Crayfish Carapace Powder Adsorbing Heavy Metal Ions from Aqueous Solution: Capacity,Characterization, Mechanism

ABSTRACT

Crayfish carapace powder is a low cost natural absorbent effective for the removal of heavy metals. Its adsorption capacity was far superior to its extracts—namely, chitin and chitosan. To understand the mechanism of heavy metals removed by this material, various techniques were implemented to characterize the samples. Scanning electron microscopy and X-ray diffraction analysis showed there was metal carbonate crystal formed on the surface of carapace granules after adsorbing heavy metal ions. The ion exchange between Ca²⁺ and M²⁺, chelation between M²⁺ and chitin, protein, chemical precipitation, and physical adsorption may be the external mechanism of adsorption.     

Chitinolytic Bacteria-Assisted Conversion of Squid Pen and Its Effect on Dyes and Pigments Adsorption

The aim of this work was to produce chitosanase by fermenting from squid pen, and recover the fermented squid pen for dye removal by adsorption. One chitosanase induced from squid pen powder (SPP)-containing medium by Bacillus cereus TKU034 was purified in high purification fold (441) and high yield of activity recovery (51%) by ammonium sulfate precipitation and combined column chromatography. The SDS-PAGE results showed its molecular mass to be around 43 kDa. The TKU034 chitosanase used for the chitooligomers preparation was studied. The enzyme products revealed that the chitosanase could degrade chitosan with various degrees of polymerization, ranging from 3 to 9, as well as the chitosanase in an endolytic manner. Besides, the fermented SPP was recovered and displayed a better adsorption rate (up to 99.5%) for the disperse dyes (red, yellow, blue, and black) than the water-soluble food colorants, Allura Red AC (R40) and Tartrazine (Y4). The adsorbed R40 on the unfermented SPP and the fermented SPP was eluted by distilled water and 1 M NaOH to confirm the dye adsorption mechanism. The fermented SPP had a slightly higher adsorption capacity than the unfermented, and elution of the dye from the fermented SPP was easier than from the unfermented. The main dye adsorption mechanism of fermented SPP was physical adsorption, while the adsorption mechanism of unfermented SPP was chemical adsorption.     

生物吸附剂 Bio －matrix 去除废水中重金属的研究

[目的]研究生物吸附剂Bio-matrix对常规重金属Cu~(2+)、Ni~(2+)、Cr~(3+)的吸附性能。[方法]考察不同温度、吸附剂投加量、吸附时间、p H对吸附量的影响,并分析了Bio-matrix对Cu~(2+)的等温吸附情况。[结果]Bio-matrix吸附剂对Cu~(2+)的吸附效果优于Ni~(2+)和Cr~(3+),温度对吸附量影响较小,3 h可达到吸附平衡,单位吸附量随p H的升高先增大后减小,在p H 4左右时对重金属的单位吸附量最大,Bio-matrix对Cu~(2+)的吸附等温线与Freundlich方程有较好的拟合性,饱和吸附量为19.3 mg/g。[结论]该研究为Bio-matrix作为生物吸附剂去除废水中重金属提供了可行途径。     

铜绿假单胞菌吸附剂对水中菲-铜复合污染的吸附研究

为研究铜绿假单胞菌(Pseudomonas aeruginosa)吸附剂对菲-铜复合污染的吸附性能,探讨菲、铜复合污染对吸附效果的影响。通过研究复合污染条件下菲、铜吸附系数的变化,复合体系中温度等对菲、铜去除的影响。研究发现复合体系可显著影响细菌吸附剂对菲、铜的吸附性能,吸附剂浓度为0.5 g·L-1,pH=5.0,温度为25℃条件下,吸附剂对菲的吸附量达1.15 mg·g~(-1),较单一体系提高了16.84%;对铜的吸附量为4.70 mg·g~(-1),较单一体系降低了5.50%。随着铜浓度的增加(0～5 mg·L-1),菲的吸附系数Kd从2.54 L·g~(-1)增加到4.73 L·g~(-1);随着菲浓度的增加(0～1 mg·L-1),铜的吸附系数KL从4.89 L·mg~(-1)增加到5.06 L·mg~(-1)。复合体系中,吸附剂对菲和铜的吸附系数均随着温度的增加而减小。扫描电镜(SEM)结果显示,吸附剂吸附菲前后表面样貌没有发生显著变化;而吸附铜离子后,细菌表面呈现明显的凹凸。傅里叶变换红外光谱(FTIR)分析表明,铜离子的吸附与细菌细胞的叁键和累积双键官能团相关,进而影响了细菌吸附剂对复合污染的吸附。     

Squid Pen Chitin Chitooligomers as Food Colorants Absorbers

One of the most promising applications of chitosanase is the conversion of chitinous biowaste into bioactive chitooligomers (COS). TKU033 chitosanase was induced from squid pen powder (SPP)-containing Bacillus cereus TKU033 medium and purified by ammonium sulfate precipitation and column chromatography. The enzyme was relatively more thermostable in the presence of the substrate and had an activity of 93% at 50 °C in a pH 5 buffer solution for 60 min. Furthermore, the enzyme used for the COS preparation was also studied. The enzyme products revealed various mixtures of COS that with different degrees of polymerization (DP), ranging from three to nine. In the culture medium, the fermented SPP was recovered, and it displayed a better adsorption rate (up to 96%) for the disperse dyes than the water-soluble food colorants, Allura Red AC (R40) and Tartrazne (Y4). Fourier transform-infrared spectroscopic (FT-IR) analysis proved that the adsorption of the dyes onto fermented SPP was a physical adsorption. Results also showed that fermented SPP was a favorable adsorber and could be employed as low-cost alternative for dye removal in wastewater treatment.     

改性橙皮对水中中性红的吸附及其动力学

以生物废料橙皮为原料,经乙醇、NaOH及CaCl2处理,得到改性橙皮生物吸附剂,对中性红染料废水进行吸附研究,考察了吸附时间、pH值、染料初始浓度、吸附温度及吸附剂投加量对吸附量的影响及其吸附动力学。结果表明,在pH为7,改性橙皮用量为0.1 g,吸附时间为5 h,吸附温度为20℃,染料初始浓度为1 200 mg.L-1的条件下,改性橙皮对中性红的最大吸附量为478.60 mg.g-1。改性橙皮对水中中性红的等温吸附平衡符合Freundlich吸附等温式,吸附动力学遵循准二级动力学方程。