One-stage Process Research Articles

Direct synthesis of nickel oxide nanoparticles from pregnant leach solution by using electrodeionization and Fenton processes in the presence of EDTA

This paper presents the results of a novel study on the direct synthesis of nickel oxide nanoparticles from a synthetic pregnant leach solution (PLS) as a middle stage product of hydrometallurgy process of nickel production. To increase the nickel proportion in the initial PLS, electrodeionization was utilized in the presence of EDTA to form an anionic complex ([Ni-EDTA]2−) with Ni2+ cations, allowing their separation from cobalt cations through the EDI process. Subsequently, the Fenton process was applied to synthesize nickel oxide nanoparticles from the complex containing solution. The proposed hybrid process was conducted in two different modes of one-stage and two-stage EDI process followed by the Fenton process. Different analysis methods including AAS, XRD, FE-SEM, and ICP were used for qualitative and quantitative evaluations. The analyses’ results revealed that by implementing one-stage EDI process followed by Fenton process resulted in producing nickel oxide nanoparticles with an average particle size of 45 nm and purity of about 98 %. Also, it was seen that about 81 % of initial nickel content of the initial PLS was recovered as nickel oxide nanoparticles. In the case of two-stage EDI process, 100 % pure nickel oxide nanoparticles with average size of 55 nm and recovery of 65 % was produced. The results showed that the innovative hybrid EDI/Fenton process can be considered as a promising approach for direct synthesis of high purity nickel oxide nanoparticles from PLS. However, it should be noted that there was a trade-off between purity of nickel oxide and nickel recovery from PLS.

Метано- и сульфидогенез в озерах полуострова Абрау (Краснодарский край)

The geographical position, tectonic and geological-hydrogeological structure of the basin of the Malyy Liman and Abrau lakes, their landscape features as natural monuments of regional importance located on the territory of the Abrau peninsula of the Krasnodar Territory are described. Using the example of the aquatic landscapes of the Malyy Liman and Abrau lakes and the river of the same name, water and bottom sediments were studied. Hydrochemical parameters, the content of methane and sulfide sulfur in bottom sediments and methane in water as components of aquatic landscapes were studied. The results of the determination of sulfides, as well as the characteristic odor and color of bottom sediments, indicate the presence of free H2S and hydrotroilite (FeS ∙ nH2O) in them. Electron microscopy revealed the presence of hollow spheres in the bottom sediments, which indicates their possible gas saturation. Microinclusions of biogenic pyrite (FeS2), which was formed on fragments of plant and organism residues, were found under an electron microscope. In aerobic-anaerobic conditions of the upper layer of bottom sediments of lakes, pyrite formation occurs both directly through a one-stage process of pyritization of reactive iron, but also through a multi-stage process of pyrite formation from iron monosulfide. It has been established that lakes are exposed to anthropogenic influences, which can increase many times during the holiday season. This leads to their eutrophication and increased meanogenesis, which in turn contributes to the activation of methane emissions into the atmosphere. Specific methane fluxes from the water surface of the Malyy Liman and Abrau lakes have been determined.

Recovery of copper from ammonia–ammonium chloride leach liquor using sterically hindered beta-diketone

In this study, the recovery of copper from ammonia–ammonium chloride (NH3–NH4Cl) leach liquor using sterically hindered beta-diketone (β-diketones), a well-known extractant, was investigated. The experimental approach entails studying how various factors, including extraction time, concentration of the extractant, pH, phase ratio, and temperature, impact the effectiveness of copper extraction. The most favourable conditions for extracting copper from ammoniacal solutions containing 871.27 mg/L Cu2+, 1.75 mol/L NH3, and 0.5 mol/L NH4Cl were determined. Optimal copper extraction was achieved through a one-stage solvent extraction process at a phase ratio of 1 : 1, utilising sulphonated kerosene containing 0.25 mol/L of β-diketones. This extraction process lasted for 10 min and yielded a copper extraction efficiency of 75.10%. Additionally, a stripping ratio of 98.52% was achieved from the loaded organic phase through a one-stage stripping procedure at a phase ratio of 1 : 1, conducted at a temperature of 298 ± 0.5 K.

