This paper reports for the first time the removal of fluoride and arsenic from natural groundwater by capacitive deionization (CDI). The CDI trials were performed in a laboratory-scale flow cell, in recirculation mode, equipped with two graphite felts (GFs) as the anode and cathode. The characterization of the cell in terms of anodic applied potential (Eapp, 0-1.3 V vs. SHE) and flow rate (Q, 0.1-0.4 L min−1) was systematically examined in a synthetic solution containing F−, finding Eapp = 1.2 V vs. SHE and Q = 0.2 L min−1 as the best conditions. Afterward, F− and arsenic removal from real groundwater (1.6 mg L−1 F−, 19.6 μg L−1 As, 0.4 mg L−1 PO43‒, pH 6.6, and 430 μS cm−1 conductivity) was performed by using Eapp = 1.2 V vs. SHE and Q = 0.2 L min−1. After three rounds of CDI, the solution reached ending values of 1.2 mg L−1 F−, 7.4 μg L−1 As, 0.2 mg L−1 PO43‒, with energy consumption (EC) of 0.023 kWh m−3. The treated water fulfills the WHO guidelines (< 1.5 mg L−1 F−, and < 10 μg L−1 As). CDI using GF electrodes is an affordable technology to supply safe drinking water.

This communication is about the removal of arsenic (As), fluoride (F−) and hydrated silica (HS) from real underground water (initial concentration: 28 µg L−1 arsenic, 1.55 mg L−1 F−, 155 mg L−1 HS, 35 mg L−1 sulfate, pH 7.4, and 470 µS cm−1 conductivity) by electrocoagulation (EC). The novel EC reactor consists of eight horizontally stacked cells using Fe and Al plates as sacrificial anodes with an upward flow. The abatement of As and the elimination at the same time of F− and HS was performed by analyzing the influence of the mean linear flow velocity (1.2 < u < 4.8 cm s−1) at different current densities (3 < j < 7 mA cm−2) imposed on the EC system. The best condition was carried out at j = 7 mA cm−2 and u = 1.2 cm s−1, achieving complete arsenic elimination, and a remaining F− concentration of 0.45 mg L−1, fulfilling the World Health Organization (WHO) guideline for arsenic (< 10 μg L−1) and fluoride (< 1.5 mg L−1). The remaining HS reached a value of 10 mg L−1. Spectroscopic techniques applied to the Fe-Al flocs evidenced the generation of iron oxides and hydroxides, as well as the formation of aluminosilicates.

Recently, valorization of lignin biomass derived pyrolysis bio-oil for production of a sustainable fuel has turned to be a vital concern. Hydrodeoxygenation (HDO) has turned to be the most suitable developing process for production of a fuel with high heating value. In the current study, the HDO of 4-methylanisole as a model compound of pyrolysis oil, is investigated over Mo/nano γ-Al2O3 catalyst at a wide range of operating conditions. 4-methylanisole mainly follows hydrogenolysis and direct HDO to produce 4-methylphenol and toluene, respectively. Increasing operating temperature (623–773 K) and inverse weight hourly space velocity (WHSV−1: 0.008–0.333 g cat× h/g 4-methylanisole) lead in promoting toluene production. However, 4-methylphenol production and alkylation reactions are favored at high pressures (12–20 bar). 4-methylanisole conversion through HDO is 98% at 12 bar, 623 K and WHSV−1 of 0.333 g cat× h/g 4-methylanisole. The selectivity of toluene and 4-methylphenol production at the mentioned conditions is 0.44 and 0.17, respectively. It is inferred that hydrogenation, hydrogenolysis of Caliphatic—O, dehydration, deoxygenation of Caromatic—O, alkylation and tautomerization are the main reaction pathways during upgrading process which influence the selectivity of the products.

Low recovery of the fully or highly liberated fine particles to the concentrate, and consequently, valuable loss to the tailing is a challenge of flotation industry, majorly due to the low probability of bubble-particle collision. Bubble size significantly affects the efficiency of collision. In this study, the effect of nano-micro bubbles and feed particle size (d80s in the range of 80 to 12 µm), on the lead and zinc minerals recovery, separation efficiency, and valuables loss to the tailings were investigated. The presence of NMBW simultaneously improved concentrate grade and metal recovery to the individual concentrates. Over 14.5% improvements in either lead and zinc recoveries, 0.95% and 2.22% enhancement in lead and zinc concentrate grades, and 15.6% and 8.9% increases in lead and zinc separation efficiencies were, respectively, gained. The application of NMBW, however, reduced metal loss to the tailings, more evident for the finest feed (order based on d100: -38>-75>-106 µm). By increasing NMBW content to 100% of the pulp water, the metal loss to the tailing for the dry-ground feed with the d80 of 12 µm, was decreased from 80.4% to 65.9% in the lead flotation, and from 54.9% to 43.2% in the zinc flotation.

