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Activated coke (ACO) has been applied in some wastewater treatment plants to advance the removal of micro-pollutants from secondary effluent. This work investigated the use of Lanthanum (La) to modify ACO (La-ACO) for enhancing the removal/degradation of micro-pollutants by activating peroxydisulfate (PDS). We report that the immobilization of La oxide on ACO significantly enhances the adsorption of tetracycline (TC) from aqueous solution as well as its persulfate-based catalytic oxidation. The pseudo-first-order Kapp value of the La-ACO/PDS process is 1.41 times that of adsorption and PDS oxidation alone, indicating an evident synergistic effect. Surface analysis confirms the introduction of La on ACO, while both La(OH)3 and La2O3 consist of La species on La-ACO. The pH values close to neutral are shown to improve the degradation of TC. Also, increasing reaction temperature improves the TC oxidation. The oxidizing species superoxide anion radical (O2·−) and active holes (h+) prove the predominant oxidizing species, while the contribution percentages of O2·− and h+ achieve 51.3% and 84.2% of the total degradation capacity, respectively. The inhibiting effect of SO42− and Cl− is insignificant, while the coexisting humic acid has actually improved the TC removal. Reusability test indicates the stable and continuable PDS catalytic ability.

Significance Chlorinated solvents are among the most recalcitrant aquifer contaminants, which can cause serious health problems such as kidney and liver damage, and some are considered carcinogenic. They are a global problem due to their wide industrial use since the beginning of the 20th century (e.g., in metal-processing plants). Conventionally, pump and treat technology (ex situ method) has been used to treat such contaminated groundwater resources. Recently, in situ techniques have been applied to lower the remediation costs (e.g., energy/water consumption) while also limiting the disruption. Nanoremediation is a new in situ technology that has shown promising results at laboratory, pilot, and field scales. This study uses 4D (time-resolved 3D) imaging to capture the dynamics of nanoremediation at the pore scale., Nanoscale zero-valent iron (nZVI) particles have excellent capacity for in situ remediation of groundwater resources contaminated by a range of organic and inorganic contaminants. Chlorinated solvents are by far the most treated compounds. Studies at column, pilot, and field scales have reported successful decrease in contaminant concentration upon injection of nZVI suspensions in the contaminated zones. However, the field application is far from optimized, particularly for treatments at—or close to—the source, in the presence of residual nonaqueous liquid (NAPL). The knowledge gaps surrounding the processes that occur within the pores of the sediments hosting those contaminants at microscale limit our ability to design nanoremediation processes that are optimized at larger scales. This contribution provides a pore-scale picture of the nanoremediation process. Our results reveal how the distribution of the trapped contaminant evolves as a result of contaminant degradation and generation of gaseous products. We have used state-of-the-art four-dimensional (4D) imaging (time-resolved three-dimensional [3D]) experiments to understand the details of this degradation reaction at the micrometer scale. This contribution shows that the gas released (from the reduction reaction) remobilizes the trapped contaminant by overcoming the capillary forces. Our results show that the secondary sources of NAPL contaminations can be effectively treated by nZVI, not only by in situ degradation, but also through pore-scale remobilization (induced by the evolved gas phase). The produced gas reduces the water relative permeability to less than 1% and, therefore, significantly limits the extent of plume migration in the short term.

Summary Climate change and global warming recently became significant concerns due to the massive emissions of greenhouse gases into the atmosphere, predominantly CO2 gases. Therefore, it is necessary to find sustainable and inexpensive methods to capture the greenhouse gasses and protect the environment for live species. The application of naturally available and cheap adsorbents of carbon such as clay minerals became a great interest. However, the minerals prone to low storage capacity despite their high affinity to adsorb carbon. This paper aims to explore ways to improve the pore volume and surface area of two selected clay minerals, ‘montmorillonite and kaolinite’ by acid treatment to overcome their low storage capacity.This study concludes that clay minerals are inexpensive and available material sources to model the realistic conditions and apply the results of carbon capture to prevent global warming, which is one of the most critical and urgent problems in the world.

In this research, two biochars derived from activated sludge (wastewater treatment plant) are prepared by two different preparation processes for the comparative studies of tetracycline (TC) adsorption. One is the two-stage process, including hydrothermal pretreatment and subsequent high-temperature pyrolysis (HSBC-600), while the other is the direct pyrolysis method (PSBC-600). Various technologies are employed to characterize physicochemical properties and structural features of the two biochars. The results indicate that hydrothermal pretreatment can increase the specific surface area (133.4 and 114.6 m2/g for HSBC-600 and PSBC-600) and pore volume (0.237 and 0.159 cm3/g for HSBC-600 and PSBC-600) of biochar. At 298 K, the qmax on HSBC-600 and PSBC-600 achieves 116.9 and 89.3 mg/g, respectively. It is noted that the Freundlich isotherm and pseudo-second-order kinetic equations better describe the adsorption behavior, indicating that the adsorption of TC onto HSBC-600 and PSBC-600 is the multi-layer adsorption and involves chemical adsorption. The thermodynamic parameters reveal that the adsorption process is spontaneous and endothermic, causing an increase in the degree of disorder. All adsorption mechanisms may be consisted of pore filling, electrostatic force, hydrogen bond, and π-π interaction. The higher adsorption capacity of HSBC-600 could be attributed to the more adsorption sites provided from high specific surface area and pore volume, in which π-π interaction plays a major role.

