ABSTRACT This study presents a comprehensive multiscale experimental and computational investigation into the synergistic strengthening mechanisms operative in graphene oxide (GO)/carbon nanotube (CNT) hybrid nanocomposites embedded in an epoxy matrix. echanical characterization encompassing tensile testing, dynamic mechanical analysis (DMA), fracture toughness measurements, and impact strength evaluation revealed that the 1:1 GO:CNT hybrid at 2 wt% loading achieved a 75% improvement in tensile strength (102.1 MPa vs. 58.3 MPa for neat epoxy), a 93% increase in fracture toughness (1.31 MPa·m0·5 vs. 0.68 MPa·m0·5), and a 139% enhancement in impact strength compared to the unfilled matrix. These synergistic improvements significantly exceeded the arithmetic sum of improvements attributable to the individual fillers alone, confirming genuine synergism. Molecular dynamics (MD) simulations and finite element analysis (FEA) were employed to elucidate the mechanistic origins of the synergy, revealing that GO–CNT junction networks augment stress transfer efficiency to 91.3%, that covalent crosslinking at GO–CNT interfaces elevates interfacial binding energy from −3.21 eV (GO/epoxy) to −7.12 eV. Thermal characterization demonstrated a 19 °C elevation in glass transition temperature and a 340% increase in thermal conductivity for the optimal hybrid.
RESUMO Este estudo investigou os efeitos da umidade e dos ciclos de molhagem e secagem nas propriedades físicas, mecânicas e na durabilidade de blocos cerâmicos empregados em edificações do tipo “caixão” na Região Metropolitana do Recife. Amostras foram submetidas a diferentes condições de exposição ambiental, incluindo imersão em água potável, imersão em água do subsolo, exposição externa e ciclos controlados de saturação e secagem, a fim de simular situações típicas das fundações dessas construções. Realizaram-se análises química (EDX), mineralógica (DRX) e térmica (TG/DTG), além de ensaios de absorção de água, porosidade aparente, massa específica aparente, resistência à tração na flexão e expansão por umidade. Os resultados indicaram estabilidade da composição química global. Observou-se redução significativa da resistência à tração na flexão nas amostras submetidas à presença de água, especialmente sob ciclos de molhagem e secagem, com perdas de até 46% em relação à amostra de referência. Verificou-se correlação entre maiores valores de expansão por umidade e menores resistências mecânicas, sugerindo degradação associada a mecanismos físicos e microestruturais, potencializados pela heterogeneidade da matéria-prima, sinterização inadequada e agentes químicos presentes na água do subsolo. Portanto, os ciclos de molhagem e secagem afetam mais significativamente a resistência mecânica do que as propriedades físicas globais.
ABSTRACT The increasing demand for sustainable construction has encouraged the development of low-carbon, high- performance concrete using industrial by-products and wastes. This study experimentally investigates the individual and combined effects of supplementary cementitious materials (SCMs), recycled concrete aggregates (RCA), and mineral admixture Icrete on the mechanical, durability, microstructural, and sustainability performance of concrete. Class F fly ash (10–50%), ground granulated blast furnace slag (10–50%), and silica fume (2.5–12.5%) were used as partial cement replacements, while RCA (10–50%) replaced natural coarse aggregates. Icrete was added at 0.5–2 wt.% of the cementitious material. Results identified optimal SCM contents of 20% fly ash, 40% GGBFS, and 7.5% silica fume, with silica fume delivering the best. Compressive strength increased by 17.4% and 13.2% at 28 and 90 days, respectively, compared to conventional concrete. Although RCA reduced strength and increased permeability, these effects were mitigated by combining SCMs with Icrete. The optimal mix (7.5% silica fume, 20% RCA, and 2% Icrete) achieved compressive strengths of 46.0 MPa and 51.5 MPa at 28 and 90 days, along with a 30% reduction in water absorption. This research optimizes three-phase SCM blends with RCA, Icrete, and a six-parameter sustainability assessment, enabling mechanistic and quantitative performance recovery in eco-efficient structural concrete.
