NUMERICAL SIMULATION OF THE EFFECT OF MALDISTRIBUTION IN A FIXED BED ADSORBER

The paper deals with the modeling of the effect of maldistribution in pollutant abatementtrichloroethylene（TCE）concerning low concentration(10-5-10-8kg·m-3)adsorption in an adsorber.Such a concentration range is rather typical in many an environmental application.Isotherms andbreakthrough curves for TCE adsorption are obtained both for a commercial activated carbonSorbonorit 4 and a laboratory adsorber of dB/dP=11.Two two-dimensional nonequilibrium isothermalmodels are developed to describe the mass transfer in the fixed bed taking into account the effect ofmaldistribution.It is found the simulation results with maldistribution are in very good agreementwith the experimental findings.Low concentration TCE adsorption in a fixed bed of activated carbonis found to be strongly influenced by maldistribution.The non-uniform distributions of concentrationand loading of the pollutant in the adsorber are predicted by the model.Maldistribution and its ef-fect on the initial breakthrough of TCE in

DIFFUSION MODES IN A DIFFUSION-CELL ADSORBER

1 INTRODUCTIONDiffusion-cells have been widely used for the measurement of the effective diffusivitiesin porous catalysts.Compared with other methods,diffusion-cell presents itself as asimple,fast and reliable technique and its response curve is very sensitive to the valueof effective diffusivity of the porous catalyst.

Characterization of P-nitrophenol Adsorption Kinetic Properties in Batch and Fixed Bed Adsorbers

P-nitrophenol（PNP） adsorption in batch and fixed bed adsorbers was studied. The homogeneous surface diffusion model（HSDM） based on external mass transfer and intraparticle surface diffusion was used to describe the adsorption kinetics for PNP in stirred batch adsorber at various initial concentrations and activated carbon dosages. The fixed bed model considering both external and internal mass transfer resistances as well as axial dispersion with non-linear isotherm was utilized to predict the fixed bed breakthrough curves for PNP adsorption under the conditions of different flow rates and inlet concentrations. The equilibrium parameters and surface diffusivity（Ds） were obtained from separate experiments in batch adsorber. The obtained value of Ds is 4.187×1012 m2/s. The external film mass transfer coefficient（kf） and axial dispersion coefficient（DL） were estimated by the correlations of Goeuret and Wike-Chang. The Biot number determined by HSDM indicated that the adsorption rate of PNP onto activated carbon in stirred batch was controlled by intraparticle diffusion and film mass transfer. A sensitivity analysis was carried out and showed that the fixed bed model calculations were sensitive to Ds and kf, but insensitive to DL. The sensitivity analysis and Biot number both confirm that intraparticle diffusion and film mass transfer are the controlling mass transfer mechanism in fixed bed adsorption system.

A novel material for passive NO_(x) adsorber:Ce-based BEA zeolite

Passive NO_(x) adsorbers(PNAs)were proposed to address the NO_(x) emissions during the cold start phase.Here we show a novel Ce-based BEA zeolite,as a noble-metal-free passive NO_(x)adsorber.The NO_(x) adsorption capacity of Ce/BEA reaches 36μmol/g in the feed gas close to realistic exhaust conditions,and the NO_(x) desorption temperature,which is around 290℃,is ideal for diesel exhaust after-treatment systems.Ce/BEA also behaves notable stability of high temperature CO exposure conditions.Multiple characterizations were performed to explore the NO_(x) adsorption chemistry of Ce/BEA.The Ce(Ⅳ)species in the BEA zeolite serves as the active center for NO_(x) adsorption.The bidentate nitrate species is responsible for the observed NO_(x) storage capacity,and the active oxygen around Ce(Ⅳ)plays a critical role in its formation.Considering the significantly better cost efficiency of Ce compared to Pd,Ce/BEA presents an enormous potential for the PNA applications and provides a novel formulation for the noblemetal choice of PNA materials.

