Simulation Analysis of Stress Field of Walnut Shell Composite Powder in Laser Additive Manufacturing Forming

A calculation model of stress field in laser additive manufacturing of walnut shell composite powder(walnut shell/Co-PES powder)was established.The DFLUX subroutine was used to implement the moveable application of a double ellipsoid heat source by considering the mechanical properties varying with temperature.The stress field was simulated by the sequential coupling method,and the experimental results were in good accordance with the simulation results.In addition,the distribution and variation of stress and strain field were obtained in the process of laser additive manufacturing of walnut shell composite powder.The displacement of laser additive manufacturing walnut shell composite parts gradually decreased with increasing preheating temperature,decreasing laser power and increasing scanning speed.During the cooling process,the displacement of laser additive manufacturing of walnut shell composite parts gradually increased with the increasing preheating temperature,decreasing scanning speed and increasing laser power.

Characterization of Unsaturated Polyester Filled with Waste Coconut Shells, Walnut Shells, and Carbon Fibers

This study aims to evaluate the erosion behavior and the hardness of hybrid composites made of varying amounts of coconut shells,walnut shells,and carbonfibers dispersed in a polyester matrix.MINITAB(L16)Taguchi experiments were used to determine the optimal combination of parameters.In particular,an erosion device con-sisting of a motor with a constantflow rate of 45 L/min,a pump with a diameter of 40 mm,a nozzle with a dia-meter of 5 mm,and a tank made of“perspex glass”55 cm long,30 cm tall,and 25 cm wide was used.The tests were conducted by varying the sample-to-nozzle distance,the pattern angle,and the sand particle size.The results have revealed that the presence of 7.5%by weight of waste coconut shell,for conditions corresponding to 90°angle,sand size 425μm,stand distance 30 cm,gives the best wear resistance(3.04×10^(-5) g/g).Thefiller content and sand particle size affect the erosive rate,with the angle playing a secondary role.The distance between the sample and the nozzle has a weaker effect on erosive wear.The hardness results show that the models(UP-5%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste coconut shell)give the best values for prayer compared to the samples(UP-5 wt.%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste walnut shell).

Synthesis of Modified Walnut Shell Biochar and Its Performance of Cadmium Adsorption

Biochar is a functional and environmentally friendly material mainly made from by-products of industrial and agricultural production as raw material, which is cracked at high temperatures and slow speeds. The preparation of biochar requires the thermochemical conversion of biomass in an oxygen-restricted environment. Different raw materials and preparation processes result in biochar with different internal structures and biofunctional groups, which often have different properties. Adsorption of heavy metal pollutants is one of the main research directions for biochar application, and there are still areas that can be improved in the current research for biochar for treating heavy metal wastewater. In this study, we take the treatment of cadmium-containing wastewater as an example, walnut shell biochar (WSBC) as a carrier, iron(VI) compounds as a modifying reagent, and test the performance of cadmium-containing wastewater treatment using simulated cadmium-containing wastewater by adjusting the pyrolysis process and modification method at the same time to find the optimal experimental scheme, and give a reasonable theoretical explanation in relation to the results of the characterization tests, such as SEM, FT-IR, and so on. The characterized results show that iron(VI) compound (K2FeO4)-modified WSBC has a significant ability to remove cadmium contamination in the wastewater (remove 96.62% of cadmium in 1 minute), and its structure is different from other iron compound-modified ones. The aim of this study is to improve the efficiency of cadmium adsorption by specific types of biochar, while realizing the whole process as environmentally friendly as possible.

Adsorption of Cr(Ⅵ) in Water with Phosphoric Acid Modified and Ordinary Walnut Shells

A comparison between the effects of ordinary walnut shell and phosphoric acid modified walnut shell on adsorption of Cr（Ⅵ） was carried out. The experimental results showed that owing to larger surface void of modified walnut shell its adsorption of Cr（Ⅵ） was better. When the temperature was 35 ℃, adsorbent particle size was 1.0-1.6 mm, shaker shock rate was 200 r/min, and dosage of walnut shell was 0.80 g, the Cr（Ⅵ） removal rate reached 99.4%. The fitting of adsorption isotherm and kinetics model showed that, Langmuir isotherm model could reflect the adsorption process of modified walnut shell; and both the adsorption processes of ordinary and modified walnut shells accorded with the pseudo-second-order kinetic equations.