ABSTRACT A rutin-loaded liquid crystalline nanoparticle (R-LCNP) formulation was developed using glyceryl monooleate and Poloxamer 407 by high-pressure homogenization to improve the solubility and biological performance of rutin. The optimized R-LCNP-2 dispersion showed a mean particle size of 176.1 ± 4.5 nm, a polydispersity index (PDI) of 0.211 ± 0.013, and a moderately negative zeta potential of –20.4 ± 1.1 mV, consistent with steric-electrostatic stabilization. The encapsulation efficiency and drug loading were 98.1 ± 1.5% and 2.45 ± 0.04%, respectively, while FTIR, XRD, and DSC analyses indicated molecular dispersion of rutin within the lipid matrix. The formulation showed biphasic diffusion-controlled release and suppressed nitric oxide, TNF-α, and IL-6 more effectively than free rutin in an in vitro LPS-stimulated RAW 264.7 model. R-LCNP-2 also reduced the IC50 values in MCF-7, HeLa, and A549 cells by 3.8–4.5 fold relative to free rutin. These findings support LCNP-based encapsulation as a promising strategy to broaden the functional performance of rutin and justify subsequent in vivo pharmacokinetic and efficacy studies.
ABSTRACT The components of the sealant are diverse and complex, and there are differences in the relative molecular weight and solubility parameters of each component, which is a thermo-dynamic unstable system. Under long-term static storage and service conditions, the joint sealant is prone to automatic condensation and segregation, which degrades its road performance. At present, little attention is paid to the storage stability of the joint sealants. The current specifications have no clear requirements for this performance, which limits the service life of the joint sealant to a certain extent. This paper investigates the influence of sealant segregation on its macroscopic properties, microstructure and components was investigated, and reveals the reasons for the segregation behavior of the sealant. At the same time, based on the shortcomings of the existing evaluation methods for storage stability and in combination with the segregation behavior of the sealant, the viscosity difference is proposed as a supplementary evaluation index for storage stability, the viscosity difference at 180 °C with a recommended threshold of 2 Pa·s, together with a softening point difference threshold of 5 °C. The segregation test conditions are optimized to a tube diameter of 50 mm, temperature of 185 °C, and duration of 8 h.
RESUMO Com a finalidade de investigar a eficácia do óleo autocicatrizante de tungue (OT) na prevenção de patologias em Concreto com Alto Desempenho (CAD), este trabalho monitorou a resistência à compressão (fc) e o módulo de elasticidade (E) de um CAD com diferentes razões entre OT e superplastificante (SP), além de sua cinética de hidratação – via relaxometria por ressonância magnética nuclear (RMN). A análise de variância (ANOVA) avaliou o impacto do OT sobre a fc, comparando as variações das médias nos diferentes tratamentos. A amostra controle, contendo 4% de SP e 0 g de OT, alcançou, em média, uma fc de 74,44 MPa e E de 42,81 GPa. A inserção de 2 g de OT na amostra controle (4% SP 2 g OT) promoveu incremento na fc e no E de 2,6 MPa e 0,46 GPa, respectivamente. Já o uso de 3% de SP e 2 g de OT causou aumento de 8,53 MPa na fc (82,97 MPa) e de 1,49 GPa no E (44,30 GPa). A ANOVA demonstrou que o OT é o aditivo regulador mais importante na matriz do concreto, sendo 3,6 vezes mais influente que o SP. Por meio da RMN, foram obtidas curvas do tempo de relaxação longitudinal (T1) em função do tempo de hidratação dos CAD testados. Nessas amostras, as curvas de relaxometria mostraram aumento na razão gel-espaço (poroso) do CAD, assim como redução da água evaporável durante o processo de hidratação. Os dados obtidos forneceram indícios importantes sobre o potencial do OT na substituição parcial do SP, promovendo um CAD mais resistente, ecológico e sustentável, além de diminuir os custos de produção. Esses dados fortalecem as ações integradas da abordagem de “Saúde Única” (do inglês, One Health), que abrange ações coletivas para o enfrentamento e adaptação aos desastres causados pelas mudanças climáticas.
