Effect of alkali treatments on apatite formation of microarc-oxidized coating on titanium alloy surface

Alkali treatments with three concentrations were used to modify a microarc-oxidized(MAO) coating on titanium alloy surface in order to further improve its surface bioactivity. Morphology, chemical compositions and phase constitues, roughness, contact angle and apatite induction of the alkali-treated coatings were studied and compared. Scanning electron microscope(SEM) was applied to observe the morphologies, X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) were used to detect the phase constitutes and chemical compositions, a surface topography profilometer was used to analyze the surface roughness, and contact angle was measured by liquid drop method. Alkali treatements result in the formation of Na2Ti6O13 and Na2Ti3O7 phase on the MAO coating, which leads to the increase of surface roughness and the decrease of contact angle. Experimental results showed that the apatite induction of the alkali-treated coatings was dependent on the applied alkali concentrations during treatments, and Na+concentration can promote the formation of apatite phase.

Creating mesopores in ZSM-48 zeolite by alkali treatment: Enhanced catalyst for hydroisomerization of hexadecane

ZSM-48 zeolites with various Si/Al ratios were hydrothermally synthesized in the H;N（CH;）;NH;（HDA）-containing media. The obtained samples were highly crystallized with minor mixed phases as evidenced by X-ray powder diffraction（XRD）. The alkaline treated ZSM-48 zeolites maintained its structure under different concentrations of Na OH aqueous solution. Micropores remained unchanged while mesopores with wide pore size distribution formed after the alkaline treatment. The surface area increased from 228 to 288 m;/g. The Br?nsted acid sites had little alteration while an obvious increase of Lewis acid sites was observed. The hydroisomerization of hexadecane was performed as the model reaction to test the effects of the alkali treatment. The conversion of hexadecane had almost no change, which was attributed to the preservation of the Br?nsted acid sites. While high selectivity to iso-hexadecane with an improved iso to normal ratio of alkanes was due to the mesopore formation and improved diffusivity.

Studies on Recovery Efficiencies of Phenols from Phenol Fraction Using Alkali Treatment

Experiments were conducted for the extraction of phenols from the phenol fraction obtained from the coal tar distillate. The phenol fraction for the present investigation has been procured from Visakhapatnam Steel Plant, Visakhapatnam whose composition is known. The phenol fraction from coal tar distillate can be treated for extracting phenols using caustic soda. An attempt has been made to find out whether the existing practice of using only 8%-15% can be modified by increasing the strength of sodium hydroxide and also explore the possibilities of substituting the sodium hydroxide with KOH as an extractant. The different streams of liquids obtained during experimentation have been analyzed by gas chromatograph. Salient features of the study are that higher concentrations of the alkali significantly improved the separation efficiencies of phenols and also regenerate the phenolate with higher phenol content. Increase in the alkali strength has greatly improved the separation as well as the phenol content in the regenerated phenols. Disposal of effluents containing phenols may lead to environmental problem of ground water pollution and the study throws a light on the removal of phenols from the effluents to the extent possible by using higher strength alkali solutions.

Effect of Alkali Treatment on the Structure and Catalytic Properties of ZSM-5 Zeolite

Catalytic properties of ZSM-5 zeolite samples pretreated with NaOH solution have been investigated. The samples are characterized by XRD, SEM, chemical analysis, and N2 adsorption. The results indicate that mesopores are created in ZSM-5 crystals under alkali treatment without change the microporous structure and acidic strength of the zeolite, but the crystallinity is greatly decreased under severe treatment. IR indicates that the concentration of silanol is greatly enriched by alkali treatment. The etherification activities of ZSM-5 zeolites are greatly increased by alkali-treatment. The noticeably improved catalytic activity of treated samples is ascribed to the formation of mesopores and greatly enriched silanol group.

Effect of Alkali Treatment on Heavy Metals Adsorption Capacity of Sewage Sludge

Sewage sludge is the promising raw material for biosorbent preparation. In this work, we evaluated the heavy metals adsorption characteristics of alkali treated sewage sludge (ATSS) by equilibrium studies. The adsorption isotherms were fitted with Langmuir and Freundlich models. Comparing with untreated sewage sludge, the total adsorption capacity (qm) of ATSS (prepared with 0.125 mol/L NaOH) for Cd, Pb, Ni, increased by 0.51, 0.70 and 0.32 mmol/g, respectively. When the NaOH concentration for ATSS preparation increased from 0.125 mol/L to 0.25 mol/L, the qm of ATSS for Pb decreased from 1.05 mmol/g to 0.84 mmol/g. However, when the NaOH concentration increased from 0.25 mol/L to 7.5 mol/L, it showed increasing trend. According to the IR spectra data, the adsorption effect of biosorbent for heavy metals was mainly due to the complexation of -N-H groups and -COOH groups.

