A Combination of N2 and CO2 Adsorption to Characterize Nanopore Structure of Organic-Rich Lower Silurian Shale in the Upper Yangtze Platform, South China： Implications for Shale Gas Sorption Capacity

The pores in shales are mainly of nanometer-scale, and their pore size distribution is very important for the preservation and exploitation of shale gas. This study focused on the organic-rich Lower Silurian black shale from four wells in the Upper Yangtze Platform, and their TOC, mineralogical composition and pore characterization were investigated. Low pressure N2 and CO2 adsorption were conducted at 77.35 K and 273.15 K, respectively, and the pore structures were characterized by modified Brunauer-Emmett-Teller （BET）, Dubinin-Radushkevich （DR）, t-plot, Barrett- Joyner-Halenda （BJH） and density functional theory （DFT） methods and then the relationship between pore structure and shale gas sorption capacity was discussed. The results indicate that （1） The Lower Silurian shale has high TOC content of 0.92%~96%, high quartz content of 30.6%-69.5%, and high clays content of 24.1%-51.2%. The total specific surface area varies from 7.56 m^2/g to 25.86 m^2/g. Both the total specific surface area and quartz content are positively associated with the TOC content. （2） Shale samples with higher TOC content have more micropores, which results in more complex nanopore structure. Micropore volumes/surface areas and non-micropore surface areas all increase with the increasing TOC content. （3） A combination of N2 and CO2 adsorption provides the most suitable detection range （~0.3-60 nm） and has high reliability and accuracy for nanopore structure characterization. （4） The TOC content is the key factor to control the gas sorption capacity of the Lower Silurian shale in the Upper Yangtze Platform.

Key factors determining biochar sorption capacity for metal contaminants:a literature synthesis

The sorption capacity and affinity of biochar for metals are both important attributes that determine biochar’s suitability as a soil amendment for contaminant mitigation,yet few analyses have considered both characteristics simultaneously.We present a systematic review of literature published between 2010 and 2018 to test the hypothesis that sorption capacity and affinity are affected by biochar properties,attributes of the metal contaminant,and experimental conditions,in that order.We used random forest(RF)and multi-objective optimization to analyze data of 559 individual Langmuir adsorption isotherms extracted from 133 studies covering the sorption capacity(C_(max))and affinity(K_(L))of biochar for 17 different metals,elabo-rated from six different feedstock classes,three different types of feedstock pretreatment,and five types of post-pyrolysis treatment.Highest sorption values were obtained for Pb(II),Cr(IV),and Cd(II).The feedstock used was the key determinant influencing biochar’s capacity and affinity to sorb metal contaminants(first and fourth most important variable in RF mod-els for C_(max) and K_(L),respectively)with best results obtained for biochar elaborated from nutrient-dense feedstocks(animal biowaste,sludge,and manure).Biochars that had both high sorption capacity and affinity were the result of a longer dura-tion of pyrolysis;they had lower C and higher N and O content,as well as lower C/N and higher O/C and H/C ratios,higher pore volumes and higher pH.Applying some form of pretreatment was better than none,whereas chemical modification was the best of the post-treatment methods analyzed.This review demonstrates clearly that multiple parameters during the preparation process influence the effectiveness of biochar to immobilize metal contaminants.Future research that focuses on mechanisms and the underlying factors for the correlations observed should allow the development of biochar formulations that are even more effective at immobilizing metal contaminants in soils and sediments.

Thermodynamics and Kinetics of Au（Ⅲ） and Ag（Ⅰ） Sorption on to Silicon-Organic Polymer

Sorption method is used for analysis of teclmological, geological and hydro-chemical samples with low content of precious metals and chemical pre-concentration of technological solution. Synthesized silicon-organic polymer containing thiocarbamide group, which named poly[bis -N,N＇-（3-silsesquioxanilpropyl）-thiocarbamide]-（PSTM-3T） was used in this investigation. Sorption of Au（III） and Ag（I） ions from aqueous solutions of nitric acid has been studied using the silicon-organic polymer （PSTM-3T） under different experimental conditions. Better sorption was obtained at temperature 55 ℃, 3 mol/L of nitric acid solution and contact time 300 min and 240 min for Ag（I） and Au（Ⅲ）.Thermodynamic parameters were calculated by Van＇t Hoffequation. The negative values of△G0 at different temperatures indicate the feasibility of the process and the values become more negative with increase in temperature. The positive values of △H0 and AS0 indicate that the sorption process is endothermic and determine the disorderliness of the sorption at solid-liquid interface. Experimental data were evaluated to find out kinetic characteristics and found that the sorption of Au（Ⅲ） followed pseudo-second order model and the sorption of Ag（Ⅰ） followed pseudo-first order model. The sorption capacity increased with the increase in temperature and reached maximum value at 323 K and 328 K for Au（Ⅲ） and Ag（Ⅰ）. The maximum sorption capacity of PSTM-3T for Au（Ⅲ） and Ag（Ⅰ） evaluated 333 and 129 mg/g.

