24% in the Japanese and 24% in the Korean population, respectively, which is similar to previous reports. The CYP2D6 genotype was analysed by Xba I and Eco RI RFLP, and by allele-specific PCR analysis for the presence of several allelic variants of the CYP2D locus. No CYP2D6A or CYP2D6B alleles, two of the most common defect alleles among Caucasians, were found among the Oriental subjects. The frequency of the CYP2D6D allele was similar to that in Caucasian populations and consistent with the low incidence of the poor metabolizer phenotype in all three Oriental populations. The CYP2D6L2-allele with duplication of an active CYP2D6L gene was identified in one Korean and one Chinese allele in association with high CYP2D6 activity. The CYP2D6Ch alleles CYP2D6Ch1 and Ch2, identified by RFLP and PCR for the -1338C-->T and 188C-->T mutations, were the most frequent allelic variants in all three populations studied, and were related to a decreased CYP2D6 activity as previously shown in Chinese. In conclusion, the present pilot study revealed major similarities in the polymorphic CYP2D locus between Korean, Japanese and Chinese populations.
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Debrisoquina/metabolismo , Oxigenases de Função Mista/genética , Adulto , Alelos , China/etnologia , Citocromo P-450 CYP2D6 , Sistema Enzimático do Citocromo P-450/metabolismo , Feminino , Genótipo , Humanos , Hidroxilação , Japão/etnologia , Coreia (Geográfico)/etnologia , Masculino , Pessoa de Meia-Idade , Oxigenases de Função Mista/metabolismo , Projetos Piloto , SuéciaRESUMO
Pronounced differences in the CYP2D6 gene between Chinese and Caucasians have previously been described. There was a low frequency of detrimental mutations in the Chinese CYP2D6 gene causing the poor metabolizer (PM) phenotype. In contrast to Caucasians where the Xba I 44 kb allele is almost always associated with the PM phenotype, Chinese with the 44/44 kb RFLP pattern are extensive metabolizers (EM). In order to evaluate whether the debrisoquine hydroxylation seen in subjects with this haplotype is catalysed by a functionally similar enzyme to CYP2D6 or is catalysed by another type of P450 isozyme, product selectivity of the 4-hydroxylation was studied in 27 Chinese. The inhibition of CYP2D6 by quinidine was also investigated. In the 26 Chinese EM the S(+)-4-hydroxy enantiomer was found to be the major urinary metabolite of debrisoquine with an enantiomeric excess of 96.8-100%, which is similar to that in Caucasians. A correlation between the amount of S(+)-4-hydroxy and the minor 7-hydroxy metabolites excreted in urine (r = 0.72; p < 0.001) was seen. The amount of these two metabolites excreted was less in Chinese EM of debrisoquine with the 44/44 kb RFLP pattern, than in those with the wild type 29/29 kb pattern (p < 0.01). The stereoselectivity was very high in both groups. All Chinese homozygous for the 44 kb fragment (n = 5) were transformed to apparent PM after a single 100 mg dose of quinidine similarly to five Caucasian EM. Both the S(+)-4- and 7-hydroxylations of debrisoquine were inhibited by quinidine in both populations. This study shows that the cytochrome P450 catalysing the 4- and 7-hydroxylations of debrisoquine in Chinese EM has the same properties (product stereoselectivity and inhibition by quinidine) as the CYP2D6 in Caucasian EM.