Alkali Treatment of Commercial Silicoaluminophosphate Molecular Sieves (SAPO_-34) Enhances the Water Adsorption and Desorption Properties

Commercial silicoaluminophosphate molecular sieves (SAPO-34) received alkali treatment with either NaOH (0.2, 0.01, 0.005, or 0.001 M) or NH4OH (0.005 M). Treatment with NaOH (0.005 M) increased the water adsorption initial rate of SAPO-34 by 1.4-fold. The alkali treatment introduced Na+ adsorption sites into the SAPO-34. The desorption ratio (adsorption at 30°C and desorption at 100°C) was 88.2% higher than the original rate (84.3%). On the other hand, after alkali treatment of SAPO-34 using NH4OH (0.005 M), calcination resulted in the highest desorption ratio at 91.3%. When combined with calcination, alkali treatment with NH4OH introduced H+adsorption sites into SAPO-34, H+ adsorption sites feature low levels of interaction with water, which enhanced the desorption ratio, but decreased the initial adsorption rate. These results indicate that treating commercial SAPO-34 with 0.005 M NaOH enhances both the adsorption and desorption behaviors.

Alkali Treatment and Cellulose Nanowhiskers Extracted from Maize Stalk Residues

The aim of this study was to investigate the use of effect of pulveriser and extraction of cellulosenanowhiskers (CNWs) on Maize stalks. Maize stalk residues were first subjected to a cutting mill for size reduction purified using mechanical, chemical extraction and bleaching. After chemical extraction, high quality cellulose resulted and cellulose nanowhiskers (CNW) were then extracted using chemical acid hydrolysis. The chemical compositions and mechanical properties of the maize stalk residues were examined before and after purification by using standard methods, Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and thermo gravimetric analysis (TGA). The morphology and dimensions of the isolated cellulose nanowhiskers were characterized using atomic force microscope (AFM). The crystallinity index increased upon mechanical and chemical extraction. Thermal stability of cellulose derived from maize stalk improved with chemical treatment due to new functional groups introduced on the surface and enhancement in crystallinity. Highly dispersed cellulose nanowhiskers (CNWs) were successfully extracted from maize stalk residues with diameters ranging between 3 and 7 nm, length ranges between 150 - 450 nm, respectively.

Corn Husk Fiber Preparation and Morphology with Alkali Treatment

The corn husks were usually discarded as useless materials,after alkali treatment from which the corn husk fiber was obtained. The corn husk fiber included half degumming corn husk bundle fiber and corn husk single fiber. This study found that corn husk single fiber was a kind of cellulose fiber,and was obtained with the fully alkali treatment technique,the process of which was NaOH concentration 0.15 g/mL,temperature at 80℃,and reaction time about 2.5 h. The morphologies of corn husk single fibers presented nature convolutions along with the fiber axis. They were closed at both ends,and they had a pentagram cavity and oval-shaped crosssection. They were flat shape,the fineness of the fibers was close to cotton fiber,and the mechanical properties of the fibers were similar to hemp fiber. So the corn husk fibers could be predicted that they could be used in textile industry because their properties were very close to cotton fiber or flax fiber.

Alkali and Plasma-Treated Guadua angustifolia Bamboo Fibers:A Study on Reinforcement Potential for Polymeric Matrices

This study focuses on treating Guadua angustifolia bamboo fibers to enhance their properties for reinforcement applications in composite materials.Chemical(alkali)and physical(dry etching plasma)treatments were used separately to augment compatibility of Guadua angustifolia fibers with various composite matrices.The influence of these treatments on the fibers’performance,chemical composition,and surface morphology were analyzed.Statistical analysis indicated that alkali treatments reduced the tensile modulus of elasticity and strength of fibers by up to 40%and 20%,respectively,whereas plasma treatments maintain the fibers’mechanical performance.FTIR spectroscopy revealed significant alterations in chemical composition due to alkali treatments,while plasma-treated fibers showed minimal changes.Surface examination through Scanning Electron Microscopy(SEM)revealed post-treatment modifications in both cases;alkali treatments served as a cleanser,eliminating lignin and hemicellulose from the fiber surface,whereas plasma treatments also produce rough surfaces.These results validate the impact of the treatments on the fiber mechanical performance,which opens up possibilities for using Guadua angustifolia fibers as an alternative reinforcement in composite manufacturing.