Phosphate Sorption Characteristics of Andosols of the Volcanic Highlands of Central African Great Lakes Region

High phosphate sorption constitutes a critical impediment to agricultural use of Andosols in the volcanic highlands of Central African Great Lakes region. A laboratory experiment was conducted on soil samples collected from an Andosol amended with a factorial combination of lime and P （phosphorus） fertiliser to determine the P sorption characteristics and derive parameter estimates relevant in the prediction and management of P in the Andosols. The potential for sorption of additional P and its binding intensity were evaluated by applying the two-surface Langmuir model to sorption isotherms. The calculated P sorption maxima ranged from 1,667 mg·kg^-1 to 10,000 mg·kg^-1 representing about 95% of the P applied to the soil. The external P requirement ranged from 1,492 mgP·kg^-1 to 2,760 mgP.kgl which is further evidence that the studied Andosols are high P sorbers. There was no significant effect of lime and P rates on P sorption capacity of the Andosols. Exchangeable iron was highly correlated with P sorption maxima b2 （r = 0.98） on the high energy sites, whereas cation exchange capacity was negatively correlated with P sorption maxima bl （r = 0.999） and positively correlated with P binding energy K1 （r = 0.998） on the low energy sites.

In-situ gas contents of a multi-section coal seam in Sydney basin for coal and gas outburst management

The gas content is crucial for evaluating coal and gas outburst potential in underground coal mining. This study focuses on investigating the in-situ coal seam gas content and gas sorption capacity in a representative coal seam with multiple sections (A1, A2, and A3) in the Sydney basin, where the CO_(2) composition exceeds 90%. The fast direct desorption method and associated devices were described in detail and employed to measure the in-situ gas components (Q_(1), Q_(2), and Q_(3)) of the coal seam. The results show that in-situ total gas content (Q_(T)) ranges from 9.48 m^(3)/t for the A2 section to 14.80 m^(3)/t for the A3 section, surpassing the Level 2 outburst threshold limit value, thereby necessitating gas drainage measures. Among the gas components, Q_(2) demonstrates the highest contribution to Q_(T), ranging between 55% and 70%. Furthermore, high-pressure isothermal gas sorption experiments were conducted on coal samples from each seam section to explore their gas sorption capacity. The Langmuir model accurately characterizes CO_(2) sorption behavior, with ft coefcients (R^(2)) greater than 0.99. Strong positive correlations are observed between in-situ gas content and Langmuir volume, as well as between residual gas content (Q_(3)) and sorption hysteresis. Notably, the A3 seam section is proved to have a higher outburst propensity due to its higher Q_(1) and Q_(2) gas contents, lower sorption hysteresis, and reduced coal toughness f value. The insights derived from the study can contribute to the development of efective gas management strategies and enhance the safety and efciency of coal mining operations.

The pore-fracture system properties of coalbed methane reservoirs in the Panguan Syncline,Guizhou,China

The Panguan Syncline contains abundant coal resources, which may be a potential source of coalbed methane. In order to evaluate the coalbed methane production potential in this area, we investi- gated the pore-fracture system of coalbed methane reservoirs, and analyzed the gas sorption and seepage capacities by using various analytical methods, including scanning electron microscopy （SEM）, optical microscopy, mercury-injection test, low-temperature N2 isotherm adsorption/desorption analyses, low- field nuclear magnetic resonance and methane isothermal adsorption measurements. The results show that the samples of the coal reservoirs in the Panguan Syncline have moderate gas sorption capacity. However, the coals in the study area have favorable seepage capacities, and are conductive for the coalbed methane production. The physical properties of the coalbed methane reservoirs in the Panguan Syncline are gener- ally controlled by coal metamorphism： the low rank coal usually has low methane sorption capacity and its pore and microfractures are poorly developed; while the medium rank coal has better methane sorption capacity, and its seepage pores and microfractures are well developed, which are sufficient for the coalbed methane＇s gathering and exploration. Therefore, the medium rank coals in the Panguan Syncline are the most prospective targets for the coalbed methane exploration and production.

Preparation of Ti-Mo getters by injection molding

Ti-Mo getters have been fabricated via metal injection molding (MIM) using three kinds of Ti powders with different mean particle sizes of 46 μm,35 μm and 26 μm,respectively. The surface morphology,porosity,and hydrogen sorption properties of Ti-Mo getters formed by MIM using paraffin wax as a principal binder constituent were examined. It has been proven that the powder injection molding is a viable forming technique for porous Ti-Mo getters. The particle size of Ti powders and the powder loading influence...

