Search Results (370)

This study investigated the performance of a hybrid desiccant dehumidification system integrated with a post-cooling mechanism, focusing on its application to energy-efficient indoor climate control. A liquid desiccant system using magnesium chloride (MgCl₂) was tested in its pure form and in combination with silica gel at 10% and 20% concentrations to enhance its moisture removal capabilities. The key parameters, including the air velocity (3–6 m/s), desiccant flow rate (1–3 LPM), and desiccant composition, were varied to analyze their effects on the dehumidification efficiency, moisture removal rate (MRR), temperature reduction after post-cooling, and coefficient of performance (COP). The results show that post-cooling using a crossflow heat exchanger effectively lowered the exit air temperature, ensuring thermal comfort. Addition of silica gel significantly improved system performance. The MgCl₂ + 20% silica gel mixture achieved the highest dehumidification efficiency of 0.86, the greatest temperature drop of 1.95 °C, and the maximum COP of 2.36 at optimal flow conditions. While the dehumidification efficiency declined with increasing air velocity due to reduced contact time, the COP increased owing to the higher thermal processing of the air stream. This study highlights the potential of optimized hybrid desiccant systems as sustainable solutions for building air conditioning, aligning with the key Sustainable Development Goals (SDGs) related to clean energy, climate action, and sustainable infrastructure. Full article

Understanding surface charge behavior is essential for improving ion separation during lithium brine treatment. This paper investigates the performance of a three-compartment electrodialysis system designed for the selective removal of divalent cations (Mg²⁺ and Ca²⁺). The relationship between zeta potential and the recovery of Li⁺, Na⁺, and K⁺ is analyzed. Zeta potential measurements at various pH values showed that Mg(OH)₂ particles maintained a positive charge. The system facilitated the precipitation of Mg(OH)₂ and Ca(OH)₂ via electrochemically generated OH⁻ ions. The specific electrical energy consumption was evaluated for each operating condition. The results showed that the zeta potential of the precipitates was affected by both the current density and temperature. This influenced lithium losses due to brine entrapment within the precipitated solids. At 600 A/m² and 50 °C, more than 99% of Mg²⁺ and Ca²⁺ were removed, and more than 90% of lithium was recovered, with a specific electric energy consumption of 2.58 kWh per kilogram of Li recovered. The system also generates HCl as a valuable by-product, which improves the sustainability of the process. This study provides a new framework for improving the energy efficiency of lithium purification from brines and lithium recovery. Full article

Boron is frequently present in saline water (e.g., seawater, geothermal water, and hydrocarbon production water) due to the natural release of boric acid from minerals. While essential to life, excess boron is toxic, particularly to citrus plants, necessitating its regulation for safe water use. Current boron removal methods, such as reverse osmosis, chelating resin adsorption, and magnesium-based precipitation softening, increase water treatment complexity and cost. Ettringite, (Ca₆Al₂(SO₄)₃(OH)₁₂·26H₂O), is a clay and an effective anion adsorbent. It is also a key hydration product of Portland cement. This study explores boron removal via precipitation softening using sulfoaluminate clinker as an ettringite precursor. Raw water, a first-stage reverse-osmosis permeate from an Italian oil-and-gas site, contained approximately 15.0 mg/L of boron. Optimal removal required sulfoaluminate clinker in excess with respect to the stoichiometric dose and 150 min of contact time. The preliminary results demonstrate the feasibility of this approach, offering a viable alternative to existing methods. Full article

Carboxylate (TCNF) and sulfonated (SCNC) cellulose nanofibers were synthesized and used as adsorbents for metallic cations in aqueous solutions: Na⁺ and Hg²⁺ (SCNC); Mg²⁺ and Hg²⁺ (TCNF). ICP-OES analysis of the liquid phase revealed metal removal efficiencies at room temperature of 89.3% (Hg²⁺) and 100% (Mg²⁺) for TCNF, 35.2% (Hg²⁺) and 63.3% (Na⁺) for SCNC after 3 h of contact. Interestingly, the nanofibers exhibited a distinct thermal degradation profile (characterized by two main events) compared to that of cellulose, suggesting that their nanostructured morphology and surface functionalization may enhance thermal instability. Additionally, the presence of metals at its surface notably altered the thermal degradation kinetics, as observed for mercury and magnesium in TCNF. Finally, the results for SCNC strongly suggest that the mechanism for thermal degradation can also change, as observed for mercury and sodium, expressed through the appearance of a new DTG peak located around 300 °C. Full article

