Surface Area Adsorption Research Articles

Interference between di(2-ethylhexyl) phthalate and heavy metals (Cd and Cu) in a Mollisol during aging and mobilization.

Diffuse pollution of the soil by phthalates and heavy metals causes numerous concerns. Their respective fates when coexisting require further investigation. In this study, di(2-ethylhexyl) phthalate (DEHP) and Cd/Cu were used as subjects, focusing on their behavior in Mollisols under combined pollution based on their concentration, fractionation, and leaching. The results indicated that when the two pollutants coexist, the dissipation rate of DEHP in the soil decreased, and its half-life was extended from 30.81 to 40.53 (Cd) and 35.40 d (Cu). DEHP altered the distribution of Cd and Cu in the soil, and this effect persisted after most of the DEHP had degraded. Leaching tests showed that the interaction of DEHP with Cd and Cu hindered leaching during the first rainfall event, but as DEHP degraded and Cd/Cu stabilized, the trapped pollutants were gradually released in subsequent rainfall events. Additionally, to investigate the partitioning of pollutants between soil water and solid surfaces, a diffusion model of DEHP and metal ions on the surface of montmorillonite (high specific surface area adsorbents abundant in soils) was built using molecular dynamics simulations. Simulations revealed their density distribution on the clay surface increased synergistically, whereas their diffusion was antagonistic. This study provides basic data and theoretical support concerning the ecological risk assessment of combined phthalate and heavy metals pollution in soil.

Effect of intercalated metal ions on the specific surface area and porosity of dibasic calcium silicate hydrate

This work aims to determine the influence of adsorbed Cu2+, Co2+, and Cr3+ ions on the porosity of synthetic calcium silicate hydrate by analyzing nitrogen adsorption and desorption isotherms. The calcium silicate hydrate sample was synthesized under saturated steam pressure at a 175 °C temperature when the duration of isothermal curing was 16 h. The intercalation of Cu2+, Co2+, or Cr3+ ions was based on the adsorption experiment at 25 °C temperature. It was obtained that after adsorption 100 mg of metal ions were intercalated in 1 g of the sample. The analysis of nitrogen adsorption-desorption isotherms showed, that the nature of intercalated metal ions strongly affects the specific surface area and porosity of adsorbent. It was calculated that the specific surfaces area of the adsorbent increases during adsorption of Cu2+ and Co2+ ions and decreases during adsorption of Cr3+ ions. During calcination, adsorbent and adsorbent with intercalated Co2+ ions became non-porous materials, while samples with intercalated Cr3+ and Cu2+ ions showed a different tendency. The classification of hysteresis loops and calculations by using the corrected Kelvin equation and Orr et al. scheme revealed that the shape of pores depends on the nature of adsorbate. The obtained results were confirmed by analysis of nitrogen adsorption-desorption isotherms as well as SEM and TEM analysis.

Pore Structure Characteristics, Genesis, and Its Controlling Effect on Gas Migration of Quaternary Mudstone Reservoir in Qaidam Basin

The Sanhu Depression in Qaidam Basin is the largest Quaternary biogenic gas exploration area with the shallowest burial depth in the world. The shallow high abundance of gas reservoirs and high-quality pure methane have become the main production areas. The development characteristics of loose mudstone reservoirs are restricted by extreme heterogeneity. Therefore, the Quaternary Qigequan Formation mudstone in Qaidam Basin is selected as the research object. Based on the study of the sedimentary background, petrological characteristics, and pore structure characteristics, by comparing the characteristics of different mudstone reservoirs, the controlling factors of the development of different mudstone reservoirs and the control of gas migration are clarified. Research shows the following: (1) The mudstone reservoirs of the Qigequan Formation mainly develop intergranular pores, clay mineral pores, and intragranular pores. The pore size distribution varies from nanometers to micrometers, and mesopores mainly contribute to the specific surface area. (2) Rigid minerals and clay minerals are the main controlling factors for the pore structure of mudstone reservoirs. The increase in the content of rigid minerals is conducive to the development of macropores or larger micropores, while the increase in the content of clay minerals is conducive to the development of mesopores and provides an important specific surface area for gas adsorption. (3) The gas migration form of pure mudstone is mainly dominated by Fick diffusion and slippage flow, which has the characteristics of self-sealing accumulation. The gas migration form of silty mudstone is the coexistence of Fick diffusion, slippage flow, and Darcy flow, which has the features of self-sealing and Darcy flow accumulation. The gas migration form of sandy mudstone is mainly Darcy flow, only with Darcy flow accumulation characteristics. The flow form of gas creates different accumulation modes of mudstone biogas. The Quaternary mudstone reservoir shows different particularity under different material components, and the exploration targets should be treated differently according to specific mudstone types.