ABSTRACT This study investigates the microstructural evolution and mechanical properties of a dissimilar tungsten inert gas (TIG) welded joint fabricated from wire arc additively manufactured (WAAM) 304 and 316L stainless steels (SS). The TIG welding was performed at 12.8 V, 70 A, with a wire feed rate of 2.5 mm/s and a 15 L/min Ar shielding gas flow. The WAAM deposition used a current of 180 A and a travel speed of 1 mm/s. Electron backscatter diffraction (EBSD) analysis revealed significant microstructural asymmetry across the joint. Due to the higher austenitic stability and lower melting point of 316L SS, a wider heat-affected zone (HAZ) and coarser grains were observed on the 316L SS side. Epitaxial growth at both fusion lines led to columnar grain formation, but competitive solidification resulted in an asymmetric fusion zone. The welding thermal cycle induced a pronounced “thermo-mechanical” effect, The coarse columnar grains formed by epitaxial growth contain a large number of low-angle grain boundaries (LAGB). Quantitatively, the proportion of LAGBs increased from 18% in the 304 SS base metal to 34% in the adjacent HAZ, while on the 316L SS side, it increased from 15% to 22%, particularly in the HAZ of the 304 SS side. This transformation is attributed to thermal strain-induced dislocation rearrangement and subgrain formation. Mechanical testing showed an ultimate tensile strength of 462 MPa and elongation of 24.5%, with fracture consistently initiating in the coarse-grained HAZ of the 316L SS side. Post-fracture analysis revealed that the 316L SS side underwent significantly greater plastic deformation, as evidenced by more pronounced slip bands and a final length of 15.07 mm compared to 9.47 mm on the 304 SS side. The 316L SS side, defined by both its lower base metal strength and welding-induced microstructural degradation, ultimately controls the integrity of WAAM dissimilar stainless steel joints.
ABSTRACT To examine the effect of different Ni content on the microstructure, microhardness, and corrosion resistance of FeCrNi fused claddings, optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, hardness testing, electrochemical measurements, and X-ray photoelectron spectrometer were conducted. At a Ni mass fraction of 5%, the microstructure consists of martensite, austenite, and a eutectic of martensite, austenite, and carbides. Increasing the Ni content to 10% results in a microstructure composed of austenite and a eutectic of austenite and carbides. At 15% Ni, the fused cladding exhibits a single-phase austenitic structure. All three fused cladding layers show lower hardness at the top surface, which is associated with grain coarsening. The average hardness is 468.8 HV0.2 at 5% Ni, increases to 529.28 HV0.2 at 10% Ni, and decreases to 399.55 HV0.2 at 15% Ni. The fused cladding containing 10% Ni exhibits the highest polarisation resistance, the lowest corrosion current density, and the best corrosion resistance.
ABSTRACT This study evaluates the fresh-state rheology and flexural performance of ambient-cured geopolymer concrete (GPC) as a sustainable alternative to M35 grade concrete. Using fly ash and GGBS activated by sodium hydroxide (SH) and sodium silicate (SS), the research investigated a parametric molarity range from 4M to 12M. Fresh-state analysis showed that increasing SH concentration significantly raised dynamic viscosity, reducing slump by up to 79%. An 8M threshold was identified for optimal workability and compaction. Mechanical testing revealed 8M as the robust performance optimum, achieving a 28-day compressive strength of 57.53 MPa (23.7% above control) and a flexural load of 112 kN. While GGBS enabled rapid early-strength gain (reaching up to 93% of 28-day strength within 7 days), the 4M configuration was insufficient for structural use. All GPC beams exhibited an under-reinforced failure mode with extensive strain-hardening, yielding capacity ratios between 1.43 to 2.50. Despite the superior ductility and energy absorption of GPC-8M, the findings are presented as indicative performance trends due to the reliance on single-beam specimens per configuration. Furtheremore, the absence of quantitative Life Cycle Assessment or durability profiles necessitates a cautious interpretation of GPC. These findings establish a deterministic benchmark for optimizing molarity in structural geopolymer applications.
ABSTRACT In the modern days, sustainable and resilient infrastructure turns into a global concern, especially because conventional concrete is sensitive to brittleness, degradation, and excessive maintenance requirements. This work tries to improve the mechanical, durability, and environmental properties of concrete through the use of mineral admixtures and industrial by products. Metakaolin, CS, and cupola slag are used as partial cement and fine aggregate replacements in the research. Metakaolin, which is a very reactive pozzolanic product, enhances strength, durability, and decreases permeability, thus cutting down on cement usage and related CO2 emissions. CS, which is high in silica and alumina, and cupola slag, which is high in calcium and iron, offer extra cementing and hydraulic characteristics. Experimental studies were carried out with CS and cupola slag as substitutes for sand at 0%, 5%, and 10% and metakaolin as a substitute for cement at 0%, 5%, 10%, 15%, and 20%. Test for strength were compressive strength, durability test comprises water absorption, sorptivity, acid resistance and microstructural analysis with XRD and SEM. Results showed that the admixtures greatly improve toughness, microstructure, and long term performance of the concrete.
