Walnut Shell Powder Research Articles

Synthesis and characterization of a new magnetic bio-adsorbent using walnut shell powder and its application in ultrasonic assisted removal of lead

In this paper, we report the use of a low-cost magnetic adsorbent from walnut shell (LMWS) as an efficient lead remover. We tried to grow magnetic domains on top of the LMWS surface via co-precipitation of minimum amounts of Fe2+ and Fe3+ ions. The results obtained from the kinetic experiments confirmed a fast accessibility of the Pb2+ ions to the adsorbent surface, reaching equilibrium within a few minutes. The experimental parameters including solution pH, adsorbent dose, concentration of metal ion solution, adsorption time, and solution temperature were optimized to find the maximum capacity of the magnetic walnut shell (MWS) bio-adsorbent. The adsorption of Pb(II) ions by MWS showed a slightly better fit with the Langmuir model compared to the Freundlich one. The experimental data obtained was tested using two different kinetic models. The pseudo-second order kinetic model represented this data very well. Moreover, the adsorbent was reused for several cycles. After elution of sorbent with a suitable eluent (HCl, 0.10M) the obtained results showed no significant reduction in the adsorption capacity and the magnetic properties of adsorbent. It was notable that the metal adsorption was quite fast and could be completed within 4minutes due to the absence of an internal diffusion resistance.

Green synthesis of Pd/walnut shell nanocomposite using Equisetum arvense L. leaf extract and its application for the reduction of 4-nitrophenol and organic dyes in a very short time.

Palladium nanoparticles (PdNPs) have been immobilized on the surface of walnut shell powder using Equisetum arvense L. leaf extract as reducing and stabilizing agents in this work. FT-IR spectroscopy, UV-Vis spectroscopy, photoluminescence spectroscopy, X-ray diffraction (XRD) pattern, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM) have been used in the characterization of the nanocomposites thus prepared. High catalytic activity was shown by these nanocomposites in the reduction of different dyes. The PdNPs' diameter on the walnut shell was predominantly found within the 5-12-nm range. The advantages of these catalysts include facile and clean synthesis, simple preparation procedure, excellent properties, alterable supports, and low cost, which make them applicable in reduction of 4-nitrophenol (4-NP), Congo red (CR), methylene blue (MB), and rhodamine B (RhB) in the presence of aqueous NaBH4 at room temperature. Pd/walnut shell nanocomposites were highly active catalysts for reduction of these dyes. Moreover, Pd/walnut shell nanocomposite can be recovered and recycled seven times without any appreciable loss of catalytic activity. Graphical abstract Waste walnut shell as a natural valuable resource support for green synthesis of Pd/walnut shell nanocomposite using Equisetum arvense L. leaf extract and its application for the reduction of 4-nitrophenol and organic dyes in a very short time.

Use of Walnut Shell Powder to Inhibit Expression of Fe(2+)-Oxidizing Genes of Acidithiobacillus Ferrooxidans.

Acidithiobacillus ferrooxidans is a Gram-negative bacterium that obtains energy by oxidizing Fe2+ or reduced sulfur compounds. This bacterium contributes to the formation of acid mine drainage (AMD). This study determined whether walnut shell powder inhibits the growth of A. ferrooxidans. First, the effects of walnut shell powder on Fe2+ oxidization and H+ production were evaluated. Second, the chemical constituents of walnut shell were isolated to determine the active ingredient(s). Third, the expression of Fe2+-oxidizing genes and rus operon genes was investigated using real-time polymerase chain reaction. Finally, growth curves were plotted, and a bioleaching experiment was performed to confirm the active ingredient(s) in walnut shells. The results indicated that both walnut shell powder and the phenolic fraction exert high inhibitory effects on Fe2+ oxidation and H+ production by A. ferrooxidans cultured in standard 9K medium. The phenolic components exert their inhibitory effects by down-regulating the expression of Fe2+-oxidizing genes and rus operon genes, which significantly decreased the growth of A. ferrooxidans. This study revealed walnut shell powder to be a promising substance for controlling AMD.

