Junxia Yu

Polymer modified biomass of baker's yeast for enhancement adsorption of methylene blue, rhodamine B and basic magenta

In this study, poly (methacrylic acid) modified biomass was prepared to improve the adsorption capacities for three dyes: methylene blue (MB), rhodamine B (RB) and basic magenta (BM). FTIR and potentiometric titration demonstrated that a large number of carboxyl groups were introduced on the biomass surface, and the concentration of the functional group was calculated to be 1.4 mmol g(-1) by using the first and second derivative method. According to the Langmuir equation, the maximum uptake capacities (q(m)) for MB, RB and BM were 869.6, 267.4 and 719.4 mg g(-1), which were 17-, 11- and 12-fold of that obtained on the unmodified biomass, respectively. Adsorption kinetics study showed that the completion of the adsorption process needed only 70 min, which is faster than that occur with the common sorbent such as activated carbon and resin. Temperature and ionic strength experiment showed that they both had effect on the adsorption capacity of the modified biomass. Good result was obtained when the modified biomass was used to treat dye wastewater.

Simultaneous removal of cationic and anionic dyes by the mixed sorbent of magnetic and non-magnetic modified sugarcane bagasse

Magnetic carboxyl groups modified (MMS) and non-magnetic amine groups modified (AMS) sugarcane bagasse were prepared and mixed to remove cationic and anionic dye simultaneously from aqueous solution. For comparison, the adsorption performances of MMS, AMS and the mixed sorbent for basic magenta (cationic dye) and congo red (anionic dye) were investigated in the binary system. Zeta potential analysis showed that MMS was negatively charged and AMS was positively charged in the investigated pH range. The adsorption capacities of MMS for basic magenta and congo red were 1.24 and 0.04mmolg(-1), while those of AMS were 0.04 and 1.55mmolg(-1), respectively. Both of MMS and AMS had high adsorption capacity and affinity toward opposite-charged dye but low adsorption capacity and affinity toward similar-charged dye. Adsorption experiments in the binary system showed that only the mixed sorbent could remove the two dyes simultaneously from aqueous solution (removal efficiencies >90%). The amounts of basic magenta and congo red absorbed on the mixed sorbent both increased linearly with the increase of their initial concentrations in the investigated range. The dye loaded mixed magnetic and non-magnetic sorbents could be separated by a magnet. MMS and AMS could be regenerated by using acid and alkaline eluents, respectively. After regeneration, the MMS and AMS could be mixed again and used repeatedly. The mixed sorbent had great potential in practical dye waste water treatment.

Adsorption Performances of Cationic Dyes from Aqueous Solution on Pyromellitic Dianhydride Modified Sugarcane Bagasse

In this study, pyromellitic dianhydride (PMDA) modified waste sugarcane bagasse (SCB) was prepared through a simple method to remove two cationic dyes: methylene blue (MB) and malachite green (MG) from aqueous solution. Adsorption performances of MB and MG on the modified sorbent were investigated in details. The adsorption capacities of the modified SCB for MB and MG were 571.4 and 377.4 mg g−1, respectively, which were 10 and 12 times than that obtained on the unmodified SCB. Adsorption kinetics study showed equilibriums were obtained after adsorption for 13 hours for both dyes. The modified SCB could be used repeatedly after regeneration. FTIR results showed that carboxyl and hydroxyl groups on the modified SCB involved in adsorption process.

Desorption behavior of methylene blue on pyromellitic dianhydride modified biosorbent by a novel eluent: Acid TiO2 hydrosol

In this study, waste beer yeast powder was modified by pyromellitic dianhydride to improve its adsorption capacities for cationic dye: methylene blue (MB). According to the Langmuir equation, the maximum uptake capacities (q(m)) of the modified biomass for MB was 830.8 mg g(-1), which was about five times than that obtained on the unmodified biomass. Adsorption mechanism was investigated by FTIR. Desorption kinetics of methylene blue in six solvents: HCl (0.1 mol L(-1)), ethanol, mixtures of HCl (0.1 mol L(-1)) and ethanol with different volume ratio and a self-clean eluent: acid TiO(2) were studied in details. Results showed that desorption kinetics curve fit the two-step kinetic model, and methylene blue release process was distinctly divided into two steps: rapid and slow desorption steps. 52.2% of the methylene blue could be desorbed into TiO(2) hydrosol after 30 h desorption at the first desorption cycle, and the desorbed dye in TiO(2) hydrosol could be degrade completely under sunlight irradiation. After three desorption-photodegradation cycles, 80.0% of the absorbed dyes could be desorbed from the surface of the modified biomass. Although there was much work to do, the self-clean eluent: TiO(2) hydrosol had great potential in practical use.

