Microwave irradiation-induced alterations in physicochemical properties and methane adsorption capability of coals:An experimental study using carbon molecular sieve

In order to comprehend the applicability of microwave irradiation for recovering coalbed methane,it is necessary to evaluate the microwave irradiation-induced alterations in coals with varying levels of metamorphism.In this work,the carbon molecular sieve combined with KMnO_(4)oxidation was selected to fabricate carbon molecular sieve with diverse oxidation degrees,which can serve as model substances toward coals.Afterwards,the microwave irradiation dependences of pores,functional groups,and highpressure methane adsorption characteristics of model substances were studied.The results indicated that microwave irradiation causes rearrangement of oxygen-containing functional groups,which could block the micropores with a size of 0.40-0.60 nm in carbon molecular sieve;meanwhile,naphthalene and phenanthrene generated by macro-molecular structure pyrolysis due to microwave irradiation could block the micropores with a size of 0.70-0.90 nm.These alterations in micropore structure weaken the saturated methane adsorption capacity of oxidized carbon molecular sieve by 2.91%-23.28%,suggesting that microwave irradiation could promote methane desorption.Moreover,the increased mesopores found for oxidized carbon molecular sieve after microwave irradiation could benefit CH4 diffusion.In summary,the oxidized carbon molecular sieve can act as model substances toward coals with different ranks.Additionally,microwave irradiation is a promising technology to enhance coalbed methane recovery.

Synthesis of Li^+ adsorbent(H_2TiO_3) and its adsorption properties

H2TiO3 was obtained from the acid-modified adsorbent precursor Li2TiO3,which was synthesized by a solid-phase reaction between TiO2 and Li2CO3.The extraction ratio of Li＋ from Li2TiO3 was 98.86%,almost with no Ti4＋ extracted.The effects of lithium titanium ratio,calcining temperature and time were investigated on the synthesis of Li2TiO3.Li2TiO3,H2TiO3 and the adsorbed Li＋ adsorbent were characterized by XRD and SEM.The lithium adsorption properties were investigated by the adsorption kinetics and adsorption isotherm.The results indicate that H2TiO3 has an excellent adsorptive capacity for Li＋.Two simplified kinetic models including the pseudo-first-order and pseudo-second-order equations were selected to follow the adsorption processes.The rate constants of adsorption for these kinetic models were calculated.The results show that the adsorption process can be described by the pseudo-second-order equation,and the process is proved to be a chemical adsorption.The adsorption process that H2TiO3 adsorbs Li＋ in LiCl solution well fits the Langmuir equation with monolayer adsorption.

Thermal decomposition of magnesium ammonium phosphate and adsorption properties of its pyrolysis products toward ammonia nitrogen

High-purity magnesium ammonium phosphate （MAP） was precipitated by controlling pH value of the reaction system of 9.0-9.5. The thermal decomposition behavior of MAP and the adsorption properties of its pyrolysis products toward ammonia-nitrogen were also studied by XRD, SEM, TGA-DTA and FT-IR methods. The results indicated that high-purity MAP was obtained at pH value of 9.0-9.5. Upon heating to 100-120℃ for 120 min, MAP was thermally decomposed, losing water and ammonia concomitantly with a reduction in grain size and crystallinity. The capacity of pyrolysis products for ammonia nitrogen adsorption reached 72.5 mg/g, with a removal rate of up to 95% from an 800 mg/L solution. The characteristic diffraction peaks corresponding to MAP mainly appeared in their XRD patterns after adsorption of ammonia nitrogen. The pyrolysis products of MAP at 100-120 ℃ could be recycling-used as the chemical treatment regents of ammonia nitrogen in the practical application.

PROPERTIES AND THERMODYNAMICS OF ADSORPTION OF BENZOIC ACID ONTO XAD-4 AND A WATER-COMPATIBLE HYPERCROSSLINKED ADSORBENT

The adsorption behavior of benzoic acid onto a water-compatible hypercrosslinked polymeric adsorbent NJ-8 wascompared with that onto macroporous Amberlite XAN-4. This paper focuses on the static equilibrium adsorption behaviors,the adsorption thermodynamics and the column dynamic adsorption profiles. Five isotherm models are used to fit the results.This shows that the Freundlich equation can give a perfect fit. The specific surface area of NJ-8 is about as high as that ofAmberlite XAD-4, but the adsorbing capacity for benzoic acid on NJ-8 is about 14.9%-64.8% higher than that on AmberliteXAD-4, which is attributed to its microporous mechanism and partial polarity. The negative values of the adsorptionenthalpy are indicative of an exothermic process. Both enthalpy and free energy changes of adsorption manifest a physicalsorption process. The negative values of the adsorption entropy indicate that adsorption is well consistent with the restrictedmobilities and the configurations of the adsorbed molecules on the surface of the studied adsorbents with superficialheterogeneity. Both adsorbents were used in mini-column experiments to demonstrate the higher breakthrough adsorbing capacity of the hypercrosslinked polymeric adsorbent NJ-8 to benzoic acid, as compared with that of Amberlite XAD-4.

