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).

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.

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.

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.

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.

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.

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.

Comparative Study on the Treatment of Leachate from a Mine Waste Dump with Two Agricultural Biowastes

Mining waste dumps are present all over the world. One of the main problems of these solid deposits is the migration of heavy metals present in them due to the aqueous solutions flowing through them. The comparison of the removal of heavy metals from an aqueous solution of a real mining waste leachate under different conditions by two different agricultural wastes has been investigated. The effect of pH, contact time and dosage was studied using coffee grounds (CG) and walnut shells (WS), without pretreatment. The results obtained in the study showed the potential use of CG and WS for the removal of heavy metals, although the coffee grounds are the best adsorbents than the walnut shell.

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.

Separation of shelled walnut particles using pneumatic method

Separation of shelled walnut particles was studied on two varieties of Persian walnut,Poost-Kaghazi and Poost-Sangi using pneumatic method.The moisture contents of the samples were determined.The particles were considered in three categories of shell,kernel and shell-kernel together.Each category was manually classified based on their size,in three portions of 1/8,1/4,and 1/2,as well as the whole kernel and whole walnut.The terminal velocity of each group was determined.The shelled walnuts were sieved and classified in three groups of small,medium and large.The effects of separation time(5,10 and 15 seconds),feeding value(50 to 80 gr)and air velocity on separation of the kernels and shells were studied for both varieties.The interaction effects were also studied for three walnut sizes(small,medium and large).The terminal velocity was the highest for the whole walnut and the whole kernel while it was lowest for 1/4 and 1/8 of the shell.The best separation was performed at air velocities of 9.20,10.04 and 10.94 m/s with 98.2%,98.9%and 98.2%,respectively.

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.

Elutriation characteristics of multi-component mixtures in a fluidized bed pyrolysis process

Multi-component mixtures were prepared to simulate a bed of walnut shells undergoing pyrolysis in acold fluidized bed.Four mixtures with different ratios of walnut shell,semi-chars,and clean char were used.Batch elutriation experiments using these mixtures were performed in a transparent fluidized bed to allow direct observation of the flow patterns and particle composition.The results indicated that the bubble wake rather than bubble nose was primarily responsible for particle entrainment at higher gas velocities,and that coarser particles would be“transformed”into elutriable particles.Dimensionless gas velocities ranged from 0.2 to 1.0 and an exponential decrease in particle concentration with respect to bed height was observed.The transport disengagement height(TDH)gradually increased with the gas velocity until the entire bed layer enters a pneumatic transport state.Notably,larger TDHs were required when the bed contained a larger fraction of light components.Two characteristic parameters were used to evaluate particle elutriation:the elutriation rate constant(K),and the residual volatile content of the elutriated particles(v′).These parameters were used to optimize operating gas velocity for the fluidized bed.