典型钙/镁基吸附剂对二氧化硒吸附特性研究

针对钙/镁基矿物吸附剂的主要组分CaO、CaCO₃、MgO在500-800 ℃下对Se的吸附特性进行研究，并选取天然矿物方解石、白云石研究其对Se的吸附效果，且对矿物煅烧所得CaO进行吸附实验。结果表明，三种组分中CaO的吸附效果最佳，800 ℃时单位质量CaO对Se的吸附量可达368 mg/g。CaCO₃对Se的吸附在700 ℃时效果最佳且其吸附产物的热稳定性较好。镁基吸附剂仅在中温段对Se具有一定吸附效果。方解石对Se的吸附效果随温度变化趋势与CaCO₃相似，因其较好的孔隙结构，吸附效果略优于CaCO₃。煅烧方解石得到的F-sor对Se的吸附效果优于CaO和CaCO₃煅烧得到的C-sor，这与其良好的比表面积、孔隙结构与抗烧结能力有关，且F-sor吸附产物的热稳定性相对较好。F-sor对Se的吸附量最高可达403 mg/g。     

Multiobjective Optimization of Fabrication Parameters of Jute Fiber/Polyester Composites with Egg Shell Powder and Nanoclay Filler

In the present study, a model is presented to optimize the fabrication parameters of natural fiber reinforced polyester matrix composites with dual fillers. In particular, jute fiber mat was chosen as reinforcement and eggshell powder (ESP) and montmorillonite nanoclay (NC) were selected as fillers. The weight per square meter (GSM) of the fiber, the weight percentage of ESP and NC have been chosen as independent variables and the influence of these variables on tensile, flexural and impact strength of the composite has been inspected. The permutations of the different combinations of factors are intended to accomplish higher interfacial strength with the lowest possible number of tested specimens. The experiments were designed by the Taguchi strategy and a novel multi-objective optimization technique named COPRAS (COmplex PRoportional ASsessment of alternatives) was used to determine the optimal parameter combinations. Affirmation tests were performed with the optimal parameter settings and the mechanical properties were evaluated and compared. Experimental results show that fiber GSM and eggshell powder content are significant variables that improve mechanical strength, while the nanoclay appears less important.     

不同钙源的羟基磷灰石的合成及表征

通过比较法研究了不同钙源在水热条件下合成羟基磷灰石的方法。SEM,XRD和FT-IR的测试结果表明,蛋壳不仅可以成为有效钙源,而且多孔结构还可充当硬模板,在磷酸二氢钠缓慢腐蚀CaCO_3的同时提供PO_4~(3-)诱导生成花状羟基磷灰石。研究表明,磷酸肌酸钠水热缓慢分解释放磷酸根在合成高纯度羟基磷灰石方面有着广阔的应用前景。     

Mechanical and electrical properties of radiation-vulcanized natural rubber latex with waste eggshell powder as bio-fillers

ABSTRACT

This work investigated the mechanical, physical, morphological, and electrical (volume) resistivity properties of radiation-vulcanized natural rubber latex (RVNRL) with additions of waste eggshell (WES) powder, which contained primarily CaCO₃ (calcite). The results showed that increasing gamma irradiation doses from 0 to 30?kGy in 10-kGy increments led to decreases in the swelling ratio and elongation at break but increases in the crosslink density, tensile modulus at 500% elongation, and tensile strength of the composites. The results also suggested that increasing the WES contents from 0 to 2, 4, or 6 parts per hundred parts of rubber by weight (phr) in the composites improved the tensile modulus at 500% elongation, tensile strength, hardness (Shore A), and electrical (volume) resistivity. In addition, after undergoing thermal aging at 70°C for 96?h, the tensile modulus and hardness (Shore A) increased, while the tensile strength and elongation at break decreased. This work also compared the properties of WES/RVNRL with commercial CaCO₃/RVNRL samples at the same 4-phr content. The results indicated that both composites had similar tensile properties, implying possible replacement of commercial CaCO₃ with WES powder as an effective reinforcing filler in RVNRL.     

双金属复合氧化物的结构与紫外阻隔性能

双金属复合氧化物（ＣＬＤＨ）是一类发展迅速的无机层状材料的煅烧产物,在催化、吸附等领域已获长足进展［１］,但作为紫外阻隔材料的性能研究尚鲜见报道．本文研究了不同双金属复合氧化物的紫外阻隔性能,结果发现二价金属离子为锌离子的ＣＬＤＨ具有良好的紫外阻隔性能．实验所用试剂均为分析纯．ＣＬＤＨ由ＮａＯＨ,Ｎａ２ＣＯ３,ＭｇＳＯ４·７Ｈ２Ｏ,ＺｎＳＯ４·７Ｈ２Ｏ,Ａｌ２（ＳＯ４）３·１８Ｈ２Ｏ为原料,按文献［２］方法制备．ＺｎＯ＋Ａｌ２Ｏ３复配物是按一定比例机械混合后,研磨,并在与ＣＬＤＨ相同的条件下煅烧…     

