Solid Recovery Research Articles

Analysis of rain-deposited dust on polysulfone membranes using proton-induced X-ray emission spectroscopy

Proton-induced X-ray emission spectroscopy (PIXE) is a long-established method of nondestructive elemental analysis for environmental samples. While a standard method of recovery of solids from rainwater involves filtration onto polysulfone media, PIXE analysis has not typically been used on such substrates. We describe methodologies of the University of North Texas Ion Beam Laboratory for PIXE analysis of dust in Texas rainwater on polysulfone membranes from the National Atmospheric Deposition Program (NADP). PIXE analyses utilized a 2 MeV proton beam of 1 × 1 mm2 spot size with beam currents of 1–5nA. A 100 µm Al absorber attenuated X-rays produced by S native to the polysulfone and minimized pileup, allowing use of higher beam currents at the expense of detecting elements of Z < 22. Uniformity of dust deposition on the membranes was evaluated by utilizing Fe concentration as a dust tracer. Areas of uniform particulate deposition with comparable results to averages across the entire membrane were located, allowing reduced acquisition time. GeoPIXE software was used for quantitative analysis, and 18 elements (Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Y, Zr, Hg and Pb) were investigated for a collaborative project. Average minimum detection limits (MDL) were ≤ 10 ng/cm2 for 21 > Z greater than 36 and 10–30 ng/cm2 for 36 < Z < 83. Polysulfone is shown to be an appropriate substrate for PIXE analysis of environmental samples, especially when quantification of low-Z elements is not a priority.

Cheese yield and nutrients recovery in the curd predicted by Fourier-transform spectra from individual sheep milk samples

The objectives of this study were to explore the use of Fourier-transform infrared (FTIR) spectroscopy on individual sheep milk samples for predicting cheese-making traits, and to test the effect of the farm variability on their prediction accuracy. For each of 121 ewes from 4 farms, a laboratory model cheese was produced, and 3 actual cheese yield traits (fresh cheese, cheese solids, and cheese water) and 4 milk nutrient recovery traits (fat, protein, total solids, and energy) in the curd were measured. Calibration equations were developed using a Bayesian approach with 2 different scenarios: (1) a random cross-validation (80% calibration; 20% validation set), and (2) a leave-one-out validation (3 farms used as calibration, and the remaining one as validation set) to assess the accuracy of prediction of samples from external farms, not included in calibration set. The best performance was obtained for predicting the yield and recovery of total solids, justifying for the practical application of the method at sheep population and dairy industry levels. Performances for the remaining traits were lower, but still useful for the monitoring of the milk processing in the case of fresh curd and recovery of energy. Insufficient accuracies were found for the recovery of protein and fat, highlighting the complex nature of the relationships among the milk nutrients and their recovery in the curd. The leave-one-out validation procedure, as expected, showed lower prediction accuracies, as a result of the characteristics of the farming systems, which were different between calibration and validation sets. In this regard, the inclusion of information related to the farm could help to improve the prediction accuracy of these traits. Overall, a large contribution to the prediction of the cheese-making traits came from the areas known as "water" and "fingerprint" regions. These findings suggest that, according to the traits studied, the inclusion of water regions for the development of the prediction equation models is fundamental to maintain a high prediction accuracy. However, further studies are necessary to better understand the role of specific absorbance peaks and their contribution to the prediction of cheese-making traits, to offer reliable tools applicable along the dairy ovine chain.

Effect of milk protein standardisation using buffalo milk protein co‐precipitates on the texture, composition and yield of paneer

Buffalo milk was utilised for preparing paneer samples after standardisation of protein:fat ratio to 0.68 with the addition of buffalo milk protein co‐precipitates (BMPC). These paneer samples along with control paneer (from buffalo milk) were analysed for yield, composition, microstructure, sensory, texture profile and protein loss in whey during manufacture. Paneer prepared using BMPC was considerably higher in yield and recovery of total solids, protein and calcium content than control paneer and could withstand the frying conditions in terms of retention of shape and integrity. Texture profile analysis and microstructure evaluation revealed the differences in textural properties of paneer samples prepared using BMPC with control paneer.