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Debrisoquina/metabolismo , Oxigenases de Função Mista/genética , Quinidina/farmacologia , Povo Asiático , Citocromo P-450 CYP2D6 , Inibidores das Enzimas do Citocromo P-450 , Sistema Enzimático do Citocromo P-450/metabolismo , Debrisoquina/análogos & derivados , Debrisoquina/urina , Genótipo , Haplótipos , Humanos , Hidroxilação , Taxa de Depuração Metabólica/efeitos dos fármacos , Oxigenases de Função Mista/antagonistas & inibidores , Oxigenases de Função Mista/metabolismo , Polimorfismo de Fragmento de Restrição , Quinidina/urina , Estereoisomerismo , População BrancaRESUMO
OBJECTIVES: To study the impact of the CYP2D6*10 allele on the disposition of nortriptyline in Chinese subjects. METHODS: A single dose of 25 mg nortriptyline was given orally to 15 healthy Chinese volunteers who were classified as extensive metabolizers after phenotyping with debrisoquin (INN, debrisoquine) and who were genotyped by allele-specific polymerase chain reaction. Five subjects were homozygous for CYP2D6*1, 5 subjects were homozygous for CYP2D6*10, and 5 subjects were heterozygous for these 2 alleles. Plasma concentrations of nortriptyline and its main metabolite 10-hydroxynortriptyline were measured by liquid chromatography-mass spectrometry, and the pharmacokinetics were studied during 168 hours after the dose. RESULTS: Subjects who were homozygous for CYP2D6*10 had significantly higher total areas under the plasma concentration-time curve (AUC), lower apparent oral clearances, and longer mean plasma half-life of nortriptyline than subjects in the CYP2D6*1/*1 and the heterozygous groups. For 10-hydroxynortriptyline, the AUC was lower and the plasma half-life was longer in subjects who were homozygous for CYP2D6*10 than in subjects in the other 2 groups. CONCLUSION: The CYP2D6*10 allele in Chinese subjects was associated with significantly higher plasma levels of nortriptyline compared with the CYP2D6*1 allele because of an impaired metabolism of nortriptyline to 10-hydroxynortriptyline, particularly in the subjects with the CYP2D6*10/*10 genotype. The results suggest that genotyping of CYP2D6 may be a useful tool in predicting the pharmacokinetics of nortriptyline.
Assuntos
Antidepressivos Tricíclicos/farmacocinética , Povo Asiático/genética , Citocromo P-450 CYP2D6/genética , Nortriptilina/farmacocinética , Adulto , Antidepressivos Tricíclicos/administração & dosagem , Antidepressivos Tricíclicos/sangue , China/etnologia , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Genótipo , Humanos , Hidroxilação , Masculino , Pessoa de Meia-Idade , Nortriptilina/administração & dosagem , Nortriptilina/análogos & derivados , Nortriptilina/sangue , Reação em Cadeia da Polimerase , SuéciaRESUMO
Cytochrome P450 2A6 is an important human hepatic P450 which activates pre-carcinogens, oxidises some drugs and constitutes the major nicotine C-oxidase. In fact, results have been presented in the literature which suggested a relationship between the distribution of defective CYP2A6 alleles and smoking behaviour as well as cigarette consumption. In the present report, we describe the structure of a novel CYP2A locus where the whole CYP2A6 gene has been deleted, resulting in an abolished cytochrome P450 2A6-dependent metabolism. The origin of this locus is apparently due to an unequal crossover event between the 3'-flanking region of the CYP2A6 and CYP2A7 genes. A rapid PCR-based method for the detection of the CYP2A6del allele was developed and the allele frequency was 15.1% among 96 Chinese subjects, but only 1.0% in Finns (n=100) and 0.5% in Spaniards (n=100). In the Chinese population, we did not detect any CYP2A6*2 alleles using an improved genotyping procedure, in contrast to the 11-20% previously reported. It is concluded that genotyping for the CYP2A6del allele is of great importance in studies correlating, for example, smoking behaviour, pre-carcinogen activation or drug metabolism to the CYP2A6 genotype, in particular when oriental populations are investigated.
