High-concentration coal–water slurry from Indian coals using newly developed additives

Coal–water slurry (CWS) holds promise to offer a long-term alternative to fuel oil, and also it is being conceived as an attractive fuel for power generation industry in India. The essential requirements of the CWS technology, viz., the additive package, concentration of additives, particle size distribution (PSD) of coal, solids loading, methodology for CWS formulation and its rheological properties, have been discussed and reported here. The effect of the two newly developed anionic additives in the formulation of CWS has been studied. The basic parameters were established taking beneficiated Ledo coal samples with 9.7% ash content. Ball milling of the coal samples in a wet grinding process could produce particle size distributions most suited for highly loaded CWS. Coal loadings to the extent of 70% in the CWS have been achieved using a concentration of 0.8 wt.% (on coal charge) of the naphthalene-based additive referred to as ‘P’. Using 0.9 wt.% of the naphthalene-toluene-based additive denoted as ‘R’, a coal loading of 69% has been achieved. The viscosities of the slurries were found to be below 1000 mPa s. The shelf lives of slurries were found to be 22 and 20 days with the use of additives P and R, respectively, in the CWS formulation. The two additives functioned well in CWS formulation with Sirka coal having relatively higher ash content (14.4%). Using the specified concentration of the additives P and R, the solid loadings of 67% and 65%, respectively, could be obtained under the established parameters. The lower values of solids loading from Sirka coal than that from Ledo coal in CWS formulation may be attributed to the higher percentages of oxygen-containing functional groups (O_OH and O_COOH), ash content and higher O/C ratio of Sirka coal.     

Octadecylamine Graft-modified Cellulose Nanofiber and Its Reinforcement to Poly(butylene adipate-co-terephthalate) Composites

Biodegradable polymers such as poly(butylene adipate-co-terephthalate) (PBAT) have attracted great interest as alternatives to traditional petroleum-based polymers. Nonetheless, it is necessary to improve some properties of PBAT, such as mechanical strength. Cellulose nanofiber (CNF) can improve PBAT mechanical strength, but its dispersion and compatibility in the PBAT matrix require further improvement. In this study, octadecylamine (ODA) was utilized to graft-modify CNF to change the fiber-to-fiber interaction and improve its compatibility with the PBAT matrix. PBAT composites with 1 wt% CNF were prepared using a masterbatch premixing method to avoid CNF aggregation during extrusion. The effects of ODA graft modification on CNF properties were studied; varying degrees of CNF modification were investigated for their effect on PBAT properties. ODA-modified CNF (OCNF)/PBAT melt-extruded composites possessing 17.2% higher tensile strength than pure PBAT polymer were obtained without affecting the thermal stability of PBAT. As a result, surface modification of CNF with ODA is an effective strategy for improving CNF-PBAT compatibility.     

超级电容器隔膜制备及其孔隙率对电化学性能的影响

根据隔膜性能要求,采用低浓轻刀打浆和高浓磨浆两种方式制备微纤化纤维,对制备的隔膜进行了物理性能检验,并针对不同孔隙率隔膜制备的超级电容器进行了电化学性能分析。结果表明,与低浓轻刀打浆方式相比,高浓磨浆可以有效地保留纤维长度,提高纤维长径比,在打浆度为85°SR时,隔膜抗张强度达到0.55kN/m,孔隙率为67%,葛尔莱透气度为41.7μm/(Pa·s)。随着隔膜孔隙率的提高,超级电容器的比电容在0.5 A/g电流密度下逐渐增大;孔隙率为68%的隔膜制备的超级电容器循环伏安特性曲线呈明显的矩形,表现出良好的电容性能。     

Compositional analysis and projected biofuel potentials from common West African agricultural residues

In recent years the focus on sustainable biofuel production from agricultural residues has increased considerably. However, the scientific work within this field has predominantly been concentrated upon bioresources from industrialised and newly industrialised countries, while analyses of the residues from most developing countries remain sparse. In this study the theoretical bioenergy potentials (bioethanol and biogas) of a spectrum of West African agricultural residues were estimated based on their compositions. We analysed 13 of the most common residues: yam peelings, cassava peelings, cassava stalks, plantain peelings, plantain trunks, plantain leaves, cocoa husks, cocoa pods, maize cobs, maize stalks, rice straw, groundnut straw and oil palm empty fruit bunches. The yam peelings showed the highest methane and bioethanol potentials, with 439 L methane (kg Total Solids)⁻¹ and 0.61 L bioethanol (kg TS)⁻¹ based on starch and cellulose alone due to their high starch content and low content of un-biodegradable lignin and ash. A complete biomass balance was done for each of the 13 residues, providing a basis for further research into the production of biofuels or biorefining from West African agricultural residues.     