Effect of Specific Adsorption of Ions on Electrokinetic Properties of Variable Charge Soils

Studies were carried out by using electrophoretic method on the effects of the specific adsorption of the anions,such as SO4^2-,PO4^3-,and F^- ions,the cations,such as Ca^2+,Mn^2+,Zn^2+,and Cu^2+,ions,and the anions and cations coexisting,such as Zn^2+ and SO4^2= ions,on electrokinetic properties of the red soils as typical variable charge soils in China concerning variation in the specific ion species and concentrations,with an emphasis on the interaction between soil colloid surfaces and the ions in soil solutions.The results showed that the adsorption of specific ions led to a very pronounced decrease in zeta potentials of the soil colloids and a shift of the IEPs to lower values for specific anions,and an obvious increase in zeta potentials of the soil colloids and a shift of the IEPs to higher values for specific cations.Under circumstances of the specific anions and cations coexisting,for instance,Zn^2+ and SO4^2- ions,the zeta potentials changed with values higher than the value for SO4^2- alone and lower than that for Zn^2+ alone,and the IEP was between that for Zn^2+ and that for SO4^2-.The adsorption of Zn^2+ and Cu^2+ ions resulted in a reversal of the zeta potentials,and appearance of two IEPs for Zn^2+ and no IEP for Cu^2+,exhibiting interesting special effects of these kinds of metal ions.The higher the concentrations of the ions,the greater the change of the electrokinetic properties.

Influences of Soluble Salts on Adsorption Properties of Polycarboxylate Superplasticizers

Polycarboxylate（PC） superplasticizers with different chemical structures were synthesized through free radical co-polymerization reaction.A total organic carbon analyzer was used to investigate adsorption behaviors of PCs,and to evaluate influences of soluble salts on absorption properties of PCs.It is found that adsorption ratios of PCs on cement particles decrease greatly with the addition of Na2SO4;the adsorption ratio of ethers PC with Hydroxyethyl methacrylate（HEMA） group first increases then decreases with the addition of NaCl;the adsorption ratio of esters PC with short side chains first decreases then increases,while the adsorption ratio of ethers PC with HEMA group decreases with the addition of CaCl2;the adsorption ratio of esters PC with short side chains decreases with the addition of Ca（NO3）2;AlCl3 causes the decrease of the adsorption ratio of ethers PC with HEMA group.

Preparation of activated carbons and their adsorption properties for greenhouse gases:CH_4 and CO_2

Three kinds of activated carbons were prepared using coconut-shells as carbon precursors and characterized by XRD, FT-IR and texture property test. The results indicate that the prepared activated carbons were mainly amorphous and only a few impurity groups were adsorbed on their surfaces. The texture property test reveals that the activated carbons displayed different texture properties, especially the micropore size distribution. The adsorption capacities of the activated carbons were investigated by adsorbing CH4, CO2, N2 and O2 at 25 ？C in the pressure range of 0-200 kPa. The results reveal that all the activated carbons had high CO2 adsorption capacity, one of which had the highest CO2 adsorption value of 2.55 mmol/g at 200 kPa. And the highest adsorption capacity for CH4 of the activated carbons can reach 1.93 mmol/g at 200 kPa. In the pressure range of 0-200 kPa, the adsorption capacities for N2 and O2 were increased linearly with the change of pressure and K-AC is an excellent adsorbent towards the adsorption separation of greenhouse gases.

Effects of coal rank on physicochemical properties of coal and on methane adsorption

For the thorough research on coal metamorphism impact on gas adsorption capacity, this paper collected and summarized parameters of experimental adsorption isotherms, coal maceral, proximate analysis and ultimate analysis obtained from National Engineering Research Center of Coal Gas Control and related literatures at home and abroad, systematically discussed the coal rank effect on its physicochemical properties and methane adsorption capacity, in which the coal rank was shown in Vitrinite reflectance, furthermore, obtained the Semi-quantitative relationship between physicochemical properties of coal and methane adsorption capacity.

