Rafael Mattos Dos Santos

University of Guelph | UOGuelph · School of Engineering

Featured Application: The focus of this review is the use of SEM imaging to gain insight into the composition and morphology of minerals in view of predicting or understanding their reactivity or the process by which they are formed. Abstract: Scanning electron microscopy (SEM) is a powerful tool in the domains of materials science, mining, and geo...

Currently, point-of-use (POU) disinfection technologies have a significant impact addressing the control of microbial pathogens in water. Among the physical factors related to microbial filtration/inactivation, the rate of particles collision with the disinfecting surface is crucial to guarantee satisfactory efficiency. Through a Computational Flui...

As climate change concerns and the demand for sustainable and environmentally friendly energy sources grows, recent advancements in nuclear power technologies suggest promising achievements in using thorium as an alternative nuclear fuel. This study presents a comprehensive analysis of thorium resources worldwide, with a particular focus on their d...

Traditional mineral processing methods are known for their high temperatures, chemically intensive processing, hazardous waste discharge, and substantial carbon emissions. To tackle these challenges, a carbon-negative mining technology is needed which can extract critical metals from low-grade minerals while simultaneously removing CO2 from the atm...

Scanning electron microscopy (SEM) is a powerful tool in the domain of material science, mining, and geology, owing to its enormous potential to provide unique insights into the micro and nanoscale worlds. This comprehensive review discusses the background development of SEM, basic SEM operation including the specimen preparation and imaging proces...

This project encompassed research on the integration of the sodium bicarbonate production from subsurface brine with steelmaking, whereby slags from steelmaking were considered and experimented with for use in either: (i) the regeneration of ammonium from the spent brine; (ii) as a co-reagent in the bicarbonate reaction process to reduce the need f...

Terrestrial enhanced rock weathering (ERW) is reckoned as a robust method to contribute to stabilizing atmospheric carbon and combat global warming. The method is particularly a matter of interest in agricultural soil, offering a vast opportunity for the application of crushed silicate minerals and secondary carbonate accumulation and migration. Al...

CONSPECTUS: The central theme of this Account is the development of intensified and sustainable chemical processes for the sequestration of CO2 in synergism with the utilization of wastes of industrial, urban, and agricultural origins. A challenge when working with solid waste−fluid reactions is that mass transfer limitations across solid−liquid, s...

Enhanced rock weathering (ERW), as a negative emissions technology for climate change mitigation, has received far more public, governmental, and academic attention (according to the authors’ account of engagement with such actors) in the past year than in the many years since its first mention in the literature. The term ERW was conceived by Beerl...

Soil organic carbon (SOC) is a vital indicator of soil health and plays a crucial role in mitigating climate emissions through carbon sequestration. Accurate and rapid estimation of SOC is essential for farmers to implement climate change mitigation strategies and claim carbon credits. In this study, we developed and validated a protocol for the ra...

Carbon concentrations in the atmosphere are increasing yearly, making it the primary contributor to climate change. To reduce CO2 emissions, various strategies and technologies have been implemented. Mineral carbonation is an effective technology for mitigating climate change. Despite its efficiency, the slow pace of mineral carbonation poses a cha...

This research presents a novel approach for estimating soil organic carbon (SOC) content in agricultural soils using a photocatalytic Chemical Oxygen Demand (PeCOD) analyzer integrated with Geographic Information System (GIS) technology for spatial analysis. The PeCOD method, which relies on photochemical oxidation of organic carbon, demonstrated a...

It is estimated that 2 to 20 quadrillion (10^15) cubic meters of methane exist in the Earth’s crust in the form of solid hydrate (also known as methane clathrate). The recovery of this methane, however, presents an enormous challenge to engineers, and it is doubtful if energy needs may not be better satisfied with more sustainable technologies that...

During production from oil wells, the deposition of asphaltene and wax at surface facilities and porous media is one of the major operational challenges. The crude oil production rate is significantly reduced due to asphaltene deposition inside the reservoir. In addition, the deposition of these solids inside the surface facilities is costly to oil...

Terrestrial enhanced weathering of alkaline silicate minerals is a promising climate change mitigation strategy with the potential to limit the global temperature rise. The formation and accumulation of pedogenic carbonate and bicarbonate in soils/subsoils and groundwater offers a large sink for C storage; the amount of soil inorganic carbon (SIC)...