Biodegradable magnesium alloys have emerged as promising alternatives to permanent metallic implants due to their unique combination of mechanical compatibility with bone and complete resorption, addressing the persistent issues of stress shielding and secondary removal surgeries. This review critically examines the historical development of magnesium-based biomaterials, highlighting advances in alloy design, manufacturing processes, and surface engineering that now enable tailored degradation and improved clinical performance. Drawing on recent clinical and preclinical studies, we summarize improvements in corrosion resistance, mechanical properties, and biocompatibility that have supported the clinical translation of magnesium alloys across a variety of orthopedic and emerging medical applications. However, challenges remain, including unpredictable in vivo degradation kinetics, limited long-term safety data, lack of standardized testing protocols, and ongoing regulatory uncertainties. We conclude that while magnesium-based biomaterials have advanced from experimental concepts to clinically validated solutions, further progress in personalized degradation control, real-time monitoring, and harmonized regulatory frameworks is needed to fully realize their transformative clinical potential. Full article

High ash content in algal biomass limits its suitability for biofuel production by reducing combustion efficiency and increasing fouling. This study presents a green deashing strategy using nitrilotriacetic acid (NTA) and deionized (DI) water to purify Scenedesmus algae, which was selected for its high ash removal potential. The optimized sequential treatment (DI, NTA chelation, and DI+NTA treatment at 90–130 °C) achieved up to 83.07% ash removal, reducing ash content from 15.2% to 3.8%. Elevated temperatures enhanced the removal of calcium, magnesium, and potassium, while heavy metals like lead and copper were reduced below detection limits. CHN analysis confirmed minimal loss of organic content, preserving biochemical integrity. Unlike traditional acid leaching, this method is eco-friendly after three cycles. The approach offers a scalable, sustainable solution to improve algal biomass quality for thermochemical conversion and supports circular bioeconomy goals. Full article

The treatment of contaminants from road infrastructure poses significant challenges due to their variable composition and the high concentrations of chloride ions, heavy metals, and oil-derived substances. Traditional methods for protecting groundwater environments are often insufficient. A promising alternative is permeable reactive barrier (PRB) technology, which utilizes recycled materials and construction waste as reactive components within the treatment zone of the ground. This paper delves into the potential of employing a composite (MIX) consisting of modified construction aggregate (as recycled material) and activated carbon (example of reactive material) to address environmental contamination from a mixture of heavy metals and chloride. The research involved chemical modifications of the road aggregate, activated carbon, and their composite, followed by laboratory tests in glass reactors and non-flow batch tests to evaluate the kinetics and chemical equilibrium of the reactions. The adsorption process was stable and conformed to the pseudo-second-order kinetics and Langmuir, Toth, and Redlich–Peterson isotherm models. Studies using MIX from a heavy metal model solution showed that monolayer adsorption was a key mechanism for removing heavy metals, with strong fits to the Langmuir (R² > 0.80) and Freundlich models, and optimal efficiencies for Cd and Ni (R² > 0.90). The best fit, at Cd, Cu, Ni = 0.96, however, was with the Redlich–Peterson isotherm, indicating a mix of physical and chemical adsorption on heterogeneous surfaces. The Toth model was significant for all analytes, fitting Cl and Cd well and Pb and Zn moderately. The modifications made to the composite significantly enhanced its effectiveness in removing the contaminant mixture. The test results demonstrated an average reduction of chloride by 85%, along with substantial removals of heavy metals: lead (Pb) by 90%, cadmium (Cd) by 86%, nickel (Ni) by 85%, copper (Cu) by 81%, and zinc (Zn) by 79%. Further research should focus on the removal of other contaminants and the optimization of magnesium oxide (MgO) dosage. Full article