Dynamic microwave-assisted extraction of total ginsenosides from ginseng fibrous roots

A dynamic microwave-assisted extraction (DMAE) method is established for the extraction of total ginsenosides from ginseng fibrous roots. The extraction process has been simulated and its main affection factors (liquid/solid ratio K of solvent to ginseng powders (V/m), irradiation time, irradiation temperature, extracting solution concentration, flow rate of solvent and microwave power) have been optimized by response surface methodology (RSM). The optimum conditions of extraction are the liquid/solid ratio of 270 mL/g, the extraction temperature of 75 °C, the extraction time of 35 min, ethanol concentration of 70% (V/V), the solvent flow rate of 1.3 mL/min, and the microwave power of 500 W. The yield of ginsenosides obtained by the proposed DAME method is (15.0±0.7) %, which is well agreement with the yield predicted by the model. Compared with static microwave-assisted extraction, DMAE has a higher extraction yield and can avoid the degradation of ginsenoside.

Adsorption of Methylene Blue on Poly (Methacrylic Acid) Modified Chitosan and Photocatalytic Regeneration of the Adsorbent

The preparation of poly(methacrylic acid) modified chitosan microspheres (PMAA-GLA-CTS) and its application for the removal of cationic dye, methylene blue (MB), in aqueous solution in a batch system were described. The modified chitosan was characterized using FTIR and XPS analysis. The effects of the pH of the solution, contact time, and initial dye concentration were studied. The adsorption capacity of the microspheres for MB increased significantly after the modification as a large number of carboxyl groups were introduced. The equilibrium process was better described by the Langmuir rather than the Freundlich isotherm. According to the Langmuir equation, the maximum adsorption capacity was 1 g · g−1 for MB. Kinetic studies showed better correlation coefficients for a pseudo-second-order kinetic model, confirming that the sorption rate was controlled by a chemisorption process. Photocatalytic regeneration of spent PMAA-GLA-CTS using UV/TiO2 is effective. Further, the regenerated PMAA-GLA-CTS exhibits 90% efficiency for a subsequent adsorption cycle with MB aqueous solutions.

Combination of biosorption and photodegradation to remove methyl orange from aqueous solutions

In this study, metal ion‐modified biomass of waste beer yeast was prepared to improve its adsorption capacity for an anionic dye: methyl orange. The adsorption capacities of Fe3+‐, Mg2+‐, Ca2+,‐ and Na+‐modified biomass preparations for methyl orange were 90.8, 51.3, 23.0, and 20.6 mg/g, which were 30, 17, 8, and 7 times that of the unmodified biomass, respectively. Adsorption isotherm experiments showed that the Freundlich model gave better fits than the Langmuir model for methyl orange adsorption on Fe3+‐, Mg2+‐, Ca2+‐modified and unmodified biomass, whereas on Na+‐modified biomass the Langmuir model gave better fits. The sorption and desorption kinetics of methyl orange on Fe3+‐ and Mg2+‐modified biomass both fitted well to the pseudo‐second‐order kinetic models, with R≥0.998, and the desorption processes in NaOH solution (pH 12) were very fast in attaining equilibrium, i.e. within 15 min. In order to avoid secondary pollution, the eluent containing the desorbed methyl orange was treated with a photocatalyst: P25. After that, the eluent could be reused, and thus saving a large volume of eluent.

Effects of co-ion initial concentration ratio on removal of Pb2+ from aqueous solution by modified sugarcane bagasse

A modified sugarcane bagasse (SCB) fixed bed column was used to remove Pb2+ from aqueous solution. To determine the optimal condition for Pb2+ separation, Ca2+ was chosen as the model interfering ion, and effects of Ca2+ and Pb2+ initial concentration ratio (C0Ca: C0Pb) on the adsorption of Pb2+ were investigated. Results showed that adsorption amount ratio of Ca2+ and Pb2+ (qeCa: qePb) had a good linear relationship with C0Ca: C0Pb. Mass ratio of Pb2+ absorbed on the modified SCB was higher than 95% at C0Ca: C0Pb<1.95, illustrating that Pb2+ could be selectively removed from aqueous solution. To verify that, simulated waste water containing co-ions of K+, Na+, Cd2+ and Ca2+ was treated, and results showed that the equilibrium amount of Pb2+, K+, Na+, Cd2+ and Ca2+ adsorbed was 134.14, 0.083, 0.058, 1.28, and 1.28mg g−1, respectively, demonstrating that the modified SCB could be used to remove Pb2+ from aqueous solution in the investigated range.

Biosorption of Pb(II) by the shell of vivipaird snail: Implications for heavy metal bioremediation

ABSTRACT The purpose of the research was to investigate the biosorption of Pb(II) by SVS (SVS, Cipangopaludina chinensis) using a batch technique. The kinetic behaviour was described better by pseudo-second-order model. The experimental isotherms obtained were fit better with Langmuir model, and according to the Langmuir equation, the maximum uptake capacity for Pb(II) was 333.3 mg g−1. Thermodynamic parameters and were calculated using the Van’t Hoff equation, and the results showed that Pb(II) sorption by SVS was an endothermic and spontaneous process. Results showed that SVS was a cost-effective biosorbent for Pb(II) biosorption.