Phallus impudicus loaded with γ-Fe2O3 as solid phase bioextractor for the preconcentrations of Zn(II) and Cr(III) from water and food samples

We investigated the application of fungus Phallus impudicus loaded γ-Fe₂O₃ nanoparticles as a biosorbent for magnetic solid phase extractions of trace levels of Zn(II) and Cr(III) ions from natural samples before their measurements by inductively coupled plasma optical emission spectrometry. The characterization of magnetized P. impudicus was performed using the scanning electron microscope, the energy dispersive X-ray and Fourier transform infrared spectroscopy. Important experimental factors were investigated. The experimental results fitted well to the Langmuir adsorption model and pseudo-second order kinetic model. Limit of detections of targeted ions by magnetic solid phase extraction method based on use of P. impudicus were found as 10.5 ngL⁻¹ and 12.6 ngL⁻¹ respectively for Cr(III) and Zn(II). The sorption capacities of the biosorbent were 22.8 mgg⁻¹ for Cr(III) and 25.6 mgg⁻¹ for Zn(II). The preconcentration factors were achieved as 100 for both of ions. RSDs for inter- and intraday precisions were found as lower than 2.0% and 2.1% respectively for both of targeted ions. The accuracy of the recommended process was tested by recovery measurements on the certificated reference materials and successfully applied for quantification recoveries of Cr(III) and Zn(II) ions from water and food samples.     

重金属抗性菌HQ-1生物吸附镉与银的比较研究

从北京市远郊东三岔地区一处废弃的铅锌尾矿中筛选到一株对铅、锌、铜、钴、银、镉等重金属均有很好抗性的蜡状芽胞杆菌Bacillus cereus HQ-1。特别是对镉的抗性高达1200mg/L,具有很高的应用价值。比较研究了HQ-1菌株吸附重金属银和镉的情况与机理,发现该菌株对两种重金属离子都有较强的吸附能力。对镉的吸附行为符合Langmuir模型,对银的吸附行为符合Freundlich模型。通过红外光谱和X射线能谱对其吸附机理做了初步推断。并通过质粒消除试验证明该菌株的重金属抗性与抗性质粒存在有关。     

Surfactant modified barley straw for removal of acid and reactive dyes from aqueous solution

A barley straw was modified by a surfactant, cetylpyridinium chloride, and used as an adsorbent for acid (acid blue 40) and reactive dye (reactive black 5) adsorption in aqueous solution. Characterization of the modified barley straw was performed using N₂ adsorption, titration, and FT-IR analysis. It was found that the surfactant modified barley straw exhibits higher adsorption to acid blue 40 than reactive black 5 and adsorption of the dyes is influenced by several parameters such as dye initial concentration, adsorbent dosage, solution pH, and adsorption temperature. Adsorption isotherms show that maximum adsorption of acid blue 40 and reactive black 5 is 1.02 × 10⁻⁴ and 2.54 × 10⁻⁵ mol/g, respectively. Desorption studies show that both dyes are strongly bounded with the adsorbent and exhibit low desorption.     

生物吸附剂-活性污泥法吸附处理含铬电镀废水

研究了复合生物吸附剂FY01和活性污泥处理含铬电镀废水的吸附性能.结果表明,铬的生物吸附分为快速15g·L^-1污泥对通用电镀废水、康力电镀废水中铬的联合去除率分别高达97.7%和88.1%,比两者单独处理电镀废水的吸附和缓慢吸附两个阶段.FY01具有良好的吸附稳定性,对废水的pH适应能力强,当pH=2.5~6时,10g·L^-1FY01和5g·L^-1污泥曝气处理2000mL电镀废水2h后,68.6mg·L^-1含铬通用电镀废水中总铬的去除率达71.5~75.6%;50.1mg·L^-1含铬康力电镀废水中总铬的去除率高达80.0~90.0%.FY01和活性污泥具有良好的协同促进作用,10g·L^-1FY01和除铬率总和分别高出39.8%、44.6%.     

