Different binding mechanisms in biosorption of reactive dyes according to their reactivity

Various binding mechanisms for the uptake of reactive dyes by the protonated waste biomass of Corynebacterium glutamicum were investigated. As model reactive dyes, Reactive Blue 4 (RB 4), Reactive Orange 16 (RO 16) and Reactive Yellow 2 (RY 2) were used in this study. The solution pH strongly influenced the sorption capacity and the binding mechanisms of reactive dyes by C. glutamicum. At acidic pH, the electrostatic interaction was found to be a major binding mechanism. The maximum uptakes of RY 2, RO 16 and RB 4 at pH 2 were estimated to be 155.0+/-14.1, 156.6+/-6.7 and 184.9+/-16.4mg/g, respectively. Under alkaline conditions, the binding mechanisms were quite different according to the reactivity of reactive dyes. It was found that chemical bonding existed between the biomass surface and dye molecules under basic pH conditions.     

Cadmium biosorption by a glyphosate-degrading bacterium,a novel biosorbent isolated from pesticide-contaminated agricultural soils

In this study, biosorption of cadmium (II) ions from aqueous solutions by a glyphosate degrading bacterium, Ochrobactrum sp. GDOS, was investigated in batch conditions. The isolate was able to utilize 3 mM GP as the sole phosphorous source, favorable to bacterium growth and survival. The effect of different basic parameters such as initial pH, contact time, initial concentrations of cadmium ion and temperature on cadmium uptake was evaluated. The adsorption process for Cd (II) is well fitted with Langmuir adsorption isotherm. Experimental data were also tested in terms of biosorption kinetics using pseudo-first-order and pseudo-second-order kinetic models. Maximum metal uptake q_max was obtained as 83.33 mg g⁻¹. The sorption process of cadmium onto the Ochrobactrum sp. GDOS biomass followed second-order rate kinetic (R² = 0.9986). A high desorption efficiency was obtained in pH 2. Reusability of the biomass was examined under successive biosorption–desorption cycle repeated thrice. The characteristics of the possible interactions between biosorbent and metal ions were also evaluated by scanning electron microscope (SEM), Fourier transform infrared (FT-IR) and X-ray diffraction analysis.     

Modeling of biosorption by Marine BrownUndaria pinnatifida based on surface complexation mechanism

Biosorption is one of the useful phenomena that can be used for removal of heavy metals in wastewater. To date, many researchers have used Langmuir or Freundlich isotherms to quantify sorption capacity; however, these isotherms lack physical meaning for the adsorption mechanism, and parameters in isotherm equations must be obtained by experiment whenever environmental conditions change. We used a surface complexation model that considered adsorption phenomena as chemical reactions in solution. Using titration, we determined a surface active site and equilibrium constants for binding parameters. This model can predict the pH effect on adsorption of Pb and could be applied to explain multi-ion and other competent chemicals such as EDTA.     

Sol–gel-immobilized recombinant E. coli for biosorption of Cd

Recombinant Escherichia coli engineered with a metal-binding peptide was immobilized by entrapment in SiO₂ gel beads using the sol–gel method. Biosorption of Cd²⁺ ions by the immobilized cells was studied in both batch and continuous systems. Adsorption equilibrium could be established within 3 h and the kinetics was well described by the pseudo-second-order kinetic model. The equilibrium data were best described by the Langmuir isotherm with the maximum uptake capacity being 79.9 mg/g cell at 25 °C. More than 95% of the adsorbed Cd²⁺ could be removed with 0.1 M CaCl₂ during desorption. No loss in adsorption capacity was found up to five repeated adsorption/desorption cycles. From mass transfer analysis, only intraparticle diffusion effect was found to be important at low Cd²⁺ concentration (50 mg/dm³), while at high concentration (250 mg/dm³), both intraparticle and external mass transfer affected biosorption. Continuous removal and recovery of Cd²⁺ could be carried out by the immobilized cells in a packed-bed reactor.     

Rapid Solvent Extraction of Indium(III) and Its Separation from Gallium(III) and Aluminum(III)

Abstract

Mesityl oxide (4-methyl-3-pentene-2-one) has been used extensively for the solvent extraction separation of several transition elements (l). In the present communication, solvent extraction behavior of indium (III) toward mesityl oxide as a function of HCl or HBr concentrations has been studied and a simple and rapid method for the solvent extraction separation of gallium, indium, and aluminum has been proposed.     

Effective biosorption of patulin from apple juice by cross-linked xanthated chitosan resin

In this work, cross-linked xanthated chitosan resin (CXCR) was prepared by inverse suspension cross-linking method, using glutaraldehyde as cross-linking agent and carbon disulfide as modification agent. The biosorption of CXCR for patulin from apple juice was investigated. Batch adsorption experiments were performed to evaluate the effect of pH, temperature, contact time and initial concentration. The adsorption of CXCR for patulin was characterized by Fourier Transform Infrared Spectroscopy (FTIR). The results showed that the optimum adsorption conditions of CXCR for patulin was achieved at pH 4, 30 °C for 18 h. The adsorption data could be fitted with pseudo–second order kinetic model and Freundlich isotherm model. It indicated that CXCR is an appropriate adsorbent for the removal of patulin from apple juice.     