Characterization, Adsorption Properties and Mechanism of Modified Sophora Japonica Leaves to Benzene

The biosorbent has been prepared with the sophora japonica leaves from the agricultural residue as the raw material by the alkaline blanching method, and characterized by BET, SEM, EDS and FTIR analysis methods. The modified sophora japonica leaves possessed more adsorption sites and had more strongly adsorbed chemical groups, which were beneficial to the adsorption. We have further investigated the adsorption performance of the indoor benzene. The secondary regression orthogonal rotation was employed to optimize the preparation process for the optimal processing conditions and regression model. The effects of single factors such as particle size, temperature, and adsorbent dosage of the sophora japonica leaves were analyzed, and adsorption isotherms and adsorption kinetics were studied. The results show that the optimal adsorption conditions were as follows: sodium hydroxide concentration with 0.1 mol/L, water bath time for 70 min, water bath temperature at 60 ℃ and Ymax = 21.38%. The best single factors included particle size with 30 mesh, temperature at 25 oC, 3 g dosage, which are consistent with the Freundlich model, and the adsorption state was more inclined to multilayer active site adsorption with 25 mg/g of saturated adsorption amount;furthermore, the adsorption kinetics followed the quasi-secondary kinetic model(R2 = 0.9731) and the adsorption process was a physicochemical mixed adsorption process controlled by chemisorption;Compared with the adsorption effect, the removal rate to the benzene of modified sophora japonica leaves was significantly superior to other materials at the level 1%, namely, modified sophora japonica leaves > diatomite> bamboo charcoal > activated carbon > macroporous resin, and the modified biosorbent had a good cycle regeneration ability.

Microwave hydrothermal synthesis,characterization and excellent uranium adsorption properties of CoFe_(2)O_(4)@rGO nanocomposite

To improve the adsorption performance and simplify uranium separation from aqueous media in post-treatment processes,a magnetic CoFe_(2)O_(4)@rGO composite was synthesized by microwave-hydrothermal method.The results of XRD,Raman,TEM/HRTEM,FTIR,BET and VSM characterization show that spinel-type cobalt ferrite CoFe_(2)O_(4) nanoparticles ca.13.4 nm in size are dispersedly anchored on the graphene sheet,and the saturation magnetization of the nanocomposite is 46.7 mA/(m^(2)·g).The effects of different pH,initial concentration and other conditions on uranium adsorption capacity were investigated,and adsorption kinetics equations were fitted to determine the adsorption behaviour of uranium on CoFe_(2)O_(4)@rGO in simulated uranium-containing seawater.It was observed that the uranium adsorption capacity of CoFe_(2)O_(4)@rGO composite at pH=5 is 127.6 mg/g,which is 1.31 and 2.43 times that of rGO and pure CoFe_(2)O_(4).The adsorption process conforms to Langmuir and quasi-second-order kinetic model.The excellent adsorption performance of CoFe_(2)O_(4)@rGO makes it potentially useful in the treatment of uranium-polluted water.

Template synthesis and adsorption properties of chitosan salicylal Schiff bases

To improve the adsorption properties of chemically modified chitosan, the chelating resin of salicylal chitosan Schiff bases was prepared by the template cross-linking method using Cu（Ⅱ） as template ion and ethylene glycol bisglycidyl ether as cross-linking agent in microwave, and was characterized by IR. The adsorption capacity and selectivity coefficient of the chemically modified chitosan for Cu（Ⅱ）, Fe（Ⅲ） and Zn（Ⅱ） were investigated, respectively. The results show that the adsorption capacity of the resin 2.73 mmol/g for Cu（Ⅱ） is bigger than that for other two metal ions, 0.22 mmol/g for Fe（Ⅲ）, and 0.42 mmol/g for Zn（Ⅱ）, and the selectivity coefficients are as follows: KCu（Ⅱ）/Fe（Ⅲ）=12.4, KCu（Ⅱ）/Zn（Ⅱ）=6.5.

Comparison and Analysis of Toluene Adsorption Properties of ZSM-5 Molecular Sieve Treated by Different Modification Methods: Adsorption Kinetic and Mechanism Studies