ABSTRACT Controlled Low Strength Material (CLSM) is a cementitious, self-compacting, and fluid-like material used as a backfill in place of compacted soil. This study analyzes CLSM engineering qualities using industrial wastes GGBS and WFS. The Paste Volume Ratio (PVR) ranged from 0.5 to 0.55, the Portland cement to Cementitious material (pc/cm) ratio was kept constant at 0.1, and the Water to Cementitious material (w/cm) ratio varied from 0.8 to 1. Trial research set the w/cm ratio. Segregation increases with w/cm greater than 1 and workability decreases at 0.5. We examined how PVR and w/cm ratio affect flowability, bleeding, density, compressive strength, and ultrasonic pulse velocity. Experimental results show that the produced CLSM mixtures flowed from 282 mm to 450 mm and bled 1% to 2.3%. The mixtures had a density of 1242–1343 kg/m3. Compressive strength at 28 days ranged from 4.81 to 7.95 MPa, with M2 Mix being strongest. CLSM matrix internal compactness varied between 2.741 km/s and 3.631 km/s, as measured by ultrasonic pulse velocity (UPV). The created CLSM combinations meet ACI 229R criteria, proving that GGBS and WFS can provide a sustainable CLSM with good fresh and hardened qualities.
ABSTRACT Recent years have observed a significant increase in interest in the development of multi-metallic materials with reinforcing with reinforcement materials in alloys for advanced engineering applications. In this study, titanium (Ti), silicon carbide (SiC) graphite (Gr) and boron carbide (B4C) were added at reinforcement percentages of 5% and 10% to develop aluminium-copper (Al–Cu) hybrid composites utilizing the Direct Ink Writing (DIW) method. Initially, to create printable inks with the required flow characteristics, the metallic and reinforcing powders were combined with a Pluronic F-127 binder and printed using printer. Further, to achieve densification and strong metallurgical bonding, the printed green parts were thermally post-processed. subsequently, the microstructural and mechanical characteristics of the final part were examined by a methodical characterization process, namely, X-ray diffraction (XRD), Vickers microhardness testing, optical microscopy and scanning electron microscopy (SEM). Moreover, the testing outcomes showed that the reinforced composites had significantly more refined grains, as compared to the base alloy. Then, EDS examination revealed no oxygen contamination, SEM analysis verified the homogeneous distribution of reinforcement particles throughout the matrix with enhanced interfacial bonding. From XRD studies a number of intermetallic phases, including Al9Cu11.5, AlCu, Al1Cu3, Al1Cu2Ti1, Al0.5Cu1Ti0.5, Al3Cu2, Al2Cu3.4, Al35.472Cu47.792 and Al4Cu9, were formed. In addition to its improved interfacial properties and refined grains, specimen S3 had the greatest hardness value of 759.9 HV of all the manufactured samples.
ABSTRACT Reinforced concrete (RC) structures in aggressive environments are highly vulnerable to rebar corrosion, which causes volumetric expansion of corrosion products and leads to cracking and deterioration of the surrounding concrete. Reliable prediction of corrosion-induced damage is therefore crucial for evaluating structural durability and safety. However, many existing phase-field modelings treat concrete as a homogeneous material and neglect its inherent multiphase microstructure as well as the mechanical behavior of interfacial regions between phases. Moreover, these phase-field formulations often fail to satisfy the orthogonal condition between the tensile and compressive components of the strain tensor, which is essential for preserving elastic energy in brittle materials. Therefore, this study develops the phase-field computational frameworks to simulate damage evolution in RC structures subjected to corrosion-induced expansion. Two phase-field modelings are proposed: one considering interfacial damage between different phases while enforcing the strain tensor orthogonal condition (Model M1), and another modeling neglecting interfacial damage but still satisfying this orthogonal requirement (Model M2). Numerical simulations investigate crack propagation and rust expansion values in various structural configurations, including different concrete cover thicknesses, confined and unconfined structures, and randomly distributed inclusions with complex shapes. The obtained results show that: (i) the multiphase characteristics of concrete significantly influence corrosion-induced cracking and rust-expansion displacements; (ii) for the same structural configuration, the rust expansion displacements at the crack initiation and full crack propagation of confined structures are greater than those of unconfined structures; and (iii) due to the influence of interfacial effects, the rust expansion displacement values at the two times predicted by the M1 model are always smaller than those obtained using the M2 model, with differences of up to 50.3%.