木质素调控制备果糖基碳微球及其电化学性能研究

本研究使用果糖作为碳源,木质素磺酸盐协同三嵌段共聚物P123作为模板剂,经过水热碳化法和高温碳化法制备果糖基碳微球材料。探究了木质素磺酸盐对果糖在水热条件下的组装过程及调控机制,并分析果糖基碳微球材料在电化学领域的应用。结果表明,木质素磺酸盐的加入是微球表面形成波纹状突起的决定因素。经高温碳化处理过后得到中空多孔的Yolk-Shell果糖基碳微球材料具有良好的电化学性能,其比表面积为535. 04 m~2/g,孔容为0. 26 cm~3/g;在电流密度为0. 1 A/g时,其比电容为96 F/g,能量密度为3. 16 Wh/kg,功率密度为28. 06 W/kg。     

Lignin-containing Microfibrillated Cellulose Prepared from Corncob Residue via Calcium Hydroxide Co-grinding and Its Application in Paper Reinforcement

In this study, lignin-containing microfibrillated cellulose (MFC) was prepared from corncob residue after xylose extraction via co-grinding with calcium hydroxide. The product was then compared with the MFC obtained by direct grinding and applied to strengthen paper. The chemical composition and morphological structure analysis results showed that the corncob residue can be used to prepare lignin-containing MFC and does not require further purification. Moreover, the co-grinding with calcium hydroxide is easier to fibrillate corncob residue. The MFC obtained by co-grinding with calcium hydroxide had a higher aspect ratio, and its surface was coated with calcium carbonate nanoparticles. MFCs obtained by both the methods mentioned above had an obvious strengthening effect on paper. Compared with the paper without MFC, the tensile index, elongation, burst index, and folding strength of the paper with MFC obtained by co-grinding with calcium hydroxide significantly increased by 17.5%, 22.1%, 19.5%, and 157.1%, respectively. This study provides a novel idea for the utilization of corncob residue, which may enhance the value and promote the comprehensive utilization of corn by-products.     

纳米纤维素增强可生物降解聚合物的研究进展

本文综述了纤维素纳米晶体(CNC)和纤维素纳米纤丝(CNF)在增强可生物降解聚合物中的研究进展。主要介绍了两种纳米纤维素及其制备方法,阐述了纳米纤维素的增强机理和复合材料的构筑方法,详细论述了纳米纤维素在增强聚乳酸(PLA)、热塑性淀粉(TPS)、聚己内酯(PCL)应用的研究进展。最后简要分析了纳米纤维素增强可生物降解聚合物在规模化和产业化上面临的挑战,并展望了其应用前景。     

壳聚糖/蜂蜡改善纸基材料水蒸气和氧气阻隔性能研究

围绕壳聚糖(CS)和蜂蜡(Wax)在改善纸基材料气体(水蒸气和氧气)阻隔性能方面开展研究,探讨了蜂蜡添加量及其与壳聚糖的复合方式(共混和分层)对纸基材料阻隔性能和涂层热稳定性能的影响。结果表明,涂布纸的水蒸气透过量随蜂蜡添加量的增加而降低,当蜂蜡添加量为15%时,在50%RH (相对湿度)条件下,分层涂布纸和共混涂布纸的水蒸气透过量分别降至21.87和24.13 g/(m²·d),与纯壳聚糖涂布纸相比,分别降低了80.3%和78.2%,分层涂布纸与共混涂布纸的水蒸气透过量差异不大;在75%RH条件下,分层涂布纸(163.69 g/(m²·d))和共混涂布纸(242.24 g/(m²·d))的水蒸气透过量与纯壳聚糖涂布纸相比,分别降低了79.4%和69.5%,而与共混涂布纸相比,分层涂布纸的水蒸气透过量降低了32%。共混涂布纸和分层涂布纸的氧气透过量随着蜂蜡添加量的增加而增大,当蜂蜡添加量为15%时,分层涂布纸和共混涂布纸的氧气透过量仍低至70.19和101.75 cm³/(m²...     

Preparation and Application of Microfibrillated Cellulose-modified Ground Calcium Carbonate

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.