Synergistic and Antisynergistic Intracrystalline Diffusional Influences on Mixture Separations in Fixed-Bed Adsorbers

Separations of mixtures in fixed-bed adsorbers are influenced by factors such as(1)selectivity of adsorption,Sads,(2)diffusional time constants,Đi/rc 2,and(3)diffusion selectivity,Đ1/Đ2.In synergistic separations,intracrystalline diffusion of guest molecules serves to enhance the selectivities dictated by thermodynamics of mixture adsorption.In antisynergistic separations,intracrystalline diffusion serves to reverse the hierarchy of selectivities dictated by adsorption equilibrium.For both scenarios,the productivities of the desired product in fixed-bed operations are crucially dependent on diffusional time constants,Đi/rc 2;these need to be sufficiently low in order for diffusional influences to be effective.Also,the ratioĐ1/Đ2 should be large enough for manifestation of synergistic or antisynergistic influence.Both synergistic and antisynergistic separations have two common,distinguishing characteristics.Firstly,for transient uptake within crystals,the more mobile component attains supraequilibrium loadings during the initial stages of the transience.Such overshoots,signifying uphill diffusion,are engendered by the cross-coefficientsΓij(i≠j)of thermodynamic correction factors.Secondly,the component molar loadings,plotted in composition space,follow serpentine equilibration paths.If cross-coefficients are neglected,no overshoots in the loadings of the more mobile component are experienced,and the component loadings follow monotonous equilibration paths.The important takeaway message is that the modeling of mixture separations in fixed-bed adsorbers requires the use of the Maxwell−Stefan equations describing mixture diffusion employing chemical potential gradients as driving forces.

Numerical Investigation into the Distributor Design in Radial Flow Adsorber

Air flow distribution in radial flow adsorber was numerically investigated using computational fluid dynamics(CFD)method,which was proved to be applicable to study the problem of non-uniform distribution in radial flow adsorber.Results showed that the degree of non-uniformity was more serious in desorption process than that is adsorption process.Therefore,it was considered that the non-uniform distribution of flow in a radial flow adsorber was mainly manifested in the desorption process.Optimum design of distributor parameters can improve the flow distribution in adsorber.Meanwhile,three different structures of distributor and the effect of breathing valve were analyzed.Results revealed that truncated cone is more effective than tubular and conical distributors in flow distribution.By inserting the truncated cone in central channel,desorption uniformity was increased by 6.56%and the breakthrough time of CO_(2)was extended from 564s to 1138s in the adsorption process.The“dead zone”problem at the top of adsorber during the desorption process was solved by opening breathing valve,which prolonged the working life of adsorber and was proved to have less effect on the uniform of airflow.

A green cross-linking method for the preparation of renewable threedimensional graphene sponges for efficient adsorption of Congo red dye

Graphene-based materials possess significant potential for the treatment of dye wastewater due to their exceptional adsorption properties toward stubborn pollutants.However,their utilization is hindered by high preparation costs,low yields,environmental pollution during synthesis,and challenges in regenerating the adsorbent.This study proposes a novel approach to address these limitations by developing nitrogen-doped three-dimensional(3D)polyvinyl alcohol(PVA)crosslinked graphene sponges(N-PGA)using a cross-linking method with ammonium carbonate.This method offers a relatively mild,environmentally friendly approach.Ammonium carbonate serves as both a reducing and modifying agent,facilitating the formation of the intrinsic structure of N-PGA and acting as a nitrogen source.Meanwhile,PVA is utilized as the cross-linking agent.The results demonstrate that N-PGA exhibits a favorable internal 3D hierarchical porous structure and possesses robust mechanical properties.The measured specific surface area(BET)of N-PGA was as high as406.538 m^(2)·g^(-1),which was favorable for its efficient adsorption of Congo red(CR)dye molecules.At an initial concentration of 50 mg·L^(-1),N-PGA achieved an impressive removal rate of 89.6%and an adsorption capacity of 112 mg·g^(-1)for CR dye.Furthermore,it retained 79%of its initial adsorption capacity after 10 cycles,demonstrating excellent regeneration performance.In summary,the synthesized N-PGA displays remarkable efficacy in the adsorption of CR dye in wastewater,opening up new possibilities for utilizing 3D porous graphene nanomaterials as efficient adsorbents in wastewater treatment.

