Biosorption Performance of Encapsulated Candida krusei for the removal of Copper(II)

Copper Tolerance of Novel Rhodotorula sp. Yeast Isolated from Gold Mining Ore in Gia Lai, Vietnam

In this study, twenty-five yeast strains were isolated from soil samples collected in the gold mining ore in Gia Lai, Vietnam. Among them, one isolate named GL1T could highly tolerate Cu2+ up to 10 mM, and the isolates could also grow in a wide range of pH (3-7), and temperature (10-40 °C). Dried biomass of GL1 was able to remove Cu2+ effectively up to 90.49% with a maximal biosorption capacity of 18.1 mg/g at pH 6, temperature 30 °C, and incubation time 60 min. Sequence analysis of rDNA indicated this strain was closely related to Rhodotorula mucilaginosa but with 1.53 and 3.46% nucleotide differences in the D1/D2 domain of the 28S rRNA gene and the ITS1-5.8S rRNA gene-ITS2 region sequence, respectively. Based on phylogenetic tree analysis and the biochemical characteristics, the strain appears to be a novel Rhodotorula species, and the name Rhodotorula aurum sp. nov. is proposed. This study provides us with more information about heavy metal-tolerant yeasts and it may produce a new tool for environmental control and metal recovery operations.

Investigation of cadmium and nickel biosorption by Pseudomonas sp. via response surface methodology

The environmental contamination of heavy metals has grown over the last several decades along with global industrialization and now constitutes a serious threat to human health. In this research, high cadmium (Cd) and nickel (Ni) resistant bacteria that were chosen for heavy metal biosorption were isolated from the Industries Factory in Sari, Mazandaran, Iran. Pseudomonas aeruginosa was recognized as the isolated bacterium based on its morphological, physiological, biochemical, antibiotic resistance testing, and 16S rRNA sequences. The bacteria had the highest concentrations of resistance to Cd (up to 1600 ppm) and Ni, according to the Minimum Inhibition Concentration (MIC) test (up to 2000 ppm). Single-factor studies in single and binary systems were used to examine the effects of temperature, contact duration, pH value, starting Cd and Ni concentration, and biomass dose on the Cd and Ni adsorption by P. aeruginosa. The Cd and Ni biosorption in binary solutions was optimized using the response surface methodology (RSM) based on Central Composite Design (CCD). The investigation revealed that at pH 7.0, 45 °C, and 1.5 gL^-1 biomass dose, the greatest biosorption efficiency for Cd and Ni was 92.43 percent and 88.45 percent, respectively. According to the adsorption of Cd and Ni in urban water, under these similarly extreme conditions, Cd adsorption drops to 54% and Ni to 60%. Analysis Potential functional groups involving interactions between cells and metal ions were identified using Fourier transform infrared spectroscopy (FTIR). Different compounds and heavy metal ions were found to have been adsorbed to the surface of the biosorbent by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS). It was determined that P. aeruginosa had a high rate of Cd and Ni adsorption and that variations in pH level had a greater impact than other parameters. The findings imply that P. aeruginosa biomass may be an effective, economical, and environmentally friendly method for removing Cd and Ni from contaminated settings. It also has a reasonable capacity for biosorption in both a natural environment and a laboratory environment.

Separation and Purification of Two Saponins from Paris polyphylla var. yunnanensis by a Macroporous Resin

An effective method for separating and purifying critical saponins (polyphyllin II and polyphyllin VII) from a Paris polyphylla var. yunnanensis extract was developed in this study which was environmentally friendly and economical. Static adsorption kinetics, thermodynamics, and the dynamic adsorption-desorption of macroporous resins were investigated, and then the conditions of purification and separation were optimized by fitting with an adsorption thermodynamics equation and a kinetic equation. Effective NKA-9 resin from seven macroporous resins was screened out to separate and purify the two saponins. The static adsorption and dynamic adsorption were chemical and physical adsorption dual-processes on the NKA-9 resin. Under the optimum parameters, the contents of polyphyllin II and polyphyllin VII in the product were 17.3-fold and 28.6-fold those in plant extracts, respectively. The total yields of the two saponins were 93.16%. This research thus provides a theoretical foundation for the large-scale industrial production of the natural drugs polyphyllin II and polyphyllin VII.