Assuntos
Hidrocarboneto de Aril Hidroxilases , Povo Asiático/genética , Sistema Enzimático do Citocromo P-450/genética , Deleção de Genes , Oxigenases de Função Mista/genética , Reação em Cadeia da Polimerase/métodos , Alelos , Sequência de Bases , Citocromo P-450 CYP2A6 , DNA Complementar , Finlândia , Frequência do Gene , Genótipo , Humanos , Dados de Sequência Molecular , FenótipoRESUMO
A series of poly-aluminum-chloride-sulfate (PACS), which has different basicities (gamma) and Al3+/SO4(2-) molar ratio, has been prepared and dried at 105 degrees C and 65 degrees C, respectively. The distribution of aluminum species of PACS was examined, and the effect of gamma value, Al3+/SO4(2-) molar ratio, dilution on the distribution of aluminum species of PACS was also investigated by using Alferron timed complex colorimetric method. The IR spectroscopy and X-ray diffraction were used to study the effect of gamma value, Al3+/SO4(2-) molar ratio and the drying temperature on the structure of PACS. The experimental results show that Al3+/SO4(2-) molar ratio has a great effect on the distribution of aluminum species, but the dilution has a little effect on the distribution of aluminum species. The lower the Al3+/SO4(2-) molar ratio, the higher the proportions of the polymer and colloidal species in PACS. The polymeric degree of PACS was related to gamma value and Al3+/SO4(2-) molar ratio. Drying temperature has an influence on the structure and the solubility of solid PACS products.
Assuntos
Compostos de Alúmen/química , Compostos de Alumínio/química , Cloretos/química , Cloreto de Alumínio , Colorimetria , Floculação , Bicarbonato de Sódio/química , Espectrofotometria Infravermelho , Purificação da Água/métodos , Difração de Raios XRESUMO
There is pronounced individual variation in the human metabolism (eg, acetylation and hydroxylation) of drugs, in many cases due to genetic factors. The genetic basis of cytochrome P4502D6 gene defects has recently been elucidated, for instance. The cytochrome P4502D6 is absent from 7 percent of the Caucasian population, usually owing to the presence of either of two different mutations in the corresponding gene. PCR amplification of genomic DNA with allele-specific primers enables rapid prediction of the patient's drug metabolism capacity and the individualization of drug treatment with respect to dosage.
Assuntos
Preparações Farmacêuticas/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Humanos , Fenótipo , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de RestriçãoRESUMO
Angioedema is a potentially life-threatening adverse reaction to angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. To study the genetic etiology of this rare adverse event, international consortia and multicenter recruitment of patients are needed. To reduce patient heterogeneity, we have standardized the phenotype. In brief, it comprises swelling in the head and neck region that first occurs during treatment. It should not coincide with urticaria or have another likely cause such as hereditary angioedema.
Assuntos
Angioedema/induzido quimicamente , Antagonistas de Receptores de Angiotensina/efeitos adversos , Inibidores da Enzima Conversora de Angiotensina/efeitos adversos , Angioedema/classificação , Angioedema/epidemiologia , Bradicinina/metabolismo , Cabeça , Humanos , Pescoço , Fenótipo , Fatores de RiscoRESUMO
Statins are widely used lipid-lowering drugs that are effective in reducing cardiovascular disease risk. Although they are generally well tolerated, they can cause muscle toxicity, which can lead to severe rhabdomyolysis. Research in this area has been hampered to some extent by the lack of standardized nomenclature and phenotypic definitions. We have used numerical and descriptive classifications and developed an algorithm to define statin-related myotoxicity phenotypes, including myalgia, myopathy, rhabdomyolysis, and necrotizing autoimmune myopathy.
Assuntos
Inibidores de Hidroximetilglutaril-CoA Redutases/efeitos adversos , Doenças Musculares/induzido quimicamente , Doenças Autoimunes/induzido quimicamente , Doenças Autoimunes/classificação , Humanos , Doenças Musculares/classificação , Mialgia/induzido quimicamente , Mialgia/classificação , Miosite/induzido quimicamente , Miosite/classificação , Fenótipo , Rabdomiólise/induzido quimicamente , Rabdomiólise/classificação , Fatores de Risco , Terminologia como Assunto , Fatores de TempoRESUMO
This critical review discusses the potential use of agricultural waste based biosorbents (AWBs) for sequestering heavy metals in terms of their adsorption capacities, binding mechanisms, operating factors and pretreatment methods. The literature survey indicates that AWBs have shown equal or even greater adsorption capacities compared to conventional adsorbents. Thanks to modern molecular biotechnologies, the roles of functional groups in biosorption process are better understood. Of process factors, pH appears to be the most influential. In most cases, chemical pretreatments bring about an obvious improvement in metal uptake capacity. However, there are still several gaps, which require further investigation, such as (i) searching for novel, multi-function AWBs, (ii) developing cost-effective modification methods and (iii) assessing AWBs under multi-metal and real wastewater systems. Once these challenges are settled, the replacement of traditional adsorbents by AWBs in decontaminating heavy metals from wastewater can be expected in the future.