Determination of Lead(II) in Liver Corpse of a Slaughtered Cattle with Preconcentration on a Chelating Sorbent

The copolymer of the maleic anhydride-styrene is modified at the presence of 4-amino-2-thiouracil and formaldehyde and the new polymeric sorbate with spatial structure is received. The received sorbate is identified by the IR-spectroscopy method. The complete static sorption capacitance was studied (CSSC+K= 7.8 mmol/g) and the ionization constants of ionic groups in a sorbate link was defined by electrometric method. Ionization constants were determined by potentiometric titration of the sorbent (). Sorption and desorption of the received sorbent with a lead ion (II) are investigated and optimum concentration conditions are defined: рНopt. = 5, ionic force μ = 0.8 pier/l, full sorption balance 4 hours, optimum eluent 5 ml of 0.5 M HCl.

Investigation of acetylated kapok fibers on the sorption of oil in water

Kapok fibers have been acetylated for oil spill cleanup in the aqueous environment. The structures of raw and acetylated kapok fiber were characterized using Fourier transform infrared （FT-IR） spectroscopy and scanning electron microscopy （SEM）. Without severe damage to the lumen structures, the kapok fibers were successfully acetylated and the resulting fibers exhibited a better oil sorption capacity than raw fibers for diesel and soybean oil. Compared with high viscosity soybean oil, low viscosity diesel shows a better affinity to the surface of acetylated fibers. Sorption kinetics is fitted well by the pseudo second-order model, and the equilibrium data can be described by the Freundlich isotherm model. The results implied that acetylated kapok fiber can be used as the substitute for non-biodegradable oil sorption materials.

Comparison of Phosphorus Sorption by Light-Weight Aggregates Produced in the United States

In this study, phosphorus(P) sorption of thirteen light-weight aggregates(LWAs) from USA was compared during batch equilibrium experiments in order to identify those materials which had the highest P sorption capacity for further study. Seven different levels of sorption activity were observed, which were broadly grouped into three categories—high performing, middle performing, and low performing aggregates. Chemical analysis of Ca, Al, Fe, and Mg was used to describe the differences between LWAs. There was a significant correlation between cation(especially Al, Ca, Fe, and Mg) content and P sorbed. Langmuir isotherms were used to describe P sorption maximum and binding affinity for four of the top five performing LWAs, Universal, Stalite "D", Stalite "Mix", and TXI.The fifth aggregate, Lehigh, exhibited more complex sorption, and was better described by the Freundlich isotherm. Universal had a mean P sorption at the highest concentration of 824 mg kg-1, well above its calculated sorption maximum(702 mg kg-1), and also had the highest binding affinity(1.1 L mg-1). This experiment suggests that the top performing LWA(Universal) may perform poorly in column and field studies due to observed precipitates, which could degrade constructed wetland performance. Other LWAs may exhibit superior field performance due to their high calculated sorption maxima. In general, these results highlight the importance of batch experiments as a first step in identifying materials suitable for column and field experiments.

Use of Fe/Al drinking water treatment residuals as amendments for enhancing the retention capacity of glyphosate in agricultural soils

Fe/Al drinking water treatment residuals（WTRs）, ubiquitous and non-hazardous by-products of drinking water purification, are cost-effective adsorbents for glyphosate. Given that repeated glyphosate applications could significantly decrease glyphosate retention by soils and that the adsorbed glyphosate is potentially mobile, high sorption capacity and stability of glyphosate in agricultural soils are needed to prevent pollution of water by glyphosate.Therefore, we investigated the feasibility of reusing Fe/Al WTR as a soil amendment to enhance the retention capacity of glyphosate in two agricultural soils. The results of batch experiments showed that the Fe/Al WTR amendment significantly enhanced the glyphosate sorption capacity of both soils（p 〈 0.001）. Up to 30% of the previously adsorbed glyphosate desorbed from the non-amended soils, and the Fe/Al WTR amendment effectively decreased the proportion of glyphosate desorbed. Fractionation analyses further demonstrated that glyphosate adsorbed to non-amended soils was primarily retained in the readily labile fraction（Na HCO3-glyphosate）. The WTR amendment significantly increased the relative proportion of the moderately labile fraction（HCl-glyphosate） and concomitantly reduced that of the Na HCO3-glyphosate, hence reducing the potential for the release of soil-adsorbed glyphosate into the aqueous phase. Furthermore, Fe/Al WTR amendment minimized the inhibitory effect of increasing solution p H on glyphosate sorption by soils and mitigated the effects of increasing solution ionic strength. The present results indicate that Fe/Al WTR is suitable for use as a soil amendment to prevent glyphosate pollution of aquatic ecosystems by enhancing the glyphosate retention capacity in soils.