Insight into adsorption-desorption of methylene blue in water using zeolite NaY: Kinetic, isotherm and thermodynamic approaches

It is critical to find an efficient method to separate methylene blue (MB) in wastewater before discharging them into environment. Adsorption using zeolites is the most commonly used one. To determine adsorption mechanism providing useful data to enhance adsorption capacity and practicability of scale-up, kinetic, isotherm and thermodynamic adsorption were evaluated and discussed intensely. Zeolite NaY was synthesized from rice husk ash with a one-stage process. Effects of pH, contact time, initial concentration, adsorbent dose, temperature, solvents and recyclic stability on MB adsorption and desorption were investigated in detail via alternating variable method. Optimal conditions for adsorption were at pH 8, 1 h, 50 mgMB/L, 303K. Adsorption kinetics and isotherms showed that the process fitted to pseudo-second-order, Freundlich and Temkin isotherm, indicating a spontaneous, exothermic and physical adsorption process with multilayer adsorption. Desorption process showed that EtOH:H2O (1:1) solvent at 323K was optimal for releasing MB and its thermodynamic studies revealed that this process was favorable with rising temperature. The maximum adsorption capacity was calculated as 49 mg/g and the adsorbent could maintain its adsorption performance after six cycles. Generally, this study provided a comprehensive approach of an efficient, cost-effective, and recyclable NaY for MB removal from water.

Enhancing PHGMS performance for recovery of ultra-fine ilmenite from tailings

In southwest China, the Panzhihua area annually produces about 80 million tons of tailings with a TiO<sub>2</sub> grade of around 5.0%, which causes serious waste of titanium resources as well as environmental and safety issues. The ilmenite contained in these tailings is ultra-fine in size, so it is difficult to recover under the regular operating conditions of pulsating high gradient magnetic separation (PHGMS). In this study, an SLon-100 PHGMS separator was applied to concentrate an ultra-fine titanium tailing under a wide range of operating conditions. The experimental results indicated that a combination of high pulsating frequency, large pulsating stroke, and low feed velocity was favorable for the highly efficient recovery of ultra-fine ilmenite from the tailings. The TiO<sub>2</sub> grade in the optimal concentrate was enhanced from 4.33% to 13.64%, at a recovery of 66.55% and an enrichment ratio of 3.15 through a one-stage PHGMS process. The size analysis of the optimal concentrate showed that the TiO<sub>2</sub> recovery in -25+18 µm and -18+10 µm fractions exceeded 70%. To further understand this PHGMS performance, the optimal ultra-fine ilmenite and larger-size ilmenite concentration conditions were compared. This study provides a valuable reference in the PHGMS operation for recovering ultra-fine weakly magnetic minerals, including ilmenite.

Production of ammonium nitrate for nitrogen recovery in a single bioreactor operating at pH 3

Ammonium nitrate (AN), i.e. NH4NO3, is extensively utilized in agricultural, mining, and civil construction sectors, with an annual production of approximately 16 million tons. Although the biological nitrification processes has been proven to be an important alternative to overcome the intensive energy consumption of the conventional chemical process for AN production, it necessitates ample chemical input for stable performance. This study marks the first demonstration of stable AN production from ammonium-rich wastewater employing a purely microbial-derived one-stage process, without the need for external chemical addition. This process functioned through an acidophilic ammonia-oxidizing bacteria (AOB), i.e., Candidatus (Ca.) Nitrosoglobus, which oxidized the ammonium in the feed to nitrite while simultaneously reducing the reactor pH to 3.2−3.4. Under these pH conditions, nitrite was chemically oxidized to nitrate with the provision of oxygen. Long-term bioreactor operation (>230 days) revealed consistent AN production from high ammonium wastewater at a nitrogen loading rate of 0.15 kg N/m3/d. Batch tests revealed that microbial ammonium oxidation was the rate-determining step in the overall AN production process. Further microbial enrichment and process optimization can enhance the microbial ammonium oxidation rate. In summary, the proposed acidic one-stage bioprocess presents a promising avenue for AN production from ammonium-rich wastewater.

