Exploring the potential of steel slag waste for carbon sequestration through mineral carbonation: A comparative study of blast-furnace slag and ladle slag.

Steel slag is a by-product of steelmaking which has emerged as a potential CO2 sequestration material due to its high reactivity and abundance. This research investigates the use of steel slag waste for the direct capture of carbon from air and its storage through mineral carbonation. Two abundant wastes, blast-furnace slag (BFS) and ladle slag (LS), were tested for their carbon sequestration potential, and the effects of operational parameters such as reaction time between CO2 and slag waste, temperature, liquid-solid ratio, and pressure on CO2 sequestration were determined. Quantitative and qualitative results reveal that much higher CO2 sequestration was achieved using LS compared to BFS after exposure to CO2 for 1 day at room temperature. By increasing the exposure time to four days, levels of CO2 sequestration increased gradually from 2.71% to 4.19% and 23.46%-28.21% for BFS and LS respectively. Increasing the temperature from 20 ± 2 °C to 90 ± 2 °C positively influenced CO2 sequestration in BFS, resulting in an enhancement from 3.45% to 13.21%. However, the impact on LS was insignificant, with sequestration levels rising from 27.72% to 29.90%. Moreover, better CO2 sequestration was observed for BFS than LS when the liquid-to-solid ratio increased from 3:1 to 4:1, whereupon the sequestration potential reached approximately 15% for BFS and 30% for LS at 90 ± 2 °C. Meanwhile, higher pressure reduced the sequestration potential of slag. The results of this study suggest that there is potential for scaling up the process to industrial applications and contributing to the reduction of CO2 emissions in the steelmaking industry.

Comparative Analysis of Hydrate Nucleation for Methane and Carbon Dioxide.

Research in the field of hydrate formation requires more focus upon its modelling to enable the researchers to predict and assess the hydrate formation and its characteristics. The main focus of the study was to analyze the deviations induced in various parameters related to hydrate nucleation caused by the choice of different measuring correlations or methods of their sub-components. To serve this purpose under a range of operational conditions, parameters of hydrate nucleation such as rates of nucleation and crystal growth, critical radius of the nucleus, and theoretical induction time for carbon dioxide and methane were considered in this study. From these measurements, we have quantitatively compared the ease of hydrate formation in CO2 and CH4 systems in terms of nucleation while analyzing how various correlations for intermediate parameters were affecting the final output. Values of these parameters were produced under the considered bracket of operational conditions and distributed among six cases using both general and guest-gas specific correlations for gas dissolution and fugacity and their combinations. The isotherms and isobars produced from some of the cases differed from each other considerably. The rate of nucleation in one case showed an exponential deviation with a value over 1 × 1028 at 5 MPa, while the rest showed values as multiples of 106. These deviations explain how sensitive hydrate formation is to processing variables and their respective correlations, highlighting the importance of understanding the applicability of semi-empirical correlations. An attempt was made to define the induction time from a theoretical perspective and derive a relevant equation from the existing models. This equation was validated and analyzed within these six cases from the experimental observations.

A state of the art of review on factors affecting the enhanced weathering in agricultural soil: strategies for carbon sequestration and climate mitigation.

As the urgency to address climate change intensifies, the exploration of sustainable negative emission technologies becomes imperative. Enhanced weathering (EW) represents an approach by leveraging the natural process of rock weathering to sequester atmospheric carbon dioxide (CO2) in agricultural lands. This review synthesizes current research on EW, focusing on its mechanisms, influencing factors, and pathways for successful integration into agricultural practices. It evaluates key factors such as material suitability, particle size, application rates, soil properties, and climate, which are crucial for optimizing EW's efficacy. The study highlights the multifaceted benefits of EW, including soil fertility improvement, pH regulation, and enhanced water retention, which collectively contribute to increased agricultural productivity and climate change mitigation. Furthermore, the review introduces Monitoring, Reporting, and Verification (MRV) and Carbon Dioxide Removal (CDR) verification frameworks as essential components for assessing and enhancing EW's effectiveness and credibility. By examining the current state of research and proposing avenues for future investigation, this review aims to deepen the understanding of EW's role in sustainable agriculture and climate change mitigation strategies.

Application of Water-Soluble Polymer/Biopolymer Combined with a Biosurfactant in Oil-Wet Fractured Carbonate Reservoirs.

