Bingjie Liu

Adsorption of heavy metal ions, dyes and proteins by chitosan composites and derivatives — A review

Chitosan composites and derivatives have gained wide attentions as effective biosorbents due to their low costs and high contents of amino and hydroxyl functional groups. They have showed significant potentials of removing metal ions, dyes and proteins from various media. Chemical modifications that lead to the formation of the chitosan derivatives and chitosan composites have been extensively studied and widely reported in literatures. The aims of this review were to summarize the important information of the bioactivities of chitosan, highlight the various preparation methods of chitosan-based active biosorbents, and outline its potential applications in the adsorption of heavy metal ions, dyes and proteins from wastewater and aqueous solutions.

Effect of NaCl on the heavy metal tolerance and bioaccumulation of Zygosaccharomyces rouxii and Saccharomyces cerevisiae.

Application of microorganisms as bioremediators for heavy metal removal in high salt environment is usually restricted by high salt concentrations. The effect of NaCl on the heavy metal tolerance and bioaccumulation of Zygosaccharomyces rouxii and Saccharomyces cerevisiae was investigated. For both yeasts, NaCl improved the cadmium and zinc tolerance, reduced the copper tolerance, and showed no obvious effect on the lead and iron tolerance. The bioaccumulation capacities of copper, zinc, and iron increased but the cadmium bioaccumulation capacities decreased after the addition of NaCl. NaCl obviously affected the amount of heavy metals removed intracellularly and on the cell surface. The heavy metal removal was not overwhelmingly inhibited by elevated NaCl concentrations, especially for Z. rouxii, and in some cases NaCl improved their removal ability. The salt-tolerant Z. rouxii that showed more powerful heavy metal tolerance and removal ability might be more suitable for heavy metal removal in high salt environment.

Biosorption of lead from aqueous solutions by ion-imprinted tetraethylenepentamine modified chitosan beads.

In this paper, the bio-based ion-imprinted tetraethylenepentamine (TEPA) modified chitosan beads using Pb(II) as imprinted ions (Pb-ITMCB) were chemically synthesized, characterized and applied to selectively adsorb Pb(II) ions from aqueous solutions containing other metal ions, which has the same concentration as that of Pb(II) ions. Batch adsorption experiments were performed to evaluate the adsorption conditions, selectivity and reusability. FTIR, SEM and TEM technologies were used to elucidate the mechanism of Pb-ITMCB adsorbing Pb(II) ions. The results showed that the adsorption capacity of Pb-ITMCB for Pb(II) ions reached 259.68 mg/g at pH 6, 40 °C. The adsorption data could be fitted well with pseudo-second order kinetics model and Langmuir isotherm model. Compared with other metal cations, Pb(II) ions showed an overall affinity of being adsorbed by Pb-ITMCB. With the participation of active groups including NH2, NH and OH, the adsorption reaction took place both inside and on the surface of Pb-ITMCB. It indicated that Pb-ITMCB is a comparatively promising biosorbent for selective removal of Pb(II) ions from aqueous solutions.

Adsorptive removal of patulin from aqueous solution using thiourea modified chitosan resin

In the present paper, thiourea modified chitosan resin (TMCR) was firstly prepared through converting hydroxyl groups of chitosan resin into thiol groups, using glutaraldehyde as cross-linking agent and thiourea as modification agent. TMCR was characterized by FTIR, EDXS, SEM, XRD and AFM technologies. Batch adsorption experiments were performed to study the adsorption capacity of TMCR for patulin at different pH, temperature, contact time and patulin concentration. The result showed that TMCR was effective in removal of patulin from aqueous solution. The adsorption capacity of TMCR for patulin was 1.0 mg/g at pH 4.0, 25 °C for 24 h. Adsorption process could be well described by pseudo-first order model, Freundlich isotherm model and intraparticle diffusion model. It indicated that TMCR is expected to be a new material for patulin adsorption from aqueous solutions.

La(III)-loaded bentonite/chitosan beads for defluoridation from aqueous solution

Abstract Developing low-cost and effective materials for excess fluoride removal is important for providing safe water. A novel adsorbent, La(III)-loaded bentonite/chitosan beads (La-BCB) was prepared for defluoridation from aqueous solution. The effects of various parameters such as dosage of La(III), pH, temperature, contact time, initial fluoride concentration and presence of co-existing anions were investigated to examine the defluoridation behavior. The maximum defluoridation capacity of La-BCB was 2.87 mg/g at pH 5, 30 °C. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR) were employed to analyze the characteristics of La-BCB. The equilibrium fluoride adsorption data fitted well with both Langmuir and Freundlich isotherm models. The R L value revealed that the defluoridation process using La-BCB was favorable. The adsorption kinetics followed pseudo-second order kinetic as well as particle and intraparticle diffusion models. The presence of carbonate and bicarbonate reduced defluoridation capacity of La-BCB while sulphate, nitrate and chloride showed slight effect. The exhausted La-BCB was regenerated using sodium hydroxide with only 17% loss. The reasonable defluoridation mechanism could be interpreted as adsorption and ion exchange.