Mechanistic insights to sorptive removal of four sulfonamide antibiotics from water using magnetite-functionalized biochar

Magnetite-functionalized biochar(MBC)is a promising engineered material for remediation of antibiotic-contaminated fields.However,sorption mechanisms of ionizable organic compounds such as sulfonamide antibiotics(SAs)on MBC are still unclear.This study employed four representative SAs including sulfamethazine(SMT),sulfamerazine(SMR),sulfadiazine(SDZ),and sulfamethoxazole(SMX),to compare the difference in sorption on MBC.Results showed that the sorption capacities and affinities of the four SAs varied with their substituents,hydrophobic properties,and dissociation constants(pKa).Synergistic effect during co-pyrolysis with Fe^(3+)enhanced the sorption performance of MBC towards SAs compared to original BC.Spectral methods confirmed structural changes of MBC such as the variance in oxygen-containing groups and defective/graphitized phases.Results of modeling pH-dependent sorption revealed that H-bonding orπ-bond assisted H-bonding determined the sorption affinities and capacities of SAs.In particular,the SAs with lower pKa were thermodynamically favorable to form H-bonding with MBC via proton exchange with water molecules.Quantum calculation results quantified the contributions of H-bonding strengths and found that the energies of H-bonding were correlated with affinities of SAs.Moreover,contributions of oxygencontaining groups instead of minerals dominated the H-bonding energies.Mechanistic insights from this study can be valuable in exploring engineered BC composites for practical application in field remediation.

Oil spill cleanup from sea water by carbon nanotube sponges

Oil spills in the sea have caused many serious environmental problems worldwide. In this study, carbon nanotube （CNT） sponges were used to cleanup oil slicks on sea waters. This method was compared with two traditional representative sorbents, including polypropylene fiber fabric and woolen felt. The CNT sponges had a larger oil sorption capacity than the other two sorbents. The maximum oil sorption capacity （Qm） of the CNT sponge was 92.30 g/g, which was 12 to 13.5 times larger than the Qm of the other two sorbents （the Qm of the polypropylene fiber fabric and woolen felt were 7.45 and 6.74 g/g, respectively）. In addition, unlike the other two sorbents, the CNT sponge was super- hydrophobic and did not adsorb any water during oil spill cleanup. CNT sponges are potentially very useful for cleaning up oil spills from sea water.

Removal of trivalent samarium from aqueous solutions by activated biochar derived from cactus fibres

The efficiency of activated biochar fibres obtained from Opuntia Ficus lndica regarding me sorpuon oi trlvalent samarium （Sm（Ⅲ）） from aqueous solutions was investigated by batch experiments. The effect of various physicochemical parameters （e.g. pH, initial metal concentration, ionic strength, temperature and contact time） on the Sm（III） adsorption was studied and the surface species were characterized by FTIR spectroscopy prior to and after the lanthanide sorption. The experimental results showed that the acti- vated biochar fibres possessed extraordinary sorption capacity for Sm（Ⅲ） in acidic solutions （qmax=90 g/kg, pH 3.0） and near neutral solutions （qmax=350 g/kg, pH 6.5）, This was attributed to the formation of samarium complexes with the surface carboxylic moieties, available in high density on the lamellar structures of the bio-sorbent.

Sponge-based materials for oil spill cleanups: A review

Elimination of leaked oil from aquatic environs has recently gained importance owing to the disasters associated with leakages into marine environments.The need for an environmentally friendly and viable line of action concerning the environs has brought forward numerous affordable,non-toxic,and decomposable materials;further,diverse biomasses for fabricating nano-to micro-scale materials,membranes,and sponges/aerogels have also been incorporated for the elimination and retrieval of oils from water.Moreover,selectivity,sorption capacity,and reusability of these materials after the retrieval of oils are also desired from the viewpoint of sustainability.This review encompasses the recent progress in the field of elimination and retrieval of oil spills using various sponge-based materials.

New generation Amberlite XAD resin for the removal of metal ions: A review

The direct determination of toxic metal ions, in environmental samples, is difficult because of the latter＇s presence in trace concentration in association with complex matrices, thereby leading to insufficient sensitivity and selectivity of the methods used. The simultaneous removal of the matrix and preconcentration of the metal ions, through solid phase extraction,serves as the promising solution. The mechanism involved in solid phase extraction（SPE）depends on the nature of the sorbent and analyte. Thus, SPE is carried out by means of adsorption, ion exchange, chelation, ion pair formation, and so forth. As polymeric supports, the commercially available Amberlite resins have been found very promising for designing chelating matrices due to its good physical and chemical properties such as porosity, high surface area,durability and purity. This review presents an overview of the various works done on the modification of Amberlite XAD resins with the objective of making it an efficient sorbent. The methods of modifications which are generally based on simple impregnation, sorption as chelates and chemical bonding have been discussed. The reported results, including the preconcentration limit, the detection limit, sorption capacity, preconcentration factors etc., have been reproduced.