Performance investigation of silica gel based consolidated composite adsorbents effective for adsorption desalination systems

Performance of an adsorption desalination system is mostly influenced by the type of adsorbent and their thermo physical properties such as thermal stability, thermal conductivity, surface area and pore volume. Silica gel and zeolite are the most widely employed conventional adsorbents in an adsorption desalination system. But they are characterised by low thermal stability, high desorption temperature and low percentage of water productivity. These limited adsorption capabilities of conventional adsorbent lead to low system performance. The motivation of this work is to synthesis a consolidated composite adsorbent using conventional adsorbent and other highly porous material such as metal organic frame work (MoFs) for a better adsorption capability. The introduction of such materials in adsorption desalination system is expected to significantly improve the performance due to their better adsorption/desorption capacity. Present study introduces three different combination of composite adsorbents synthesised from silica gel and MOFs with poly vinyl pyrrolidine as binder. Silica gel is used as the parent adsorbent in all three combinations. Aluminium fumarate and nickel based MoFs (CPO-27Ni) are used as the secondary adsorbents. Three combination are namely, composite 1 (silica gel and CPO-27Ni MOF), composite 2 (silicagel and aluminium fumarate) and composite 3 (silica gel, CPO-27-Ni and aluminium fumarate). Surface area, pore volume, thermal stability and adsorption capacity of composite adsorbents are evaluated in this study. It is found that the composite 2 gives maximum BET surface area of 590 ± 10 m2/g with a pore volume of 0.279cc/g. It also exhibit superior adsorption capacity than other composite adsorbents. Maximum adsorption capacity of composite 2 is found to be 0.315 kg/kg of adsorbent. Performance evaluation of composite adsorbents in a single bed adsorption desalination system is also included in this study. A single bed adsorption desalination system is designed, fabricated and tested under the meteorological condition of Kollam, Kerala, India. Performance evaluation reveals that the three composite adsorbent can co generate potable water and cooling effect in the adsorption desalination system. At an evaporation temperature of 200 C, composite 2 exhibits comparatively better desalination and cooling effect. Water productivity and coefficient of performance of composite 2 is found to be 1.12 kg/kg of adsorbent and 0.315 respectively. Composite 1 and composite 3 gives moderate or more minor desalination and cooling effect in the system. The yield of adsorption desalination system using composite 2 is found to be 16% higher than that of conventional adsorbent such as silica gel. Results highlight that composite adsorbent composed of conventional adsorbent and MOF can be a potential candidate for adsorption desalination application.

A Search for New Mesoporous Carbon Solids with Cubic Ordered Porosity

A three-dimensional material comprised exclusively of carbon whose underlying structure lies on a triply periodic minimal surface (TPMS) is a member of the class of hypothetical carbon allotropes known as schwarzites. Such materials are highly sought-after due to their fundamental significance (the last remaining unknown crystalline allotrope of sp2-hybridized carbon) and likely interesting properties (e.g., ballistic conduction at room temperature). Other properties include a large pore volume and high surface area for gas and ion adsorption, making them a class of candidate materials for many applications such as supercapacitor electrodes and gas storage. A true schwarzite has never been synthesized, despite their predicted low energies of formation compared to fullerenes.This research focuses on the synthesis of an interpenetrating schwarzite-like material. A hard-templating strategy has been designed to achieve this through the synthesis of a free-standing graphene foam material whose structure lies on a cubic TPMS. The specific material of interest herein requires an ordered mesoporous silicate template that carries the Ia-3d space group with an optimal pore to wall ratio. Pore and wall structure as well as composition for these materials can be optimized by changing the hydrothermal synthesis temperature, the addition of different precursors, and by varying the cationic and neutral structure-directing agents. We present our recent progress in this effort and also propose future work to achieve optimal templates for schwarzite-like materials synthesis. Figure 1

The Use of Modified Fe3O4 Particles to Recover Polyphenolic Compounds for the Valorisation of Olive Mill Wastewater from Slovenian Istria.