Extraction of saponins, total soluble solids and antioxidant activity from Polyscias fruticosa roots

Polyscias fruticosa is a tropical plant that has been used as medicine and food in Asian countries for centuries. The roots of Polyscias fruticosa contain a significant amount of beneficial bioactive compounds including saponins, polyphenols and flavonoids. Although a few reports on the extraction of bioactive from Polyscias fruticosa roots have been published, the literature related to the effects of extraction parameters on the recovery of saponins, the predominant bioactive group in this medicinal plant is limited. In this study, the effects of ethanol concentration, temperature, extraction time and liquid-solid ratio on the recovery of total soluble solids (TSS), saponins and antioxidant activity (AA) of extracts from Polyscias fruticosa roots were investigated. The yield of saponins, TSS and AA were significantly affected by the extraction conditions. The extraction time of 120 mins resulted in the highest yield of TSS while the extraction time of 90 mins led to the highest recovery of saponins and AA. Total saponin recovery increased along with the increase in ethanol concentration and reached a plateau at 40% of ethanol concentration. In addition, the temperature of 50oC and the liquid-solid ratio of 40/1 (mL/g) were found to be the most favourable conditions for the extraction. The results of this study were applicable for the process development on larger scales to produce saponin-rich products from Polyscias fruticosa roots.

In depth characterisation of hydrocyclones: Ascertaining the effect of geometry and operating conditions on their performance

Hydrocyclones are used for densification of waste streams prior to drying or for classification of solid and liquids in two-phase streams. They are becoming popular in industrial units due to their simplicity, low energy consumption and high versatility. However, the effect of geometry and operating conditions on the cut diameter and solid recovery efficiency have been independently studied, and therefore there are no studies approaching the influence of all the parameters simultaneously. Thus, a detailed experimental study was conducted to ascertain the effect of the hydrocyclone body (diameter and angle) and the vortex finder and spigot size and shape, as well as operating conditions (inlet pressure and solid concentration) on the separation efficiency curve, cut diameter, solid and volume recovery and the main features of the outlet streams. It has been proven that separation efficiency and outlet stream composition are sensitive to both the geometry of the hydrocyclone and the operating parameters. Therefore, knowledge of their influence is essential for the design of industrial units where liquid reutilisation is a major concern.

Preparation of Cellulose Nanocrystals by Synergistic Action of Ionic Liquid and Recyclable Solid Acid under Mild Conditions

Cellulose nanocrystals (CNCs) are nanoscale particles made from cellulose. They have many unique properties such as being lightweight, stiff, and renewable, making them promising for a variety of applications in a wide range of industries, including materials science, energy storage, and biomedicine. In this paper, a two-stage (swelling-SA-catalyzed) method including IL pretreatment and solid acid hydrolysis process was developed to extract CNCs with high purity and good thermal stability from microcrystalline cellulose (MCC). In the first stage, the swelling of MCC in ionic liquid was studied with the assistance of ultrasonication, and it was found that the amorphous regions became more disordered while the crystalline areas were selectively retained under the conditions of 30 min of reaction time, 45 °C of temperature, 2% of ionic liquid water content and 1:4 mass ratio of cellulose to ionic liquid. CNCs were extracted using solid acid hydrolysis, with a 45 wt% solid acid to cellulose ratio and a 5.0 h hydrolysis process at 45 °C. The morphology, crystallinity, surface characteristics and thermo stability of the sample were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA), respectively. Results demonstrated the highly thermostable CNCs were successful extracted with rodlike shape of 300 ± 100 nm in length and 20 ± 10 nm in width. Solid acid recovery and reuse were also studied, revealing a promising candidate that can reduce the environmental impact associated with chemical products.