There is an increasing interest to use CO2 selective membrane to purify methane from natural or biogas because of the ease of access to this membrane configuration. The use of this membrane, however imposed an additional strain on the system because there was H2S contamination in the enriched product stream and requirement of high CO2/CH4 selectivity. To address this issue, an empirically validated complete mixing model integrated with a multi-factorial central composite design was applied to optimize the membrane process in methane enrichment from biogas containing H2S. The optimization resulted in 100% methane purity and 91.51% recovery using a methane selective membrane at 837.43 CH4/CO2 selectivity, 35.00 bar feed pressure, and 0.643 stage cut, without H2S contamination in the product stream. For comparison with CO2 selective membrane, methane purity of 91.74% and 90.26% recovery were achieved using CO2/CH4 selectivity of 1086.87, 31.82 bar feed pressure, and 0.310 stage cut. Methane selective membrane was performed better than CO2 selective membrane on four fronts, namely lower selectivity, higher CH4 recovery, higher CO2 recovery, higher CH4 purity, and the product stream was H2S free. CO2 selective membrane was superior in other aspects, namely higher CO2 purity, lower stage cut and feed pressure.

Water hyacinth is a proliferative aquatic weed which destructs biodiversity. Though water hyacinth is a notorious weed, it is a useful resource if used judiciously. One of the important compounds in water hyacinth is shikimic acid, a precursor to produce antiviral drug oseltamivir phosphate. A greener extraction of shikimic acid, phenolic compounds and estimation of antioxidant activity of extract were performed using microwave-assisted extraction from the different morphological parts of water hyacinth. Impact of parameters such as extraction time, solvent volume, temperature and power has been studied. Among various parts of the plant, stem contained higher shikimic acid (2.70 %, w/w), leaves had higher total phenolic content (12.15 mg GAE/ g biomass) and extract from stem exhibited the maximum antioxidant activity (75.13 %). Further, the optimization of process parameters using central composite design was employed to maximize the yield of shikimic acid (2.61 %, w/w) which was achieved at 1.08 min, 45 °C, and 30 mL. Although Ultrasound-assisted extraction has provided a higher yield (3.2 %, w/w) of shikimic acid compared to microwave-assisted extraction, the extraction time was reduced by 96 % in case of microwave-assisted extraction, thereby reducing energy consumption, utility requirement and carbon emission.

Phosphogypsum (PG) has stood out as an alternative source of rare earth elements (REE) since it has a promising content and is generated in high amounts. Although the literature has already demonstrated the possibility of using leaching to recover REE from PG, the leaching efficiencies are generally relatively low, or drastic conditions are required. Ultrasound-assisted leaching is a promising alternative to overcome these problems and has not been sufficiently explored. This work investigated the REE leaching from PG using an ultrasound probe system and optimized it through a central composite rotational design. The temperature of the system was maintained at around 40 °C. A leaching efficiency of 84% was obtained at the optimized conditions of 0.6 mol L–1 H2SO4, ultrasonic amplitude of 77%, and pulse of 93.6%. The same leaching efficiency was not observed using conventional leaching with mechanical stirring (silent condition), around 68%. In addition, the kinetic study showed a considerable reduction in the leaching time with the assistance of ultrasound, reaching the equilibrium in about 20 min. The improvement in the REE leaching was attributed to the acoustic cavitation effects, which mainly led to a considerable reduction in the PG particle size, as demonstrated by SEM images. Overall, ultrasound proved to be a suitable alternative, allowing high REE recovery from PG with a diluted acid solution, low leaching time, and relatively low temperature, thus representing savings in reagents and energy.