Innovative method for encapsulating highly pigmented biomass from Aspergillus nidulans mutant for copper ions removal and recovery

Biosorption has been considered a promising technology for the treatment of industrial effluents containing heavy metals. However, the development of a cost-effective technique for biomass immobilization is essential for successful application of biosorption in industrial processes. In this study, a new method of reversible encapsulation of the highly pigmented biomass from Aspergillus nidulans mutant using semipermeable cellulose membrane was developed and the efficiency of the encapsulated biosorbent in the removal and recovery of copper ions was evaluated. Data analysis showed that the pseudo-second-order model better described copper adsorption by encapsulated biosorbent and a good correlation (r2 > 0.96) to the Langmuir isotherm was obtained. The maximum biosorption capacities for the encapsulated biosorbents were higher (333.5 and 116.1 mg g-1 for EB10 and EB30, respectively) than that for free biomass (92.0 mg g-1). SEM-EDXS and FT-IR analysis revealed that several functional groups on fungal biomass were involved in copper adsorption through ion-exchange mechanism. Sorption/desorption experiments showed that the metal recovery efficiency by encapsulated biosorbent remained constant at approximately 70% during five biosorption/desorption cycles. Therefore, this study demonstrated that the new encapsulation method of the fungal biomass using a semipermeable cellulose membrane is efficient for heavy metal ion removal and recovery from aqueous solutions in multiple adsorption-desorption cycles. In addition, this reversible encapsulation method has great potential for application in the treatment of heavy metal contaminated industrial effluents due to its low cost, the possibility of recovering adsorbed ions and the reuse of biosorbent in consecutive biosorption/desorption cycles with high efficiency of metal removal and recovery.

Removal of Manganese and Copper from Aqueous Solution by Yeast Papiliotrema huenov

Papiliotrema huenov was previously reported to be highly tolerant of a range of extremely toxic heavy metals. This study aimed to identify the potential of P. huenov to remove manganese and copper from aqueous solution. Physical conditions which affect removal of Mn(II) and Cu(II) were determined. Optimal temperature for adsorption of both metal ions was 30 °C, and optimal pH for maximum uptake of Mn(II) and Cu(II) were 5 and 6, respectively. Under these conditions, living cells of P. huenov accumulated up to 75.58% of 110 mg/L Mn(II) and 70.5% of 128 mg/L Cu(II) over 120 h, whereas, the removal efficiency of metal ions by dead cells over 1 h was 60.3% and 56.5%, respectively. These results indicate that living cells are more effective than dead biomass for bioremediation, but that greater time is required. The experimental data extends the potential use of P. huenov in biosorption and bioaccumulation of toxic heavy metals to copper and manganese, two of the most common industrial contaminants.

Bioremediation mechanism and potential of copper by actively growing fungus Trichoderma lixii CR700 isolated from electroplating wastewater

Present study investigated the Cu²⁺ removal potential of Trichoderma lixii CR700, isolated from enormously heavy metal polluted electroplating wastewater. In the batch study, actively growing CR700 was able to remove 84.6% of Cu²⁺ at the concentration 10 mg/L of Cu²⁺ within 120 h after incubation and the accumulated and surface adsorbed amount of Cu was 0.51 and 0.47 mg/g of dry biomass respectively. T. lixii CR700 also showed efficient Cu²⁺ removal potential in the pH ranges from 5.0 to 8.0, in the presence of other co-occurring contaminant such as heavy metal, anions and metabolic inhibitor as well from real tannery wastewater. Alteration on cell surface of Cu²⁺ treated mycelia of T. lixii CR700 was analyzed using scanning electron microscope. Fourier transform infrared spectroscopic analysis was performed to identify the role of surface functional group in Cu²⁺ adsorption which revealed that COO^─ functional group lead Cu²⁺ adsorption onto the surface of T. lixii CR700. Thus, T. lixii CR700 uses simultaneous surface sorption and accumulation mechanism in Cu²⁺ removal and can be potentially applied for bioremediation of Cu²⁺ contaminated wastewater in ecofriendly, safe and sustainable way.

The improved methods of heavy metals removal by biosorbents: A review

For decades, a vast array of innovative biosorbents have been found out and used in the removal of heavy metals, including bacteria, algae and fungi, etc. Although extensive biological species have been tried as a biosorbent for heavy metals removal, for removal efficiency or economy efficiency limited, it has failed to make a substantial breakthrough in practical application. Thus, many improved methods based on biosorbents emerged. In this review, based on the literature and our research results, we highlight three types of novel methods for biosorbents removal of heavy metals: chemical modification of biosorbents; biomass and chemical materials combination; multiple biomass complex systems. We mainly focus on their configuration, biosorption performance, their creation method, regeneration/reuse, their application and development in the future. Through the comparative analysis of various methods, we think that intracellular autogenous nanomaterials may open up another window in biosorption of heavy metals area. At the same time, the combination of various treatment methods will be the development tendency of heavy metal pollution treatment in the future.