壳聚糖固定化葡萄糖氧化酶生物传感器测定葡萄糖的含量

应用壳聚糖将葡萄糖氧化酶固定于鸡蛋膜上,结合氧电极制得葡萄糖传感器.实验表明,壳聚糖比戊二醛能更好地固定葡萄糖氧化酶,最佳条件为壳聚糖浓度0.3%、固定化酶量0.8 mg、 pH 7.0、缓冲溶液浓度300 mmol/L和温度25 ℃.本葡萄糖传感器的线性范围为0.016～1.10 mmol/L;检出限为8.0 μmol/L(S/N=3), 响应时间<60 s,有很好的稳定性,寿命>3个月.同一个传感器重复使用以及同方法制作的不同传感器之间都有很好的重现性,RSD分别为2.5%(n=10)和4.7%(n=4).实际样品中可能存在的烟酰胺、 VB6、 VB12、 VE、Ca2+、 Mg2+、 K+和Zn2+等对葡萄糖的测定不产生干扰.本传感器已成功地应用于市售饮料中葡萄糖含量的测定.     

改性硫氧镁胶凝材料的配制及性能研究

为确定工业级轻烧氧化镁粉与七水硫酸镁溶液配制改性硫氧镁胶凝材料的最优参数,分别研究了不同氧化镁/七水硫酸镁摩尔比,硫酸镁溶液浓度及水稳剂水玻璃对硫氧镁胶凝材料工作和力学性能的影响.结果表明:随着氧化镁/硫酸镁摩尔比的提高,硫氧镁水泥的初凝时间逐渐缩短,流动性逐渐降低,抗压和抗折强度逐渐提高;随着七水硫酸镁浓度的提高,硫氧镁水泥的抗压抗折强度也呈现增长趋势,MgO:MgSO4·7H2O:H2O摩尔比为14:1:12时,硫氧镁胶凝材浆体的28d抗压和抗折强度分别达到38.3MPa和7.0MPa.耐水性研究表明,加入氧化镁质量2%的水玻璃可以很好地改善硫氧镁水泥的耐水性.     

菱镁矿悬浮态与堆积态煅烧对产物特性的影响

利用实验室自制小型模拟悬浮态煅烧装置和马弗炉,对菱镁矿进行快速煅烧试验制备轻烧氧化镁,分别对悬浮态和堆积态的煅烧产物进行分解率、XRD、SEM、活性等分析,探讨两种煅烧方式对轻烧氧化镁特性的影响.结果表明:相对于堆积态煅烧,菱镁矿经悬浮态煅烧1 min后分解率即可达到98;以上,得到的轻烧氧化镁晶粒尺寸小、结晶度低,比表面积大、表现出很高的活性;悬浮态煅烧显著强化了热传递过程,加快了反应速度,生产效率成倍提高,产品性能好、质量稳定,可应用于大规模生产高活性轻烧氧化镁.     

AB24在MgAl-LDO上的吸附性能及机理研究

本文探讨了nMg/nAl=3的水滑石焙烧产物(MgAl-LDO)对染料酸性黑24(AB24)的吸附性能及其机理。考察了不同因素对MgAl-LDO吸附AB24性能的影响,并研究了吸附过程的热力学和动力学机理。实验结果表明:MgAl-LDO对AB24具有优异的吸附性能,在298 K,pH=10条件下,1.0 g.L-1MgAl-LDO对1 000 mg.L-1AB24溶液的吸附容量和去除率分别达到998.31 mg.g-1和99.83%。动力学和热力学研究表明:MgAl-LDO对AB24的吸附过程同时符合Langmuir和Freundlich等温吸附方程,并且是个放热、自发的过程。计算所得的吉布斯自由能绝对值在10~15 kJ.mol-1,这主要是由染料分子与水滑石层板的氢键作用产生,结合Materials Studio 5.5软件模拟AB24染料分子在MgAl-LDHs上的排列分布,推测MgAl-LDO对AB24的吸附机理是表面吸附(占优势)与层间插层的协同作用。同时,该吸附过程符合准二级反应动力学模型。     

Adsorptive treatment of phenol from aqueous solution using chitosan/calcined eggshell adsorbent: Optimization of preparation process using Taguchi statistical analysis

Phenol and its derivatives are known to be toxic causing adverse impact on human health and environment. Adsorption utilising waste materials is a cost effective method for abatement of such pollutants. The present study thus aims to remove the phenol from aqueous solutions using chitosan/calcined eggshell adsorbent. Taguchi L₂₇ Orthogonal array design methodology was used for the optimization of preparation variables. The statistical results obtained using ANOVA and S/N ratios showed that adsorption of phenol was significantly influenced by activation temperature (54.90%) and activation time (43.70%) whereas the mix ratio had fairly low impact on the output response (1.14%). The confirmation run in optimum preparation conditions of temperature (800 ?°C), time (60mins) and mix ratio (1:1) resulted in maximum adsorption capacity (10.82 ?mg/g) which confirmed that the optimization done by Taguchi model was valid and reliable. The characterization of adsorbent prepared under optimum conditions were done using scanning electron microscopy, X-ray diffraction (XRD), and the Fourier transform Infrared spectroscopy (FTIR). Adsorption and kinetic studies manifested that the adsorption phenomenon onto prepared adsorbent is illustrated well by linear Langmuir isotherm and pseudo second order kinetics.