Arundo donax L Processing in Catalyzed Butanol-Water Media in the Scope of Lignocellulose Biorefineries.

Arundo donax L samples, before or after aqueous extraction to remove extractives, were subjected to chemical fractionation in H2SO4-catalyzed mixtures of 1-butanol and water. The partial miscibility of 1-butanol and water at room temperature allowed the separation of the three major feedstock components in separate streams (lignin, accumulated in the 1-butanol-rich phase; hemicellulose-derived products, accumulated in the aqueous acidic phase; and cellulose, present in the solid phase). The effects of selected variables (temperature, catalyst concentration, reaction time and 1-butanol content of the reaction media) on variables measuring the solid recovery yield and the compositions of phases from fractionation were measured. Using water-extracted A. donax L as a substrate, the best operational conditions enabled 93.2% hemicellulose removal and 85.4% delignification with limited cellulose solubilization (15%). The experimental results provided key information to assess the proposed process in the scope of biorefineries.

Zeolite 4A activates peroxymonosulfate toward the production of singlet oxygen for the selective degradation of organic pollutants

Zeolite 4A (Z4A), synthesized from natural kaolin by an easy and low-cost method, was used to activate inorganic peroxides for degrading organic pollutants in water. Z4A had a high catalytic capability for the activation of peroxymonosulfate (PMS) but a low effect on peroxydisulfate (PDS) or hydrogen peroxide (H2O2). The non-radical pathway dominated the degradation of the pollutants, due to acid-base interactions of PMS with Z4A, as indicated by the characterization of the fresh and used zeolite. Additionally, in the Z4A/PMS system, synergistic effects in the elimination of two representative contaminants (ciprofloxacin “CIP” and methyl orange “MO”) were observed. The Z4A/PMS system induced the opening of the piperazyl ring of CIP, and the cleavage of the azo-benzene bond of MO. These primary transformations occurred in electron-rich groups, as supported by theoretical analyses on atomic charge developed herein. Interestingly, Z4A showed high activating/degrading capability even after three reuse cycles without the involvement of the typical recycling steps (filtration, washing, and drying) for a solid recovery. Furthermore, when compared with a sonochemical process, the Z4A/PMS system was highly efficient and more selective for the degradation of both CIP in synthetic fresh urine and MO in simulated textile wastewater. This study offers relevant findings on the PMS activation toward the non-radical pathway using the zeolite 4A, which represents an interesting alternative to those materials composed of transition metals or carbonaceous structures, to treat organic pollutants in aqueous samples in a selective way.

Development of novel ternary deep eutectic pretreatment solvents from lignin-derived phenol, and its efficiency in delignification and enzymatic hydrolysis of peanut shells

This work evaluated the effectiveness of a novel deep eutectic solvents (DES) prepared from guaiacol (GG), and p-hydroxybenzoic acid (PB) as a double hydrogen bond donor and choline chloride (ChCl) as a hydrogen bond receptor. The effect of ChCl-GG-PB on the structural properties and enzymatic hydrolysis of peanut shell was analyzed. Furthermore, the performance of ChCl-GG-PB as a hydrogen bond donor was compared with two other DES of PB and GG as hydrogen bond donors, and the effects of molar ratio, temperature and time were studied. The results showed that after ChCl-GG-PB pretreatment, hemicellulose and lignin were effectively removed, the removal rate was about 63.36% and 69.54%, respectively, and the enzymatic glycosaccharification efficiency was significantly improved, of which the xylose content was 5.5 times higher than the untreated. In addition, ChCl-GG-PB pretreated showed significant changes in the structure and morphology, with the highest crystallinity and lowest solid recovery. These results affirms that the proposed novel ternary DES is a promising pretreatment solvent that can effectively deconstruct lignocellulose and improve cellulose digestibility, thereby achieving an economically viable biomass conversion method.