Effects of alkali and heat treatment on strength of porous Ti35Nb

Porous Ti35Nb alloy with a porosity of 66% was made by a powder metallurgical method, and then it was treated by a standard treatment for activating the surface of Ti implant materials involving alkali and heat treatment. The alkali and heat treatment causes damages of the struts of the porous Ti35Nb in the form of reaction products layer, grain-pullout and cracks. Consequently, it leads to a significant degradation of the strength of the porous alloy. The effect of the alkali and heat treatment on the strength of the porous alloy was discussed.

PREPARATION OF HOLLOW LATEX PARTICLES BY ALKALI-ACID TREATMENT

Hollow polymer latex particles were prepared by seeded emulsion polymerization. A seed latex consisting of styrene (St), butyl acrylate(BA) copolymer was first prepared, and seeded terpolymerization of St BA MA(methacrylic acid) were then carried out in the absence of surfactant. Final latex was treated by a two step treatment under alkaline and acidic conditions, thus, the particles with hollow structure were obtained. We discussed the effects of pH value, temperature and time in alkali and acid treatment processes on hollow structure within the polymer latex particles and amount of carboxylic group on particle surface. The results show that the hollow polymer latex particles with the largest hollow size can be obtained under a certain condition (pH12.5, 90°C, 3 h in alkali treatment stage and pH2.5, 85°C, 3 h in acid treatment stage).

Comparison of Alkaline Treatment of Lead Contaminated Wastewater Using Lime and Sodium Hydroxide

A lead-acid storage battery manufacturing industry in India produces several thousand liters of lead con-taminated acidic wastewater on a daily basis and uses hydrated lime to render the lead-contaminated acidic wastewater alkaline (pH = 8.0). Alkaline treatment of the acidic wastewater with lime though a cost-effective method, generates copious amount of lead-contaminated gypsum sludge. Other alkali agents such as sodium hydroxide, sodium carbonate and dolomite are also used for alkali treatment of the acid wastewaters. The present paper compares the relative efficiency of hydrated lime and 0.05 M to 1 M NaOH solutions with re-spect to 1) amounts of sludge produced, 2) immobilization of the soluble lead in the acidic wastewater (AWW) and 3) increase in TDS (total dissolved solids) levels upon treatment of AWW with NaOH solutions and lime. The study also performs equilibrium speciation upon alkaline treatment of AWW with lime and NaOH (sodium hydroxide) solutions using the Visual MINTEQ program to understand the chemical reac-tions occurring during treatment process.

Effect of mesopore spatial distribution of HZSM-5 catalyst on zinc state and product distribution in 1-hexene aromatization

1-hexene aromatization is a promising technology to convert excess olefin in fluid catalytic cracking(FCC)gasoline to high-value benzene(B),toluene(T),and xylene.Besides,the increasing market demand of xylene has put forward higher requirements for new generation of catalyst.For increasing xylene yield in 1-hexene aromatization,the effect of mesopore structure and spatial distribution on product distribution and Zn loading was studied.Catalysts with different mesopore spatial distribution were prepared by post-treatment of parent HZSM-5 zeolite,including NaOH treatment,tetra-propylammonium hydroxide(TPAOH)treatment,and recrystallization.It was found the evenly distributed mesopore mainly prolongs the catalyst lifetime by enhancing diffusion properties but reduces the aromatics selectivity,as a result of damage of micropores close to the catalyst surface.While the selectivity of high-value xylene can be highly promoted when the mesopore is mainly distributed interior the catalyst.Besides,the state of loaded Zn was also affected by mesopores spatial distribution.On the optimized catalyst,the xylene selectivity was enhanced by 12.4%compared with conventional Zn-loaded parent HZSM-5 catalyst at conversion over 99%.It was attributed to the synergy effect of mesopores spatial distribution and optimized acid properties.This work reveals the role of mesopores in different spatial positions of 1-hexene aromatization catalysts in the reaction process and the influence on metal distribution,as well as their synergistic effect two on the improvement of xylene selectivity,which can improve our understanding of catalyst pore structure and be helpful for the rational design of high-efficient catalyst.