Effects of walnut shells on friction and wear performance of eco-friendly brake friction composites

The paper addresses utilization of 0–14.6 vol.% alkaline-treated walnut shell powders (WSPs) as a functional filler in the proposed eco-friendly brake friction materials. Five non-asbestos friction material samples containing WSP and jute fibers from biomass as biodegradable components were prepared, also including several from natural resources, such as wollastonite, basalt fibers, zircon, barite, and vermiculite. The friction-wear properties of the prepared composites were tested by using Chase friction performance testing device. Furthermore, an extension evaluation method was introduced to rank the composites based on their overall friction-wear characteristics. The coefficient of friction (COF) and wear rate of the samples could be effectively improved, especially for the sample with a WSP content ≤5.6 vol.%. With confirmation of the analysis and characterization results, chars were very possibly formed by the degradation of organic ingredients, such as WSP and jute fibers, which played a key role in affecting the friction performance of the friction composites.

Biosorption Studies of Cr(VI) Ions from Electroplating Wastewater by Walnut Shell Powder

Biosorption of Cr(VI) ions from aqueous solutions and electroplating wastewater by walnut shell powder has been investigated in a batch biosorption process. The biosorption of Cr(VI) ions was found to be dependent pH, initial chromiu m ion concentrations, biosorbent dose, contact time and temperature. The experimental equilib riu m biosorption data were analy zed by Lang muir, Freundlich, and Temkin isotherm models. The Lang muir model gave a better fit than the Freundlich and Temkin models. The maximu m biosorption capacity calculated from the Langmu ir isotherm was 138.89 mg/g at optimu m conditions. The kinetic studies indicated that the biosorption process of the chromiu m ions fo llo wed well pseudo-second-order model. The negative values of ∆G o (-3.51 kJ/ mo l) and positive value of ∆H o (12.95 kJ/ mol) revealed that the biosorption process was spontaneous and endothermic. Biosorption process was successfully applied to the treatment of an electroplating wastewater sample, where the concentration of chro miu m (VI) ions, organic materials and COD were effectively reduced. According to the sorption capacity, walnut shell powder considered as an effective, low cost, and environmentally friendly biosorbent for the removal of Cr(VI) ions fro m aqueous solution and electroplating wastewater.

Dirt-binding particles consisting of hydrogenated castor oil beads constitute a nonirritating alternative for abrasive cleaning of recalcitrant oily skin contamination in a three-step programme of occupational skin protection

In occupational fields with exposure to grease, oil, metal particles, coal, black lead or soot, cleansing formulations containing abrasive bodies (e.g. refined walnut shell, corn, wood, plastic or pumice) are used. These may constitute an irritant per se. As an alternative, hydrogenated castor oil (also known as castor wax) beads have been developed as dirt-binding particles. A polar surface contributes to their mechanical cleaning effects in removal of oily grime. Standardized examination of the in vivo effects upon the skin barrier of castor wax beads in comparison with abrasive bodies and pure detergent. Three cleansing preparations - (i) detergent, (ii) detergent containing castor wax beads, (iii) detergent containing walnut shell powder - were each repetitively applied in vivo (four times daily for 3 weeks), mimicking workplace conditions, in 30 healthy volunteers (15 with and 15 without an atopic skin diathesis) and compared vs. (iv) no treatment. The treatment effects upon the skin barrier were monitored by repeated measurements of functional parameters [transepidermal water loss (TEWL), redness] and surface topography. After a 3-week treatment, a significant global treatment effect (P < 0.0001) was found in the atopic group concerning TEWL as indicator for barrier function. A significantly higher TEWL and increasing erythema in the area treated with detergent containing walnut shell powder reflected its irritant effect compared with castor wax beads dispensed in the identical detergent. Cleaning properties of the two formulas were comparably superior to detergent alone. Castor wax beads constitute a novel nonirritating alternative for abrasive cleaning of recalcitrant oily skin contamination appropriate for individuals with an atopic skin diathesis in a three-step programme of occupational skin protection. As the skin barrier may additionally be influenced by the composition of dirt and use of skin protection and skin care measures under real workplace conditions, this component may now be used and examined further in different occupations.