Assuntos
Agricultura , Metais Pesados/isolamento & purificação , Águas Residuárias/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , AdsorçãoRESUMO
This is the first attempt to use cationic polyacrylamide (PAM) as coagulant aid with titanium tetrachloride (TiCl4) to improve the coagulation performance and floc properties. Coagulation-flocculation treatment was applied to simulated water (with fulvic acid (FA) as model organic matter) for both coagulation behavior investigation and floc characterization. The effect of PAM on floc reformation properties after cyclic breakage/regrowth was also investigated. Ultrafiltration experiments were performed to investigate the influence of PAM aided TiCl4 coagulation on the membrane fouling. The results showed that organic removal was enhanced by PAM addition at low TiCl4 doses. Floc growth rate and floc size were significantly affected by dosing sequence. TiCl4-PAM significantly improved the floc strength factors (Sf) and recovery factors (Rf). The dosing sequence of TiCl4 and PAM significantly influenced the floc structure. Characterization of the flocculated sludge indicated that TiO2 with anatase structure and high photocatalytic activity could be obtained from the TiCl4-PAM flocculated sludge.
Assuntos
Resinas Acrílicas/química , Titânio/química , Purificação da Água/métodos , Água/química , Floculação , Concentração de Íons de HidrogênioRESUMO
The objectives of this study are to investigate the impacts of anionic polymer compound bioflocculant (CBF) as a coagulant aid on coagulation performance and floc characteristics with titanium tetrachloride (TiCl(4)) and aluminum sulfate (Al(2)(SO(4))(3)). The effect of dosing sequence was also investigated. Floc size, breakage, regrowth and floc fractal dimension were examined using a laser diffraction instrument. The results showed that CBF with TiCl(4) or Al(2)(SO(4))(3) coagulants exhibited synergistic effects by promoting dissolved organic carbon (DOC) removal. For both TiCl(4) and Al(2)(SO(4))(3), the floc recoverability was improved by CBF addition, and the flocs formed by TiCl(4) and the corresponding dual-coagulants showed weaker recovery ability than those by Al(2)(SO(4))(3) and the corresponding dual-coagulants. Fractal dimension analysis demonstrated that the floc fractal dimension values increased with the increasing coagulant dose. The effect of CBF on fractal dimension of the flocs generated by TiCl(4) was different from that of Al(2)(SO(4))(3).
Assuntos
Compostos de Alúmen/química , Polímeros/química , Titânio/química , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Ânions , Floculação , Modelos QuímicosRESUMO
Characteristics of flocs formed by charge neutralization and sweep coagulation using titanium tetrachloride (TiCl(4)) were investigated with humic acid-kaolin suspension by continuous optical monitoring. This paper focused on the regrowth ability of broken flocs after addition of second TiCl(4) dose. Variation of floc size and the fractal dimension of flocs versus second TiCl(4) dose after regrowth were investigated. Second TiCl(4) dose was added during the floc breakage period, and addition time of second TiCl(4) dose was also investigated. The results showed that, when coagulated by charge neutralization at pH 6, an appropriate second TiCl(4) dose improved regrowth ability of broken flocs at low initial TiCl(4) doses. While for high initial TiCl(4) doses, second TiCl(4) dose lowered floc re-growth ability. When coagulated by sweep coagulation at pH 10, second TiCl(4) dose made regrown flocs larger than those without second TiCl(4) dose. Floc structure analysis showed that it was determined by not only the fractal dimension of flocs, but also the chemical characteristics of floc surface. Addition time of second TiCl(4) dose had a great effect on floc regrowth ability, suggesting that the broken flocs had better regrowth when second TiCl(4) dose was added at the end of the breakage period.