Olive mill waste water (OMWW), a by-product created during the processing of olive oil, contains high amounts of polyphenolic compounds. If put to further use, these polyphenolic compounds could be a valuable resource for the speciality chemical industry. In order to achieve this, isolation of the polyphenolic compounds from OMWW is needed. Several techniques for this process already exist, the most widely used of which is adsorption beds. This research describes new ways of collecting polyphenolic compounds by using unmodified iron oxide (Fe3O4) particles and Fe3O4 modified with silica gel (Fe3O4@C18), citric acid (Fe3O4@CA), and sodium dodecyl sulphate (Fe3O4@SDS). This approach is superior to adsorption beds since it can be used in a continuous system without clogging, while the nano-sized shapes create a high surface area for adsorption. The results of this study show that, if used in a loop system of several adsorption and desorption cycles, (un)modified Fe3O4 has the potential to collect high concentrations of polyphenolic compounds. A combination of different modifications of the Fe3O4 particles is also beneficial, as these combinations can be tailored to allow for the removal of specific polyphenolic compounds.

Preparation of Zn/Al-chitosan Composite for the Selective Adsorption of Methylene Blue Dye in Water

Layered double hydroxide (LDHs) are widely used adsorbents for methylene blue removal. However, LDHs have a perishable structure that cannot be used repeatedly. Modifying LDHs with chitosan produces a strong material with a large surface area for methylene blue adsorption. Adsorption conditions were optimized by determining the adsorption isotherms and the adsorbent regeneration process. Results showed that the adsorption process was balanced in 90 min with maximum adsorption capacities of 86.207 mg/g, 35.336 mg/g, and 98.039 mg/g for Zn/Al, chitosan, and Zn/Al-chitosan, respectively. The adsorption in this study followed the Freundlich isotherm model. Regeneration analysis of the adsorbent showed that Zn/Al-chitosan can be used repeatedly in methylene blue adsorption.

Efficient photocatalytic hydrogen production under visible-light irradiation on SrTiO3 without noble metal: dye-sensitization and earth-abundant cocatalyst modification

Efficient visible-light-driven H2 production without noble metal is one of the major challenges in photocatalysis. Herein, SrTiO3 nanoparticles synthesized from a facile hydrothermal process are adopted as supporting material for a fluorescein-sensitized photocatalytic system, and considerable H2 production is obtained without cocatalyst due to the relatively large surface area for sufficient adsorption of dye molecules. Upon further modification with earth-abundant Ni cocatalyst, the activity of H2 production from the as-established noble-metal-free fluorescein-sensitized photocatalytic system could be drastically enhanced, achieving an apparent quantum yield of ∼4.1% at 500 nm. The excellent photocatalytic performance is attributed to the synergistic contribution of the efficient electron excitation and injection, the significantly promoted charge transfer, and the abundant reactive sites provided by Ni cocatalyst.

Novel fluorescence biosensor custom-made for protein tyrosine phosphatase 1B detection based on titanium dioxide-decorated single-walled carbon nanohorn nanocomposite

This paper presents a new fluorescent approach for the detection of protein tyrosine phosphatase 1B (PTP1B) based on titanium dioxide-decorated single-wall carbon nanohorns (TiO2-SWCNHs). The novel TiO2-SWCNHs nanocomposite was synthesized and characterized for the first time and the phosphorylated peptide as the substrate of PTP1B was designed. Properties of SWCNHs and TiO2 were combined by growing nano-sized TiO2 particles on SWCNHs, resulting in TiO2-SWCNHs. TiO2 provides SWCNHs a large adsorption surface area and can specifically bind to phosphopeptide substrate. TiO2-SWCNHs effectively quenched the fluorescence of the phosphorylated peptide substrate labeled by the fluorophore, and the system had a low fluorescence background. In the presence of PTP1B, dephosphorylation of the peptide occurred owing to the reaction between PTP1B and the peptide, causing the separation of the dye-labeled peptide from TiO2-SWCNHs, which resulted in fluorescence enhancement of the reaction system. Thus, a simple and rapid strategy for the detection of PTP1B activity was developed, with a detection limit of 0.01 ng/mL and linear range of 0–10 ng/mL. The system can be used to detect PTP1B in serum using the standard addition method. This system provides a new approach for screening PTP1B inhibitors.

