Removal and recovery of heavy metals from aqueous solution using b-cyclodextrin polymer and optimization of complexation conditions
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Removal of heavy metal contaminants from spent streams can be done in many ways using conventional and membrane techniques.Recovering the heavy metal contaminants is very important to prevent recontamination as well as to realize the potential value.Ultrafiltration (UF) has the potential to offer a simple solution in conjunction with size enhancement of the species to be removed referred to as size-enhanced ultrafiltration in literature.The present study focuses on the use of functionalized cyclodextrin, that is, carboxymethyl b-cyclodextrin (CM-b-CD is a derivative of natural material which is easily available) which not only enables the removal of heavy metal contaminants but also amenable for recovering back the contaminant species and the chelating agent for reuse.The experimental studies were conducted using the ultrafiltration system equipped with 50 kDa MWCO (molecular weight cut-off) PES membrane.The design of experiments was done using central composite design of response surface methodology (RSM).The experiments were conducted as per the statistical design to analyze and optimize the process conditions, such as initial pH of the feed, polymer to metal loading rate and initial concentration of the feed solution.The optimization study was done to maximize the rejection, performance index of the membrane (PFI) and recovery of metal.The analysis of variance was performed to examine the developed regression models.Our studies indicated that the CM-b-CD could remove the heavy metal species as well facilitate the recovery of heavy metal species.The experimental values were consistent with the predicted values, which confirm the good validity of the models developed by RSM.본 연구의 목적은 누룩과 입국의 발효제를 달리하고 β-Cyclodextrin을 농도별로 처리한 후 발효시킨 막걸리의 쓴맛의 변화를 비교하고자 하였다. 모두 18~20% 알코올 농도로, 발효제와 β-Cyclodextrin의 처리와는 큰 관련이 없었으나 농도가 증가할수록 알코올이 감소하였다. pH 변화는 누룩과 입국 모두 4~4.3으로 차이가 없었다. 당도는 입국보다 누룩이 높았고, β-Cyclodextrin의 첨가량이 증가할수록 당도가 증가하였다. 총산도는 누룩보다 입국이 다소 높았다. 유기산 함량 측정 결과 누룩의 경우 β-Cyclodextrin의 각 농도별로 비교시 각 농도에서 Lactic acid가 가장 함량이 높았고, 5,000ppm의 첨가 농도를 제외하고 그 다음으로 Acetic acid 순이었다. β-Cyclodextrin 투입에 따른 막걸리의 향기성분 변화 결과 누룩의 경우 아세트알데히드의 함량은 20,000ppm 투입시 가장 높게 나타났으며 디아세틸의 경우 국의 종류에 관계없이 β-Cyclodextrin의 투입량이 많을수록 그 농도가 높아졌다. 에스터류의 경우는 누룩과 입국시험구 모두에서 β-Cyclodextrin을 5,000ppm 투입한 술덧에서 유의하게 높았다. 고급 알코올류의 경우는 누룩 입국 모두 β-Cyclodextrin을 20,000ppm 투입한 술덧에서 유의하게 농도가 가장 높았으며 β-Cyclodextrin의 투입량이 많을수록 고급 알코올의 농도가 증가하였다. 누룩과 입국의 β-Cyclodextrin 투입에 따른 쓴맛의 변화도를 알아보기 위해 관능평가 결과 누룩과 입국 모두에서 5000ppm에서 쓴맛의 감소가 확연되었으며, 10,000ppm에서도 감소가 뚜렷하였다.
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An affinity capillary electrophoresis wasused to determine thebinding constantsof β-cyclodextrinand sulfonated β-cyclodextrin with Z-, E-resveratroland Z-,E-resveratrolglucosidein adual cyclodextrin system(β-cyclodextrin and sulfonated β-cyclodextrin). The resultsshowed that1∶1 inclusion complex was formed of CDwith four isomersof resveratrol respectively. The difference of the binding constants between β-cyclodextrin and four isomers of resveratrol were compared, and the mechanism was also discussed.
Binding constant
Inclusion compound
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Photodegradation is one pathway of pesticides degradation in natural environments, and methyl- β - cyclodextrin and hydropropyl - β - cyclodextrin may play a protective role in pesticide decomposition under natural exposure. The photodegradation of parathion- methyl involved with 3 g· L- 1 and 6 g· L- 1 methyl- β - cyclodextrin and hydropropyl- β - cyclodextrin were investigated. The photolytic rates of parathion- methyl increased 4.87～ 6.85 times under the treatment of methyl- β - cyclodextrin or hydropropyl- β - cyclodextrin. The half- life of parathion- methyl decreased from 103.9 h to 18.19 h and 15.16 h, and the photosensitive efficiency is per 84.96 and per 90.29 respectively in the presence of 6 g· L- 1 methyl- β - cyclodextrin and hydropropyl- β - cyclodextrin, indicating the positively photosensitive degradation. The photosensitive efficiency of hydropropyl- β - cyclodextrin to parathion- methyl significantly increased from 0 h to 3 h and 48 h to 60 h, while increased slowly from 3 h to 48h.The positive correlations were observed between photosensitive efficiency of methyl- β - cyclodextrin and hydropropyl- β - cyclodextrin and irradiation time and the treatment concentration of methyl- β - cyclodextrin and hydropropyl- β - cyclodextrin. It was suggested that methyl- β - cyclodextrin and hydropropyl- β - cyclodextrin should have the potential to be widely used in the environmental science in the future.