Continuous recovery of phosphoric acid and Rare-Earths containing particles from phosphoric acid sludge using a decanter centrifuge

Recovery of rare earth elements (REEs) from various industrial and natural streams currently draws significant attention in efforts to meet the demands of the manufacturing industry. Among many industrial byproducts and waste streams, phosphoric acid sludge could be one of the most economically feasible resources for the recovery of REEs because solid particles in the sludge contain relatively concentrated REEs, up to 3,000 ppm, while the liquid component of the sludge is valuable phosphoric acid (P2O5) that can be recovered and returned to the main product. Due to high viscosity and large solids content (e.g., 30–40 %), however, this byproduct stream requires multistep separation and purification processes. In this study, a single-step process involving a continuous-flow decanter centrifuge (CFDC) was employed to investigate its feasibility for continuous solid/liquid separation from real phosphoric acid sludge. High centrifugal forces generated from up to 1500 G gravity acceleration separate solid particles from the sludge, generating a liquid-rich stream and a solids-rich stream at the exit of the CFDC. A single pass of phosphoric-acid sludge through the CFDC yielded 95 % liquid recovery and 90 % recovery of REEs-containing solids from 20 to 34 wt% solids-containing sludge. A reduced order model developed for the CFDC operation showed good agreement with experimental data, and preliminary technoeconomic analysis revealed potential process feasibility.

Mechanochemistry and the Evolution of Ionic Bonds in Dense Silver Iodide.

External mechanical stress alters the nature of chemical bonds and triggers novel reactions, providing interesting synthetic protocols to supplement traditional solvent- or thermo-based chemical approaches. The mechanisms of mechanochemistry have been well studied in organic materials made of a carbon-centered polymeric framework and covalence force field. They convert stress into anisotropic strain which will engineer the length and strength of targeted chemical bonds. Here, we show that by compressing silver iodide in a diamond anvil cell, the external mechanical stress weakens the Ag-I ionic bonds and activate the global diffusion of super-ions. In contrast to conventional mechanochemistry, mechanical stress imposes unbiased influence on the ionicity of chemical bonds in this archetypal inorganic salt. Our combined synchrotron X-ray diffraction experiment and first-principles calculation demonstrate that upon the critical point of ionicity, the strong ionic Ag-I bonds break down, leading to the recovery of elemental solids from a decomposition reaction. Instead of densification, our results reveal the mechanism of an unexpected decomposition reaction through hydrostatic compression and suggest the sophisticated chemistry of simple inorganic compounds under extreme conditions.

Effect of alkaline hydrogen peroxide assisted with two modification methods on the physicochemical, structural and functional properties of bagasse insoluble dietary fiber.

Bagasse is one of major by-product of sugar mills, but its utilization is limited by the high concentration of lignin. In this study, the optimal alkaline hydrogen peroxide (AHP) treatment conditions were determined by the response surface optimization method. The results showed that the lignin removal rate was 62.23% and the solid recovery rate was 53.76% when bagasse was prepared under optimal conditions (1.2% H2O2, 0.9% NaOH, and 46°C for 12.3 h), while higher purity of bagasse insoluble dietary fiber (BIDF) was obtained. To further investigate the modification effect, AHP assisted with high-temperature-pressure cooking (A-H) and enzymatic hydrolysis (A-E) were used to modify bagasse, respectively. The results showed that the water holding capacity (WHC), oil holding capacity (OHC), bile salt adsorption capacity (BSAC), and nitrite ion adsorption capacity (NIAC) were significantly improved after A-H treatment. With the A-E treatment, cation exchange capacity (CEC) and BSAC were significantly increased, while WHC, OHC, and glucose adsorption capacity (GAC) were decreased. Especially, the highest WHC, OHC, BSAC and NIAC were gained by A-H treatment compared to the A-E treatment. These changes in the physicochemical and functional properties of bagasse fiber were in agreement with the microscopic surface wrinkles and pore structure, crystallinity and functional groups. In summary, the A-H modification can effectively improve the functional properties of bagasse fiber, which potentially can be applied further in the food industry.