Bioremediation of Heavy Metals in Liquid Media Through Fungi Isolated from Contaminated Sources

Wastewater particularly from electroplating, paint, leather, metal and tanning industries contain enormous amount of heavy metals. Microorganisms including fungi have been reported to exclude heavy metals from wastewater through bioaccumulation and biosorption at low cost and in eco-friendly way. An attempt was, therefore, made to isolate fungi from sites contaminated with heavy metals for higher tolerance and removal of heavy metals from wastewater. Seventy-six fungal isolates tolerant to heavy metals like Pb, Cd, Cr and Ni were isolated from sewage, sludge and industrial effluents containing heavy metals. Four fungi (Phanerochaete chrysosporium, Aspegillus awamori, Aspergillus flavus, Trichoderma viride) also were included in this study. The majority of the fungal isolates were able to tolerate up to 400 ppm concentration of Pb, Cd, Cr and Ni. The most heavy metal tolerant fungi were studied for removal of heavy metals from liquid media at 50 ppm concentration. Results indicated removal of substantial amount of heavy metals by some of the fungi. With respect to Pb, Cd, Cr and Ni, maximum uptake of 59.67, 16.25, 0.55, and 0.55 mg/g was observed by fungi Pb3 (Aspergillus terreus), Trichoderma viride, Cr8 (Trichoderma longibrachiatum), and isolate Ni27 (A. niger) respectively. This indicated the potential of these fungi as biosorbent for removal of heavy metals from wastewater and industrial effluents containing higher concentration of heavy metals.     

Heavy metal chelation by non-living biomass of three color forms of Kappaphycus alvarezii (Doty) Doty

Water pollution by toxic heavy metals is a burning environmental problem and has presented a challenge to humans. Removal of heavy metals using non-living biomass of seaweeds could be a potential solution to this problem. In the present investigation, biomass of three color forms of Kappaphycus alvarezii, viz. brown, green and pale yellow, were studied in the laboratory for their heavy metal chelating capacity using cadmium, cobalt, chromium and copper. Amongst the four concentrations used (25, 50, 75 and 100 mg L⁻¹) maximum chelation of Cd, Co and Cu was recorded at 25 mg L⁻¹ concentration. The highest amount of Cr was chelated at 100 mg L⁻¹ by all the three color forms. The pale yellow form showed maximum chelation for all four metals studied. Further, chelation in all the color forms was found to be: Cd 5.37 ± 0.59–15.84 ± 0.32 %, Co 21.19 ± 0.13–32.32 ± 0.62 %, Cr 65.38 ± 0.27–88.09 ± 0.51 % and Cu 59.53 ± 0.37–90.28 ± 0.89 %. All the three color forms of K. alvarezii serve as an excellent biodetoxifier as they all chelated considerable amounts of heavy metals.     

Microwave treated Salvadora oleoides as an eco-friendly biosorbent for the removal of toxic methyl violet dye from aqueous solution—A green approach

In the present study, microwave treated Salvadora oleoides (MW-SO) has been investigated as a potential biosorbent for the removal of toxic methyl violet dye. A batch adsorption method was experimented for biosorptive removal of toxic methyl violet dye from the aqueous solution. The effect of various operating variables, viz., adsorbent dosage, pH, contact time and temperature on the removal of the dye was studied and it was found that nearly 99% removal of the dye was possible under optimum conditions. Kinetic study revealed that a pseudo-second-order mechanism was predominant and the overall process of the dye adsorption involved more than one step. Hence, in order to investigate the rate determining step, intra-particle diffusion model was applied. Adsorption equilibrium study was made by analyzing Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) adsorption isotherm models and the biosorption data was found to be best represented by the Langmuir model. The biosorption efficiency of MW-SO was also compared with unmodified material, Salvadora oleoides (SO). It was found that the sorption capacity (q_max) increased from 58.5 mg/g to 219.7 mg/g on MW treatment. Determination of thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) confirmed the spontaneous, endothermic and feasible nature of the adsorption process. The preparation of MW-SO did not require any additional chemical treatment and a high percentage removal of methyl violet dye was obtained in much lesser time. Thus, it is in agreement with the principles of green chemistry. The results of the present research work suggest that MW-SO can be used as an environmentally friendly and economical alternative biosorbent for the removal of methyl violet dye from aqueous solutions.     