不同木纤维对水泥基胶凝材料水化进程的影响研究

木纤维的加入可改善水泥基胶凝材料的抗拉强度,但只采用机械破碎及沸煮处理的木纤维对水泥基胶凝材料有缓凝、阻凝作用,阻碍了木纤维在水泥制品中的应用,为提升木质家具企业的木纤维利用率,从机械破碎的松木、杂木纤维的长径比着手,研究经碱法预处理的木纤维对水泥基胶凝材料水化进程的影响。结果表明:未预处理的杂木纤维只影响水泥早期水化热释放速率,对水泥水化热释放总量影响较小,未预处理的松木纤维具有明显的阻凝作用;采用Ca(OH)_(2)溶液浸泡可以有效降低木纤维对水泥水化的缓凝作用,与其他碱液浸泡相比,采用Ca(OH)_(2)浸泡可避免水泥胶凝体系引入其他物质。

Facile Surface Engineering of NiCo_(2)O_(4) to Boost Propane Oxidation Activity

Spinel oxide(NiCo_(2)O_(4))has demonstrated great potential to replace noble metal catalysts for the oxidation reaction of air pollutants.To further boost the oxidation ability of such catalysts,in this study,a facile surface-engineering strategy wherein NiCo_(2)O_(4) was treated with different alkali solvents was developed.The obtained catalyst(NiCo_(2)O_(4)-OH)showed a higher surface alkalinity and more surface defects compared to the pristine spinel oxide,including enhanced structural distortion as well as promoted oxygen vacancies.The propane oxidation ability of NiCo_(2)O_(4)-OH was greatly enhanced,with a propane conversion rate that was approximately 6.4 times higher than that of pristine NiCo_(2)O_(4) at a reaction temperature 193℃.This work sets a valuable paradigm for the surface modulation of spinel oxide via alkali treatment to ensure a high-performance oxidation catalyst.

酶法破壁提取蜂花粉功能成分的工艺优化及抗氧化活性分析

目的探索酶解结合超声和碱解从而高效破壁和提取蜂花粉中的活性成分。方法采用扫描电镜对蜂花粉微观结构进行分析,并使用高效液相色谱法分析酚类物质的组成和含量变化。结果经12.5%碱性蛋白酶酶解1 h后,蜂花粉酶解上清液的总酚含量、总黄酮含量和2,2’-联氮-二(3-乙基-苯并噻唑啉-6-磺酸)二铵盐[2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)ammonium salt,ABTS]阳离子自由基清除能力最高,分别为(14.14±0.23)mg GAE/(g·dw),(2.34±0.04)mg RE/(g·dw)和(167.06±1.39)μmol TE/(g·dw)。将酶解辅以超声协同0.3 mol/L NaOH处理后,总酚、总黄酮、ABTS阳离子自由基清除能力及铁离子还原能力相比未处理花粉分别提高了191%、39%、69%和162%。扫描电镜结果显示,碱处理酶解后花粉细胞壁破碎程度显著增加,花粉内含物质从裂口处向外溢出,与理化指标趋势一致。最佳工艺条件为0.3mol/LNaOH超声-碱处理1h,调节pH至7,12.5%的碱性蛋白酶于50℃下酶解1 h。结论超声碱处理可辅助酶解实现蜂花粉的高效破壁,同时小肽、多酚、黄酮等营养成分也进一步溶出,促进了蜂花粉的高值化利用。