Most fractured carbonate reservoirs are characterized by a highly permeable fracture zone surrounded by a low-permeability oil-wet matrix. These features make the displacement of oil from the matrix into the fracture zone almost impossible during water flooding. This paper presents the results of flooding with the polymer polyacrylamide (PAM) and the biopolymer xanthan gum (XG) in combination with a biosurfactant to enhance water imbibition into oil-wet fractured carbonate rocks. Core flooding experiments were conducted on induced horizontally fractured (at 180°) carbonate cores in room conditions (20 ± 2 °C). The polymer or biopolymer was used to plug the fracture zones, while the biosurfactant was added to the system to alter the wettability state of the rock matrix from oil-wet to water-wet. Rock surface characterization before and after core flooding was conducted using scanning electron microscopy (SEM). The results indicate that PAM flooding led to a higher reduction of 35.6% in fracture-matrix permeability than that with XG at 18.3%. The monitoring of oil production also showed that ultimate oil recovery levels from oil-wet fractured carbonate cores for the aforementioned systems were 16 and 8.7%, respectively, which can be attributed to the drive mechanisms of temporary fracture plugging as well as mobility ratio improvement due to the polymer and wettability alteration by the biosurfactant. SEM images confirm the proposed mechanisms, where the presence of the polymer/biopolymer followed by the biosurfactant can be detected at the rock surface as a result of chemical flow through the system.

Application of polymer integration technique for enhancing polyacrylamide (PAM) performance in high temperature and high salinity reservoirs.

Polyacrylamides (PAM) are widely used as water-soluble polymers producing gel in oil reservoirs to assist in oil extraction from reservoirs with high levels of heterogeneity. These gels are susceptible to degradation due to hydrolysis in harsh reservoir conditions such as elevated temperature and salinity. This study uses a polymer integration technique in attempting to optimize the performance of PAM in the enhanced oil recovery process for reservoirs with high temperature and salinity. The results show that, at high temperature, hydrolysis is suppressed and gel stability is maintained via the addition of Polyvinylpyrrolidone (PVP) to PAM solutions. The optimum composition was identified as being 20/80 wt% PAM: PVP for oilfield operations at 90 °C and a moderate salinity of 43,280 ppm. The degree of hydrolysis at 30 days was suppressed from 75% to 29.9%, with associated increases in viscosity from 11 to 38.2 mPa.s and from 18 to 44.3 mPa.s corresponding to rotational speeds of 30 and 10 rpm respectively. The issue of high salinity was considered by increasing the salinity of the optimised PAM: PVP mixture to 200,000 ppm. Under these conditions the degree of hydrolysis of the optimised solution increased from 29.9 to 46.9% and viscosity decreased from 38.2 to 28.6 and from 44.3 to 40.4 mPa.s for rotational speeds of 30 and 10 rpm respectively. 2-Acrylamido-2-MethylpropaneSulfonic acid (AMPS) was added to the mix to try to improve temperature stability. It was observed that, with an optimum composition of 18/72/10 wt% PAM:PVP:AMPS, the degree of hydrolysis decreased to 22% with viscosity levels of 30.6 and 22.8 mPa.s corresponding to rotational speeds of 10 and 30 rpm respectively.

Study on CO2 Hydrate Formation Kinetics in Saline Water in the Presence of Low Concentrations of CH4.

Gas-hydrate formation has numerous potential applications in the fields of water desalination, capturing greenhouse gases, and energy storage. Hydrogen bonds between water and guest gas are essential for hydrates to form, and their presence in any system is greatly influenced by the presence of either electrolytes or inhibitors in the liquid or impurities in the gas phase. This study considers CH4 as a gaseous impurity in the gas stream employed to form hydrates. In developing gas-hydrate formation processes to serve multiple purposes, CO2 hydrate formation experiments were conducted in the presence of another hydrate-forming gas, CH4, at low concentrations in saline water. These experiments were conducted in both batch and stirred tank reactors in the presence of sodium dodecyl sulfate (SDS) as a kinetic additive at 3.5 MPa and 274.15 K, under isobaric and isothermal conditions. Gas loading was taken as the detection criterion for hydrate formation. It was observed that overall gas loading was hindered by more than 70% with the addition of salts after 2 days. The addition of CH4 to the gas stream led to a further reduction of approximately 30% of gas loading in the batch reactor under quiescent conditions. However, the addition of 100 ppm of SDS improved the gas loading by recovering 34% of the loss observed in volumetric gas loading through the addition of salts and CH4. The introduction of stirring improved the gas loading, and 64% of the loss was recovered through the addition of salts and CH4 after 34 h. The investigation was continued further by substituting CH4 with N2, whereupon accelerated hydrate formation was observed.