Osmotic dehydration is a process involving a two-way mass transfer, during which water and substances dissolved in it are removed from the product and, at the same time, substances dissolved in a hypertonic solution penetrate into the tissues. This process has a significant effect on, among other things, the nutritional and sensory parameters, as well as the texture and shelf life of the dehydrated product. This study analyzed the effect of osmotic dehydration of beet on magnesium content following the addition of various chemical forms of magnesium (magnesium oxide, magnesium citrate, magnesium chloride) to a hypertonic solution. Magnesium was added in concentrations of 2.5 or 5.0% relative to the mass of the solution. The following compounds were used to prepare hypertonic solutions (25 and 50%): inulin, xylitol, erythritol, and sucrose. The control sample was water. A significant increase in magnesium content in the dehydrated material was confirmed. This effect was determined by many factors, among which the most important were the chemical form of magnesium, the type of osmotically active substance, magnesium concentration, and process time. The highest magnesium content was found in samples dehydrated in a 50% inulin solution with a 5.0% addition of magnesium chloride under the following conditions: 120 min/30 °C. It was also demonstrated that osmotically dehydrated samples exhibited approximately 3–5 times lower antioxidant activity in DPPH, ABTS, and ORAC tests. Full article

Eutrophication driven by nitrogen and phosphorus discharge remains a critical global environmental challenge. This study developed a sustainable strategy for synergistic nutrient removal and recovery by fabricating MgO-coated biochar (Mg-MBC600) through co-pyrolysis of municipal sludge and sunflower stalk (300–700 °C). Systematic investigations revealed temperature-dependent adsorption performance, with optimal nutrient removal achieved at 600 °C pyrolysis. The Mg-MBC600 composite exhibited enhanced physicochemical properties, including a specific surface area of 156.08 m²/g and pore volume of 0.1829 cm³/g, attributable to magnesium-induced structural modifications. Advanced characterization confirmed the homogeneous dispersion of MgO nanoparticles (~50 nm) across carbon matrices, forming active sites for chemisorption via electron-sharing interactions. The maximum adsorption capacities of Mg-MBC600 for nitrogen and phosphorus reached 84.92 mg/L and 182.27 mg/L, respectively. Adsorption kinetics adhered to the pseudo-second-order model, indicating rate-limiting chemical bonding mechanisms. Equilibrium studies demonstrated hybrid monolayer–multilayer adsorption. Solution pH exerted dual-phase control: acidic conditions (pH 3–5) favored phosphate removal through Mg₃(PO₄)₂ precipitation, while neutral–alkaline conditions (pH 7–8) promoted NH₄⁺ adsorption via MgNH₄PO₄ crystallization. XPS analysis verified that MgO-mediated chemical precipitation and surface complexation dominated nutrient immobilization. This approach establishes a circular economy framework by converting waste biomass into multifunctional adsorbents, simultaneously addressing sludge management challenges and enabling eco-friendly wastewater remediation. Full article

This study explores the utilization of waste grape pomace-derived hydrochar as an efficient adsorbent for lead (Pb²⁺) removal from aqueous solutions. Hydrochar was produced via hydrothermal carbonization (HTC) at 220 °C, followed by doping with magnesium and iron salts, and subsequent pyrolysis at 300 °C to obtain Fe/Mg-pyro-hydrochar (FeMg-PHC). The material’s structural and morphological changes after Pb²⁺ adsorption were examined using FTIR. FTIR revealed chemisorption and ion exchange as key mechanisms, shown by decreased hydroxyl, carbonyl, and metal–oxygen peaks after Pb²⁺ adsorption. Adsorption tests under varying pH, contact time, and initial Pb²⁺ concentrations revealed optimal removal at pH 5. Kinetic modeling indicated that the process follows a pseudo-second-order model, suggesting chemisorption as the dominant mechanism. Isotherm analysis showed that the Sips model best describes the equilibrium, with a maximum theoretical adsorption capacity of 157.24 mg/g. Overall, the simple two-step synthesis—HTC followed by pyrolysis—combined with metal doping yields a highly effective and sustainable adsorbent for Pb²⁺ ion removal from wastewater. Full article