THE EFFECT OF VARIATION OF ZEOLITE AS ADSORBENT MEDIUM AND ADSOPTION PRESSURE TOWARD THE QUALITY OF OXYGEN PRODUCED FROM PRESSURE SWING ADSORPTION (PSA)

One of the most important element in human life is oxygen. To produce good quality of oxygen, a purification process is needed. Pressure Swing Adsorption with the adsobent of zeolite is the most comon method used for oxygen purification. This study aimed to find out media variation of of zeolite as adsorbent medium and adsoption pressure toward oxygen quality produced from PSA. Variation of adsrobent medium used were 13X zeolite and combination of 13X zeolite and Bayah zeolite (zeolite 13X+ZAB). The study result shows that the use of 13X zeolite and 13X+ZAB zeolite can significanly increase the quality of oxygen in PSA compare to without using zeolite. The use of 13X zeolite produce higher quality of oxygen, this is because 13X zeolit is a zeolite which has high ability to adsorb nitrogen and 13X zeolite has high surface area. The higher the adsorbent surface area the more adsorbat was adsrobed so that 13X zeolite will adsorb niotrogen. Meanwhile the addition of Bayah natural zeolite into 13x zeolite (13X zeolite +ZAB) is to overcome the problem of the vapor releasing which can hinder the performance of PSA in certain period of time, so that it is needed one media of adsorbent of natural zeolite which can adsorb liquid produced from this PSA. The effect of pressure variation toward oxigen quality produced from PSA is that the higher the pressure applied the faster the process of lowering the quality of oxygen would be, this is because the adsorben was more saturated. The pressure highly affect the adsorbability occur in PSA colomn.

Malic acid cross-linked chitosan based hydrogel for highly effective removal of chromium (VI) ions from aqueous environment

The acrylamide grafted chitosan hydrogel was synthesized through cross-linking of malic acid using a simple one pot synthesis method involving free radical polymerization. The hydrogel with porous infrastructure and diverse functionalities offered large surface area for adsorption. The synthesized hydrogel exhibited high adsorption capacity (427 mg/g) for Cr(VI) ions in an aqueous medium under optimized conditions and it was quite high in comparison to the previously reported literature. The process of adsorption of Cr(VI) as oxyanion at pH 2 was endothermic and driven by entropy. It demonstrated the suitability of Langmuir adsorption isotherm, specifying monolayer adsorption of the metal ions over the hydrogel. The kinetics of adsorption was well suited with pseudo-second-order kinetic model indicating chemisorption and dependence of adsorption rate upon the adsorption capacity of hydrogel. The adsorption mechanism studied using FTIR spectroscopy and XPS indicated the strong intermolecular interactions of the negatively charged Cr(VI) species (HCrO4− & CrO42− at pH 2) to the various functional groups (hydroxyl, protonated amine and amide groups) of the hydrogel and further partial reduction of Cr(VI) to Cr(III) by the functionalities present on the hydrogel. The synthesized hydrogel with good mechanical and thermal characteristics and recycling potential can act as an efficient adsorbent for adsorption and removal of Cr(VI) ions in an aqueous environment.