ABSTRACT Considering the chloride permeability and mechanical characteristics of cement-based materials in cold marine environment are significantly affected by coupling action of freezing and thawing cycles as well as chloride penetration during early curing phase, a serial of experimental measurements were conducted to study the influence degree of curing age and salt freeze-thaw (SFT) environment on chloride permeability as well as mechanical characteristics of early age cement-based materials in present study. Firstly, salt freeze-thaw tests were conducted after representative curing age, i.e., 3, 7, 14, and 28 days. Then experimental tests for chloride permeability and mechanical characteristics were conducted after certain number of SFT cycles to determine the chloride concentration, compression strength, mass loss, and the relative dynamic elastic modulus (RDEM). Experimental results showed that with the decrease of curing age, both chloride permeability and mechanical characteristics degenerate apparently. Meanwhile a noticeable effect of curing age on cement-based materials suffered from SFT environment was detected: chloride diffusion coefficient, compression strength and RDEM of specimens after early curing age firstly increase slightly and then decrease dramatically. This study confirmed that early curing age play a critical role in chloride permeability and mechanical characteristics of cement-based materials subjected to SFT environment.
ABSTRACT In almost all machining processes there are several constraints associated and the objective functions are in conflict with the another objective function. In these situations, where equal importance is to be given to all constraints, multi criteria decision making is involved to determine the best optimal solution taking into consideration of all the objective functions in the turning process of AISI4140 steel. In this paper, PEG, PSI and CURLI method are employed. The PEG provides effective discrimination among the alternatives and ranking of alternatives is done effectively without any transition. PSI method is used in identifying the suitable alternatives without assigning the subjective weight assignment. In CURLI method, pairwise scoring matrix is obtained by computing the pairwise absolute difference between the values of the each alternative. Gini index is used in this work to quantify the level of disagreement among the PEG, PSI and CURLI ranking results for each alternative. In this work, PEG and CURLI approaches for MCDM for turning process parameters for AISI 4140 steel, the experimental run ‘#A14’ achieved the highest utility value and minimum radial deviation from the ideal solution, resulting combined acceptance of superior productivity in achieving minimum surface roughness and maximum MRR.
ABSTRACT To achieve effective in-depth control of injection water for the heterogeneous reservoir of offshore oilfields, a new profile control agent is developed. The co-polymer is prepared by using the cross-linking method with AM and the cross-linker. After the polymer is treated by grinding control technology, the dispersed co-polymer micro-particle gel (DMG) is prepared. Results show that DMG is made of pseudo-spherical particles, and sizes can be controlled from nm to μm by adjusting shearing rates, and thus indicating a good injectivity. The preparation is easy-handling, economical, heat-resistant, and environmental-friendly. When the concentration of monomer (5%) and AM/MBA mass ratio (250:1) are fixed, the effect of shearing rates and time on the viscosity and particle sizes is tested. Results show that the grinding rate and time have great influence on particle sizes. The experimental results of the plugging effect under simulated formation conditions show that the dispersed co-polymer micro-particle gel has good injectivity, deep migration ability and plugging performance. Under the same dosage, the plugging effect of the dispersed co-polymer micro-particle gel is significantly better than that of polymer gel. The dispersed co-polymer micro-particle gel has great application value in profile adjustment of offshore oilfield in middle and high water cut stage.
ABSTRACT Hydrogen energy has attracted considerable attention and stimulated discussions as a favorable vector for the sustainable energy transition that is increasingly being pursued worldwide. This article presents an analysis of the possible impacts of hydrogen on the energy transition of Brazil and Paraguay. Due to the diversity of possibilities for the use of hydrogen, its inclusion as an energy vector in energy matrices is particularly relevant both in the analysis of each of the two countries individually, as well as their common points and complementarities due to their shared border and energy integration. The results describe, analyze and compare the strengths, weaknesses, opportunities and threats of each country, aiming to contribute to their national strategies. Political, economic, social, technological, environmental and legal scenarios are also considered, verifying whether they are aligned with international strategies. The objective is to evaluate whether Brazil and Paraguay are adequately prepared to participate in the “Hydrogen Economy”, considering the potential impacts of including hydrogen as an energy vector in their energy matrices, seeking to contribute to increasing potential benefits and mitigating potential environmental, economic and technical problems associated with hydrogen production. It presents potential results in the areas of energy generation, as a component of industrial decarbonization and transportation, establishing relationships with theoretical references and analyzing the implications in the energy context. It explores the impacts of the hydrogen economy and its prospects, considering the challenges and opportunities for its implementation in energy matrices and presents conclusions and suggestions for the continuous improvement of the hydrogen economy in both countries.
