Novel insights into the enrichment of phenols from walnut shell pyrolysis loop: Torrefaction coupled fractional condensation

Eco-friendly composites are proposed to substitute commonly available polymers. Currently, wood–plastic composites and natural fiber-reinforced composites are gaining growing recognition in the industry, being mostly on the thermoplastic matrix. However, little data are available about the possibility of producing biocomposites on a silicone matrix. This study focused on assessing selected organic fillers’ impact (ground coffee waste (GCW), walnut shell (WS), brewers’ spent grains (BSG), pistachio shell (PS), and chestnut (CH)) on the physicochemical and mechanical properties of silicone-based materials. Density, hardness, rebound resilience, and static tensile strength of the obtained composites were tested, as well as the effect of accelerated aging under artificial seawater conditions. The results revealed changes in the material’s properties (minimal density changes, hardness variation, overall decreasing resilience, and decreased tensile strength properties). The aging test revealed certain bioactivities of the obtained composites. The degree of material degradation was assessed on the basis of the strength characteristics and visual observation. The investigation carried out indicated the impact of the filler’s type, chemical composition, and grain size on the obtained materials’ properties and shed light on the possibility of acquiring ecological silicone-based materials.

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Ideal pH for the adsorption of metal ions Cr6+, Ni2+, Pb2+ in aqueous solution with different adsorbent materials

Open Agriculture ◽

10.1515/opag-2021-0225 ◽

2021 ◽

Vol 6 (1) ◽

pp. 115-123

Author(s):

Luísa P. Cruz-Lopes ◽

Morgana Macena ◽

Bruno Esteves ◽

Raquel P. F. Guiné

Keyword(s):

Heavy Metals ◽

Metal Ions ◽

Walnut Shell ◽

Lead Adsorption ◽

Viable Solution ◽

Chestnut Shell ◽

Adsorption Processes ◽

Irreversible Effects ◽

Optimal Values ◽

Ph Range

Abstract Industrialization increases the number of heavy metals released into the environment. Lead (Pb2+), nickel (Ni2+) and chromium (Cr6+) are among these toxic metals and cause irreversible effects on ecosystems and human health due to their bio-accumulative potential. The decontamination through adsorption processes using lignocellulosic wastes from agricultural and/or forestry processes is a viable solution. Hence, this work aimed at studying the effect of pH on the biosorption of the metal ions using four different by-product materials: walnut shell, chestnut shell, pinewood and burnt pinewood. These experiments were conducted with solutions of the three heavy metals in which the adsorbents were immersed to measure the rate of adsorption. A range of pH values from 3.0 to 7.5 was used in the experiments, and the concentrations were determined by atomic absorption. The results showed different behaviour of the biosorbent materials when applied to the different metals. The lead adsorption had an ideal pH in the range of 5.5–7.5 when the walnut shell was used as an adsorbent, corresponding to values of adsorption greater than 90%, but for the other materials, maximum adsorption occurred for a pH of 7.5. For the adsorption of chromium, the pH was very heterogeneous with all adsorbents, with optimal values of pH varying from 3.0 (for chestnut shell) to 6.5 (for walnut shell and wood). For nickel, the best pH range was around pH 5, with different values according to the lignocellulosic material used. These results indicate that the tested biosorbents have the potential to decontaminate wastewater in variable extensions and that by controlling the pH of the solution; a more efficient removal of the heavy metals can be achieved.

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Modified sorbents based on walnut shell for sorption of toxic gases

Materials Today Proceedings ◽

10.1016/j.matpr.2020.12.948 ◽

2021 ◽

Author(s):

Z.A. Mansurov ◽

P. Lodewyckx ◽

L.F. Velasco ◽

S. Azat ◽

A.R. Kerimkulova

Keyword(s):

Walnut Shell ◽

Toxic Gases ◽

Modified Sorbents

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Preparation and Characterization of Novel Magnesium Composite/Walnut Shells-Derived Biochar for As and P Sorption from Aqueous Solutions

Agriculture ◽

10.3390/agriculture11080714 ◽

2021 ◽

Vol 11 (8) ◽

pp. 714

Author(s):

Vladimír Frišták ◽

Martin Pipíška ◽

Vladimír Turčan ◽

Stephen M. Bell ◽

Haywood Dail Laughinghouse ◽

...

