Biosorption of hazardous textile dyes from aqueous solutions by hen feathers: Batch and column studies

The biosorption potential of hen feathers (HFs) to remove hazardous textile dyes, namely congo red (CR) and crystal violet (CV), from their aqueous solutions was investigated in batch and dynamic flow modes of operation. The effect of biosorption process parameters such as solution pH, initial dye concentration, temperature, feed flow rate and bed height was studied. Biosorption equilibrium data were well described by the Langmuir isotherm model. Kinetic studies at different temperatures showed that the rate of biosorption followed the pseudo second-order kinetics well. A thermodynamic study showed that biosorption of both CR and CV was spontaneous and endothermic. Breakthrough time increased with increase in bed height but decreased with increase in flow rate. The Thomas model showed good agreement with the dynamic flow experimental data. Overall, the results suggest the applicability of HFs as an efficient biosorbent for removal of carcinogenic textile dyes from aqueous media.     

Biosorption of basic violet 10 onto activated Gossypium hirsutum seeds:Batch and fixed-bed column studies

Sulphuric acid activated immature Gossypium hirsutum seed (AIGHS) was prepared to biosorbe basic violet 10 (BV10) from aqueous solutions. Methylene blue number, iodine number and Brunauer-Emmett-Teller surface analysis indicated that the AIGHS were hetero-porous. Boehm titrations and Fourier-transform infrared spectra demonstrated the chemical heterogeneity of the AIGHS surface. Batch biosorption studies were used to examine the effects of process parameters in the following range: pH 2-12, temperature 293-313 K, contact time 1-5 h and initial concentration 200-600 mg·L^-1. The matching of equilibrium data with the Langmuir-Freundlich formof isotherms indicated that the BV10 was adsorbed via chemisorption and pore diffusion. Kinetic investigation indicated multiple order chemisorption through an Avrami kinetic model. Film diffusion controlled the rate of BV10 biosorption onto AIGHS. The spontaneous and endothermic nature of sorptionwas corroborated by thermodynamic study. Continuous biosorption experimentswere performed using a fixed-bed column and the influence of operating parameters was explored for different ranges of initial concentration 100-300 mg·L^-1, bed height 5-10 cm, and flow rate 2.5-4.5 ml·min^-1. A dose response model accurately described the fixed-bed biosorption data. An external mass transfer correlation was formulated explaining BV10-AIGHS sorption.     

Removal of toxic metal ions from aqueous systems by biosorptive flotation

Biosorptive flotation was used as a combined operation for the simultaneous abstraction of nickel, copper and zinc ions from aqueous streams. Laboratory‐scale batch experiments, as well as pilot‐scale continuous experiments, have been conducted. Grape stalks, a by‐product of the winery industry, were used as sorbent material. The experimental procedure consisted of two consecutive stages: (i) biosorption, and (ii) flotation. The possibility of reusing biomass, after appropriate elution, was also examined. The main parameters examined were biomass concentration, particle size of sorbent, surfactant concentration, pH and flocculation. Flotation removals, following laboratory‐scale experiments, were found to be in the order of 100, 85 and 70% for copper, zinc and nickel, respectively. In pilot‐scale experiments, biomass sorption capacities were determined as 25 for copper, 81 for zinc and 7 µmol dm^?3 for nickel. The order of biomass affinity regarding the studied metals was Cu > Zn > Ni. Short retention time and high effectiveness suggest that biosorptive flotation is a promising treatment process for the removal of toxic metals from contaminated aqueous solutions. © 2002 Society of Chemical Industry     

Synthesis,characterization, and adsorption properties of collagen and attapulgite-filled copolymer biocomposites: Batch and column studies

Several biocomposites were synthesized by copolymerizing hydroxyethyl methacrylate (HEMA) and itaconic acid (IA) at varied molar ratios in the presence of different wt% of collagen (CLG) and attapulgite (APG) clay. The structure and properties of the biocomposite adsorbents were characterized by Fourier transform infrared apectroscopy, nuclear magnetic resonance, X-ray photo electron spectroscopy, X-ray diffraction, scanning electron microscope, transfer electron microscopy, energy-dispersive X-ray analysis, differential thermal analysis–thermogravimetric analysis, point zero charge analysis, mechanical properties, and pH reversibility tests. The synthesis variables were optimized with a central composite design of response surface methodology (RSM). The biocomposite prepared with an optimized composition of 1.5 wt% CLG, 1.7 wt% APG, and 5:1 molar ratio of HEMA:IA showed an adsorption capacity (Q_e, mg/g) of 674.4/602.4 for methylene blue (MB)/Rose Bengal (RB) dye from a feed containing 200 mg/L of MB + RB dye mixture in batch mode. In a fixed bed in column mode, the optimized biocomposite showed a removal% of 82.8/71.3 for 100 mg/L inlet concentration, 20 ml/min flow rate, and 20 mm bed height with a breakthrough time of 23/31 min and a mass transfer coefficient (k_mtc × 10⁵ cm/s) of 8.36/7.67 for MB/RB as single dye solution.     

