L-tryptophan is an essential amino acid for human health. Nanofibrillated cellulose (NFC) from marram grass (Ammophila arenaria) extracted from plants harvested in the center of Tunisia was used for the first time for...L-tryptophan is an essential amino acid for human health. Nanofibrillated cellulose (NFC) from marram grass (Ammophila arenaria) extracted from plants harvested in the center of Tunisia was used for the first time for the modification of a glassy carbon electrode (GCE), for the sensitive detection of L-tryptophan (Trp). After spectroscopic and morphological characterization of the extracted NFC, the GC electrode modification was monitored through cyclic voltammetry. The NFC-modified electrode exhibited good analytical performance in detecting Trp with a wide linear range between 7.5 × 10−4 mM and 10−2 mM, a detection limit of 0.2 µM, and a high sensitivity of 140.0 µA∙mM−1. Additionally, the NFC/GCE showed a good reproducibility, good selectivity versus other amino acids, uric acid, ascorbic acid, and good applicability to the detection of Trp in urine samples.展开更多
A novel chemically modified cellulose (DTD) adsorbent bearing pendent methyl benzalaniline chelating group was synthesized. This new adsorbent was used for the removal of Cu2+ and Pb2+ heavy metal ions from aqueous so...A novel chemically modified cellulose (DTD) adsorbent bearing pendent methyl benzalaniline chelating group was synthesized. This new adsorbent was used for the removal of Cu2+ and Pb2+ heavy metal ions from aqueous solution. The chemical and structural characteristics of the adsorbent were determined using FT-IR, 13C CP-MAS NMR, SEM, EDX and TGA analysis. The adsorption parameters, such as pH, adsorbent dose, contact time, initial metal ion concentration and temperature were optimized. Adsorption kinetic parameters were fitted into pseudo-first-order and pseudo-second-order models. The kinetic data fitted well to the pseudo-second-order kinetic model. The adsorption isotherms such as Freundlich and Langmuir isotherms have been investigated. Thermodynamic parameters have also been evaluated. The negative values of △G0 and △H0 reveal that the adsorption system is spontaneous and exothermic in nature. The modified cellulose was challenged with microorganisms as a function of contact time. The biocidal results showed that the chemically modified cellulose has bactericidal effect against the bacterial species.展开更多
Microfibrillated cellulose(MFC) was first prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO) oxidation pretreatment and mechanical grinding in the presence of a certain amount of ground calcium carbonate(GCC).The...Microfibrillated cellulose(MFC) was first prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO) oxidation pretreatment and mechanical grinding in the presence of a certain amount of ground calcium carbonate(GCC).The effects of GCC dosage and grinding concentration on the fibrillation were investigated.The obtained MFC was then added to the bulk GCC to form MFC-modified GCC fillers.The properties of MFCmodified GCC fillers were compared to those of the traditional GCC fillers.Results showed that the resulting fibrils became more uniform when the dosage of GCC was 10%~15% and the concentration of the suspension was 6.97%.Compared to traditional GCC,the average particle size of the MFCmodified GCC fillers was larger.Scanning electron microscopy images showed that GCC and MFC formed a bridge structure in the MFC-modified GCC fillers.In the process of papermaking,the MFC-modified GCC fillers decreased the drainage rate but increased the retention of fillers.The prepared papers filled with MFC-modified GCC fillers had higher tensile strength than those filled with traditional GCC fillers.展开更多
The aim of this work is to evaluate the feasibility of applying the technology of oxidation-reduction potential （ORP） control on the municipal wastewater treatment system for nitrogen and phosphorus removal. Meanwhi...The aim of this work is to evaluate the feasibility of applying the technology of oxidation-reduction potential （ORP） control on the municipal wastewater treatment system for nitrogen and phosphorus removal. Meanwhile the relation between the optimal ORP （ ORPopt ） and influent C/N ratio was evaluated, in which the influent chemical oxygen demand （ COD ） concentration was stabilized at （290 ± 10 ） mg/L, the influent total phosphorus （TP） concentration was stabilized at （7.0 ± 0.5 ） mg/L. The results indicated that： （1） the ORP in the second anoxic zone had effect on nitrogen and phosphorus removal capability, and the average percentages of phosphorus uptake in ANO2 zone （ ηa ） increased with increasing ORP, i. e. , increasing from 12. 