Fabricating an oxygen-vacancy-rich urchin-like Co3O4 nanocatalyst to boost peroxymonosulfate activation to degrade high-concentration crystal violet

Due to the in-situ generation of reactive oxygen species (ROS), sulfate radical-based advanced oxidation processes (SR-AOPs) have emerged for the oxidative degradation of organic contaminants. Developing highly efficient heterogeneous catalysts is of great importance for SR-AOPs. In this work, an urchin-like Co3O4 nanocatalyst with oxygen vacancies (VO) was elaborately fabricated and employed for enhanced peroxymonosulfate (PMS) activation to degrade the high-concentration active dye crystal violet (CV). The obtained sample was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and N2 adsorption/desorption isotherms. Characterization results indicated that this unique VO-rich urchin-like Co3O4 nanocatalyst was endowed with a larger surface area and abundant reactive sites for PMS adsorption and activation. The experimental results of CV degradation showed that nearly complete removal of 100 mg L−1 CV could be realized within 30 min of reaction time under neutral conditions at room temperature, and the degradation process followed retarded-first-order kinetics. Electron paramagnetic resonance (EPR) spectra accompanied by quenching experiments of radicals demonstrated that the contribution of ROS to CV degradation followed this sequence: 1O2 > ▪OH > SO4▪- > O2▪-. The degradation pathways of CV were proposed by a combination of density functional theory (DFT) calculations along with frontier orbit theory while the toxicity of intermediate products was evaluated by quantitative structure-activity relationship (QSAR) prediction.

Basic Aspects in the Application of QCMs as Sensors: A Tutorial

Quartz crystal microbalances (QCMs) are devices that have been proven to function as sensors for detecting specific chemical species; this usually requires that the QCM is modified with a material that is capable to interact with the desired compound. Zeolites are an example of materials used as sensitive layer. This due to their capacity for selective adsorption and large surface area; moreover, they can grow directly on the QCM surface. After, the interaction between sensitive layer and analyte, there is a mass change on the QCM surface, which induces a frequency shift in the frequency generated by the QCM. However, the application of QCMs requires that some factors are considered, such as QCM functioning, wiring and surface functionalization. Even when there are commercial devices for QCM operation, a literature revision shows that some concepts are not understood, or some misconceptions are observed. In this work, the basics of QCM are discussed, from principles of operation to an application where a QCM was functionalized to work as sensor for water vapor.

Preparation, Modification and Characterization of Chitosan-Oxalic Kola Nut Pod Adsorbent

Abstract: This work investigated the preparation, modification and characterization of prepared adsorbent from kola nut pod (agro waste).The kola nut pod waste was obtained from Ipetu-Ijesha farm, modified using chitosan-oxalic gel and characterized using Scanning Electron micrograph -Energy dispersive X-ray and FTIR spectrophotometer. The morphological study revealed that the chemically modified adsorbent has high porosity and large surface area for effective adsorption of metal ions in aqueous solution, The EDX analysis revealed that the chitosan-oxalic modified kola nut pod adsorbent contains C (0.01%), N (14.46%), K (7.76%), O (14.48%), Si (0.09%) and Ca (62.24%). The FTIR spectrum shows some adsorption peaks that indicate the functional groups on the adsorbent This further suggested that the adsorbent has potential adsorption sites as represented by the functional groups OH, C-H, C-C, and COOH. The results of Physico chemical properties showed that moisture; 8.32±0.07, Ash; 6.31±0.04, lignin; 12.97±0.03, cellulose; 23.53±0.04, Hemicellulose; 16.76±0.02, pectin; 7.74±0.03 and extractives 24.37±0.04. This results showed that this kola nut pod contains considerable amount of lignin, cellulose and hemicelluloses thus, will form a very good adsorbent for removal of dyes and heavy metals in wastewaters. Keyword: modification, characterization, chitosan-oxalic, kola nut pod waste, Physico chemical properties, morphological study.

Highly Efficient Multisubstrate Agricultural Waste-Derived Activated Carbon for Enhanced CO2 Capture.

Activated carbon (AC) made of single-substrate agricultural wastes is considered to be a suitable raw material for the production of low-cost adsorbents; however, the large-scale application of these materials is highly limited by their low efficiency, seasonal scarcity, poor stability, low surface area, and limited CO2 adsorption performance. In this study, composite activated carbon (CAC) was prepared via controlled carbonization followed by chemical activation of four wastes (i.e., peanut shell, coffee husk, corn cob, and banana peel) at an appropriate weight ratio. The Na2CO3-activated CAC showed a higher surface area and valuable textural properties for CO2 adsorption as compared with KOH- and NaOH-activated CAC. The CAC production parameters, including impregnation ratio, impregnation time, carbonization temperature, and time, were optimized in detail. The as-prepared CACs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectroscopy, N2 adsorption–desorption isotherm, and iodine number analysis. The CAC produced at optimal conditions exhibited the highest CO2 removal efficiency and adsorption capacity of 96.2% and 8.86 wt %, respectively, compared with the single-biomass-derived activated carbon. The enhanced CO2 adsorption performance is due to the large surface area, a considerable extent of mesopores, and suitable pore width. The adsorbent in this study reveals a promising strategy for mitigating the CO2 emission problems instead of more expensive and ineffective materials.