Biosorption of toxic metal ions by alkali-extracted biomass of a marine cyanobacterium,Phormidium valderianum BDU 30501

Alkali-extracted biomass of Phormidium valderianum BDU 30501, a marine filamentous, non-heterocystous cyanobacterium adsorbed more than 90% of cadmium ions from solutions containing 0.1–40mM. Cadmium binding accounted up to 18% of biomass weight (w/w). The algal biosorbent was also efficient is sequestering metal ions (Cd²+, Co²+, Cu²+, Ni²+) from a mixture. Biosorbent placed in dialysis tubing could concentrate Cd2+ (50–65%) from 1l solution (10 and 100ppm) at equilibrium. Biosorbent immobilized in polyvinyl foam also removed cadmium and cobalt efficiently, but required longer contact times (24h). Most of the bound metal ions (> 80%) could be desorbed with 0.1M HCl or EDTA, while other reagents were less efficient in the order: H2SO4 > NH4Cl > CaCl2 > Na_{2SO 4} > KSCN > KCl > NH_4OH > NaHCO₃. The regenerated biosorbent retained 80% of the initial binding capacity for Cd2+ and 50% binding capacity for Co2+ up to three cycles of reuse. Infrared spectra of the biosorbent preparation suggested carboxyl groups to be the primary sites for metal binding.     

Performance of durian shell waste as high capacity biosorbent for Cr(VI) removal from synthetic wastewater

The capability of durian shell waste biomass as a novel and potential biosorbent for Cr(VI) removal from synthetic wastewater was studied. The adsorption study was performed in batch mode at different temperatures and pH. Langmuir and Freundlich isotherm models fit the equilibrium data very well (R² > 0.99). The maximum biosorption capacity of durian shell was 117 mg/g. On modeling its kinetic experimental data, the pseudo-first order prevails over the pseudo-second order model. Thermodynamically, the characteristic of Cr-biosorption process onto durian shell surface was spontaneous, irreversible and endothermic.     

Biosorbents for heavy metals removal and their future

A vast array of biological materials, especially bacteria, algae, yeasts and fungi have received increasing attention for heavy metal removal and recovery due to their good performance, low cost and large available quantities. The biosorbent, unlike mono functional ion exchange resins, contains variety of functional sites including carboxyl, imidazole, sulphydryl, amino, phosphate, sulfate, thioether, phenol, carbonyl, amide and hydroxyl moieties. Biosorbents are cheaper, more effective alternatives for the removal of metallic elements, especially heavy metals from aqueous solution. In this paper, based on the literatures and our research results, the biosorbents widely used for heavy metal removal were reviewed, mainly focusing on their cellular structure, biosorption performance, their pretreatment, modification, regeneration/reuse, modeling of biosorption (isotherm and kinetic models), the development of novel biosorbents, their evaluation, potential application and future. The pretreatment and modification of biosorbents aiming to improve their sorption capacity was introduced and evaluated. Molecular biotechnology is a potent tool to elucidate the mechanisms at molecular level, and to construct engineered organisms with higher biosorption capacity and selectivity for the objective metal ions. The potential application of biosorption and biosorbents was discussed. Although the biosorption application is facing the great challenge, there are two trends for the development of the biosorption process for metal removal. One trend is to use hybrid technology for pollutants removal, especially using living cells. Another trend is to develop the commercial biosorbents using immobilization technology, and to improve the biosorption process including regeneration/reuse, making the biosorbents just like a kind of ion exchange resin, as well as to exploit the market with great endeavor.