Properties and Possibilities of Using Biochar Composites Made on the Basis of Biomass and Waste Residues Ferryferrohydrosol Sorbent.

Biochar enriched with metals has an increased potential for sorption of organic and inorganic pollutants. The aim of the research was to identify the possibility of using biochar composites produced on the basis of waste plant biomass and waste FFH (ferryferrohydrosol) containing iron atoms, after CO2 capture. The composites were produced in a one-stage or two-stage pyrolysis process. Their selected properties were determined as follows: pH, ash content, C, H, N, O, specific surface area, microstructure and the presence of surface functional groups. The produced biochar and composites had different properties resulting from the production method and the additive used. The results of experiments on the removal of methylene blue (MB) from solutions allowed us to rank the adsorbents used according to the maximum dye removal value achieved as follows: BC1 (94.99%), B (84.61%), BC2 (84.09%), BC3 (83.23%) and BC4 (83.23%). In terms of maximum amoxicillin removal efficiency, the ranking is as follows: BC1 (55.49%), BC3 (23.51%), BC2 (18.13%), B (13.50%) and BC4 (5.98%). The maximum efficiency of diclofenac removal was demonstrated by adsorbents BC1 (98.71), BC3 (87.08%), BC4 (74.20%), B (36.70%) and BC2 (30.40%). The most effective removal of metals Zn, Pb and Cd from the solution was demonstrated by BC1 and BC3 composites. The final concentration of the tested metals after sorption using these composites was less than 1% of the initial concentration. The highest increase in biomass on prepared substrates was recorded for the BC5 composite. It was higher by 90% and 54% (for doses of 30 g and 15 g, respectively) in relation to the biomass growth in the soil without additives. The BC1 composite can be used in pollutant sorption processes. However, BC5 has great potential as a soil additive in crop yield and plant growth.

ТЕРМОСТОЙКОСТЬ ЗАЛИВОЧНЫХ ПЕНОПОЛИИЗОЦИАНУРАТОВ

In the modern construction industry for increasing the thermal resistance of structures and reducing heat losses, casting foams based on reactive oligomers with high performance characteristics are widely used. At the same time, special attention is paid to the use of polyisocyanurate foams (PIR). However, in the scientific and technical literature there are practically no data on the influence of the composition of polyisocyanurate foams on their thermal properties. The purpose of this work is to determine the influence of isocyanate/polyol ratio, modifier content (trichloropropyl phosphate) and apparent density of foams on thermal properties of casting PIRs. The thermal properties of PIRs, when heated in the temperature range of 30-800 ⁰C in nitrogen atmosphere and in air, were investigated using a multimodal thermal analytical complex DuPont-9900 (heating rate 20°C/min). It is revealed that thermo-oxidative decomposition of polyisocyanurate foams is a pronounced, two-stage process, and the destruction of PIR in inert medium (nitrogen) is a one-stage process, which indicates different mechanisms of decomposition of foams in air and nitrogen. As a result of experimental studies, it was revealed that the investigated PIRs are more resistant to thermo-oxidative degradation than to thermal degradation. The thermal properties of the above foams depend on the isocyanate/polyol ratio and TCPP content. The density of polyisocyanurate foams insignificantly affects their thermal stability. At the optimal content of initial components PIRs have higher thermal resistance compared to rigid polyurethane foams (FPU).

Clarification of appropriate conditions for forming complex shapes with multiple steps in two-stage deep drawing process

In this study, appropriate conditions for forming complex shapes with multiple steps, such as automotive side door inner in a two-stage deep drawing process are investigated, and the effectiveness of the process is verified in a test. In this forming process, the inner area of the part is formed in the first stage and the outer area is formed in the second stage. And in the second stage, a forming pad is used to reduce strain in the inner area that is formed in the first stage. The results of the forming test showed that it is necessary to control the blank holding force (BHF) and the pad force (PF) in the second stage to avoid blank ruptures in all areas. Therefore, the concept of the BHF and PF for blank rupture risk at each site was studied using the finite element method (FEM). An appropriate range of BHF and PF was estimated from the results of FEM and the validity of the estimated values was confirmed in an actual test. In addition, it was confirmed that a two-stage deep drawing process using the above appropriate values can form a more severe shape than a one-stage deep drawing process.