Adsorption of Chromium Using Apu Wood (Pistia stratiotes L) Root Bioadsorbent and Modification of Apu Wood Root

The adsorbent is a material used for the adsorption process. One alternative used in the selection of adsorbents is biological materials. One type of plant that can be used to adsorb heavy metals is Apu Wood. This study aims to examine the effect of Cr (VI) concentration on the adsorption capacity of adsorbent, examine the time adjustment to the adsorption capacity of adsorbent, examine the characterization of adsorbent using SEM and FTIR, assess the adsorption equilibrium using the Langmuir and Freundlich methods and the kinetics of the adsorption reaction using pseudo order 1 and pseudo order 2. In this study, variables are the concentration of initial solution Cr(VI) of 2, 4, 6, 8, and 10 ppm and contact time of 15, 30, 45, 60, and 75 minutes. The result of this research is the capacity of adsorption increases in line with the increase in the initial concentration of Cr(VI) solution as adsorbate. Contact time affects the capacity of adsorption where the longer the contact time, the adsorption capacity increases until it reaches equilibrium at 70 minutes. In SEM and FTIR analysis both tests showed that aluminum adsorbtion using apu wood adsorbent and its modification changed the composition of the function group and the structure of the adsorbent surface area. The Langmuir Isoterm model produces a greater value R2 than the Freundlich isotherm model which indicates that the adsorbent surface is in direct contact with adsorbate and adsorbate attaches to the active site of the adsorbent of only one layer (monolayer). Kinetics adsorption pseudo order 1 produces a value of R2 greater than kinetics adsorps pseudo order 2 which indicates the mechanism that occurs is the transfer of mass in addition to the use of electrons together between heavy metals Cr (VI) with apu wood root.

The use of a flocculant additive and its effect on biofloc formation, nitrification, and zootechnical performance during the culture of Pacific white shrimp Penaeus vannamei (Boone, 1931) in a BFT system

Biofloc technology is a culture system that intensively uses microbial communities. Most bacteria can form aggregates around organic or inorganic surfaces. The high adsorption capacity, surface area, and flocculant properties of clay minerals make these compounds good candidates to stimulate biofloc formation, increase bacterial biomass, and improve nitrification. The objective of this study was to evaluate the addition of clay minerals to biofloc formation and its influence on the microbial community, nitrification, and zootechnical performance of Penaeus vannamei cultivated in a biofloc technology system. Experiment 1 involved the following treatments: control (without adding clay minerals), 10, 50, and 100 mg L-1, applied daily in the water. The treatments in experiment 2 were: control without product and inoculum, control without product and with inoculum, 50 mg L-1 clay mineral without inoculum and 50 mg L-1 clay mineral with inoculum. Both experiments with a density of 400 ind m-3. NO2 levels, total suspended solids, turbidity, differed significantly (P < 0.05) between treatments in experiment 1 and zootechnical performance parameters, where higher flocculant concentrations negatively affected these indices. In experiment 2, statistical differences were verified for NH3 and NO2 concentrations and the proximate composition of the bioflocs (P < 0.05), the addition of the inoculum of bioflocs influenced these results. In summary, the addition of clay minerals influenced biofloc formation, proximal composition, and the zootechnical performance of the cultivated shrimp but did not affect the abundance of microorganisms and nitrification.