The sulfonated magnetic porous biochar-based solid catalysts have a significant potential to replace homogeneous acid catalysts in order to decrease corrosion issues and the environmental risks brought on by homogeneous acid catalysts. For this purpose, produced biochar from the rice husk pyrolysis at 700 °C was employed for the synthesis of a biochar-based magnetic acid catalyst. The base structure of the catalyst was modified and magnetized using different ratios of ZnCl2 and FeCl3. The magnetic porous biochar was sulfonated with two sulfonation agents including H2SO4 and ClSO3H. Characteristic analyzes of BET (Brunauer, Emmett, and Teller), Scanning Electron Microscopy, vibrating-sample magnetometer, Fourier Transform Infrared Spectroscopy, Energy-Dispersive X-ray Spectroscopy, and elemental analysis were used to investigate the physicochemical properties of the synthesized catalysts. The magnetic biochar-sulfonated with ClSO3H was evaluated as the selected catalyst in the biodiesel generation process from oleic acid (OA) as a representative of bio-oils. The central composite design (CCD) based on the response surface methodology (RSM) was used to optimize the process and examine the effectiveness of various parameters, including catalyst concentration based on the OA weight (3–15 wt.%), experiment duration (1–5 h), MeOH: Oil molar ratio (5–25), and reaction temperature (40–100 °C), on the efficiency of biodiesel generation. The optimum yield was achieved at 98.11% under the optimal condition, which included an experiment duration of 4.8 h, catalyst concentration of 9.9 wt.%, MeOH: Oil ratio of 16:1, and reaction temperature of 74.8 °C.

The achievement of efficient micromixing inside microfluidic devices is crucial to perform biological assays. Slow mass transfer is a limiting factor in these devices. In this paper, a high-throughput acousto-inertial micromixer is proposed to assess the impact of parameters affecting the passive section of the micromixer, including Reynolds number (Re) and curvature radius (rc), as well as the parameters affecting the active section, such as the applied frequency (f) and displacement amplitude (d0). It is found that the background flow in the active section of the micromixer becomes stronger as Re is increased, which suppresses the acoustic streamings, limiting their effect near the sharp edges. The results demonstrate that the second-order velocity is enhanced with f, improving the acoustic field strength and mixing performance. Furthermore, reducing rc and increasing f and d0 improve the mixing performance of the micromixer. The proposed micromixer can be utilized for fast chemical and biological reactions and assays.

Coaxial mixers with double central impellers and an anchor have demonstrated promising results in the intensification of gas dispersion in complex fluids. While previous studies have evaluated power consumption for gas dispersion in pseudoplastic fluids, no investigation has been conducted on aerated dual coaxial mixers containing pseudoplastic fluids with yield stress. This study aimed to evaluate the power consumption of the aerated double coaxial mixer under various operating conditions, including anchor and central impeller speed, rotational mode, pumping direction, and aeration rate. Experimental power consumption measurements were performed for both gassed and ungassed systems. Our findings showed that the anchor power contributed substantially less to overall power consumption than the central impellers. The counter-rotational mode used more power than the co-rotational mode due to the opposing flow created by the rotation of the central impellers and anchor impeller. The co-rotational mode had a higher relative power demand (RPD) than the counter-rotational mode, with the upward pumping mode of the central impellers yielding the highest RPD values. The modified Jamshidzadeh's correlation successfully predicted the impact of the anchor speed, central impeller speed, and aeration rate on power consumption for the investigated double coaxial mixers containing the xanthan gum solution.

Removal of pharmaceuticals from wastewaters is of particular importance nowadays. If biodegradable molecules can be nearly totally eliminated by biological treatments such as membrane bioreactor (MBR), many pharmaceutics are recalcitrant. To improve the removal of these micropollutants, an advanced oxidation process (AOP), based on TiO2 photocatalyst, has been implemented on a recirculation loop on a 15-L MBR operated with a sludge retention time (SRT) of 30d and a hydraulic retention time (HRT) of 48 h.This innovative process did not negatively impact the bacterial community of the MBR which maintained same a Total Suspended Solids (TSS) concentration of 5 g.L−1 and a high carbon removal yield (> 92%). For different flux densities tested (4, 17 and 40 W.m−²), similar degradation efficiency was observed for two pharmaceuticals: ibuprofen (IBU) and carbamazepine (CBZ). Thus, a flux density of 4 W.m−² was selected for the coupling. This configuration intensified the degradation of CBZ by a factor 10 (up to 28% removal) in comparison with the MBR alone and the removal of IBU was maintained close to 99%.