WATER RECLAMATION THROUGH NANOREMEDIATION &amp; BIOREMEDIATION: A WEAL AGAINST CONVENTIONAL CHEMICAL TECHNIQUES

Worldwide unprecedented challenge has been posed due to socio- economical-demographic and environmental transitions. These threats mainly sprout from rapid pace in modernization and advancement of technologies for economic escalation and raising live standards. These however is a bane since over the years there are instances of loss of considerable biodiversity, risks in public health, aggravation of already existing health issues, decline of soil salinity and to add to the plight there is water scarcity that mainly had resulted due to imbalance in the potable water available and its demand. Climate change, indiscriminate efflux of contaminants encompassing household to industrial waste water has profound effects on the standards of water quality. To cope with this situation there should be judicious planning leading to recycling the waste water in a more convenient way over prevalent robust technologies. The focus lies on the participation of nano-based materials that have been revered highly for their large surface to volume ratio and are efficient candidates for solid waste recovery. Nanomaterials both metallic non-metallic and polymeric materials have been the subject of interest for their diligent participation as catalyst, nano sorbents. Besides the participation of natural materials and benevolent biological components in bioremediation of waste water has been discussed herein.

A Study on the Investigating Items for the Surrounding Environment of Solid Recovery Fuel (SRF) Facilities to Improve Acceptability of Residents

A Study on the Investigating Items for the Surrounding Environment of Solid Recovery Fuel (SRF) Facilities to Improve Acceptability of Residents

Utilization of Construction and Demolition Mix Waste in the Fired Brick Production: The Impact on Mechanical Properties.

The European Green Deal, which emphasizes zero-waste economies, and waste recycling in construction and building materials, has arisen due to significant worldwide needs for solid waste recovery and usage. This ambitious study focuses on recycling mixed construction and demolition (C&D) waste into burnt bricks and investigating the influence of firing temperature. While pursuing its objectives, this is dependent on raw material characterization and burnt-brick product quality assessment. The recycling of mixed C&D waste is explored by mixing the waste into two soil types (alluvial and laterite) in ratios ranging from 5% to 45% at three firing temperatures (700 °C, 850 °C and 900 °C). The utilization of mixed C&D waste in amounts of 10% at 700 °C and 25% at 850 °C and 900 °C fulfilled the Indian standard. Although a fire at 700 °C results in less optimal waste utilization, it is beneficial and recommended for reducing the carbon footprint and energy use. Additional mineralogical and microstructural analyzes are performed on the optimal fired samples. The study's findings are promising for sustainable resource usage, reducing carbon footprint, and reducing waste disposal volume. This research is a big step toward the Sustainable Development Goals of the United Nations and a circular economy.

Analysis of gas–solid two-phase flow and structure optimization of mobile shot blasting machine recovery device

To address the problem of low efficiency of recycling process waste by gas–solid two-phase flow of the shot blasting machine recycling device, a method and structure by increasing the negative pressure value and optimizing the outlet pipe position are proposed. Computational fluid dynamics (CFD), discrete element method (DEM) and discrete phase model (DPM) were used to study the waste recovery efficiency at different pressure outlet conditions and outlet pipe locations. The validity of the model was verified by velocity tests at the outlet and inlet compared with simulations. The effect of particle size and particle generation rate on solid particle recovery efficiency was further investigated by analyzing the flow field distribution of the recovery unit. The results show that the maximum velocity of the gas phase in the recovery device increases with the increase of the absolute value of the outlet pressure, when the outlet pressure is -6500 Pa, the maximum velocity is 67.59 m/s. When the absolute value of the outlet pressure is greater than 6000 Pa, a small amount of steel shot particles is discharged from the recovery bin under the action of the outlet pressure, resulting in the loss of steel shot particles. After the outlet pipe position optimization, the steel shot particle recovery efficiency increased by 10% and the waste particle recovery efficiency increased by 18.9%.