0% at - 143 mV to 22.0%,30.0%,37.0%, and45.0% at -123, -111, -105 and -95 mV, respectively; （2） the ORPopt as function of influent C/N ratio could be calculated by the equation： y ffi 252. 73e〈 -x/3.39） _ 131.01 ; the maximum percentage of phosphorus uptake in ANO2 as function of the ORPopt could be calculated by the equation： y ffi -0.49e（x/15.58） ＋ 1. 51. The ORPopt was the important process control parameter that must be optimized for operation of enhanced biological phosphorus removal （ EBPR ） system. Moreover, ORP sensor is very simple, and the industrial applications of this strategy is practical.展开更多
Various lignocellulosic materials such as wood, agricultural and forest residues has the potential to be valuable substitute for, or complement to, commercial sorbents for removing heavy metal ions or dyes from waste ...Various lignocellulosic materials such as wood, agricultural and forest residues has the potential to be valuable substitute for, or complement to, commercial sorbents for removing heavy metal ions or dyes from waste water or spilled oil from inland water or sea. More than 9 million tons of straw pulp are produced annually in china, which account for about 90% of the world’s total straw pulp. However, huge quantity of remain straw is not used as industrial raw material and is burnt in the fields or on the side of road. These resources can be chemical modified such as acetylation. Modified straws have the characteristics of low cost, high capacity, quick uptake, and easy to desorb. This paper reviews the current status of the technology for modified agricultural residues, which focus on hemicellulose and cellulose. The potential of these natural sorbents in main industry is also indicated.展开更多
以提取的玉米秸秆纤维素为原料制备羧甲基纤维素,在其中添加甘油和不同浓度的AgNO_(3)后制得改性复合膜。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、热重分析(TGA)、傅里叶红外光谱(FT-IR)对改性复合膜进行结构...以提取的玉米秸秆纤维素为原料制备羧甲基纤维素,在其中添加甘油和不同浓度的AgNO_(3)后制得改性复合膜。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、热重分析(TGA)、傅里叶红外光谱(FT-IR)对改性复合膜进行结构和形貌表征,结果表明:改性复合膜质地均匀,部分Ag^(+)以单质银的形式与膜中的成分相互作用,膜热稳定性良好,满足保鲜材料要求。改性复合膜对大肠杆菌(E.coli)及白色葡萄球菌(S.albus)的抑制情况进一步证明了其中存在单质Ag粒子,对S.albus的抑制能力更强。用改性复合膜包裹蓝莓,存储10 d后的失重率低于7%、颜色几乎没有变化;可溶性固形物损失小于3%、可滴定酸下降不明显,当加入1 mL 0.01 mol/LAgNO_(3)时,改性复合膜的保鲜性能相对较好。展开更多
文摘L-tryptophan is an essential amino acid for human health. Nanofibrillated cellulose (NFC) from marram grass (Ammophila arenaria) extracted from plants harvested in the center of Tunisia was used for the first time for the modification of a glassy carbon electrode (GCE), for the sensitive detection of L-tryptophan (Trp). After spectroscopic and morphological characterization of the extracted NFC, the GC electrode modification was monitored through cyclic voltammetry. The NFC-modified electrode exhibited good analytical performance in detecting Trp with a wide linear range between 7.5 × 10−4 mM and 10−2 mM, a detection limit of 0.2 µM, and a high sensitivity of 140.0 µA∙mM−1. Additionally, the NFC/GCE showed a good reproducibility, good selectivity versus other amino acids, uric acid, ascorbic acid, and good applicability to the detection of Trp in urine samples.
文摘A novel chemically modified cellulose (DTD) adsorbent bearing pendent methyl benzalaniline chelating group was synthesized. This new adsorbent was used for the removal of Cu2+ and Pb2+ heavy metal ions from aqueous solution. The chemical and structural characteristics of the adsorbent were determined using FT-IR, 13C CP-MAS NMR, SEM, EDX and TGA analysis. The adsorption parameters, such as pH, adsorbent dose, contact time, initial metal ion concentration and temperature were optimized. Adsorption kinetic parameters were fitted into pseudo-first-order and pseudo-second-order models. The kinetic data fitted well to the pseudo-second-order kinetic model. The adsorption isotherms such as Freundlich and Langmuir isotherms have been investigated. Thermodynamic parameters have also been evaluated. The negative values of △G0 and △H0 reveal that the adsorption system is spontaneous and exothermic in nature. The modified cellulose was challenged with microorganisms as a function of contact time. The biocidal results showed that the chemically modified cellulose has bactericidal effect against the bacterial species.