In this investigation, a unique approach using a green surfactant extracted from the Avena sativa (AS) plant in conjunction with three different salts, including Na2CO3, NaCl, and Na2SO4, was examined for enhanced oil recovery. In addition, the efficiency of NaOH as a supplementary chemical in the process was investigated. Based on the results of t...

The textile sector of Bangladesh has positively contributed to a significant impact on its national economy and employment opportunities due to its rapid growth. The increasing number of wet processing units has led to a growing amount of wastewater volume as well as textile sludge (a byproduct of wastewater or effluent treatment plants). In 2015,...

The presented work aimed to investigate pre-recorded tutorials' impact on online fatigue and students' performance. An anonymous survey was conducted to explore students' note-taking habits, perceptions, and preferences for live or pre-recorded tutorials. Interestingly, results suggest an even split between preferences for live and pre-recorded tut...

The advancement of computers and information technologies introduces modern threats to the traditional education system and raised new concerns even about academic integrity. This work explores a positive fightback approach to combat academic dishonesty by improving students’ experience and learning rate through active learning, interactive learnin...

Thorium is a naturally occurring radioactive element that has been identified as a potential alternative fuel for nuclear energy production. Additionally, thorium-based nuclear reactors have inherent safety features that reduce the risk of nuclear accidents and proliferation. As a result, there has been growing interest in the development of thoriu...

It is well known that waterborne bacteria is a significant health concern in water safety, which can cause immediate illness. However, the presence and health impact of waterborne viruses are less appreciated. It is reported that 219 virus species are pathogenic to humans, and the WHO has classified the waterborne viruses to have a moderate to high...

In the present study, we have looked into evidence of the vertical distribution of weathering products in soils amended with crushed wollastonite, whose relatively rapid weathering rate helps in the shorter-term to inform what occurs in the longer-term with slower weathering minerals. The experimental setup includes soil columns with and without wo...

Rare earth elements (REEs) are typically found in low concentrations within natural rocks that make up mine tailings, such as carbonates in association with silicates within carbonatite igneous rocks, so it is of interest to develop (bio)hydrometallurgical ways to liberate them from the silicate matrix. This work investigated, through geochemical m...

Metals are essential in our daily lives and have a finite supply, being simultaneously contaminants of concern. The current carbon emissions and environmental impact of mining are untenable. We need to reclaim metals sustainably from secondary resources, like waste. Biotechnology can be applied in metal recovery from waste streams like fly ashes an...

The present research investigates the biodegradability of straws made from agave waste. The benefit of agave straws are two-folds i.e., utilizing the agave waste resulting from tequila production, and producing biodegradable straws to eliminate a single-use plastic straws. The testing is conducted under possible disposal environments such as ocean...

The present work investigates the production of sodium bicarbonate in combination with the co-utilization of saline brine and carbon capture, utilization, and sequestration (CCUS). The use of ammonia in the traditional Solvay process could be eliminated by using a modified Solvay process. This study compared the modification with the addition of th...

The reviewed paper investigated enhanced rock weathering (ERW) in the core soils taken from dry croplands in UK. These soils were treated with crushed basalt and were exposed to natural weathering condition for a period of 14 months within columns. In the core, the soil dissolution was sampled in 10-20 cm intervals to understand the fate of dissolu...

Enhanced weathering of silicate minerals is a negative emissions technology that captures atmospheric CO2 via the formation of carbonates. When certain silicate rocks are mixed with agricultural soils, improved agricultural yields are witnessed, implying that the benefits are twofold. Natural silicates, such as basalt and olivine, weather too slowl...

Following the emergence of COVID-19, nations around the world implemented effective restrictions that limited people's movements and economic activity, which reportedly led to environmental improvements. The lowering of air emissions is one environmental indicator that has been connected to the pandemic. The diurnal temperature range (DTR) is one e...

The use of natural green surfactants has become one of the most popular techniques for enhanced oil recovery (EOR) because these types of surfactants are environmentally-friendly, efficient, sustainable, and less expensive than commercial surfactants. In the current study, the extraction of natural surfactant from the Red Beet (RB) plant is introdu...

Potential competing interests: The author(s) declared that no potential competing interests exist. The reviewed paper investigated the effects of pH and charged compounds on the integrity of synthetic magnesium silicate. The problem of Mg 2+ dissociation from magnesium silicate and its interaction with charged compounds specifically, was explored i...