Boosted Bio-Jet production: Unveiling the potential of a one-stage concurrent process of deoxygenation/upgrading versus two-stage sequential processes using Pt/Cl-Al2O3@Ni/ZSM-5 catalysts

Bio-jet fuel production from renewable bioresources is an increasingly attractive approach for mitigating the environmental impacts of aviation. Among the different methods available for deriving bio-jet fuel from fatty acids, catalytic hydroprocessing has emerged as a promising and commercially viable technique. Recent studies have focused on identifying suitable catalysts to produce kerosene-type bio-jet fuel, which can serve as blend stocks for aviation fuel after further cracking and isomerization. In this study, a bi-layer catalyst Pt/Cl-Al2O3@Ni/ZSM-5 catalyst was prepared and characterized using various techniques (including XRD, TEM, NH3–TPD, FTIR, H2–TPR, XPS, surface area, and pore size measurements). The thus-prepared catalyst is tested for bio-jet fuel production from Palm kernel oil (PKO). A novel one-stage process yields a high iso-alkane content with a low freezing point of –57 °C. The proposed Pt/Cl-Al2O3@Ni/ZSM-5 bi-layer catalysts in a one-stage process provided satisfactory results, with a conversion rate of 96%. The primary component of the resulting bio-jet fuel was alkanes in the C8-C16 range, with an isomers/normal-alkane (I/N) ratio of 2 and a proportion of 75.6 wt%. Interestingly, the produced bio-jet fuel using the one-stage strategy has significant potential for use as a blend stock to enhance the properties of traditional jet fuels (Jet A and Jet A-1, JP-5, and JP-8).

Spark plasma sintering of SiC-based bulk materials from carbonaceous residue of rice husk thermal processing

Relevance. The search for a useful application of carbonaceous residues of rice husks thermal processing. These residues due to high silicon content in the inorganic part can potentially be used to produce silicon carbide – an important functional material for various fields of science and technology. Useful utilization of this waste will allow not only solving the environmental problem associated with their inefficient application and formal disposal, but also obtaining value-added products in the form of SiC-based ceramics. Aim. To obtain SiC-based bulk products from carbonaceous residues of rice husk thermal processing by spark plasma sintering with a minimum number of additional stages of feedstock processing. Objects. SiC-based bulk products obtained using carbonaceous residues of rice husk thermal processing. The samples were obtained by spark plasma sintering at 1800 °C, pressure of 60 MPa and holding time of 10 minutes. Methods. Spark plasma sintering; X-ray diffractometry (X-ray phase analysis); scanning electron microscopy; vacuumless arc discharge synthesis method. Results. The authors have carried out the experimental studies to assess the possibility of applying carbonaceous residue of rice husk thermal processing as a precursor for the synthesis of silicon carbide in bulk (ceramics) and dispersed (powder) forms. A series of experiments on spark plasma sintering of carbonaceous residue from rice husk thermal processing in the initial and milled form, with SiO2 silica sand additives, as well as with the use of silicon carbide powders synthesized from carbonaceous residue by vacuumless arc discharge method were implemented. The latter is performed within a one-stage fast-flowing process in an air environment and does not require the use of a vacuum system. Preliminary results demonstrated the possibility of obtaining bulk products and dispersed powders based on silicon carbide with a content of at least 50 and 60 wt %, respectively, and indicate the prospects of further increasing phase purity by optimizing spark plasma sintering and vacuumless arc discharge synthesis.