Boosting kinetic separation of ethylene and ethane on microporous materials via crystal size control

The adsorptive separation of C_(2)H_(4)and C_(2)H_(6),as an alternative to distillation units consuming high energy,is a promising yet challenging research.The great similarity in the molecular size of C_(2)H_(4)and C_(2)H_(6)brings challenges to the regulation of adsorbents to realize efficient dynamic separation.Herein,we reported the enhancement of the kinetic separation of C_(2)H_(4)/C_(2)H_(6)by controlling the crystal size of ZnAtzPO_(4)(Atz=3-amino-1,2,4-triazole)to amplify the diffusion difference of C_(2)H_(4)and C_(2)H_(6).Through adjusting the synthesis temperature,reactant concentration,and ligands/metal ions molar ratio,ZnAtzPO4 crystals with different sizes were obtained.Both single-component kinetic adsorption tests and binary-component dynamic breakthrough experiments confirmed the enhancement of the dynamic separation of C_(2)H_(4)/C_(2)H_(6)with the increase in the crystal size of ZnAtzPO_(4).The separation selectivity of C_(2)H_(4)/C_(2)H_(6)increased from 1.3 to 98.5 with the increase in the crystal size of ZnAtzPO_(4).This work demonstrated the role of morphology and size control of adsorbent crystals in the improvement of the C_(2)H_(4)/C_(2)H_(6)kinetic separation performance.

Few-layered hexagonal boron nitride nanosheets stabilized Pt NPs for oxidation promoted adsorptive desulfurization of fuel oil

A few-layered hexagonal boron nitride nanosheets stabilized platinum nanoparticles(Pt/h-BNNS)is engineered for oxidation-promoted adsorptive desulfurization(OPADS)of fuel oil.It was found that the few-layered structure and the defective sites of h-BNNS not only are beneficial to the stabilization of Pt NPs but also favor the adsorption of aromatic sulfides.By employing Pt/h-BNNS with a Pt loading amount of 1.19 wt%as the active adsorbent and air as an oxidant,a 98.0%sulfur removal over dibenzothiophene(DBT)is achieved along with a total conversion of the DBT to the corresponding sulfones(DBTO_(2)).Detailed experiments show that the excellent desulfurization activity originates from the few-layered structure of h-BNNS and the high catalytic activity of Pt NPs.In addition,the OPADS system with Pt/h-BNNS as the active adsorbent shows remarkable stability in desulfurization performance with the existence of different interferents such as olefin,and aromatic hydrocarbons.Besides,the Pt/h-BNNS can be recycled 12 times without a significant decrease in desulfurization performance.Also,a process flow diagram is proposed for deep desulfurization of fuel oil and recovery of high value-added products,which would promote the industrial application of such OPADS strategy.

Antagonism effect of residual S triggers the dual-path mechanism for water oxidation

Transition metal chalcogenides(TMCs)are recognized as pre-catalysts,and their(oxy)hydroxides derived from electrochemical reconstruction are the active species in the water oxidation.However,understanding the role of the residual chalcogen in the reconstructed layer is lacking in detail,and the corresponding catalytic mechanism remains controversial.Here,taking Cu_(1-x)Co_(x)S as a platform,we explore the regulating effect and existence form of the residual S doped into the reconstructive layer for oxygen evolution reaction(OER),where a dual-path OER mechanism is proposed.First-principles calculations and operando~(18)O isotopic labeling experiments jointly reveal that the residual S in the reconstructive layer of Cu_(1-x)Co_(x)S can wisely balance the adsorbate evolution mechanism(AEM)and lattice oxygen oxidation mechanism(LOM)by activating lattice oxygen and optimizing the adsorption/desorption behaviors at metal active sites,rather than change the reaction mechanism from AEM to LOM.Following such a dual-path OER mechanism,Cu_(0.4)Co_(0.6)S-derived Cu_(0.4)Co_(0.6)OSH not only overcomes the restriction of linear scaling relationship in AEM,but also avoids the structural collapse caused by lattice oxygen migration in LOM,so as to greatly reduce the OER potential and improved stability.