文摘Microfibrillated cellulose(MFC) was first prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO) oxidation pretreatment and mechanical grinding in the presence of a certain amount of ground calcium carbonate(GCC).The effects of GCC dosage and grinding concentration on the fibrillation were investigated.The obtained MFC was then added to the bulk GCC to form MFC-modified GCC fillers.The properties of MFCmodified GCC fillers were compared to those of the traditional GCC fillers.Results showed that the resulting fibrils became more uniform when the dosage of GCC was 10%~15% and the concentration of the suspension was 6.97%.Compared to traditional GCC,the average particle size of the MFCmodified GCC fillers was larger.Scanning electron microscopy images showed that GCC and MFC formed a bridge structure in the MFC-modified GCC fillers.In the process of papermaking,the MFC-modified GCC fillers decreased the drainage rate but increased the retention of fillers.The prepared papers filled with MFC-modified GCC fillers had higher tensile strength than those filled with traditional GCC fillers.
基金National Natural Science Foundation of China(NSFC)(No.50978118)
文摘The aim of this work is to evaluate the feasibility of applying the technology of oxidation-reduction potential （ORP） control on the municipal wastewater treatment system for nitrogen and phosphorus removal. Meanwhile the relation between the optimal ORP （ ORPopt ） and influent C/N ratio was evaluated, in which the influent chemical oxygen demand （ COD ） concentration was stabilized at （290 ± 10 ） mg/L, the influent total phosphorus （TP） concentration was stabilized at （7.0 ± 0.5 ） mg/L. The results indicated that： （1） the ORP in the second anoxic zone had effect on nitrogen and phosphorus removal capability, and the average percentages of phosphorus uptake in ANO2 zone （ ηa ） increased with increasing ORP, i. e. , increasing from 12. 0% at - 143 mV to 22.0%,30.0%,37.0%, and45.0% at -123, -111, -105 and -95 mV, respectively; （2） the ORPopt as function of influent C/N ratio could be calculated by the equation： y ffi 252. 73e〈 -x/3.39） _ 131.01 ; the maximum percentage of phosphorus uptake in ANO2 as function of the ORPopt could be calculated by the equation： y ffi -0.49e（x/15.58） ＋ 1. 51. The ORPopt was the important process control parameter that must be optimized for operation of enhanced biological phosphorus removal （ EBPR ） system. Moreover, ORP sensor is very simple, and the industrial applications of this strategy is practical.
文摘Various lignocellulosic materials such as wood, agricultural and forest residues has the potential to be valuable substitute for, or complement to, commercial sorbents for removing heavy metal ions or dyes from waste water or spilled oil from inland water or sea. More than 9 million tons of straw pulp are produced annually in china, which account for about 90% of the world’s total straw pulp. However, huge quantity of remain straw is not used as industrial raw material and is burnt in the fields or on the side of road. These resources can be chemical modified such as acetylation. Modified straws have the characteristics of low cost, high capacity, quick uptake, and easy to desorb. This paper reviews the current status of the technology for modified agricultural residues, which focus on hemicellulose and cellulose. The potential of these natural sorbents in main industry is also indicated.
文摘以提取的玉米秸秆纤维素为原料制备羧甲基纤维素,在其中添加甘油和不同浓度的AgNO_(3)后制得改性复合膜。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、热重分析(TGA)、傅里叶红外光谱(FT-IR)对改性复合膜进行结构和形貌表征,结果表明:改性复合膜质地均匀,部分Ag^(+)以单质银的形式与膜中的成分相互作用,膜热稳定性良好,满足保鲜材料要求。改性复合膜对大肠杆菌(E.coli)及白色葡萄球菌(S.albus)的抑制情况进一步证明了其中存在单质Ag粒子,对S.albus的抑制能力更强。用改性复合膜包裹蓝莓,存储10 d后的失重率低于7%、颜色几乎没有变化;可溶性固形物损失小于3%、可滴定酸下降不明显,当加入1 mL 0.01 mol/LAgNO_(3)时,改性复合膜的保鲜性能相对较好。