基于响应面法的菌草重组材制备工艺优化

菌草资源是目前世界上最丰富的农业资源之一,具有广阔的发展前景。以菌草绿洲一号为原料,制备菌草重组材,采用响应面Box-Behnken试验设计方法研究不同浸胶时间、热压时间、热压温度对菌草重组材主要物理力学性能的影响。在响应面试验结果基础上增加碱处理和帚化处理,探究改性对菌草表面结构及物理力学性能的影响。结果表明,菌草重组材的较佳制备工艺参数为浸胶时间33 min,热压时间1.12 min/mm,热压温度155℃。帚化制备的菌草重组材浸胶时间降低至15 min,其静曲强度(MOR)136.56 MPa和弹性模量(MOE)14.80 GPa比未帚化制备的菌草重组材分别提高154%和14%;吸水厚度膨胀率(TSR)5.84%和吸水宽度膨胀率(WSR)0.93%分别比未帚化制备的菌草重组材降低7和1.82个百分点,均达到GB/T 40247—2021《重组竹》的要求。碱处理试验结果显示,在NaOH质量分数为2%时MOR和MOE最佳,分别143.13 MPa和15.05 GPa;在NaOH质量分数1%时TSR和WSR最低,分别为1.85%和0.30%。通过扫描电镜分析可知,碱处理后菌草表面蜡质层出现降解,粗糙度增加;帚化处理产生的裂隙有利于酚醛树脂胶黏剂渗透到菌草内部,有利于菌草重组材的胶合,提高了力学性能和耐水性。本研究制备的菌草重组材为菌草新材料的开发提供新途径,对加快推进菌草重组材产业发展具有重要意义。

碱溶性聚酯/碳酸钙/聚酯(COPET/CaCO_(3)/PET)多孔纤维制备及性能研究

采用自制的碱溶性聚酯/碳酸钙(COPET/CaCO_(3))母粒与聚酯(PET)母粒,经熔融纺丝实现对传统PET纤维的改性,结合单因子控制变量法优选碱酸处理制备COPET/CaCO_(3)/PET多孔纤维的最佳工艺参数,并对纤维性能进行测试与表征。结果表明,当NaOH质量分数为4%、HCL质量分数为3%时,纤维具有较好的表观形态和孔隙结构。在最优处理条件下,纤维内部含有较多分布均匀的孔隙,孔径主要集中分布在15~54nm。此时,纤维的断裂强度、线密度、比表面积和熔融温度分别为1.29cN/dtex、4.84dtex、5.5273m^(2)/g和253.85℃。

改性丝光沸石催化果糖脱水制备5-羟甲基糠醛

分别采用酸处理、碱处理及氨基化处理对丝光沸石(HMOR)进行改性后制备了系列HMOR催化剂,采用X射线衍射(XRD)、氨程序升温脱附(NH 3-TPD)、傅里叶红外光谱(FT-IR)、X射线荧光(XRF)等手段对HMOR进行表征,并采用间歇式不锈钢高压反应釜考察其催化果糖脱水生成5-羟甲基糠醛(HMF)反应性能。结果表明:改性后催化剂仍保持丝光沸石的晶体结构,酸中心强度与酸量有改变,硅烷化试剂3-氨丙基三乙氧基硅烷(APTES)中的氨基基团成功嫁接到丝光沸石表面;得到了较优反应条件:N 2压力2.0 MPa,反应温度150℃,果糖质量1.0 g,催化剂质量0.2 g,助剂聚乙烯吡咯烷酮质量0.06 g,反应时间180 min。在此反应条件下,以氨基化处理改性制备的NH 2-MOR 0.5为催化剂时,果糖转化率84.1%,HMF产率78.6%,HMF选择性93.4%;与其他催化剂相比,虽果糖转化率略微下降,但HMF选择性明显提高。

薰衣草蒸馏废渣/环氧树脂复合材料的制备及力学性能

为了实现薰衣草蒸馏废渣资源利用,将薰衣草蒸馏废渣与环氧树脂复合,通过模压工艺制备薰衣草蒸馏废渣/环氧树脂复合材料,通过傅里叶变换红外光谱(FTIR)、万能力学试验机和扫描电子显微镜(SEM)等对复合材料的力学性能、形态结构和吸水率等进行分析。结果表明,随着薰衣草蒸馏废渣含量的增加,复合材料的力学性能呈先增大后减小的趋势;在薰衣草蒸馏废渣质量分数为60%时复合材料具有最优异的冲击强度(1.56 kJ/m^(2))和弯曲强度(40.1MPa);在此含量基础上,采用氢氧化钠处理薰衣草蒸馏废渣,结果表明,所获得的环氧树脂复合材料的冲击强度和弯曲强度分别达到了3.04 kJ/m^(2)和66.2 MPa,较未处理时增加了94.9%和65%。FTIR分析结果表明,碱处理可以消除薰衣草蒸馏废渣表面的脂类等物质,改善了其与环氧树脂的界面性能;SEM结果证实,经碱处理后的复合材料内部有大量丝状物产生;吸水率结果表明,复合材料的吸水率随薰衣草蒸馏废渣含量的增加而增大,且经过碱处理后,复合材料具有较高的吸水率。