Keyword(s):

Aqueous Solutions ◽

Anthropogenic Sources ◽

Walnut Shell ◽

Natural Ecosystems ◽

Functional Changes ◽

P Sorption ◽

Sorption Efficiency ◽

Walnut Shells ◽

Potential Capacity ◽

Sorption From Aqueous Solutions

Elevated or unnatural levels of arsenic (As) and phosphorus (P) concentrations in soils and waterbodies from anthropogenic sources can present significant hazards for both natural ecosystems and human food production. Effective, environmentally friendly, and inexpensive materials, such as biochar, are needed to reduce mobility and bioavailability of As and P. While biochar features several physicochemical properties that make it an ideal contaminant sorbent, certain modifications such as mineral-impregnation can improve sorption efficiencies for targeted compounds. Here, we conducted sorption experiments to investigate and quantify the potential utility of magnesium (Mg) for improving biochar sorption efficiency of P and As. We synthesized a Mg-modified walnut shells-derived biochar and characterized its ability to remove As and P from aqueous solutions, thereby mitigating losses of valuable P when needed while, at the same time, immobilizing hazardous As in ecosystems. SEM-EDX, FTIR and elemental analysis showed morphological and functional changes of biochar and the formation of new Mg-based composites (MgO, MgOHCl) responsible for improved sorption potential capacity by 10 times for As and 20 times for P. Sorption efficiency was attributed to improved AEC, higher SSA, chemical forms of sorbates and new sorption site formations. Synthetized Mg-composite/walnut shell-derived biochar also removed >90% of P from real samples of wastewater, indicating its potential suitability for contaminated waterbody remediation.

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Organosolv Fractionation of Walnut Shell Biomass to Isolate Lignocellulosic Components for Chemical Upgrading of Lignin to Aromatics

ACS Omega ◽

10.1021/acsomega.0c05936 ◽

2021 ◽

Author(s):

Rebecca N. Nishide ◽

Julianne H. Truong ◽

Mahdi M. Abu-Omar

Keyword(s):

Walnut Shell

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Experimental and numerical study to investigate the usability of walnut shell waste as an additive for foundations of highway embankments

Arabian Journal of Geosciences ◽

10.1007/s12517-021-08195-9 ◽

2021 ◽

Vol 14 (18) ◽

Author(s):

Zülal Akbay Arama

Keyword(s):

Numerical Study ◽

Walnut Shell ◽

Shell Waste ◽

Highway Embankments

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Investigating the performance of agricultural wastes and their ashes in removing phenol from leachate in a fixed-bed column

Water Science & Technology ◽

10.2166/wst.2020.274 ◽

2020 ◽

Vol 81 (10) ◽

pp. 2109-2126 ◽

Cited By ~ 1

Author(s):

Seyed Omid Ahmadinejad ◽

Seyed Taghi Omid Naeeni ◽

Zahra Akbari ◽

Sara Nazif

Keyword(s):

Activated Carbon ◽

Large Scale ◽

Fixed Bed ◽

Walnut Shell ◽

Continuous Systems ◽

Phenol Removal ◽

Adsorption Method ◽

Fixed Bed Column ◽

Saturation Time ◽

Coconut Shell Activated Carbon

Abstract One of the major pollutants in leachate is phenol. Due to safety and environmental problems, removal of phenol from leachate is essential. Most of the adsorption studies have been conducted in batch systems. Practically, large-scale adsorption is carried out in continuous systems. In this research, the adsorption method has been used for phenol removal from leachate by using walnut shell activated carbon (WSA) and coconut shell activated carbon (CSA) as adsorbents in a fixed-bed column. The effect of adsorbent bed depth, influent phenol concentration and type of adsorbent on adsorption was explored. By increasing the depth of the adsorbent bed in the column, phenol removal efficiency and saturation time increase significantly. Also, by increasing the influent concentration, saturation time of the column decreases. To predict the column performance and describe the breakthrough curve, three kinetic models of Yon-Nelson, Adams-Bohart and Thomas were applied. The results of the experiments indicate that there is a good match between the results of the experiment and the predicted results of the models.

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