New effective 3-aminopropyltrimethoxysilane functionalized magnetic sporopollenin-based silica coated graphene oxide adsorbent for removal of Pb(II) from aqueous environment

A new effective adsorbent, 3-aminopropyltrimethoxysilane functionalized magnetic sporopollenin (MSp@SiO₂NH₂) based silica-coated graphene oxide (GO), (GO@SiO₂-MSp@SiO₂NH₂) was successfully synthesized and applied for the first time in the removal of hazardous Pb(II) ions from aqueous solution. The properties of the composite were characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX) and vibrating-sample magnetometery (VSM). Evaluation of GO@SiO₂-MSp@SiO₂NH₂ adsorption performance at optimum conditions revealed that the adsorbent has a maximum adsorption capacity of 323.5 mg/g for Pb(II) using 50-200 mg/L initial Pb(II) ions concentrations. Initial and final concentrations of Pb(II) ions in aqueous solution were analyzed using graphite furnace atomic absorption spectroscopy (GF-ASS). The adsorption behavior of Pb(II) ions onto GO@SiO₂-MSp@SiO₂NH₂ was studied using Langmuir, Freundlich and Temkin isotherms models. The values of coefficient of determination showed that the adsorption best fitted the Langmuir model (R² = 0.9994). Kinetic studies suggested that the adsorption of Pb(II) ion followed a pseudo-second-order rate model (R² = 1.00) and thermodynamic studies revealed that the adsorption process is endothermic and spontaneous. The effect of co-existing ions on Pb(II) ion adsorption were also studied and found to have considerable effects only at higher matrix concentration. The adsorbent can be reused up to ten times and retain its good adsorption capacity. In addition, GO@SiO₂-MSp@SiO₂NH₂ showed great potential for Pb(II)removal from industrial wastewater samples.

Synthesis of novel sepiolite-iron oxide-manganese dioxide nanocomposite and application for lead(II) removal from aqueous solutions

In this study, the sepiolite-iron oxide-manganese dioxide (Sep-Fe₃O₄-MnO₂) nanocomposite was synthesized and applied as a magnetically separable adsorbent for removal of Pb(II) ions from water in a batch system. The effects of initial Pb(II) concentration, adsorbent dosage, contact time, pH value, and temperature were investigated to optimize the conditions for maximum adsorption. The equilibrium adsorption data were analyzed with the Langmuir, Freundlich, and Temkin models. The adsorption process closely agreed with the Langmuir adsorption isotherm, and the monolayer saturation adsorption value was achieved as 131.58 mg g^-1. The adsorption kinetics follow the pseudo-second-order (PSO) model that illustrated the rate controlling step might be chemisorption. Thermodynamic investigations for the removal process were conducted by determining the values of ∆G°, ∆H°, and ∆S°. The adsorption behavior of Pb(II) on the Sep-Fe₃O₄-MnO₂ was a spontaneous and endothermic process. Several consecutive adsorption-desorption cycles confirmed that the proposed Sep-Fe₃O₄-MnO₂ nanocomposite could be reused after successive lead removal. Furthermore, the practical application of the adsorbent was successfully realized by the treatment of real Pb-contaminated water samples.

Recovering metals from aqueous solutions by biosorption onto phosphorylated dry baker's yeast

Biosorption is a cost-effective and simple technique for removing heavy metals and rare earth elements from aqueous solution. Here, metals were recovered from aqueous solutions using phosphorylated dry baker’s yeast cells. The cells were phosphorylated using cyclo-triphosphate, Na₃P₃O₉. The total P content of the phosphorylated cells was ~1.0 mmol/g dry cell weight (DCW). The zeta potential of the phosphorylated cells was −45 mV, two times higher than for the non-phosphorylated cells. The strong negative charges of the phosphorylated cells allowed the cells to adsorb heavy metal ions such as Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺, the adsorption capacities of which reached ~1.0 mmol/g DCW. This adsorption capacity was the highest level found in the previous studies using yeast dead biomass. The adsorbed metal ions were easily desorbed in 0.1 M HCl. The phosphorylated cells also adsorbed rare earth ions including Ce³⁺, Dy³⁺, Gd³⁺, La³⁺, Nd³⁺, Y³⁺, and Yb³⁺ with high efficiency. Furthermore, the phosphorylated yeast cells selectively adsorbed the rare earth ions (Nd³⁺ and Yb³⁺) from a solution containing heavy metals and rare earth ions because trivalent positively charged ions were adsorbed preferentially over divalent ions. Thus, phosphorylated yeast cells therefore have great potential for use as novel bioadsorbents. It is also expected that this technique can be applied to many microbial materials as well as yeast.