The demand for lithium-ion batteries (LIBs) has been growing rapidly in the last decade, and thus it is expected that the demand for LIB electrolyte will increase by 30% annually over the next 3 years (Wei et al., 2022). Recycling can potentially meet part of the need for LIB raw materials, however the current recycling process for LIBs disregards...

There is now a dire demand for negative emissions technologies (which sequester CO2 from the atmosphere) that can be rapidly deployed, are scalable, and are demonstrably safe and effective. Enhanced weathering of silicate minerals has demonstrated a significant potential for CO2 capture and sequestration by the formation of pedogenic carbonates in...

The world is facing a major environmental issue: the increasing carbon dioxide (CO2) concentration in the atmosphere, causing global warming. The National Aeronautics and Space Administration (NASA) provides a monthly measurement of the CO2 concentration in the atmosphere: the last data are alarming, with 417 ppm in January 2022. The continued rise...

The global climate crises is getting more and more urgent. Human population is emitting CO2 and other greenhouse gases (GHG) every day and the trend of atmospheric pollution is increasing nowadays in many places. To act against global warming is one of the most important topics of the current generations. All parts of society and economy need to ad...

Terrestrial enhanced weathering of alkaline silicate minerals is a promising climate change mitigation strategy with the potential to limit the global temperature rise. The formation of pedogenic carbonate (PC) offers a sink for C storage and the amount of soil inorganic carbon (SIC) presently held within soils has been estimated to be 720–950 Gt C...

A continued challenge of mineral carbonation is to react as much CO2 as possible via accelerated conditions, substantial energy is thus needed to achieve those conditions. The mineral carbonation process will eventually include capture (optional), pressurization, mineral comminution, heating, mixing, and post-processing. All have an energetic cost...

The battle against global warming is one of the most important concerns confronting today's generation. Greenhouse gas emissions (GHG) are increasing daily, resulting in environmental degradation and a variety of other detrimental impacts. Therefore, all sectors of the socioeconomic system, particularly those with the highest levels of emissions, s...

Terrestrial enhanced weathering of alkaline silicate minerals is a promising climate change mitigation strategy with the potential to limit the global temperature rise. The formation of pedogenic carbonate (PC) offers a sink for C storage and the amount of soil inorganic carbon (SIC) presently held within soils has been estimated to be 720–950 Gt C...

Among the ex-situ carbon capture and sequestration (CCS) techniques that have been developed to mitigate the damages of anthropogenic climate change, Enhanced Rock Weathering (ERW) is recently gaining traction. It is the spreading of finely ground silicate rock in agricultural settings to increase soil alkalinity and form secondary (pedogenic) carb...

As a principal part of the atmosphere-lithosphere interface, soil plays a key role in regulating the atmospheric CO2 concentration and global climate. Comprising two major pools (carbonate in soils and bicarbonate in groundwater), soil inorganic carbon (SIC) is deemed as the primary carbon (C) sink and source in areas with low mean annual rainfall....

Mining is an important industry, accounting for 6.9% of global GDP. However, global development promotes accelerated demand, resulting in the accumulation of hazardous waste in land, sea, and air environments. It reached 7 billion tonnes of mine tailings generated yearly worldwide, and 19 billion solid tailings will be accumulated by 2025. Adding t...

Enhanced weathering of silicate minerals is a negative emissions technology that captures atmospheric CO2 via the formation of carbonates. When certain silicate rocks are mixed with agricultural soils, improved agricultural yields are witnessed, implying that the benefits are two-fold. Natural silicates, such as basalt and olivine, weather too slow...

Mining is an important industry, accounting for 6.9% of global GDP. However, global development promotes accelerated demand, resulting in the accumulation of hazardous waste in land, sea, and air environments. It reached 7 billion tonnes of mine tailings generated yearly worldwide, and 19 billion solid tailings will be accumulated by 2025. Adding t...

Carbon capture, utilization, and storage (CCUS) is an important technology to mitigate the accumulation of atmospheric greenhouse gases. To contribute towards this, steelmaking is an industry in need of novel approaches for hard-to-abate CO2 emissions. Additionally, geological carbon sequestration has proven difficult in locations close to major st...

Fertilizers play an essential role in increasing crop yield, maintaining soil fertility, and provide a steady supply of nutrients for plant requirements. The excessive use of conventional fertilizers can cause environmental problems associated with nutrient loss through volatilization in the atmosphere, leaching to groundwater, surface run-off, and...