Effect of HPT straining and further natural aging on the structure and hardness of aluminum alloy 1965 with nanosized TM aluminides

Pre-quenched samples cut from a homogenized ingot of commercial aluminum alloy 1965 with a grain size of about 21 µm were compressed at 6 GPa and then strained by torsion up to 10 revolutions at room temperature. TEM, SEM and XRD analyses showed that the strengthening / softening of the alloy during further natural aging up to 500 hrs was controlled by simultaneous decomposition of the aluminum solid solution and recovery of its deformation structure. It was found that the two-level nanostructuring of the alloy (precipitates and matrix) is accompanied by more than twofold strengthening up to a hardness of about 250 HV. The main contribution was made by dislocation and structural hardening due to the formation of a highly work-hardened structure of the nanofragmented type. During subsequent aging, the change in hardness was controlled by both the preliminary strain and the aging time. A continuous increase in strength with strain and aging time was found in the samples after pressing and torsion up to 1 revolution. In other conditions, strengthening was preceded by softening, the magnitude and duration of which were also proportional to the strain. The nature of the alloy behavior and the role of nanosized aluminides of transition metals are discussed in details.

Process analysis and optimisation for a sustainable circular economy

A sustainable circular economy could be generally achieved via process analysis and optimisation. The circular system or design has to be optimised based on sustainability (economically, environmentally and socially) rather than focus on the degree of circularity in the view that circular is not equivalent to sustainable. The articles that compose this Virtual Special Issue (VSI) provide an overview of process analysis and optimisation works that could contribute to a sustainable circular economy. The selected articles ranged from energy, water, and solid waste recovery to negative emission technologies-related topics.

Simulation on the influence of inlet velocity and solid separation gap on the separation characteristics of a separating device for three phases: Oil, water and solid

Water and solid particles, such as wear particles and sand, will enter lubricating oil during the operation of machinery, seriously affecting the performance and lifetime of the oil, and adversely affecting the machinery. Therefore, a device for simultaneously extracting water and solid particles mixed with lubricating oil is proposed. For such a device, a numerical model is established by combining mixture, Reynolds-stress, population-balance, and discrete-phase models to investigate the influence of inlet velocity and solid separation gap on separation characteristics, and the three-phase separation experiment is carried out. Results show that the oil-water-solid phase separating device delivers an excellent performance, and that the dewatering, deoiling, and solid particle recovery rates reach 76.9 %, 88.55 %, and 88.97 %, respectively; and separation time of solid particles and droplets and the tangential velocity increases with the increase of the solid separation gap. Furthermore, at an inlet velocity of 9 m/s, a large tangential velocity is generated to provide a strong centrifugal force while maintaining the stability of the internal flow field. This work provides a valuable guide for the design of high-performance devices for lubricating oil purification using physical methods.

An energy-efficient plasma methane pyrolysis process for high yields of carbon black and hydrogen

A novel thermal plasma process was developed, which enables economically viable commercial-scale hydrogen and carbon black production. Key aspects of this process are detailed in this work. Selectivity and yield of both solid, high-value carbon and gaseous hydrogen are given particular attention. For the first time, technical viability is demonstrated through lab scale reactor data which indicate methane feedstock conversions of >99%, hydrogen selectivity of >95%, solid recovery of >90%, and the ability to produce carbon particles of varying crystallinity having the potential to replace traditional furnace carbon black. The energy intensity of this process was established based on real-time operation data from the first commercial plant utilizing this process. In its current stage, this technology uses around 25 kWh per kg of H2 produced, much less than water electrolysis which requires approximately 60 kWh per kg of H2 produced. This energy intensity is expected to be reduced to 18–20 kWh per kg of hydrogen with improved heat recovery and energy optimization.