This work investigates the removal of non-aqueous phase liquids (NAPLs) from groundwater resources using nanotechnology. We present results of a series of multiphase fluid displacement experiments conducted in a naturally occurring sandstone rock. These experiments involve injection of an aqueous suspension of silica nanoparticles to remove a trapped NAPL phase. Specifically, the effect of nanoparticle concentration on the efficiency of the NAPL removal is studied. Our results show that silica nanoparticles successfully remobilised the trapped NAPL phase and resulted in 13% increase in its removal efficiency. The optimal concentration for NAPL removal efficiency is found to be 0.3 wt%.

In this contribution, we apply a soft-template-assisted hydrothermal route using polyethylene-polypropylene glycol (F127) as soft-template agent and biomass batatas as carbon precursor to synthesis a novel hydrothermal mesoporous biochar (HMC-800) for adsorptive removal of tetracycline (TC) from wastewater. We use the biochar prepared without F127 and direct pyrolytic biochar for comparison. The physicochemical properties of all the studied biochar samples are measured using a suite of characterization techniques. Our results show that the HMC-800 displays the highest specific surface area (286.3 m2/g) and total pore volume (0.249 cm3/g), manifesting the introduction of F127 can result in formation of well-developed pore structures. Regarding adsorption properties, the HMC-800 outperforms other biochar samples for TC removal. Our finding shows that solution with near-neutral pH is favorable for TC removal, and the highest adsorption capacity is observed at initial solution pH value 7. In addition, our findings show that applying the pseudo-second-order kinetic and Freundlich isotherm equation closely models the recorded adsorption behavior. The maximum adsorption capacity is measured to be as much as 238.7 mg/g by Langmuir isotherm model. Pore filling, hydrogen-bonding and n-π interaction are suggested to be the prevailing adsorption mechanisms compared to the other mechanisms. Furthermore, the HMC-800 performs better in regeneration and reuse experiments, making it a promising adsorbent material for TC removal from wastewater.

In recent years, a large number of metal foams and porous metals have been developed. Due to the high cost of these materials alternative manufacturing methods for cellular metallic materials are being explored. Crumpled metallic foil meshes, manufactured via die compression techniques, are evolving as a potential alternative method. However, the non-availability of sufficient data on their load response is limiting their uptake. Uniaxial compressive load response of crumpled aluminium foil meshes (CAFMs) of varying densities, forged by open and closed die compression, are studied. A 0.05 mm thick aluminium sheet mesh, manufactured by the expanded metal process is used. X-ray computed micro-tomography is employed to image the CAFM’s internal cellular structure. The stress-strain relation demonstrates that the CAFMs produce identical load response profile irrespective of their relative density. Power law functions E R = 17110 ρ r 3.6547 and σ Y , E = 53.092 ρ r 2.2249 define the relationships between real Young’s Modulus E R and effective yield strength, σ Y , E . The study provides new knowledge on the effect of relative density on the compressive properties of CAFMs which have applications across lightweight structural design.

A multi-scale network integration approach introduced by Jiang et al. [2013] is used to generate a representative pore-network for a carbonate rock with a pore-size distribution across several orders of magnitude. We predict the macroscopic flow parameters of the rock utilising i) 3D images captured by X-ray computed micro-tomography and ii) pore-network flow simulations. To capture the multi-scale pore-size distribution of the rock we imaged four different rock samples at different resolutions and integrated the data to produce a pore-network model that combines information at several length-scales that cannot be recovered from a single tomographic image. A workflow for selection of the number and length-scale of the required input networks for the network integration process, as well as fine tuning the model parameters is presented. Mercury injection capillary-pressure data were used to evaluate independently the multi-scale networks. We explore single-scale, two-scale, and three-scale network models and discuss their representativeness by comparing simulated capillary-pressure versus saturation curves with laboratory measurements. We demonstrate that for carbonate rocks with wide pore-size distributions, it may be required to integrate networks extracted from two or three discrete tomographic data sets in order to simulate macroscopic flow parameters. This article is protected by copyright. All rights reserved.

Groundwater resources in need of cleanup are a worldwide problem. In many cases, industrialization and human activities have introduced contamination to groundwater, rendering it unsuitable for human use. The contaminants are both of organic (e.g., chlorinated solvents) and inorganic (e.g., chromium and arsenic) nature. Conventionally, intrusive methods were used to clean up the contamination source/plume. These include the pump-and-treat method that extracts the contaminated water for surface treatment. Such ex situ methods are less practicable when there is limited access to the contaminated subsurface layer. A more efficient approach will be to plan for in situ remediation of the contaminants which would minimize the need to extract the contamination. This chapter looks into a new technology that uses metal nanoparticles to deliver in situ remediation of chlorinated solvents. We explore this technology from technical, economical, and operational point of view.