Efektifitas Reaksi Transesterifikasi Minyak Kelapa dan Sereh untuk Pembuatan Perisa Alami dengan Biokatalisator Lipase serta Penggunaan Ultrasonik

In general, flavor are synthesis through enzymatic hydrolysis and esterification reactions (up to 20 hours) using commercial ingredients based on free fatty acids and alcohol. Efficient endeavors utilizing enzymatic transesterification to expedite reactions are necessary to acquire flavored products. Substrates may originate from commercial or natural sources abundant in fatty acids and alcohol. Commercial fatty acids and alcohol (geraniol) are readily available in pure forms. Alternatively, fatty acids can be sourced from coconut oil, while geraniol can be derived from lemongrass oil, which is more cost-effective compared to commercial ingredients. Ultrasonics have emerged as a means to expedite enzymatic. The objective of this study is to investigate the impact of ultrasonic power and transesterification reaction time between coconut oil and geraniol on geraniol conversion. Utilizing lipase (415.99 U/g), coconut oil was subjected to transesterification with commercially obtained pure geraniol in a 1:3 weight ratio, conducted in an ultrasonic tank filled with water. Reaction durations spanned 30, 60, 90, 120, and 150 minutes, with ultrasonic powers set at 50, 70, and 90 watts. The study findings elucidated that the highest geraniol conversion rate of 50.59% was achieved with 70 watts of ultrasonic power over a 90-minute period. These optimal conditions were subsequently applied to transesterify coconut oil with geraniol from lemongrass oil, yielding a conversion rate of 90.29%. This finding demonsttrate the posibility of employing coconut oil and lemongrass oil in a one-stage transesterification process to produce natural flavors via enzymatic lipase catalysis expedited by ultrasonic technology, facilitating swift reaction times.

NaY zeolite synthesis from rice husk ash for Chromium(VI) ion adsorption

NaY zeolite in this study is novelly synthesized from rice husk ash with a one-stage process instead of passing the solid silica recovery process as usual. NaY zeolite applies to assess adsorption ability of chromium(VI) ions in water with varying key factors. The as-synthesized zeolite is characterized by X-ray diffraction, X-ray fluorescence, scanning electron microscope, specific surface area analysis and inductively coupled plasma mass spectrometry with optical emission spectroscopy. As a result, the optimal conditions for silica extraction are at 90oC with a NaOH concentration of 4 M for 4 h with recovery efficiency 87.5%. NaY zeolite is successfully synthesized with Si/Al ratio of 10, aging time of 24 h and crystallization time of 24 h with synthesis yield of 31.25% and crystallinity of 96%. The optimal conditions for the chromium(VI) adsorption in aqueous solution are at pH 2.0, adsorption time of 120 min, initial concentration of 20 mg/L with an adsorbent mass of 0.1 g. The kinetics and adsorption isotherms show a good agreement with pseudo-second order and Freundlich adsorption isotherm model. NaY zeolite is synthesized via environmentally friendly approach with time and energy savings and shows its high adsorb-ability of chromium(VI) in water.

Kinetic and elemental characterization of HAP-based high-rate partial nitritation/anammox system orienting stability and inorganic elemental requirements

Anammox-based processes are attractive for biological nitrogen removal, and the combination of anammox and hydroxyapatite (HAP) is promising for the simultaneous removal of nitrogen and phosphorus from wastewater. However, the kinetics of one-stage partial nitritation/anammox (PNA) in which ammonia-oxidizing bacteria (AOB) and anammox bacteria (AnAOB) exist in a reactor are poorly understood. Moreover, inorganic elements are required to promote microbial cell synthesis and growth; therefore, monitoring of elements to prevent the limitation and inhibition of the process is critical. The minimum amounts of inorganic elements required for a one-stage PNA process and the elemental flow remain unknown. Therefore, in this study, kinetics, stoichiometry, and element flow in the long-term, high-rate, continuous, one-stage HAP-PNA process with microaerobic granular sludge at 25 °C were determined using process modeling, parameter estimation, and mass balance. The biomass elemental composition was determined to be CH2.2O0.89N0.18S0.0091, and the biomass yield (Yobs) was calculated to be 0.0805 g/g NH4+-N. Therefore, a stoichiometric reaction equation for the one-stage HAP-PNA system was also proposed. The maximum specific growth rate (μm) of AnAOB and AOB were 0.0360 and 0.0982 d−1 with doubling times of 19 and 7.1 d, respectively. Finally, the elemental requirements for stable and high-rate performance were determined using element flow analysis. These findings are essential for developing the anammox-based process in a stable and resource-efficient manner and determining engineering applicability.