A facile continuous flow micromixer with a novel internal structure is developed to improve the mixing effect through computational fluid dynamics (CFD) simulation. Meanwhile, an authentic transparent micromixer was prepared following the mathematical model of the micromixer, and reliability of the simulation was verified by result comparison of fluid mixing performance. Moreover, several internal structures were designed and their mixing effect was calculated. Using velocity inlet and pressure outlet, ignoring the change of energy during the mixing process, it is shown that the structure of the micro-mixer has a positive effect on the mixing effect at Re < 1200. In the cubic structure, the fluid is dominated by molecular diffusion, the increase of concavity and convexity structure makes the fluid produce spiral flow, and the fluid separates and recombines many times in the mixed structure, the convective mixing process is superior to the molecular diffusion process and the mixing effect is improved. Furthermore, it was astonished that the addition of cubic structure inside convex-concave structures (a recombination structure), improve the mixing index as well as reducing the flow resistance by increasing fluid-to-fluid interface area.

Aiming at the problem of low extraction efficiency of germanium in zinc oxide dust, a process of strengthening germanium leaching by ultrasonic wave in sulfuric acid leaching process was proposed. The effects of acidity, temperature, time, liquid-solid ratio, ultrasonic power and amount of iron powder on germanium leaching were investigated by response surface method, and the ultrasonic enhanced leaching process was optimized. Based on process mineralogy analysis, and germanium phase distribution analysis, which is obtained by self-establishment step-by-step extract method, the studied zinc oxide dust contains 94.1% germanium oxide and germanate, 5.13% germanium sulfide and 0.77% insoluble germanium. The results showed sulfuric acid concentration 131 g/L(1.34 mol/L), temperature 78 °C, time 22 min, liquid-solid ratio 7.6:1, ultrasonic power 270 W, iron powder content 0.71%. The leaching efficiency of germanium is 95.19%, which is 5.79% higher than that of conventional leaching method. It was found that ultrasound can destroy the particle size, reduce the cluster structure of leached products by 13.5%, inhibit the agglomeration of particles, and promote the leaching of germanate and germanium sulphide. This study is of great significance for the production of germanium.

The present study aims to enhance the iron ore fines through reduction roasting using a muffle and hybrid microwave furnace. The Taguchi statistical design was used to optimise the process variables such as temperature, time, and reductant concentration. The reduction roasting was followed by multi-pass low-mid intensity magnetic separation to treat the low-grade iron ore fines (Fe 44.53%, 40.13% silica). The results showed that the conventional reduction roasting at optimum conditions (800 °C, 60 min, 7% coal) produced a concentrate with 52.6% Fe grade and 77.3% recovery. The microwave roasting produced a concentrate with 53.06% Fe grade and 75.7% recovery at 750 °C, 2 min, and 7% coal as the reductant. The effect of both heating methods on compressive strength (CCS) and surface morphology was also studied. The results indicated that microwave heating resulted in a finer and more porous structure that improved the reducibility and ease of grinding. The techno-economic comparison showed that microwave reduction reduced the processing time by 85% and energy consumption by 73%. The study concludes that microwave heating followed by multi-pass magnetic separation can significantly improve the economic viability of exploiting lean iron ore fines.

Abstract not available

In this study, tropical acerola and jambolan pomaces were submitted to four water-based polyphenol extraction methods: conventional solid-liquid extraction CSLE; heated conventional solid-liquid extraction HCSLE; static ultrasound-assisted extraction SUAE; and ultrasound-assisted extraction and mechanical stirring UAES. Our objective was to evaluate and compare the extraction protocols regarding their performance, extraction kinetics, mathematical modelling, and environmental viability using the life cycle assessment (LCA) tool. The highest total polyphenol content was obtained by UAES after 90 min (1,606.8 mg GAE/100g for acerola and 1,580.7 mg GAE/100g for jambolan). These results are significantly higher (p ≤ 0.05) compared to CSLE (1,296.4 mg GAE/100g for acerola, 644.1 mg GAE/100g for jambolan). The Power Law model showed the best experimental fit compared to Peleg's and second-order models. Regarding the environmental viability, the LCA tool revealed that UAES had the lowest environmental impact among all extraction protocols, mainly due to its lower energy consumption. Overall, the combination of mechanical stirring and ultrasound improved water-based polyphenol extraction rates with reduced energy consumption. This study shows UAES as an environmentally friendly strategy to achieve efficient extraction of naturally occurring polyphenols from tropical fruit pomaces.