High adsorption selectivity of activated carbon and carbon molecular sieve boosting CO_(2)/N_(2) and CH_(4)/N_(2) separation

Flue gas and coal bed methane are two important sources of greenhouse gases.Pressure swing adsorption process has a wide range of application in the field of gas separation,and the selection of adsorbent is crucial.In this regard,in order to assess the better adsorbent for separating CO_(2) from flue gas and CH_(4) from coal bed methane,adsorption isotherms of CO_(2),CH_(4) and N_(2) on activated carbon and carbon molecular sieve are measured at 303.15,318.15 and 333.15 K,and up to 250 kPa.The experimental data fit better with Langmuir 2 compared to Langmuir 3 and Langmuir-Freundlich models,and Clausius-Clapeyron equation was used to calculate the isosteric heat.Both the order of the adsorbed amount and the adsorption heat on the two adsorbents are CO_(2)>CH_(4)>N_(2).The adsorption kinetics are calculated by the pseudo-first kinetic model,and the order of adsorption rates on activated carbon is N_(2)-CH_(4)>CO_(2),while on carbon molecular sieve,it is CO_(2)-N_(2)>CH_(4).It is shown that relative molecular mass and adsorption heat are the primary effect on kinetics for activated carbon,while kinetic diameter is the main resistance factor for carbon molecular sieve.Moreover,the adsorption selectivity of CH_(4)/N_(2) and CO_(2)/N_(2) were estimated with the ideal adsorption solution theory,and carbon molecular sieve performed best at 318.15 K for both CO_(2) and CH_(4) separation.The study suggested that activated carbon is a better choice for separating flue gas and carbon molecular sieve can be a strong candidate for separating coal bed methane.

A functionalized activated carbon adsorbent prepared from waste amidoxime resin by modifying with H_(3)PO_(4) and ZnCl_(2) and its excellent Cr(Ⅵ)adsorption

With the application of resins in various fields, numerous waste resins that are difficult to treat have been produced. The industrial wastewater containing Cr(Ⅵ) has severely polluted soil and groundwater environments, thereby endangering human health. Therefore, in this paper, a novel functionalized mesoporous adsorbent PPR-Z was synthesized from waste amidoxime resin for adsorbing Cr(Ⅵ). The waste amidoxime resin was first modified with H3PO4 and ZnCl_(2), and subsequently, it was carbonized through slow thermal decomposition. The static adsorption of PPR-Z conforms to the pseudo-second-order kinetic model and Langmuir isotherm, indicating that the Cr(Ⅵ) adsorption by PPR-Z is mostly chemical adsorption and exhibits single-layer adsorption. The saturated adsorption capacity of the adsorbent for Cr(Ⅵ) could reach 255.86 mg/g. The adsorbent could effectively reduce Cr(Ⅵ) to Cr(Ⅲ) and decrease the toxicity of Cr(Ⅵ) during adsorption. PPR-Z exhibited Cr(Ⅵ) selectivity in electroplating wastewater. The main mechanisms involved in the Cr(Ⅵ) adsorption are the chemical reduction of Cr(Ⅵ) into Cr(Ⅲ) and electrostatic and coordination interactions. Preparation of PPR-Z not only solves the problem of waste resin treatment but also effectively controls Cr(Ⅵ) pollution and realizes the concept of “treating waste with waste”.

Recent progress of Pd/zeolite as passive NO_(x) adsorber: Adsorption chemistry, structure-performance relationships, challenges and prospects