An Analysis of Fixed-Bed Catalytic Reactors Performances for One-Stage Butadiene Synthesis from Ethanol

The present study assesses, using a theoretical approach, the performances of two widely used fixed-bed reactors for the ethanol-to-butadiene (ETB) one-stage (Lebedev) process: multibed adiabatic reactors (MBAR) with inter-bed heating and a multitubular reactor (MTR). The mathematical model consists of mass and heat conservation equations at catalyst particle and particle bed scales, coupled with a published kinetic model specific for a modified MgO–SiO2 catalyst. The process simulations at the level of catalyst particle have shown that the inter-phase concentration and temperature gradients are negligible, the only physical step with a limiting influence on process kinetics being the internal diffusion. A simplified version of the reactor model was also formulated, including empirical expressions developed in the study for the calculation of internal effectiveness factors. The reactor simulations highlighted that the MBAR with inter-bed heating by injection of hot reactants provides worse butadiene (BD) yields as a consequence of reduced reaction times (due to reactant by-pass of catalyst beds). The MBAR with inter-bed heating using heat exchangers provides better performances but inferior to those of MTR if the number of catalyst beds is less than six. A preliminary optimization study for the MBAR and MTR is also presented. The results showed that the maximization of BD yield has the drawback of a low BD production rate, whereas the maximization of BD production rate corresponds to a relatively low BD yield and high ethanol and inert recycles. A trade-off between the two extreme cases can be attained by maximizing the income generated by reactor operation.

Two-Stage and One-Stage Anaerobic Co-digestion of Vinasse and Spent Brewer Yeast Cells for Biohydrogen and Methane Production.

This study aimed to evaluate the two-stage and one-stage anaerobic co-digestion of vinasse and spent brewer yeast cells (SBY) for biohydrogen and methane production. Optimization of the vinasse-to-SBY ratio and fly ash concentration of the two-stage and one-stage production processes was investigated. In the two-stage process, the vinasse-to-SBY ratio and fly ash concentration were optimized, and the leftover effluent was used for methane production. The optimum conditions for biohydrogen production were a vinasse-to-SBY ratio of 7:3% v/w and fly ash concentration of 0.4% w/v, in which the maximum hydrogen yield was 43.7ml-H2/g-VSadded. In contrast, a vinasse-to-SBY ratio of 10:0% v/w and fly ash concentration of 0.2% w/v were considered optimal for methane production, and resulted in a maximum methane yield of 214.6ml-CH4/g-VSadded. For the one-stage process, a vinasse-to-SBY ratio of 10:0% v/w and fly ash concentration of 0.1% w/v were considered optimal, and resulted in a maximum methane yield of 243.6ml-CH4/g-VSadded. In the two-stage process, the energy yield from hydrogen (0.05-0.47kJ/g-VSadded) was 0.62%-11.78%, and the major fraction was approximately 88.22%-99.38% gain from methane (3.19-7.73kJ/g-VSadded). For the one-stage process, the total energy yield distribution ranged from 4.20 to 8.77kJ/g-VSadded.

Network Technology, Whole-Process Performance, and Variable-Specific Decomposition Analysis: Solutions for Energy-Economy-Environment Nexus

The sustainability of the industrial sector is often evaluated in a one-stage process. On the other hand, industrial activities are characterized by complex and multistage natures, which creates challenges for industrial performance assessment. Properly measuring industrial sustainability and understanding the driving factors (e.g., energy use or labor) of whole-process industrial operation is important for sustainable industrial sector management. To address these difficulties, we propose two new frameworks: the network variable-specific bounded-adjusted measure and network variable-specific Luenberger productivity indicators decomposition. These both take into account the whole-process context and network nature of industrial production, and unpack and quantify the contributions of specific components of the industrial process affecting sustainability. In order to capture both the status and evolution of sustainability performance, two indices are constructed. These are then decomposed to investigate the contribution of particular components to overall sustainability. The proposed approach is applied to analyze the sustainability of the industrial sector in 30 of China's provincial administrative regions between 2006 and 2015. The static sustainability inefficiency indicator results indicate that in the production and treatment process, use of the most efficient existing technology would allow a further 48.0% and 23.6% of pollutant emissions to be reduced and treated, respectively. In the production process, the most efficient technology could produce a 10.7% improvement in energy conservation. The average annual dynamic environmental performance was 2.45% and 2.07% for the production and treatment processes, respectively. There is significant heterogeneity between regions and for different variables.