Study on the Extraction Technology of Tannin from Mountain Walnut Shells

In this study, tannin was extracted from mountain walnut shells with organic solvent method. The extraction rate of tannin was affected by various fac- tors, including solvents, extraction temperature, extraction time, and solid-liquid ratios. L9 （4^3 ） orthogonal experimental design was employed. The content of tannin in the extraction solution was determined with zinc ion eomplexometrie titration method. According to the experimental methods, the optimal extraction condi- tions were as follows： extraction solvent water, extraction time 12 h, extraction temperature 50 ℃, solid-liquid ratio 1： 6.

Preparation of Magnesia Insulation Materials by Walnut Shell Powder Impregnated with Silica Sol

In order to reduce the thermal energy loss of high temperature kilns and furnaces and lower the surface temperature of the kiln body,magnesia insulation materials were prepared using self-made magnesia porous aggregates(using high purity magnesia powder as starting material and potassium oleate as the foaming agent),middle grade magnesia powder,calcium aluminate cement,and SiO_(2) micropowder as starting materials,introducing walnut shell powder impregnated with silica sol(short for Sws)as a pore-forming agent.The effects of the Sws addition(0,10%,15%,and 20%,by mass)and the sintering temperature(1300,1350,1400,and 1480℃)on the properties of magnesia insulation materials were studied.The results show that(1)for the specimens fired at 1480℃,when the Sws addition is 10%,the cold compressive strength is 22 MPa;when the Sws addition is 20%,the thermal conductivity is 0.368 W·m^(-1)·K^(-1)(350℃);(2)nano-silica in the silica sol reacts with MgO in the matrix to form forsterite,which encapsulates the pores volatilized from the walnut shell powder and forms closed pores.

Dyeing of S/J Cotton Knit Fabric with Natural Dye Extracts from Green Walnut Shells: Assessment of Mordanting Effect on Fastness Properties

In this study, aqueous extraction method is used because of its high extraction ratio, light fastness and also functional properties. In 1st phase, for dyeing S/J cotton knit fabric with green walnut power ferrous sulfate is considered as a mordant. In this study, three different mordanting methods such as pre-, meta-, and post-mordanting are conveyed the dyeing process with the state of metallic mordant and without metallic salt mordants. In 2nd phase, in dyeing for fixation ferrous sulfate was considered as mordants. Furthermore, the analysis and evaluation of each colour dyed material was done through following two terms for instance CIELAB (L*, a*, and b*) and K/S values. According to AATCC test methods, colour fastness to washing, crocking, perspiration of the dyed samples is determined whereas according to the ISO standard, the colour fastness to light was estimated and tested. When dyeing was carried out on S/J cotton knit fabric through considering optimum parameter like at 80&degC for 60 min and at pH 4 which showed optimum results. From the results we can see, very good wash fastness was obtained while there is no fading of the colour, whereas the outstanding and moderate level of colour fastness to light and crocking is achieved.

Effect of Ultrasound-Assisted Extraction of Phenolic Compounds on the Characteristics of Walnut Shells

Walnuts are one of nature’s more waste-heavy products. 67% of the nut is shell and husk, low value by-products that are rich in phenolic compounds. The phenolic compounds extracted from walnut shells are potentially good natural sources of antioxidants for the food and pharmaceutical industries. In this study, phenolic compounds were extracted using an ultrasonic bath, an ultrasonic probe and a standard shaking method. The extraction yield achieved with an ultrasonic probe was 51.2 mg GAE/g DW, two times higher than both the shaking method and the ultrasonic bath method which were 20.6 mg GAE/g DW and 25.8 mg GAE/g DW, respectively. Phenolic extraction was further improved by a size reduction of the walnut shells. The best extraction yield of 52.8 mg GAE/g DW was attained when the particle size was between 45 - 100 mesh. The ultrasonic probe treatment is the best method for extraction of phenolic compounds from walnut shells. Scanning electron microscopy (SEM) imaging indicated that the ultrasonic probe treatment could better rupture the hard structure of the cells, increasing the penetration of solvents and thus the extraction yield.