This study reveals the pore-scale details of oil mobilisation and recovery from a carbonate rock upon injection of aqueous nanoparticle (NP) suspensions. X-ray computed micro-tomography (μCT), which is a non-destructive imaging technique, was used to acquire a dataset which includes: (i) 3D images of the sample collected at the end of fluid injection steps, and (ii) 2D radiogram series collected during fluid injections. The latter allows monitoring fluid flow dynamics at time resolutions down to a few seconds using a laboratory-based μCT scanner. By making this dataset publicly available we enable (i) new image reconstruction algorithms to be tested on large images, (ii) further development of image segmentation algorithms based on machine learning, and (iii) new models for multi-phase fluid displacements in porous media to be evaluated using images of a dynamic process in a naturally occurring and complex material. This dataset is comprehensive in that it offers a series of images that were captured before/during/and after the immiscible fluid injections.

This work provides new insights into the dynamics of silica nanoparticle-based removal of organic fluids (here oil) from naturally occurring porous media. We have used 4D (time-resolved 3D) imaging at pore-scale using X-ray computed micro-tomography (μCT) technique. The captured 3D tomographic time-series data reveal the dynamics of immiscible oil displacement from a carbonate rock upon injection of nanoparticle (NP) suspensions (0.06 and 0.12 wt% SiO2 in deionised water). Our analysis shows significant pore-scale remobilisation of initially trapped oil upon injection of the NP suspensions, specifically, at higher concentration. Our data shows that oil clusters become significantly smaller with larger fluid/fluid interface as a result of the higher concentration NP injection. This paper demonstrates that use of 2D radiograms collected during fluid injections allows monitoring flow dynamics at time resolutions down to a few seconds using conventional laboratory-based μCT scanners. Here, as an underlying mechanism for oil remobilisation, we present the first 4D evidence of in-situ formation of an oil in water emulsion induced by nanoparticles.

Significance Fluid displacement processes in carbonate rocks are important because they host over 50% of the world's hydrocarbon reserves and are aquifers supplying water to one quarter of the global population. A previously unidentified pore-scale fluid displacement event, droplet fragmentation, is described that occurs during the flow of two immiscible fluids specifically in carbonate rocks. The complex, heterogeneous pore structure of carbonate rocks induces this droplet fragmentation process, which explains the increased recovery of the nonwetting phase from porous carbonates as the wetting phase injection rate is increased. The previously unidentified displacement mechanism has implications for ( i ) enhanced oil recovery, ( ii ) remediation of nonaqueous liquid contaminants in aquifers, and ( iii ) subsurface CO 2 storage.

Sudden changes in key parameters such as pressure, temperature, and fluid composition may result in asphaltene precipitation and deposition, consequently reducing permeability and porosity as well as well injectivity and productivity. Sandstone cores of an Iranian reservoir were studied under high pressure and temperature. Asphaltene deposition was studied in recycled gas injection, CO2 injection, and natural depletion experiments. The authors observed that these processes could be ranked for the deposition severity viewpoint in the aforementioned order. Qualitatively investigation of cores indicated nonuniform deposition of precipitated asphaltene along a flooded core and reducing deposition from entering core terminal to the core outlet.

The physics of multi-phase displacement processes in the individual pores of a connected pore-network of a rock ultimately controls how oil, gas and water move in reservoir rocks and how readily they can be produced. These pore scale processes, including piston-like displacement, snap off, film-flow and fluid redistribution have been studied traditionally in pore-network simulations as well as in 2D micro-model experiments. However, recent advances in X-ray computed micro-tomography (CT) techniques now enable us to visualize and monitor these processes in 3D during in-situ core flooding experiments at pore-scale resolution. This provides new information on the spatial and temporal evolution of oil and water phase clusters and films. In this paper, we present results of a suite of two-phase fluid displacement experiments performed on a dolomite core plug. The experiments consist of a series of fluid injections and in-situ CT scans of the core in certain time steps during the drainage and imbibition displacement processes. The fluid phases are brine and a mineral oil. A simple, low-cost and highly X-ray transparent design for core flooding cells is introduced. Our experiments and CT images allow us to visualize the 3D fluid structures of each phase during fluid displacements in carbonate rocks with excellent clarity. Piston-like displacement and snap off mechanisms have been captured clearly in 3D. In addition, the formation, collapse and reorganisation of brine films surrounding oil blobs in individual pores were clearly visualised. However, the formation of oil films, which could provide connectivity for the hydrocarbon phase at low saturations, could not be observed in these experiments. The observed displacement processes and the particular oil-water/rock configurations seen in the displacements suggest the rock is preferentially water wet.