MFI molecular sieve with high specific surface area,adjustable pore size and low production cost have been recognized as an effective adsorbent for VOCs removal.In this paper,NaOH solution was used to etch ZSM-5 to increase specific surface area and micro-mesoporous content.Graphene oxide(GO)was loaded on ZSM-5 by ultrasonic-assisted heating immersion method,and largeπ-bond structure and oxygen-containing functional groups were added to ZSM-5 for improving the composite adsorption performance.In addition,the properties of OH-ZSM-5 and ZSM-5@GO composites for toluene adsorption under different factors were also studied.It was positively correlated with initial concentration and adsorbent mass,but was negatively correlated with temperature.Meanwhile,the results showed that the saturated adsorption capacity of OH-ZSM-5(107.3 mg/g)was 1.34 times higher than that of ZG-15%(80.2 mg/g).The pseudo-first-order and pseudo-second-order kinetic model can well describe the adsorption behavior of toluene on the OH-ZSM-5 and ZG-15%,respectively.The adsorption mechanism of OH-ZSM-5 was mainly pore-filled adsorption.However,the adsorption mechanisms of ZSM-5@GO composite were pore-filled adsorption,π-πinteraction,and H-bond interaction.This study will help to design a new strategy for enhancing the performance of traditional adsorbent ZSM-5 in VOCs removal.

Preparation of Polysulfonamide Porous Paper and Its Adsorption Properties

Three-dimensional porous paper was prepared by using polysulfonamide (PSA) fiber and pulp as the raw materials. The effect of PSA fiber to pulp ratios on the mechanical strength and adsorption properties (using methyl orange and rhodamine B dyes in their aqueous phase) of the paper were studied. The results showed that the tensile strength and elongation characteristics decreased as the PSA fiber to pulp ratio increased, while the tear strength increased. PSA paper showed good adsorption performance for both methyl orange and rhodamine B, with the adsorption process conforming to the pseudo-second-order and Langmuir isotherm models, indicating monolayer chemical adsorption. The study has provided an improved theoretical and scientific basis for the further development and application of PSA paper.

Comparable Studies of Adsorption and Magnetic Properties of Ferrite MnFe_2O_4 Nanoparticles,Porous Bulks and Nanowires

The spinel ferrites MnFe2O4 nanowires were synthesized by hydrothermal route,porous MnFe2O4 and nanoparticles morphologies were synthesized by sol-gel method with egg white.The structures,morphologies,magnetic properties and adsorption properties of these obtained ferrites with different morphologies were studied contrastively.Results show that the obtained samples exhibit ferromagnetic properties.This realizes convenient magnetic separation from solution when they are used in the treatment of organic dyes wastewater.However,the contrastive studies show that the saturation magnetizations（Ms） of MnFe2O4 with different morphologies are different and the Ms follows the order：Ms（porous）〈Ms（nanoparticles）〈Ms（nanowires）.In addition,the adsorptions of methylene blue（MB） onto these ferrites depend on ferrites＇ morphologies seriously.The adsorption rate of MB on the porous MnFe2O4 is much higher than those onto the other two samples because the porous structure can provide high efficient mass transport through the pores.

SYNTHESES AND ADSORPTION PROPERTIES OF POLYMER RESINS CONTAINING BENZIDINE AND ITS DERIVATIVES

Three chelating resins were prepared by reacting poly (beta-chloroethyl glycidyl ether) with benzidine, o-tolidine and o-dianisidine respectively, and their structures were confirmed by IR spectra and elementary analyses. The adsorption properties of the resins for Au(III), pd(II), Pt(IV), Hg(II), Cu(II), Pb(II) and Zn(II) were also investigated. The results show that the resin incorporating o-dianisidine exhibits high affinity for Au(III) within a broad range of hydrochloric acid, and selectively sorbs Au(III) in the coexistance of Cu(II), Zn(II) and Mg(II). Desorption of Au(III), Pd(II) and Pt(IV) sorbed proceeded quantitatively using 0.1 mol/l hydrochloric acid containing 2%-10% thiourea as desorbents.

Effects of Solution Chemistry Conditions and Adsorbent Surface Properties on Adsorption of Ni(Ⅱ) on Laiyang Bentonite

The effects of solution chemistry conditions and adsorbent surface properties on the adsorption of Ni(II) on Laiyang bentonite were investigated via the batch technique. Potentiometric and mass titration techniques were employed in the batch experimental methods, and the results showed that the point of zero net proton charge(PZNPC) of bentonite at different ionic strength denoted p HPZNPC to be 8.2±0.1. The removal of Ni(II) from the solution increased with an increasing bentonite dosage, with the maximum removal efficiency equating up to 99%. The adsorption of Ni(II) on bentonite increased with an increasing p H value at a p H value of <8.5, and reached a Ni(II) removal efficiency of >99% at a p H value of >10.2. The Ni(II) adsorption performance exhibited different responses to cations(K+, Na+) but was not influenced by the background anions(NO3-, Cl-, and Cl O4-). The adsorption of Ni(II) was dominated by the outer-sphere surface complexation and ion exchange with Na+/H+ on bentonite surface at low p H value, whereas the inner-sphere surface complexation and surface precipitation were the main adsorption mechanisms at high p H value. The adsorption isotherms of Ni(II) on bentonite can be described well by the Langmuir model. The thermodynamic parameters of adsorption, including the Gibbs free energy, the enthalpy change, and the entropy change, at different temperatures indicated that the adsorption of Ni(II) on bentonite was endothermic and spontaneous.