Due to the technology limitation and inferior deNO_(x) efficiency of urea selective catalytic reduction (SCR) catalysts at low temperatures, passive NO_(x) adsorber (PNA) for decrease of NO_(x), CO and hydrocarbons (HCs) during “cold start” of vehicles was proposed to meet the further tighten NO_(x) emission regulations in future. Among them, Pd modified zeolite PNA materials have received more attention because of their excellent NO_(x) storage capacity, anti-poisoning and hydrothermal stability and since Pd/zeolite PNA was proposed, a variety of advanced characterization methods have been applied to investigate its adsorption behavior and structure-performance relationship. The comprehension of the active sites and adsorption chemistry of Pd/zeolite PNA was also significantly improved. However, there are few reviews that systematically summarize the recent progress and application challenges in atomic-level understanding of this material. In this review, we summarized the latest research progress of Pd/zeolite PNA, including active adsorption sites, adsorption mechanism, material physicochemical properties, preparation methods, storage and release performance and structure-performance relationships. In addition, the deactivation challenges faced by Pd/zeolite PNA in practical applications, such as chemical poisoning, high temperature hydrothermal aging deactivation, etc., were also discussed at the micro-level, and some possible effective countermeasures are given. Besides, some possible improvements and research hotspots were put forward, which could be helpful for designing and constructing more efficient PNA materials for meeting the ultra-low NO_(x) emission regulation in the future.

Effects of Papyrus Plants (Cyperus papyrus) on the Physicochemical Parameters and Nutrient Levels of Water and Sediments in Yala Swamp Wetland in Western Kenya

Yala swamp wetland is the largest fresh water wetland ecosystem in Kenya supporting a broad biodiversity. It comprises of River Yala, the Yala swamp, Lakes Kanyaboli, Namboyo and Sare, and a portion of Lake Victoria neighboring the swamp. Approximately 2300 ha of land have been reclaimed and has been used for large-scale agriculture resulting in mass destruction of papyrus to create room for framing. Papyrus are known to be important in phytoremediation but despite this role information is limited, lacks supportive evidence and the empirical aspect on the levels of these pollutants in relation to the papyrus biomass is limited. The study is aimed at determining the effects of Cyperus papyrus on the water and sediment quality in Yala Swamp wetland. Six sampling sites were purposefully selected to monitor the variations of the physicochemical parameters (temperature, dissolved oxygen: DO, pH, biological oxygen demand: BOD, total suspended solids: TSS, turbidity, electrical conductivity: EC and total dissolved solids: TSS) and the levels selected nutrients (phosphorus and nitrates) in water and sediments as River Yala flows through Dominion Farms, Lake Sare which surrounded by Cyperus papyrus and finally into Lake Victoria. The samples were collected in triplicates during the wet and dry seasons (May and September 2015 respectively). The physicochemical parameters were measured in situ using a Hydrolab muiltimeter while the nutrients were analyzed using UV/Vis spectroscopy. Statistical analysis was done using SAS V9.0 software. The mean temperature was 26.19˚C ± 0.71˚C, DO: 3.72 ± 1.02 Mg/l, BOD: 3.9 ± 0.32 Mg/l, pH: 7.52 ± 0.17, TDS: 109 ± 86.33, EC: 173.26 ± 13.8 μS/cm, TSS: 12.42 ± 18.51 Mg/l and Turbidity: 12.29 ± 10.03 NTU. The values varied significantly at P 0.05 among all the sites. The results show that papyrus is useful in maintaining the required levels of physicochemical parameters. The study will assist in conservation of the papyrus to help phytoremediate pollutants from Dominion farms and the adjacent farms in order to have ecologically sound wetland.

