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In response to the narrow pH application range and difficult separation and recovery of dicyandiamide formaldehyde (DDF) for decolorization of dye wastewater, a wide area pH efficient adsorbent (HF-APT-DDF) suitable for removing anionic dyes was prepared by grafting DDF onto hemp fiber (HF) using 3-aminopropyltriethoxysilane (APTES) coupling agent. We investigated the effects of different factors on the adsorption performance of three dyes, congo red (CR), acid blue 9 (AO9), and reactive yellow K-6G (RBY K-6G), under single and mixed components. The results show that HF-APT-DDF has good decolorization effect in the pH range of 4-10. At a temperature of 298 k, initial dye concentration of 20 mg/L, pH of 8, adsorption time of 1.5 h, and dosage of 1.0 g/L and 1.4 g/L, the decolorization efficiency of HF-APT-DDF for single and mixed component dyes exceeded 97%. The maximum adsorption capacities for CR, AO9, and RBY K-6G were 116.62 mg/g, 80.16 mg/g, and 103.86 mg/g, respectively. After 5 cycles of use, the decolorization rate of HF-APT-DDF is still above 80%. The influence of inorganic salt ions on adsorption performance ranges from large to small: PO3-4>CO2-3>SO2-4>NO-3>Cl-. The adsorption of dyes by HF-APT-DDF is a spontaneous exothermic process, following the quasi second order kinetic model and Langmuir isotherm adsorption model. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The current status of research on modified silica materials for dye adsorption and removal at home and abroad was reviewed in recent years, and introduces the physical and chemical properties, adsorption principles and three main modification methods (surface chemical modification, physical modification and composite modification) of silica materials. New functionalized silica gel adsorbent materials were synthesized by modification to achieve efficient removal of different types of dyes. Finally, suggestions are made on the current problems still existing in the application of silica gel modified materials in dye treatment, which provide some reference value for its further study. [ABSTRACT FROM AUTHOR]

To solve the problems that cationic flocculant dicyandiamide formaldehyde(DDF) has small floc, high turbidity of effluent and complicated and time-consuming operation process of ordinary modified DDF method when treating anionic dye wastewater, a kind of PVP-DDF flocculant with high molecular weight which can be grafted quickly was prepared by microwave method with polyvinylpyrrolidone (PVP) as graft, DDF as matrix and ceric ammonium nitrate(CAN) as initiator. The removal effects of congored, reactive brilliant yellow K-6 G and acid blue 9 by flocculants prepared under different dosage of DDF and CAN were analyzed. The results show that when the mass ratio of PVP∶CAN∶DDF was 1 ∶0.3∶15, the decolorization performance of flocculants was the best. Under the optimum conditions, the decolorization rates of Congored, reactive brilliant yellow K-6 G and acid blue 9 simulated printing and dyeing wastewater with concentration of 20mg/L by PVP-DDF flocculant were 94.93%, 91.12% and 85.87% respectively. The turbidity values are a slow as 5.94 NTU, 5.94 NTU and 5.74 NTU, respectively. PVP-DDF flocculant has a large molecular weight, has a good decolorization effect on anionic dye wastewater, and can effectively reduce the turbidity of effluent. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Xi'an Polytechnic University is the property of Editorial Department of Journal of Xi'an Polytechnic University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to obtain high performance adsorbent for removing heavy metal lead ions(Pb2+), a new granular adsorbent (Fe-Mn-Ce-SA gel beads) was prepared by coprecipitation and gel method using sodium alginate as skeleton structure. The morphology characteristics of the adsorbent were observed by scanning electron microscope. The adsorption of Pb2+ by Fe-Mn-Ce-SA gel beads in water was studied, and the effects of pH, ion concentration and temperature on the removal rate of Pb2+ were investigated. At the same time, adsorption kinetics and adsorption isotherm experiments were carried out to explore its adsorption laws. The adsorption results show that Fe-Mn-Ce-SA gel beads have high efficiency adsorption properties to Pb2+, when temperatures rises to 298.15 K, pH=5, the ion concentration is 0.1 mol/L, and the adsorption time is 24 h, the Fe-Mn-Ce-SA gel beads for Pb2+ maximum adsorption reached 182.071 mg/g, the adsorption kinetics of gel ball met the secondary kinetic model, and the thermodynamic behavior was in accordance with Freundlich adsorption isothermal model.  [ABSTRACT FROM AUTHOR]