多粘类芽孢杆菌HY96-2制剂中活菌的稳定性研究

考察了芽孢、贮存温度、含水率、光照和pH对多粘类芽孢杆菌HY96-2制剂稳定性的影响。结果表明，与非芽孢制剂相比，芽孢制剂在-20℃～37℃的范围内贮存时活菌存活率较高；含水率为5％左右的芽孢制剂的贮存稳定性较好；当含水率低于5％时，HY96-2芽孢制剂在-20℃贮存30d、20℃贮存90d和54℃贮存14d过程中，活菌存活率均在85％以上；光照2d后制剂中活菌的存活率仅为32．0％；pH在5．5-8时，HY96-2芽孢制剂中活菌能够正常地生长，并具有较高的活菌量。实际使用HY96-2芽孢制剂时，应选择阴天或傍晚，避开光照强烈的时间，并且施药土壤的pH宜在5．5-8范围内。     

Lignocellulosic jute fiber as a bioadsorbent for the removal of azo dye from its aqueous solution: Batch and column studies

The feasibility of the use of jute fiber for the adsorption of azo dye from an aqueous solution was evaluated with batch and fixed‐bed column studies. The batch studies illustrated that dye uptake was highly dependent on different process variables, namely, the pH, initial dye concentration of the solution, adsorbent dosage, contact time, ionic strength, and temperature. The exothermic and spontaneous nature of adsorption was revealed from thermodynamic study. The equilibrium adsorption data were highly consistent with the Langmuir isotherm and yielded an R² value of 0.999. Kinetic studies divulged that the adsorption followed a pseudo‐second‐order model with regard to the intraparticle diffusion. In the column studies, the total amount of adsorbed dye and the adsorption capacity decreased with increasing flow rate and increased with increasing bed height and initial dye concentration. Also, the breakthrough time and exhaustion time increased with increasing bed depth but decreased with increasing flow rate and influent dye concentration. The column performances were predicted by the application of the bed‐depth service time model and Thomas model to the experimental data. The virgin and dye‐adsorbed jute fiber was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy analyses. The investigation suggested that jute fiber could be applied as a promising low‐cost adsorbent for dye removal. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Catalytic hydrodesulfurization and liquefaction of coal: Batch autoclave studies

The hydrodesulfurization and liquefaction of a high sulfur West Virginia coal has been studied in batch autoclave experiments with tetralin and several Co-Mo-Al₂O₃ catalysts. Monolith catalysts made from Corning monolith aluminas have been studied in three configurations. The most favorable liquefaction and desulfurization were obtained with a nominal configuration of 200 square cells/in.². Four particulate catalysts made from controlled pore size aluminas were studied in two sets of experiments. Significant differences in the effects of pore size and stirring rate for sulfided and not-sulfided catalyst were observed. The most favorable distributions were obtained with a large pore, unsulfided catalyst at a low stirring rate and a small pore, sulfided catalyst at a high stirring rate.     

Genome Mining of the Lipopeptide Biosynthesis of Paenibacillus polymyxa E681 in Combination with Mass Spectrometry: Discovery of the Lipoheptapeptide Paenilipoheptin

Paenibacillus polymyxa strains are qualified for agro‐biotechnological uses such as plant growth promotion and for biocontrol strategies against deleterious phytopathogenic competitors in the soil depending on their attractive arsenal of bioactive compounds. Moreover, they are potent producers of antibiotics for medical applications. To identify new products of such organisms, genome mining strategies in combination with mass spectrometry are the methods of choice. Herein, we performed such studies with the Paenibacillus strain E681. Bioinformatic evaluation of its genome sequence revealed four gene clusters A–D encoding nonribosomal peptide synthetases (NRPSs). Accordingly, four lipopeptide families were detected by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS). Clusters A and D codify the well known fusaricidins and polymyxins. A yet‐unknown lipoheptapeptide was discovered and structurally characterized by de novo sequencing by using MALDI‐LIFT‐TOF/TOF MS. It was designated as paenilipoheptin. From structure predictions we infer that the production of this agent is encoded by gene cluster C. Gene cluster B encodes the synthesis of tridecaptins, a family of open‐chain lipotridecapeptides. Strain E681 produces new subspecies of such compounds (tridecaptins E) showing variations both in their fatty‐acid part as well as in their peptide part.     