Adsorption of Basic Dyes Using Walnut Shell-based Biochar Produced by Hydrothermal Carbonization

Hydrothermal carbon（HC） was prepared from walnut shells, which are abundant in Northeastern China. The prepared HC was used as a precursor to produce mtric acid modified carbon（MC）. The hydrothermal carbonization included dehydration and decarboxylation processes wherein the hemicellulose was completely decomposed and the celhilose was partly decomposed, with some oxygen-containing functional groups being produced. The aromati- city, specific surface area and pore content of the HC increased, but its polarity decreased. With 6 mol/L nitric acid and a modification time of 15 min, the specific surface area and pore content decreased, but the proportion of oxy- gen-containing fimctional groups on the surface increased significantly, thereby improving the dye adsorption performance. The adsorption of methylene blue and malachite green was best desclibed by the pseudo-second-order kinetic and Langmuir isotherm models. The adsorption capacity of MC was determined to be much larger than that of HC.

Catalytic fast pyrolysis of walnut shell for alkylphenols production with nitrogen-doped activated carbon catalyst

Alkylphenols are a group of valuable phenolic compounds that can be derived from lignocellulosic biomass.In this study,three activated carbons(ACs)were prepared for catalytic fast pyrolysis(CFP)of walnut shell to produce alkylphenols,including nitrogen-doped walnut shell-derived activated carbon(N/WSAC),nitrogen-doped rice husk-derived activated carbon(N/RHAC)and walnut shell-derived activated carbon(WSAC).Pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS)experiments were carried out to reveal the influences of AC type,pyrolytic temperature,and AC-to-walnut shell(AC-to-WS)ratio on the product distributions.Results showed that with nitrogen doping,the N/WSAC possessed stronger capability than WSAC toward the alkylphenols production,and moreover,the N/WSAC also exhibited better effects than N/RHAC to prepare alkylphenols.Under the catalysis of N/WSAC,yields of alkylphenols were significantly increased,especially phenol,cresol and 4-ethylphenol.As the increase of pyrolytic temperature,the alkylphenols yield first increased and then decreased,while high selectivity could be obtained at low pyrolytic temperatures.Such a trend was also observed as the AC-to-WS ratio continuously increased.The alkylphenols production achieved a maximal yield of 44.19 mg/g with the corresponding selectivity of 34.7%at the pyrolytic temperature of 400℃and AC-to-WS ratio of 3,compared with those of only 4.67 mg/g and 6.1%without catalyst.In addition,the possible formation mechanism of alkylphenols was also proposed with the catalysis of N/WSAC.

Removal of Rhodamine B from aqueous solutions and wastewater by walnut shells： kinetics, equilibrium and thermodynamics studies

An adsorption study ofRhodamine B （RB） dye from aqueous solutions was carried out using walnut shells pretreated by different methods. In addition to the effects of the pretreatment, the effects of various parameters like pH, adsorbent dose, contact time, initial dye concentration and temperature on the adsorption of RB was studied. The adsorption process was highly pH dependent and a maximum adsorption was achieved at pH 3.0. The best fit for the rates of dye adsorption was a pseudo-second- order kinetic model with good correlation coefficients （R2〉 0.99）. Langmuir isotherms were used to determine that the maximum loading capacity of the different walnut shells and the RB capacities ranged from 1.451-2.292 mg ~ gl. The dye adsorption was also evaluated thermodyna- mically. Positive standard enthalpy （M-P） values were obtained indicating that the RB adsorption process is endothermic as well as AG~ and AS~ values showed that adsorption process is spontaneous with an increased randomness at the solid-liquid interface~ Desorption studies were carried out to explore the feasibility of regenerating the used walnut shells and it was found that 97~71%-99.17% of the retained RB was recovered with 0.1 mol＂ L 1 NaOH solution. The walnut shells were also successfully used to remove RB from industrial effluents.

Changes in Lignin Content and Activity of Related Enzymes in the Endocarp During the Walnut Shell Development Period

Lignification was observed using the phloroglucinol–HCl method and the content of lignin,cellulose,and polyphenol and the activity of related enzymes were measured during development with the materials of walnut of ‘Zanmei' and ‘Zhenzhuxiang'.Results showed that lignification occurred at the beginning of June,initially took shape in mid-June and finished in late July.From shell lignification to harvest,the concentrations of lignin,cellulose,and phenolic content increased before harvest,but phenolic content decreased slightly.The activities of both POD and PAL decreased and PPO varied somewhat.Correlation analysis showed lignin content to be significantly positively correlated with the cellulose content.Phenolic content had a significant positive correlation with that of lignin.Phenolic content was positively correlated with cellulose.The activity of POD had a significant negative correlation with lignin,cellulose,and phenolic content,but it was positively correlated with the activity of PAL.