Tuning Structural,Electronic,and Magnetic Properties of Black-AsP Monolayer by Adatom Adsorptions:A First Principles Study

Black Arsenic-phosphorus(AsP)monolayer is a novel two-dimensional nanomaterial with the characteristics of modest direct bandgap and superhigh carrier mobility.However,little is known about how the surface adsorption affects the property of AsP monolayer.Motivated by this,we researched systematically the geometry,adsorption energy,magnetic moment and electronic structure of 11 different adatoms adsorbed on AsP monolayer using firstprinciples calculations.The adatoms used in this study include light nonmetallic(C,N,O)adatoms,period-3 metal(Na,Mg,Al)adatoms,and transition-metal(Ti,V,Cr,Mn,and Fe)adatoms.The adatoms cause an abundant variety of structural,magnetic and electronic properties.This study shows that AsP binds strongly with all adatoms under study and the adsorption energies in all systems are much stronger than that on graphene,Si C,BN,or MoS2.The semiconductor property of AsP is affected by the introduction of adsorbed atoms,which can induce mid-gap states or cause n-type doping.Moreover,the adatom adsorptions cause various spintronic characteristics:N-,Ti-,and Fe-adsorbed AsP become bipolar semiconductors,while the Mn-decorated AsP becomes a bipolar spin-gapless semiconductor.Our results suggest that atomic adsorption on AsP monolayers has potential application in the field of nanoelectronics and spintronics.

Activated Carbon Adsorption Properties of the Residual Matters in Textile Dyeing and Printing Secondary Effluent

The research employed the adsorption isotherm measurement, the batch kinetic adsorption and the rapid small-scalecarbon column test （RSSCT） to find out the characteristics and main impacting factors of＇granular activated carbon （GAC） adsorption, in treating the textile dyeing-printing/polyester alkali de-weighting secondary effluent （TSE）. The adsorption affinities and capacities for the organics surrogated by CODCr, color and UV254 （UV absorbency-at λ= 254 nm） predicted by isotherm, small- seale-fixed bed were discussed. ＇Adsorption rates for CODCr, color and UV254 are much different and carbon particle size dependent. The color adsorption rate and capacity should be taken as the main consideration factors in designing bioactivated carbon filter（BACF）. The breakthrough of GAC adsorption column is mainly influenced by the low MW readily adsorbable organics in TSE. UV254, is a good adsorption breakthrough indicator. The study provides references for BACFs＇ design and operation control in textile secondary effluent （TSE） tertiary treatment.

Study of ss-DNA Adsorption and Nano-mechanical Properties on Mica Substrate with Surface Forces Apparatus

Many DNA?based devices need to build stable and controllable DNA films on surfaces. However, the most com?monly used method of film characterization, namely, the probe?like microscopes which may destroy the sample and substrate. Surface Forces Apparatus(SFA) technique, specializing in surface interaction studies, is introduced to investigate the e ects of DNA concentration on the formation of single?stranded DNA(ss?DNA) film. The result demonstrates that 50 ng/μL is the lowest concentration that ss?DNA construct a dense layer on mica. Besides, it is also indicated that at di erent DNA concentrations, ss?DNA exhibit diverse morphology: lying flat on surface at 50 ng/μL while forming bilayer or cross?link at 100 ng/μL, and these ss?DNA structures are stable enough due to the repeatabil?ity even under the load of 15 mN/m. At the same time, an obvious adhesion force is measured:/m at 100 ng/μL, respectively, which is attributed to the ion?correlation e ect. M-6.5 mN/m at 50 ng/μL and-5.3 mNoreover, the atomic force microscopy(AFM) images reveal the entire surface is covered with wormlike ss?DNA and the measured surface roughness(1.8±0.2 nm) also matches well with the film thickness by SFA. The desorption behaviors of ss?DNA layer from mica surface occur by adding sodium salt into gap bu er, which is mainly ascribed to the decreased ion?ion cor?relation force. This paper employing SFA and AFM techniques to characterize the DNA film with flexibility and stable mechanical ability achieved by ion bridging method, is helpful to fabricate the DNA?based devices in nanoscale.