Mining is an important industry that provides products and services through infrastructure systems worldwide. However, the global development promotes the steady growth and accelerated demand for minerals, resulting in the accumulation of hazardous waste in land, sea and air environments and, consequently a series of environmental and health proble...

Enhanced weathering is a proposed carbon dioxide removal (CDR) strategy to accelerate natural carbon sequestration in soils via the amendment of silicate rocks to agricultural soils. Among the suitable silicates (such as basalt and olivine), the fast-weathering mineral wollastonite (CaSiO3) stands out. Not only does the use of wollastonite lead to...

Mining is an important industry that provides products and services through infrastructure systems worldwide. However, the global development promotes the steady growth and accelerated demand for minerals, resulting in the accumulation of hazardous waste in land, sea and air environments and, consequently a series of environmental and health proble...

This article reports the results of a survey with Canadian farmers (n = 166) to analyze the mechanisms that shape their intention to adopt farming practices that can mitigate climate change. Specifically, we are interested in assessing the farmers' fertilizer purchase behavior in the face of climate change challenges. We thus proposed and tested a...

The amendment of silicate minerals to soils is considered a feasible means to sequester atmospheric carbon in soils through reaction mechanisms termed “enhanced rock weathering”, “pedogenic carbonate formation”, and “carbon drawdown”, which transport inorganic (bi)carbonates via the subsoil and aquifers to marine carbon sinks. Our research group ha...

Among the several methods that have been proposed for mitigating carbon concentration in the atmosphere, enhanced rock weathering is regarded as a low-cost, low-energy and readily scalable approach that can store atmospheric CO2 for up to thousands of years through converting alkaline earth metals into stable carbonates. Application of silicate-ric...

In this study, a unique surfactant extracted from a quinoa plant was introduced for enhanced oil recovery (EOR). The physico-chemical characteristics of extracted saponin as the surfactant agent were confirmed by 1 H NMR, FESEM, and FT-IR analyses. The natural surfactant extracted from quinoa exhibited appropriate thermal stability at reservoir tem...

Microplastics (MPs) and per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment due to consumer and industrial use. These compounds are very persistent in the environment and human body, which has made them hot environmental topics in recent years; but how this did come about? What factors have been driving the trends of their...

X-ray diffraction (XRD) is an important and widely used material characterization technique. With the recent development in material science technology and understanding, various new materials are being developed, which requires upgrading the existing analytical techniques such that emerging intricate problems can be solved. Although XRD is a well-...

This thesis investigated the recovery of critical metals from waste streams, by means of (bio)hydrometallurgical leaching and bio-precipitation. The literature reviews covered urban solid wastes and coal ashes containing rare earth elements (REEs). The numerical investigations focused on three critical metals: Arsenic (As) contained in metal-contam...

The art of using animal hides, an apparent waste from the meat processing industry, goes back to the dawn of humanity and was highly demanded for leather manufacturing. In Ontario (Canada), small-and medium-sized abattoirs process all together approximately 300,000 sheep and 100,000 cattle per year, and for decades, the collected hides and skins ha...

For many decades, X-ray diffraction (XRD) has been used for material characterization. With the recent development in material science understanding and technology, various new materials are being developed, which requires upgrading the existing analytical techniques such that intricate problems can be solved. Although, XRD is a well-established no...

Canada’s mineral reserves can play a very important role in curbing climate change if natural alkaline minerals are used for the process of mineral carbonation. In this work, the potential of using two Canadian natural silicates for accelerated carbonation is experimentally assessed: kimberlite mine tailing (Mg0.846Al0.165Fe0.147Ca0.067SiO3.381) fr...

Microplastics (MPs) and per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment due to consumer and industrial use. These compounds are very persistent in the environment and human body, meaning they do not break down and can accumulate over time. While an increasing number of studies have been published on these topics in rece...

Constructed wetlands (CWs) are engineered systems that are constructed to mimic natural wetlands. These systems simulate the processes that happen in natural wetlands and remove pollutants from wastewater. CWs have been used to treat a wide range of waste streams, including landfill leachate, and they have shown relatively good removal efficiencies...

Loss of phosphorus from agricultural land through water runoff causes serious detrimental effects on the environment and on water quality. Phosphorous runoff from excessive use of fertilizers can cause algal blooms to grow in nearby water systems, producing toxins that contaminate drinking water sources and recreational water. In this study, a risk...