Characterization of Metal Oxide-modified Walnut-shell Activated Carbon and Its Application for Phosphine Adsorption: Equilibrium, Regeneration, and Mechanism Studies

We prepared a kind of metal oxide-modified walnut-shell activated carbon(MWAC) by KOH chemical activation method and used for PH_3 adsorption removal. Meanwhile, the PH_3 adsorption equilibrium was investigated experimentally and fitted by the Toth equation, and the isosteric heat of PH_3 adsorption was calculated by the Clausius-Clapeyron Equation. The exhausted MWAC was regenerated by water washing and air drying. Moreover, the properties of five different samples were characterized by N_2 adsorption isotherm, SEM/EDS, XPS, and FTIR. The results showed that the maximum PH_3 equilibrium adsorption capacity was 595.56 mg/g. The MWAC had an energetically heterogeneous surface due to values of isosteric heat of adsorption ranging from 43 to 90 kJ/mol. The regeneration method provided an effective way for both adsorption species recycling and exhausted carbon regeneration. The high removal efficiency and big equilibrium adsorption capacity for PH_3 adsorption on the MWAC were related to its large surface area and high oxidation activity in PH_3 adsorption-oxidation to H_3 PO_4 and P_2 O_5. Furthermore, a possible PH_3 adsorption mechanism was proposed.

Characterization and Methanol Adsorption of Walnutshell Activated Carbon Prepared by KOH Activation

Walnut-shellactivated carbons（WSACs）were prepared by the KOH chemicalactivation.The effects of carbonization temperature,activation temperature,and ratio of KOH to chars on the pore development of WSACs were investigated.Fourier transform infrared spectroscopy（FTIR）,X-ray powder diffraction（XRD）,and scanning electron microscopy（SEM）were employed to characterize the microstructure and morphology of WSACs.Methanoladsorption performance onto the optimalWSAC and the coal-based AC were also investigated.The results show that the optimalpreparation conditions are a carbonization temperature of 700 ℃,an activation temperature of 700 ℃,and a mass ratio of 3.The BET surface area,the micropore volume,and the micropore volume percentage of the optimalWASC are 1636 m^2/g,0.641 cm^3/g and 81.97%,respectively.There are a lot of micropores and a certain amount of meso-and macropores.The characteristics of the amorphous state are identified.The results show that the optimalWSAC is favorable for methanoladsorption.The equilibrium adsorption capacity of the optimalWSAC is 248.02mg/g.It is shown that the equilibrium adsorption capacity of the optimalWSAC is almost equivalent to that of the common activated carbon.Therefore the optimalWSAC could be a potentialadsorbent for the solar energy adsorption refrigeration cycle.

Study on Adsorption of Hg(Ⅱ) by Chinese Walnut(Juglans mandshurica Maxim.) of Biomass Material

[Objective] The aim of the study was to make research on adsorption of Chinese walnut（Juglans mandshurica Maxim.） Shell（CWS） to Hg（Ⅱ） in water.[Method] Shells of Juglans mandshurica Maxim were used as biosorption to remove Hg（Ⅱ） in water solution to explore the influence to adsorption of Hg（Ⅱ） under different conditions,like pH solution,adsorption time,and Hg（Ⅱ）.[Result] The experimental results show that when absorptivity of Hg（Ⅱ） by CWS reached the highest,pH ranged within 5.0-6.0.The adsorptivity decreased as initial Hg（Ⅱ） concentrations increased.Fourier Transform Infrared Spectroscopy（FTIR） spectrum revealed some chemical groups of CWS may affect the adsorption of Hg（Ⅱ）,such as hydroxyl groups,methyl groups,aromatic methoxyl groups,unconjugated carbonyl,and typical aromatic ring,etc.Adsorption equation can be concluded considering the biosorption process relationship with Langmuir and Frendrich isotherm.[Conclusion] The study found that CW could be employed as a promising biosorption to remove Hg（Ⅱ） from aqueous environments.