Identification of Genes Involved in Fe–S Cluster Biosynthesis of Nitrogenase in Paenibacillus polymyxa WLY78

NifS and NifU (encoded by nifS and nifU) are generally dedicated to biogenesis of the nitrogenase Fe–S cluster in diazotrophs. However, nifS and nifU are not found in N₂-fixing Paenibacillus strains, and the mechanisms involved in Fe–S cluster biosynthesis of nitrogenase is not clear. Here, we found that the genome of Paenibacillus polymyxa WLY78 contains the complete sufCDSUB operon, a partial sufC2D2B2 operon, a nifS-like gene, two nifU-like genes (nfuA-like and yutI), and two iscS genes. Deletion and complementation studies showed that the sufC, sufD, and sufB genes of the sufCDSUB operon, and nifS-like and yutI genes were involved in the Fe–S cluster biosynthesis of nitrogenase. Heterologous complementation studies demonstrated that the nifS-like gene of P. polymyxa WLY78 is interchangeable with Klebsiella oxytoca nifS, but P. polymyxa WLY78 SufCDB cannot be functionally replaced by K. oxytoca NifU. In addition, K. oxytoca nifU and Escherichia coli nfuA are able to complement the P. polymyxa WLY78 yutI mutant. Our findings thus indicate that the NifS-like and SufCDB proteins are the specific sulfur donor and the molecular scaffold, respectively, for the Fe–S cluster formation of nitrogenase in P. polymyxa WLY78. YutI can be an Fe–S cluster carrier involved in nitrogenase maturation in P. polymyxa WLY78.     

Efficient acetoin production by optimization of medium components and oxygen supply control using a newly isolated Paenibacillus polymyxa CS107

BACKGROUND: Acetoin is a natural flavor commonly used in wine, buffer, honey, garnet berry and strawberry as a food additive. It also has been widely applied in cosmetics, pharmacy and chemical synthesis. Culture medium optimization and process control were carried out for efficient production of acetoin by a newly isoliated P. polymyxa CS107. RESULTS: An acetoin high producing strain, designated as CS107, was newly isolated and identified as P. polymyxa based on its physiological and biochemical characteristics as well as the 16S rDNA sequence. The medium composition was optimized in shake flask fermentations by a sequential statistical experimental design. Under the optimized conditions, acetoin concentration of 30.98 g L^?1 was achieved with 71.83% of theoretical glucose conversion efficiency. Fed‐batch fermentation based on a suitable agitation speed was carried out in a 5 L jar, the maximum acetoin concentration of 55.3 g L^?1 was obtained with the productivity of 1.32 g L^?1 h^?1 and the yield of 75.62%. CONCLUSION: A new strain for efficient production of acetoin, designated as P. polymyxa CS107, was obtained. The optimization of fermentation variables and fed‐batch culture resulted in a maximum acetoin concentration of 55.3 g L^?1 in 5 L jar. Copyright © 2012 Society of Chemical Industry     

Adsorption and desorption behaviors of S-adenosyl-L-methionine in a fixed-bed ion-exchange column

S-adenosyl-L-methionine (SAM) is one of most versatile molecules in nature and has wide medical applications. The ion-exchange separation process of SAM of the extract of yeast cells has many advantages over selective precipitation by picrolonic acid. Experiments of the dynamic column process of SAM on JK110 resin were carried out in a fixed-bed ion-exchange column. The effects of different operation parameters on the adsorption and desorption behaviors of SAM were investigated. The results show that the ion-exchange adsorption of SAM is successfully implemented at 2BV/h, 10 g/L, pH 5.0; the adsorbed SAM in the ion-exchanged bed is efficiently desorbed by 0.2 N H₂SO₄ solution at the flow rate of 2BV/h. According to material balance, the recovery yield of SAM for this ion-exchange process is 90.1%. Finally, this ion-exchange process was successfully scaled up to separate SAM at high yield and purity.     

电镀废水中重金属处理方法

介绍了电镀废水中重金属处理的3种方法:中和沉淀法、硫化物沉淀法及螯合物沉淀法。讨论了中和沉淀法和硫化物沉淀法的优点及存在的问题,并给出了解决方法。螯合物沉淀法有待进一步研究。     

Batch and column adsorption of perfluorooctane sulfonate on anion exchange resins and granular activated carbon

Perfluorooctane sulfonate (PFOS) has been detected widely in the natural water matrix and is persistent, bioaccumulative, and toxic. To prevent the adverse effects of PFOS contamination on human health and the environment, effective removal techniques are needed. Adsorption is considered an effective technique for PFOS removal. In this study, five anion exchange resins and granular activated carbon (GAC) were examined to evaluate their performance for the removal of PFOS in both batch and column experiments. Experimental adsorption data for all of the adsorbents exhibited a high correlation with the Freundlich isotherm (R² = 0.95 – 0.98). Most of the anion exchange resins demonstrated a higher adsorption capacity than the GAC. PFA300 had the highest adsorption capacity (455 mg/g). Continuous adsorption of PFOS was performed in column experiments using the same adsorbents that had been used in the batch experiments. The experimental breakthrough curves were set at C/C₀ = 0.1. PFA300 showed the longest operation time before reaching the breakthrough point. The Yoon and Nelson model was used to predict the half‐saturation time of the anion exchange resins. Moreover, the anion exchange resins exhibited high recovery of PFOS by an organic solvent. Continuous PFOS adsorption on a column can be achieved using anion exchange resins for water/wastewater treatment. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39782.     