Photodegradation
Parathion methyl
Beta-Cyclodextrins
Degradation
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Gamma cyclodextrin was produced synthesized from beta cyclodextrin in the presence of glycyrrhizin, using Cyclodextrin glucanotransferase (EC 2.4.1.19) from Alkalophilic Bacillus . The results showed that more than 32.7% of beta cyclodextrin substrate was converted to the corresponding gamma cyclodextrin under the following conditions, viz. 200 units enzyme/g of β-CD, 10mmol/L of β-CD concentration, 3% of glycyrrhizin concentration, 27 h of reaction time, 65°C of temperature and a reaction pH of 7.0.
Glycyrrhizin
Beta-Cyclodextrins
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Abstract The production of γ‐cyclodextrin usually includes the utilization of organic complexants. However, the non‐complexant production of γ‐cyclodextrin is always being explored due to the defects of organic complexants. However, in non‐complexant production, the separation of γ‐cyclodextrin from α‐ and β‐cyclodextrin is still a challenge. Here, the selective hydrolysis ability of a cyclodextrinase designated PpCD (cyclodextrinase from Palaeococcus pacificus ) on α‐cyclodextrin, β‐cyclodextrin, and γ‐cyclodextrin was proved. The k cat /K m values of PpCD for α‐cyclodextrin and β‐cyclodextrin were roughly 12‐fold and 5‐fold higher than that of γ‐cyclodextrin. It was proved that PpCD had selective hydrolysis ability and its γ‐cyclodextrin purification performance was apparent on various simulated cyclodextrin mixtures with reported proportions derived from different CGTases. Besides, the hydrolysis temperature was optimized and it could be seen that 85°C was appropriate for the production of γ‐cyclodextrin. In addition, the production of γ‐cyclodextrin was achieved by using PpCD in the γ‐CGTase reaction products.
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Although it has already been found that cyclodextrin glucanotransferase (CGTase) produces cyclodextrins(CDs) composed of six to thirteen glycopyranose units, the existence of CDs which have more than fourteen glycopyranose units has still not been confirmed. Cyclomaltotetradecaose (ι-CD), cyclomaltopentadecaose (κ-CD), cyclomaltohexadecaose (λ-CD) and cyclomaltoheptadecaose (μ-CD) are a new series of large-ring CDs composed of 14-17 α-(1→4)-linked D-glycopyranose units, respectively. ι-, κ-, λ- and μ-CD were purified from the commercially available CD powder produced by CGTase, by a combination of HPLC and column chromatography. The molecular weights of ι-, κ-, λ- and μ-CD were determined by FAB-MS, and their cyclic structures were identified by 1H-NMR and 13C-NMR. The 13C-NMR chemical shifts of ι-, κ-, λ- and μ-CD were elucidated and compared with those of δ-, ε-, ζ-, η- and θ-CD, and their structures were predicted from the results.
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Background: Polyvinyl alcohol(PVA) has been widely used in the industry of textile,however,its aqueous solution was difficult to be biodegraded under natural conditions.Purpose: In this study,the PVA in aqueous solution was degraded by electron beam irradiation.Methods: Radioactive ray from electron accelerator was used for degradation of PVA aqueous solution.The effects of different radiation dose and pH on the CODCr and BOD5 values of PVA aqueous solution were investigated.The precipitation generated from acidic irradiated PVA aqueous solution was used for infrared spectroscopy analysis.Results: CODCr values of neutral and alkaline PVA aqueous solution were not significantly changed in the radiation dose range of 0 30 kGy.Acidic PVA aqueous solution after 20 30 kGy dose irradiation produced precipitation obviously.The CODCr values were significantly reduced by 97% 98%.Infrared spectrum analysis showed that precipitation was cross-linked PVA.With radiation dose increasing,BOD5 values of different pH of PVA aqueous solution was gradually reduced,the acidic BOD5 values were minimal under the same radiation dose.The B/C values of neutral and alkaline PVA aqueous solution irradiated by the dose range of 0 30 kGy was no significantly changed.However,the B/C values of acidic PVA aqueous solution increased obviously after 20 30 kGy irradiation,and it increased 14 16 times.Conclusions: This study indicated that under the acidic circumstance,the CODCr values of PVA aqueous solution decreased significantly,PVA in aqueous solution was removed efficiently by electron beam irradiation,and the potential of biodegradation was also improved.
Polyvinyl Alcohol
Degradation
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This study aimed to examine the effects of α-cyclodextrin and β-cyclodextrin as stabilizing agents on gold nanoparticles (AuNPs) reduced by o-hydroxybenzoic acid. Comparative studies were carried to compare the size of AuNPs after the addition of stabilizing agents. The optimization was done under stabilizing agent concentration. AuNPs with α-cyclodextrin and β-cyclodextrin were optimum at 0.040 M stabilizing agent. DLS analysis showed that after the addition of α-cyclodextrin and β-cyclodextrin as stabilizing agents, the size of AuNPs decreased. This result indicated that AuNPs, added with α-cyclodextrin and β-cyclodextrin had better stability and increase the uniformity of AuNPs.
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The complexation of various flavonoids with cyclodextrins and cyclodextrin derivatives was studied using thin layer chromatography on cellulose. The results indicate that the flavonoids examined do not complex readily with α-cyclodextrin or with succinylated α-cyclodextrin. However, most do complex with β-cyclodextrin, succinylated β-cyclodextrin, succinylated γ-cyclodextrin, α-cyclodextrin polymer, β-cyclodextrin polymer and γ-cyclodextrin polymer. With γ-cyclodextrin elongated trails are obtained, suggesting that the kinetics are somewhat slower. © 1997 John Wiley & Sons, Ltd.
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