山核桃破壳裂纹试验与仿真分析

研究山核桃在冲击力下裂纹产生和发展的规律。用万能力学试验机进行冲击破壳试验,分别对山核桃在长轴、斜向和短轴加载方向各进行3种不同高度的15次重复试验。结果表明,无论加载方向如何,破壳冲击力的最大值都在240 N左右,且越靠近横轴方向力越小,越靠近长轴方向力越大。以此为依据,将山核桃横向截面简化为圆形,通过在传统弹塑性元素接触模型基础上增加强结合力的方法,构建压头—山核桃离散单元模型。仿真结果显示,水平压头会造成山核桃模型对称裂纹形式被压溃;与此同时,竖直状态压头会以S型裂纹形式分裂山核桃模型。通过高速摄像机拍摄山核桃破壳裂纹产生过程,与仿真结果基本一致。为山核桃破壳机械的设计、优化与深入地理解山核桃裂纹产生与发展机理提供重要参考。

基于EDEM的核桃壳仁混合物振动筛分级工艺优化

为提高核桃壳仁混合物的分级效果,对现有核桃壳仁混合物分级设备进行三维实体建模,利用EDEM软件模拟核桃壳仁混合物的分级过程,以筛面上物料的运动速度、质量以及各等级颗粒在统计区域的数量为指标,以振幅、振动频率、振动方向角、筛面倾角为考察因素,对振动筛分级工艺进行优化。结果表明:在振动频率12 Hz、振幅5 mm、振动方向角45°、筛面倾角4°的工艺参数组合下,各等级核桃壳仁的透筛率最高,分级效果最好。

山核桃破壳裂纹产生与扩展试验研究

探究山核桃受冲击力破壳裂纹产生与裂纹延展的规律,对突破制约核桃破壳取仁环节装备的瓶颈有较好的指导意义。以皖浙交界天目山区的山核桃为试验材料,采用不同形状的冲头预制裂纹,结合仿真分析研究其对裂纹萌生引导的影响。通过烘烤试验,观察裂纹延展趋势与规律。借助试验结果的启示,设计了山核桃破壳机。破壳部件的敲击锤头与果臼槽采用内附七窝眼的凹槽型结构,使得山核桃在冲击力的作用下,密集分布的棱线能够有效地实现裂纹引导,利于壳仁分离,获得更好的破壳质量。样机通过试验达到了预期效果,其破壳物料为后续加热、振动加工等工序提供便利。

锰改性核桃壳基生物炭去除水中刚果红的研究

以农业废弃物核桃壳作为原材料,通过炭化与共沉淀法两步制备锰改性生物炭,用于去除水中典型的阴离子染料刚果红。研究刚果红不同初始浓度、接触时间、生物炭投加量、溶液pH对刚果红去除效果的影响。结果表明,在pH为3,刚果红初始浓度为10 mg/L,生物炭投加量为10 mg,振荡时间60 min时,锰改性核桃壳对水中刚果红的去除率可达97.31%,与未改性的核桃壳相比,去除率提高至1.51倍。结合傅里叶红外光谱(FT-IR)与X射线衍射分析(XRD)对生物炭的结构变化以及吸附特征进行分析,通过动力学模型与热力学模型拟合,表明该吸附过程主要受化学吸附影响,该吸附为自发且不可逆的吸热反应。

基于定向挤压的核桃破壳有限元分析及破壳装置设计

针对目前核桃破壳机构适应性不强、破壳率不高、整仁率低的问题,从核桃破壳前定向预处理的视角,探索核桃在破壳加工前果体姿态定向处理对挤压破壳受力的影响因素。同时,以云南漾濞核桃为研究对象,通过3D扫描获取核桃三维实体模型,进行多组过静态压力有限元仿真试验,结果表明:在核桃果体上最佳受力区为核桃中线位置的横径方向,该位置受力最均匀、裂纹扩展效果最佳、最易破壳。基于有限元分析结果,设计出一次破壳与二次破壳相继进行的核桃定向破壳机构,并对核桃的破壳过程进行了力学分析,结果表明:破壳机构中弹簧的刚度系数及锤头旋转角度为影响核桃破壳的关键因素。研究结果可为核桃破壳设备的设计提供有创新意义的理论支撑。