Background: Vertical alveolar ridge augmentation (ARA) > 3 mm is associated with increased surgical complexity and higher complication rates. Despite the availability of various ARA techniques and graft materials, robust comparative clinical data remain limited. This retrospective multicenter study aimed to evaluate and compare surgical and patient-relevant outcomes across seven established vertical ARA techniques. Methods: This retrospective multicenter study included 70 cases of vertical ARA > 3 mm using seven different techniques (10 cases each): an iliac crest graft (ICG), intraoral autogenous bone block (IBB), allogeneic bone block (ABB), CAD/CAM ABB, CAD/CAM titanium mesh (CAD/CAM TM), magnesium scaffold (MS), and the allogeneic shell technique (ST). The outcome parameters included harvesting and insertion time, bone gain (vertical and horizontal, after a minimum of one year), graft resorption (after one year), donor site morbidity, dehiscence rate, need for material removal, and biological and general financial costs. Results: Harvesting time significantly varied among the different ARA techniques (p = 0.0025), with the longest mean durations in ICGs (51.6 ± 5.8 min) and IBBs (36.5 ± 10.8 min), and no harvesting was required for the other techniques. Insertion times also significantly differed between the different ARA techniques (p < 0.0001) and were longest in IBBs (50.1 ± 7.5 min) and the ST (47.3 ± 13.9 min). ICGs achieved the highest vertical and horizontal bone gain (5.6 ± 0.4 mm), while ABBs and CAD/CAM ABBs showed the lowest (~3.0 mm). Resorption rates significantly differed between the different ARA techniques (p < 0.0001) and were highest for ICGs (25.9 ± 3.9%) and lowest for MSs (5.1 ± 1.5%). Donor site morbidity was 100% in ICGs and 50% in IBBs, with no morbidity in the other groups. Dehiscence rates were 10% in most techniques but 30% in CAD/CAM TMs. Removals were required in all techniques except MSs. Biological and financial costs were high for ICGs and CAD/CAM ABBs and low for MSs. Conclusions: Vertical ARA techniques significantly differ regarding harvesting and insertion time, bone gain, graft resorption, donor site morbidity, dehiscence rates, removals, and costs. While ICGs achieved the highest bone volume, less invasive techniques, such as CAD/CAM-based or resorbable scaffolds, reduced biological costs and complication risks. Technique selection should be individualized based on defects, patients, and reconstructive goals. Full article

The removal of heavy metals from industrial wastewater remains a major environmental challenge, demanding efficient, sustainable solutions. This study explores the combined use of Chlorella vulgaris and amine-functionalized magnesium ferrite (MgFe₂O₄-NH₂) nanoparticles to remove cobalt ions from battery effluents. The research aims to explore the capacity of C. vulgaris to adsorb heavy metals, followed by their separation using magnetic nanoparticles. Cobalt adsorption by C. vulgaris was facilitated through the interaction of metal ions on the cell wall, achieving a removal efficiency of 96.44% within 30 min, which increased to 98.78% over 10 h. Amine-functionalized MgFe₂O₄ nanoparticles, synthesized and characterized using HRTEM, FTIR, and VSM, displayed high surface reactivity due to the presence of -NH₂ and -OH groups. At neutral pH, zeta potential measurements revealed a slightly negative charge (−5.6 ± 4.3 mV), while protonation at lower pH levels enhanced electrostatic interactions with the negatively charged algal biomass. Magnetic separation of the cobalt-adsorbed biomass achieved efficiencies ranging from 94.9% to 99.2% within 60 s, significantly outperforming conventional sedimentation methods. SEM and FTIR analyses confirmed the binding of nanoparticles to algal cell walls. The even distribution of MgFe₂O₄ nanoparticles on algal surfaces was further validated by TEM imaging, and the strong magnetic properties of the nanoparticles enabled rapid and efficient separation under an external magnetic field. Full article