Hydrogen production from acid hydrolyzed molasses by the hydrogen overproducing Escherichia coli strain HD701 and subsequent use of the waste bacterial biomass for biosorption of Cd(II) and Zn(II)

This study was devoted to investigate production of hydrogen gas from acid hydrolyzed molasses by Escherichia coli HD701 and to explore the possible use of the waste bacterial biomass in biosorption technology. In variable substrate concentration experiments (1, 2.5, 5, 10 and 15 g L⁻¹), the highest cumulative hydrogen gas (570 ml H₂ L⁻¹) and formation rate (19 ml H₂ h⁻¹ L⁻¹) were obtained from 10 g L⁻¹ reducing sugars. However, the highest yield (132 ml H₂ g⁻¹ reducing sugars) was obtained at a moderate hydrogen formation rate (11 ml H₂ h⁻¹ L⁻¹) from 2.5 g L⁻¹ reducing sugars. Subsequent to H₂ production, the waste E. coli biomass was collected and its biosorption efficiency for Cd²⁺ and Zn²⁺ was investigated. The biosorption kinetics of both heavy metals fitted well with the pseudo second-order kinetic model. Based on the Langmuir biosorption isotherm, the maximum biosorption capacities (q_max) of E. coli waste biomass for Cd²⁺ and Zn²⁺ were 162.1 and 137.9 (mg/g), respectively. These q_max values are higher than those of many other previously studied biosorbents and were around three times more than that of aerobically grown E. coli. The FTIR spectra showed an appearance of strong peaks for the amine groups and an increase in the intensity of many other functional groups in the waste biomass of E. coli after hydrogen production in comparison to that of aerobically grown E. coli which explain the higher biosorption capacity for Cd²⁺ or Zn²⁺ by the waste biomass of E. coli after hydrogen production. These results indicate that E. coli waste biomass after hydrogen production can be efficiently used in biosorption technology. Interlinking such biotechnologies is potentially possible in future applications to reduce the cost of the biosorption technology and duplicate the benefits of biological H₂ production technology.     

Modeling of chromium (VI) biosorption by immobilized Spirulina platensis in packed column

This study describes biosorption of chromium (VI) by immobilized Spirulina platensis, in calcium alginate beads. Three aspects viz. optimization of bead parameters, equilibrium conditions and packed column operation were studied and subsequently modeled. Under optimized bead diameter (2.6 mm), calcium alginate concentration (2%, w/v) and biomass loading (2.6%, w/v) maximum biosorption was achieved. 140 g l⁻¹ loading of optimized beads resulted in 99% adsorption of chromium (VI) ions from an aqueous solution containing 100 mg l⁻¹ of chromium (VI). The quantitative chromium (VI) uptake was effectively described by Freundlich adsorption isotherm. The immobilized S. platensis beads were further used in a packed bed column wherein the effects of bed height, feed flow rate, inlet chromium (VI) ion concentration were studied by assessing breakthrough time. The performance data were tested for various models fitting in order to predict scale up-design parameters such as breakthrough time and column height. Results were encouraging.     

紫外诱变菌株去除废电解液中Cu2+的实验研究

以L -5的诱变菌株作为生物吸附剂 ,展开吸附Cu2 + 的实验研究。结果表明 :L -5最佳诱变时间为 5min ,到达稳定期的时间要比未诱变菌株缩短 10h左右 ,诱变后菌株L -5在 3 0℃、pH =4、摇床转速为 160r/min的条件下 ,对 [Cu2 + ] =1g/L进行吸附 ,最大吸附率达到 97.4% ,比未诱变菌株提高 11.3 % ;诱变菌株L -5对实际废电解液中Cu2 + 吸附率达到 98.5 % ,出水中Cu2 + <0 .5mg/L ,可达标排放。     

Cu(II) binding by dried biomass of red, green and brown macroalgae

Dried biomass of the marine macroalgae Fucus spiralis and Fucus vesiculosus (brown), Ulva spp. (comprising Ulva linza, Ulva compressa and Ulva intestinalis) and Ulva lactuca (green), Palmaria palmata and Polysiphonia lanosa (red) were studied in terms of their Cu(II) biosorption performance. This is the first study of its kind to compare Cu(II) uptake by these seaweeds in the South-East of Ireland. Potentiometric and conductimetric titrations revealed a variety of functionalities on the seaweed surface including carboxyl and amino groups, which are capable of metal binding. It was also found that, of the seaweeds investigated, F. vesiculosus contained the greatest number of acidic surface binding sites while Palmaria palmata contained the least. The metal uptake capacities of the seaweeds increased with increasing pH and kinetic behaviour followed a similar pattern for all seaweeds: a rapid initial sorption period followed by a longer equilibrium period. P. palmata reached equilibrium within 10min of exposure while F. vesiculosus required 60min. Correlation was found between the total number of acidic binding sites and the time taken to reach equilibrium. Fourier transform infra-red (FTIR) analysis of the seaweeds revealed the interaction of carboxyl, amino, sulphonate and hydroxyl groups on the seaweed surface with Cu(2+) ions while time course studies established the relative contribution of each of these groups in metal binding.