Temperature swing adsorption (TSA) is one of the promising separation techniques for large-scale CO2 capture, and many adsorbents are being developed today. However, it is difficult to identify the optimal operating configurations of multi-bed TSA process to fully utilize the potential of a given adsorbent. This is because optimal operating conditions and cycle configurations are highly dependent on the adsorbent properties. In this work, we propose a comprehensive approach that maps adsorption isotherms to the optimal multi-bed TSA operation identified from various alternatives. A case study for separation of CO2 and N2 is presented where isotherm properties of the adsorbent are parameterized to analyze the influence on the optimal TSA operating cycle configurations and process performance. Our analysis shows that the optimal throughput increases by 68% when the CO2 selectivity is doubled, and 96% when the CO2 selectivity and capacity are both doubled. Furthermore, the frequency of the reflux operations and the cycle time in the optimal operating cycle are found to be dependent on the CO2 capacity.

This work explored the feasibility of implement of polymer inclusion membranes (PIMs) in the desalination industry. The methyltrioctylammonium oleate (MTOAO) was imbedded in a blend of polyvinylidene fluoride (PVDF) and polysulfone (PSU) prepared via Non-Solvent Induced Phase Separation (NIPS). The investigation encompassed the analysis of the chemical compositions and morphologies of the novel PIMs, with the objective of identifying the optimal MTOAO concentration within the PVDF/PSU matrix. The membrane characterizations revealed that addition of 33% of MTOAO in PVDF/PSU significantly increased the porosity (from 73.4% to 89.8%) and conferred a highly-hydrophobic character (WCA=123°). In direct contact membrane distillation experiments, PVDF/PSU doped with 33% of MTOAO resulted in a flux of 21.9 kg·m−2·h−1 and a 99.98% NaCl rejection where the salinity and temperature were 30 g/L and 70 °C, respectively. Remarkably, the inclusion of the MTOAO led 625% in transmembrane flux of. Moreover, PVDF/PSU load with 33% of MTOAO demonstrated a long-term stable performance over 10 weeks, whereas the PVDF/PSU membrane exhibited a poor stability in terms of salt rejection because of pore wetting caused by the poor hydrophobic character. Lastly, the performance of the process was positively assessed by desalting seawater from Atlantic Ocean.

A rotary flow reversal reactor with a fixed packed bed and rotary intake is established to study the combustion stability with ultra-lean toluene/air mixture. The experimental results show that the stable temperature distribution in the packed bed is vertically graded and circumferentially uniform with bottom rotary intake. The three-dimensional numerical simulation using sliding grid technology on the combustion process is presented. The effects of intake toluene concentration, axial velocity and circumferential rotation speed on the combustion stability are analyzed numerically. High intake toluene concentration or feed axial velocity will decrease the propagation velocity of the flame front and raise the peak temperature and the maximum reaction rate to achieve a quasi-steady state finally. However, the intake rotation speed has little effect on the combustion process. The work will enrich the investigation of flame stability during the filtration combustion of ultra low-calorific value gas.

Lycopene extraction from tomato processing waste / peels is a challenging process. The present work reports a one-step integrated ultrasound-surfactant assisted extraction (IUSAE) of lycopene from tomato peels using non-ionic surfactant L62 as a superior extraction method among other methods (surfactant assisted extraction, i.e., SAE, ultrasound assisted extraction (UAE), and two-step ultrasound treatment followed by surfactant assisted extraction (USAE)). IUSAE resulted in 77% lycopene extraction, which was 19–33% more than SAE or UAE, and the integrated method required 30–90% less extraction time than SAE or UAE. As compared to two-step USAE, for the same extraction efficiency (75–77%), one step IUSAE required 30% less surfactant, with 85% reduction in extraction time, and 40% reduction in power. A life cycle assessment of the process showed that single step IUSAE has less environmental impact than two-step USAE. IUSAE also preserved the antioxidant activity of lycopene and the structure of the surfactant. Thus, one-step IUSAE is a more promising method than SAE, UAE, and two-step USAE. The superior performance of IUSAE is mainly due to the intensification of ultrasound and surfactant assisted extraction processes.