Extreme precipitation events are one of the common hazards in eastern Texas, generating a large amount of storm water. Water running off urban areas may carry non-point source (NPS) pollution to natural resources such as rivers and lakes. Urbanization exacerbates this issue by increasing impervious surfaces that prevent natural infiltration. This study evaluated the efficacy of rain gardens, a nature-based best management practice (BMP), in mitigating NPS pollution from urban stormwater runoff. Stormwater samples were collected at inflow and outflow points of three rain gardens and analyzed for various water quality parameters, including pH, electrical conductivity, fluoride, chloride, nitrate, nitrite, phosphate, sulfate, salts, carbonates, bicarbonates, sodium, potassium, aluminum, boron, calcium, mercury, arsenic, copper iron lead magnesium, manganese and zinc. Removal efficiencies for nitrate, phosphate, and zinc exceeded 70%, while heavy metals such as lead achieved reductions up to 80%. However, certain parameters, such as calcium, magnesium and conductivity, showed increased outflow concentrations, attributed to substrate leaching. These increases resulted in a higher outflow pH. Overall, the pollutants were removed with an efficiency exceeding 50%. These findings demonstrate that rain gardens are an effective and sustainable solution for managing urban stormwater runoff and mitigating NPS pollution in eastern Texas, particularly in regions vulnerable to extreme precipitation events. Full article

Secondary Al-Si alloys typically encompass several impurities that substantially influence the materials’ microstructure and mechanical performance. This study employed a composite addition of chlorinated salt fluxing and an aluminum–boron master alloy to reduce the levels of the impurity elements magnesium (Mg), titanium (Ti), and vanadium (V) in secondary Al-Si alloys. The investigation of the performance mechanism revealed that the distribution of alloys’ grain orientation and the ratio of small-angle grain boundaries were modified via synergistic purification, leading to the refined microstructure and mechanical performance of secondary Al-Si alloys. The removal rates of impurity elements under these optimal refining conditions were 89.9% for Mg, 68.9% for Ti, and 61.5% for V. The refined alloy exhibited a 45.5% decrease in grain size and a 28.7% improvement in tensile strength compared to the raw material. These findings demonstrate that fluxing can improve the extraction of Ti and V from secondary Al-Si alloy melts of aluminum–boron master alloys, providing a new cost-effective strategy for the removal of impurities and the optimization of the properties of secondary Al-Si alloys. Full article

Background: Periapical cysts are the most common odontogenic cysts, often resulting in large bone defects. Guided tissue regeneration techniques support tissue healing by means of membranes and bone grafts. The present case report evaluates for the first time clinical application of a resorbable magnesium membrane in guided bone regeneration (GBR) following cystectomy. Case report: A 35-year-old male patient presented with a large periapical cystic lesion in the maxillary anterior region. Treatment involved marsupialization followed by cyst enucleation and GBR using a resorbable magnesium membrane and bovine xenograft. The magnesium membrane served as a structural support to bridge the bony discontinuity in the palatal bone. Cone-beam computed tomography (CBCT) was used for diagnosis, treatment planning, and follow-up assessments. At 16 months post-treatment, CBCT imaging revealed significant bone regeneration, with restoration of the palatal contour and cortication of the palatal wall. Clinical examination showed asymptomatic teeth with normal mobility and optimal soft tissue healing. Conclusions: This case demonstrates the potential of resorbable magnesium membranes in managing large periapical defects, offering a promising alternative to traditional GBR materials by combining mechanical strength with complete resorption, therefore eliminating the need for membrane removal surgery. However, future studies on larger patient samples should focus on confirming the long-term outcomes of this approach and investigating patient-specific factors that are important in choosing effective treatment options. Full article