By combined the PVA gel carrier with SBR, the domestic sewage is treated and the best process conditions are determined.The effects of sludge settling ratio,aeration time,reaction temperature and pH change on the removal rate of COD and NH3-N are studied and the optimal control conditions are determined.The results show that in the best process conditions, the treatment effect is stable,the COD removal rate is about 80% and the NH3-N removal rate is about 79%.The effluent COD reaches the first-level standard B of Domestic Sewage Discharge Standard(GB18918—2002); the effluent NH3-N reaches A standard of the first-level standard. [ABSTRACT FROM AUTHOR]

The method of simulated CASS process with polyvinyl alcohol(PVA)gel ball packing is used to solve the difficult problem of nitrogen removal from domestic sewage in cold winter in the north. The optimal operating conditions are as follows: the aeration time is 2 h, the reflux ratio 300%, the continuous influent 5 L, and the stirring speed 2 r/s. Under the above treatment conditions, the removal rate of ammonia nitrogen is about 15% without the PVA gel ball the removal rate of ammonia nitrogen is about 65% with PVA gel ball. The experimental results show that PVA gel ball filler can effectively improve the removal rate of ammonia nitrogen in domestic sewage and solve the problem of biological nitrogen removal in low temperature domestic sewage. [ABSTRACT FROM AUTHOR]

In view of the problem of high detection limit of Perfluorooctanoic acid(PFOA)in textiles,the inport derivatization-gas chromatography/mass spectrometry(GC/MS)method was developed for the determination of PFOA.Solid phase extraction(SPE)was used to extract PFOA in textiles,and the TBAH was used as a derivative reagent via an in situ pyrolytic alkylation reaction which occurred in the GC injector.Finally the derivative of butyl-PFOA was detected by GC/MS.The method was linear over a range from 0.5 mg/L to 50 mg/L with the correlation coefficient 0.999 7. The recoveries were 86.2%,94.9%,99.3% respectively,and the relative standard deviation(RSD)is less than 5.4%,the method can detect the PFOA of textiles rapidly and effectively. [ABSTRACT FROM AUTHOR]

Aiming at the problems of high COD concentration, complex composition and poor biodegradability of the cutting waste liquid produced by mechanical processing, the degradation process is carried out by thermal persulfate method combined with coagulation, and the factors influencing the treatment effect are studied by single factor experiment.The experimental results show that the optimum dosage of PAC is 20 g/L,pH is 5, Zeta potential increases from -60. 59mV to -38. 68 mV, which enhances the flocculation effect.The removal rate of COD after coagulation is 76. 36%.After coagulation and the thermal persulfate treatment, the dosage of potassium persulfate is PS : 12C()D=2, the temperature 90 °C , pH 6 ~ 7, reaction time 4 hours, COD removal rate reaches 81. 73%; and UVv-i removal rate and COD removal rate show a certain correspondence; the effluent COD is 1 463. 43 mg/L. The results show that the thermal activation of persulfate combined with coagulation has good degradation effect on metal cutting waste liquid, and the biodegradability of the subsequent treatment is improved. [ABSTRACT FROM AUTHOR]

Aiming at the problem of poor biodegradability and difficult treatment of emulsion wastewater, the treatment of emulsified water is studied by the method of acidification and thermal persulfate oxidation to pave the way for the following biochemical treatment. Through single factor experiment, the parameters of the treatment effect are tested. Results show that when aluminum sulfate is used as coagulation demulsification, with optimum dosage 40g/L, pH 6 ~ 7, the COD removal rate reaches 45.24% after treatment.Then in thermally activated persulfate oxidation, with potassium sulfate dosage of PS:12COD0=2, temperature 80℃, solution pH 6, and reaction time 4h, the COD removal rate of effluent is 91.06%. After the pretreatment of coagulation and the thermally activated persulfate oxidation, the COD of total removal rate is 95.10%, the removal efficiency is good, and the biodegradability is greatly improved. [ABSTRACT FROM AUTHOR]

In view of the problem of difficult enrichment and high detection limit of phthalate esters (PAEs), the method of solid phase extraction (SPE) and gas chromatography (GC) was established for the determination of phthalate esters in textiles. Through comparison of four kinds of solid phase extractant eluting agent type, eluent amount, sample and the elution rate, the optimal extraction conditions were determined as: C18 column as extraction agent, 3mL methanol and 3mL ultrapure water are sequentially activated, the sample rate of 1mL/min, elution solvent is hexane acetone (30:1, V/V), the elution solvent dosage is 3mL, elution rate 1mL/min. The method has a good relationship in the low concentration range. The recoveries of spiked samples range from 84% to 102%, and the relative standard deviation (RSD) is less than 5%. DMP, DEP and DBP minimum detection limit respectively is 0.014mg/L, 0.015mg/L and 0.018mg/L.The method can quickly and effectively detect the PAEs of actual textile samples. [ABSTRACT FROM AUTHOR]