Study on preparation and properties of tannins immobilized chitosan-Ce4+ resins

The tannins immobilized chitosan-Ce4+ resins (TCCR) were prepared. The optimum conditions on activating and coupling of chitosan resins were obtained by means of orthogonal design experiments. TCCR were characterized by DSC and FT-IR. The adsorption capacity for bovine serum albumin (BSA) of TCCR was investigated. The results show that TCCR have an excellent adsorption capacity for BSA in water, comparing with chitosan-Ce4+ resins (CCR). The TCCR can be a novel functional material for removal protein in some beverages.

Hydrophobicity and physicochemical properties of agarose film as affected by chitosan addition

The blend films were prepared with different ratio of agarose (AG) and chitosan (CH) using the casting method. The fundamental performance and characteristics of AG, CH and blend films were investigated. The results showed that the tensile strength (TS) and elongation at break (EB) values of blend films were significantly (p<0.05) increased compared with AG film. The water contact angle (WCA) increased from 66.2 to 97.7° with the increasing ratio of blend film from AG70:CH30 to AG50:CH50. The thickness of blend films in this paper was varied from 0.010mm to 0.020mm, while the water vapor permeability (WVP) value of the blend film was higher than that of AG film mainly due to the increasing thickness. Moreover, hydrogen bonding and excellent compatibility were observed between agarose and chitosan according to thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses.

Effective Biodegradation of Mycotoxin Patulin by Porcine Pancreatic Lipase

Patulin is a common contaminant in fruits and vegetables, which is difficult to remove. In this study, the biodegradation of patulin using porcine pancreatic lipase (PPL) was investigated. The method of HPLC was used to analyze the concentration of patulin. Batch degradation experiments were performed to illustrate the effect of PPL amount, pH, temperature, contact time, and initial concentration. Besides, the degradation product of patulin was characterized by full wavelength scanning and MS technologies. The results showed that the optimum degradation conditions of PPL for patulin was observed at pH 7.5, 40°C for 48 h. The percentage of degradation could reach above 90%. The structure of degradable product of patulin was inferred by the molecular weight 159.0594, named C7H11O4+. It indicated that PPL was effective for the degradation of patulin in fruits and vegetables juice.

Synthesis of a novel chitosan-based Ce(IV) complex with proteolytic activity in vitro toward edible biological proteins.

The occurrence of enzymatic activities is attributed to proper spatial organization of functional groups from first principles. A novel chitosan-based Ce(IV) complex (CC[Ce(IV)]), an artificial metalloproteinase, was synthesized by attaching cyclen, Ce(IV), and chlorophyll-Cu(II) to a chitosan-based matrix. The enzymatic hydrolytic efficiency (HE) and the procedure of catalyzing myoglobin (Mb) by CC[Ce(IV)] in vitro were investigated using spectrophotometry, electrophoresis, and liquid chromatography. The results showed that the HE of Mb was up to 60% at 60°C within 24h, displaying a catalytic proficiency. The pseudo-first-order kinetic constant (kobs) for CC[Ce(IV)] treatment within 24h was 3.85×10(-2)h(-1), higher than that for α-chymotrypsin treatment, which was 2.63×10(-2)h(-1). Moreover, the peptide bond derived from Asp-Phe/Phe-Asp in Mb could be specifically cleaved by CC[Ce(IV)], which could simulate the functionality of α-chymotrypsin. This work provides an experimental basis for potential utilization of the chitosan-based Ce(IV) complexes in the food industry.

As(III) Removal from Aqueous Solution Using a-Fe2O3-impregnated Chitosan Beads

A novel, bio-based sorbent for As(III), α-Fe2O3-impregnated chitosan beads (FICB), has been successfully synthesized and tested. Batch wise adsorption experiments were performed to evaluate the adsorption conditions, reusability as well as the effect of ionic strength and coexistence of other ions. The results indicated that the maximum adsorption capacity of FICB for As(III) was 4.46 mg/g at pH 5.0 and 20 °C with equilibrium adsorption time 8 h. The ionic strength and coexistence of other ions had no significantly effect on the adsorption of FICB. It was also revealed that FICB could be reused for at least 6 times with only 7% regeneration loss. This suggests that FICB is a very promising adsorbent for the removal of As(III) from aqueous solution.