Continuous slurry hydrotreating of sewage sludge-derived hydrothermal liquefaction biocrude on pilot-scale: Comparison with fixed-bed reactor operation

In this study, we demonstrate the continuous catalytic hydrotreating of sewage sludge-derived hydrothermal liquefaction oil on a versatile, pilot-scale testing unit, equipped with both a slurry and a fixed-bed reactor. Comparison of the two reactors shows that slurry hydrocracking is consistently more efficient in both heteroatom removal and cracking performance compared to the fixed-bed operation. The upgraded HTL oil from the slurry reactor contains 35% less nitrogen that the equivalent oil produced from the fixed-bed reactor at 350 °C and is lighter, consisting of 84 wt% molecules in the gasoline and diesel range, compared to 63 wt% in its counterpart. This is tentatively ascribed to the higher residence time and the lower mass-transfer limitations in the slurry reactor that enhance the hydrogenation and cracking reactions. Upgrading the HTL oil in a two-stage configuration improves only the nitrogen removal, which increases from 40‐55% in the one-stage process to 83%. Overall, slurry hydrocracking appears to be a promising strategy for the upgrading of bio-oils from renewable feedstocks, such as waste and biomass. Further research is required to study operability and stability issues for longer time-on-stream and investigate the process in the presence of dispersed liquid catalysts.

One-Stage Process of Reduction, Fluorination, and Doping with Nitrogen of Graphene Oxide Films

One-Stage Process of Reduction, Fluorination, and Doping with Nitrogen of Graphene Oxide Films

Pathways to magnesium supplementation of drinking water: An overview of the saline water conversion corporation experience

Magnesium (Mg) in drinking water is essential for human health, with low concentrations in drinking water being reported to be correlated with poor cardiovascular health outcomes. Based on the literature and suggestions that the World Health Organization would soon announce guidelines for Mg content of drinking water, the Saline Water Conversion Corporation (SWCC) announced specifications in October 2020 targeting 15–25 ppm of Mg in product water. SWCC produces approximately 6 million m3 of potable water daily for domestic and industrial use in the Kingdom of Saudi Arabia, so meeting this Mg target will require the allocation of significant resources. In this report the different approaches to adding Mg in post-treatment of the product water from the SWCC's network of desalination plants are reviewed in order to optimise the additional capital investment and ongoing operational expenses. The most cost-effective option is to mix produced water with groundwater containing Mg, but where this is not feasible the next most cost-effective method for achieving a 15 ppm target was assessed to be treating desalination brine with nanofiltration (NF) to generate a magnesium-rich brine fraction that can be mixed with produced water. A one-stage NF process can meet the 15 ppm Mg target only with levels of chloride and total dissolved solids exceeding regulatory maximums in the produced water, so a multi-stage NF process with intermediate dilution was designed. While this has a significantly higher capital expenditure and energy requirement than one-stage NF, at the cost of energy in the Kingdom of Saudi Arabia it is still significantly less expensive than alternative approaches (0.009 USD/m3). This solution was implemented at an SWCC desalination plant on the Red Sea and has been delivering Mg-enriched water (∼15 ppm) to approximately 1.3 million people since May 2022 at an estimated additional operational cost of 0.007 USD per m3. For lower target levels of Mg supplementation (∼5 ppm), replacement of limestone with dolomite in post-treatment limestone contactors has been found to be a cost-effective process in plant-scale trials at another SWCC plant on the Red Sea.