RESUMO A crescente demanda por eficiência energética na construção civil tem motivado o desenvolvimento de argamassas leves para revestimentos em envoltórias de edificações, produzidas com agregados porosos ou incorporadores de ar, como a hidroxipropilmetilcelulose (HPMC). Este estudo avalia, em condições laboratoriais controladas, o efeito da substituição parcial da areia natural por pó de poliestireno expandido (EPS), associada à adição de HPMC, sobre o desempenho mecânico e térmico de argamassas leves. Adotou-se uma argamassa de referência 1:3 (cimento:areia, em volume), sendo a areia substituída por EPS nos teores de 10%, 20%, 30%, 40% e 50%, com adição de 0,2% de HPMC em relação à massa de cimento. Os resultados são apresentados de forma comparativa em relação à argamassa de referência e indicam que a formulação com 50% de EPS e HPMC, observaram-se reduções de 64,4% na resistência à compressão, de 62,22% na absorção de água por capilaridade e de 48,43% na condutividade térmica, bem como aumento de 81,82% na resistência de aderência à tração e de 113,35% no índice de isolamento térmico. Os resultados indicam ganhos no desempenho térmico e na aderência, acompanhados de expressiva redução da resistência à compressão, caracterizando um trade-off entre propriedades mecânicas e térmicas nas condições experimentais estudadas.
Structural health monitoring (SHM) systems increasingly rely on high-dimensional time-series data to identify incipient material degradation and safeguard the operational integrity of critical infrastructure. However, the inherent stochastic noise and complexity of raw sensor data often cause conventional deep learning (DL) models to suffer from elevated computational cost and suboptimal generalization. To address these empirical limitations, this study proposes SAX-1DCNN-BiGRU, a novel hybrid framework that synergizes symbolic representation with advanced DL architectures for robust material degradation monitoring. Specifically, symbolic aggregate approximation (SAX) is introduced as a pre-processing layer to transform continuous acceleration signals into discrete symbolic sequences. This innovative integration effectively mitigates measurement noise and reduces data dimensionality while preserving the essential features indicative of the structural response. Subsequently, the model employs a dual-stage learning process: a one-dimensional convolutional neural network (1DCNN) extracts local spatial features, followed by a bidirectional gated recurrent unit (BiGRU) to capture global, long-term temporal dependencies. The proposed methodology was rigorously evaluated on a finite element model of the Chuong Duong steel truss bridge across diverse scenarios of material degradation. Experimental results demonstrate that the SAX-1DCNN-BiGRU model achieves a superior mean accuracy of 95.63% (5-fold cross-validation, sigma = +/- 1.23%), significantly outperforming standalone baselines (1DCNN, BiGRU, GRU) and standard hybrid variants. Furthermore, the integration of SAX is proven to accelerate convergence and enhance model stability, establishing a highly efficient and noise-resilient model for real-time SHM.
Effective management of water resources demands rigorous quality monitoring, with Chemical Oxygen Demand (COD) serving as a key indicator of organic pollution. Traditionally, COD determination relies on oxidation with potassium dichromate in a strongly acidic medium containing concentrated sulfuric acid and silver sulfate as a catalyst, with mercury sulfate added to minimize chloride interference. The process involves heating under closed reflux, followed by titration of excess dichromate with ammonium ferrous sulfate. Although analytically robust, this method generates hazardous waste containing hexavalent chromium, mercury, silver, and high concentrations of sulfuric acid, posing environmental risks. This study aimed to validate an optimized alternative based on closed reflux digestion coupled with UV-Vis spectrophotometric detection of trivalent chromium, in accordance with Standard Methods for the Examination of Water and Wastewater. To ensure compliance with ABNT NBR ISO/IEC 17025, the method underwent full validation, including selectivity, linearity, limits of detection and quantification, repeatability, intermediate precision, and accuracy. Results demonstrated excellent analytical performance, with precision comparable to the traditional titrimetric method. The approach reduced reagent consumption and toxic waste generation, proving robust, cost-effective, and environmentally sustainable, enabling up to 24 samples per hour and reducing analysis time by approximately 60-70%.