Boron removal from aqueous solutions by ion-exchange resin: Batch studies

In this study, boron removal from aqueous solutions was examined using Dowex 2 × 8 anion exchange resin. The sorption behaviour of resin was investigated as a function of pH, contact-time and temperature, initial boron concentration of solution, resin dosage and effect of other ions. The maximum sorption value for boron was observed at pH 9. The percent removal of boron decreased as temperature and initial boron concentration increased. The presence of other ions in solutions affected the sorption of boron significantly. The Langmuir isotherm was used to describe observed sorption phenomena. The maximum sorption capacity of Dowex 2 × 8 was determined as 16.98 mg B/g at pH 9 and 25°C. The quantitative stripping of boron from resin was obtained with 0.5 M H₂SO₄ or 0.5 M HCl solutions at 25°C. A generalised ion exchange kinetic model was applied to fit the kinetic data obtained by using the Dowex 2 × 8 and the rate-determining step is determined as film-intraparticle diffusion.     

A structured catalytic bubble column reactor: hydrodynamics and mixing studies

This paper reports the results of a comprehensive experimental study of the hydrodynamics and mixing in two bubble column reactors of 0.1 and 0.24 m in diameter with KATAPAK-S^® as packing material. Total gas hold up and axial dispersion coefficients were measured in the structured bubble columns and the values were compared with experimental results obtained in the same work with empty bubble columns. The results reveal that the gas hold up in structured bubble columns is practically the same as in empty bubble columns when compared at the same superficial gas velocity based on open area available for gas–liquid dispersion. The presence of the structured elements in the bubble column reactor reduces the liquid phase backmixing by one order of magnitude.     

Heavy metal contaminants in inorganic and organic fertilizers

Commercial phosphate (P) fertilizers contain small amounts of heavy-metal contaminants which were minor constituents in phosphate rock (PR). Animal manures and sewage sludges (biosolids) are the main organic fertilizers and the latter also may contain heavy-metal contaminants. Heavy metals in biosolids may be found in the inorganic form or may be organically complexed, which could affect their chemical reactions in soil. These heavy metals may accumulate in soil with repeated fertilizer applications. Cadmium (Cd) is the heavy metal of most concern because it may affect human health. Other heavy metals of possible significance are arsenic (As), chromium (Cr), lead (Pb), mercury (Hg), nickel (Ni), and vanadium (V). Some countries have set tolerance limits on heavy-metal additions to soil because their long-term effects are unknown. These limits usually are set for the tillage layer (surface 20–30 cm) of soil where most root activity occurs. Controls on heavy-metal concentrations in sewage biosolids and their maximum total and annual loading rates to soil have been imposed in some countries. Regulations also have been proposed for phased-in limits on maximum heavy metal concentrations permitted in P fertilizers, or they are already in effect. Most of the fertilizer regulations relate Cd limits to P concentrations, so P application rates dictate Cd inputs to soil. Regulations affecting sewage biosolids include a number of heavy metals, while those concerning P fertilizers only include limits on Cd at this time.     

Sorptive removal of Pb(II) ions from aqueous solution using sweetmeat waste: Batch and column study

This article deals with removal of Pb(II) ions from aqueous media using sweet industry byproduct, that is, sweetmeat waste (SMW). The SEM images revealed highly heterogeneous sorbent surface. XRD and FTIR studies were done. The sorption equilibrium time was found 45 min only, and the sorption followed pseudo-second-order reaction model, indicating chemisorption as the rate-limiting step. Pb(II) removal followed Langmuir isotherm model best, and the maximum sorption capacity was 11.38 mg/g. The fixed bed column study was performed and analyzed using Logit, Bohart-Adams and Wolborska models. The sorption rate and capacity constants were 0.143(±0.017) L/mg.h and 39(±7) mg/L, respectively.     

Heavy metal removal by olive pomace: biosorbent characterisation and equilibrium modelling

This paper concerns with metal biosorption onto an agricultural waste, olive pomace. Experimental tests of adsorbent characterisation (potentiometric titration, IR analyses, selective extractions) and titration modelling (accounting for adsorbent heterogeneity by the introduction of a two-peak proton affinity distribution function) evidence that carboxylic and phenolic groups are the main active sites involved in metal removal. Potentiometric titration and single metal system biosorption tests (Pb, Cu, Cd) onto native and treated olive pomace samples are represented by an equilibrium model describing the competition among heavy metals and hydrogen ions in solution.