Influences of SO2 contamination in long term supercritical CO2 treatment on the physical and structural characteristics of the Zululand Basin caprock and reservoir core samples

Understanding the mineral and microstructure changes in sandstone samples during supercritical CO2 gas treatment is an important aspect of geological CO2 sequestration. To gain insight into the effects of SO2 contamination in CO2 in South Africa, two core samples extracted from the reservoir lateral seal (ZC) and Cenomanian sandstone aquifer (ZG) within the Zululand Basin were studied. The samples were treated with CO2 and CO2/SO2 gas streams at typical reservoir temperature and pressures (10 MPa and 316 K, and 17,5 MPa and 346 K) under supercritical conditions. High pressure Parr reactors were used for storing the rock-gas-water mixtures for up to two months using a water:rock ratio of 23:1. Tests were conducted using pure CO2 and a 99% by weight (wt.) CO2 and 1% (wt.) SO2 mixed gas stream. Due to the prohibitive costs associated with CO2 purification, the knowledge of the consequences of key impurities relevant to geological sequestration is critical. Pre-and post- CO2/CO2–SO2 treatment characterisation was conducted using X-ray Diffraction (XRD) Analyses, Fourier transform infrared spectroscopy (FTIR), and low-pressure gas adsorption (LPGA). Varying mineral alterations were observed in the CO2 treated samples, mainly comprising of calcite, plagioclase and smectite dissolution and the precipitation of quartz, plagioclase, calcite and smectite. Dissolution pores and pore clogging were observed and increased microstructure heterogeneity was reported. Increases in the adsorption capacity, surface area and pore volume were observed in all samples. After treatment with CO2–SO2 gas mixture, increases in mineral reactivity were observed in the ZC sample along with gypsum precipitation, indicating potential improvement in the lateral seal's self-sealing capacity. The introduction of SO2 lead to the increase in quartz and plagioclase precipitation and increased dissolution of smectite and stilbite in the ZG sample. The study presents a novel investigation of the changes expected to take place during CO2 injection in sandstone basins.

Clariant wins major contracts to supply petrochemical catalysts for China's Lihuayi Group

The use of pesticides has increased uncontrollably due to population growth and, consequently, the increasing demand for agricultural products. At the same time, waters have become polluted with pesticides, which are demonstrated to be hazardous to both health and the environment, as well as being persistent in the environment. Therefore, it is necessary to find sustainable solutions to remove pesticides from aqueous environment, and the adsorption process using sustainable activated carbons is an interesting alternative. A review of different sustainable activated carbons derived from various biomass sources used for pesticide removal by adsorption has been included. Some sustainable activated carbons synthesized by chemical activation showed a significant development of porosity and high adsorption capacities, observing a direct relationship between adsorption capacity and surface area (SBET) of the synthesized materials. Furthermore, kinetic and isothermal models of the adsorbents for the removal of the pesticide have also been studied, concluding that the pseudo-second-order kinetic model and Langmuir and Freundlich equations are the best options to fit the experimental data.

Nitrogen-functionalized bone chars with developed surface area for efficient adsorption of multiple aquatic pollutants

Bone chars pyrolyzed from bone residuals exhibit impressive performances to remove heavy metals given the integration of hydroxyapatite and carbon components. Considering the complexation of functional groups with metal ions and the adsorption of molecules by porous pores, this work prepared nitrogen-functionalized bone chars (NMBCs) with developed surface area (16.99- to 6.71-fold enhancement) and favorable surface modification (maximum 6.03 at% of N) via a ball milling of pristine bone chars with the assistance of ammonia hydroxide. NMBCs presented excellent maximum adsorption capacities for Cr(VI) (339.8 mg/g), U(VI) (466.5 mg/g), and methylene blue (338.3 mg/g) (pH 5.0, T 293 K) from ideal solutions. The effects of geochemical conditions including contact time, solution pH, ionic strength, humic acid, and ambient temperature on adsorption behaviors were investigated. NMBCs favorably adsorbed Cr(VI) (221.8 mg/g at pH 2.0, 175.4 mg/g at pH 4.0) and U(VI) (202.1 mg/g) from simulated wastewater and seawater respectively. With the analysis using spectroscopic technologies, the dominant mechanisms of Cr(VI), U(VI), and methylene blue were the integration of electrostatic attraction, surface complexation, precipitation, cation exchange, cation-π coordination and π–π interaction. This work provided a promising reference for the functionalization of bone chars with enhanced performance and multifunctionality in the remediation of pollutants.