Adsorption Effect of Phosphate Modified Grape Branch Biochar on Cd2

Two major problems facing agriculture at present are soil pollution and the disposal of solid wastes generated during plant growth. The method of preparing biochar from solid wastes produced by plants is a means of maximizing the use of resources to combat the problem of soil pollution. In this study, we did not choose straw in the traditional sense but the waste branches from grape pruning, which has higher lignin cellulose, as the raw material. The biochar derived from grape branches pyrolyzed at 300˚C for two hours was utilized as a raw material to prepare modified biochar with varying concentrations of phosphoric acid. The adsorption performance and mechanism of Cd2 were explored through experiments involving different concentrations, addition amounts, reaction times, kinetic analyses, and isothermal adsorption tests. The findings indicated that the optimal adsorption of Cd2 occurred with a 20% phosphoric acid concentration, achieving the highest adsorption rate of 84.62%. At a dosage of 10 g/L, the maximum adsorption capacity reached 7.02 mg/g. The adsorption kinetics and isothermal adsorption of Cd2 on biochar modified with 0.2% phosphoric acid (0.2 PB) closely followed the pseudo-first-order kinetics model (R2 > 0.98) and the Freundlich model (R2 > 0.97), respectively. This suggests that the adsorption process involves both physical and chemical mechanisms. SEM and FTIR analyses revealed that phosphoric acid modification primarily increased the biochar’s specific surface area and enhanced certain original functional groups. The adsorption process predominantly involved rapid ion diffusion and chemical adsorption, as confirmed by kinetic analysis and isothermal adsorption model analysis. In summary, the adsorption efficiency of 0.2 PB significantly improved, showing potential and feasibility for heavy metal remediation in soil. This supports the environmentally friendly concept of “treating waste with waste”.

Research Progress on Removal of Oxygenatesin Fischer-Tropsch Oil by Adsorption

The oxygen-containing compounds in Fischer Tropsch synthetic oil greatly affect the downstream deep processing of hydrocarbons,and effective removal is required.Com-pared to traditional removal technologies such as hydrogenation deoxygenation,solvent extraction,and extraction distillation,adsorption deoxygenation technology has the advantages of low cost,mild operating conditions,easy removal and recovery,and mini-mal impact on oil quality.Therefore,adsorption deoxygenation technology has devel-oped rapidly in various removal processes and has become a research hotspot in the cur-rent Fischer Tropsch oil deoxygenation.Adsorbents are the core of adsorption deoxygen-ation technology.Therefore,this article briefly introduces the adsorption mechanism and summarizes the research progress of adsorbents widely used in recent years,such as silica gel,alumina,molecular sieves,and metal organic frameworks,in adsorbing oxygen-containing compounds in Fischer Tropsch synthetic oils.And provide reference sugges-tions for further adsorption and deoxygenation directions in the future.

Adsorption behavior of activated carbon for the elimination of zearalenone during bleaching process of corn oil

Zearalenone is a mycotoxin produced by Fusarium species.It frequently contaminates cereals used for foods or animal feeds,especially deposited in crude corn oil.Certain amounts of zearalenone can be removed during refining processes.In this study,we studied the influence of activated carbon and six industial absorbents(zeolite,diatomite,attapulgite,perlite,montmorillonite and activated clay)on the elimination of zearalenone during bleaching process of corn oil and explored the absorption mechanism of activated carbon.Results showed that activated carbon had an excellent adsorption capacity of zearalenone compared with the other six industrial adsorbents.For activated carbon,a high removal rate of zearalenone(exceeding 83%)from heavily zearalenone-polluted corn oil was achieved and the removal rate of zearalenone was kept above 60%after five regeneration cycles.The research on the adsorption mechanism of activated carbon showed that Freundlich adsorption isotherm model and pseudo-second-order kinetic model could well described the adsorption process.The thermodynamic study demonstrated that adsorption process was spontaneous and exothermic.Fourier transform infrared spectroscopy and Raman spectroscopy further revealed that activated carbon was effectively combined with zearalenone viaπ-πinteraction.Thus,activated carbon is an efficient and suitable adsorbent to control the levels of zearalenone during bleaching process of corn oil.This study not only proposed a systematic research scheme for the mechanism study of activated carbon for the elimination of zearalenone in corn oil,but also provided the scientific basis for developing effective methods to eliminate zearalenone in refined vegetable oils.

Design, synthesis, and nanoengineered modification of spherical graphene surface by layered double hydroxide (LDH) for removal of As (Ⅲ) from aqueous solutions

In this study, new nano spherical graphene modified with LDH(Layered Double Hydroxide) was prepared and used to remove As(Ⅲ) ion from aqueous solutions. At first, graphene oxide was synthesized from graphite using a well-known Hammer method. The obtained graphene oxide solution was sprayed in octanol solution under different temperatures and sprayed speed as influenced variables. The structure and physical characterization of synthesized spherical graphene oxide were determined by various techniques,including FT-IR, N_(2) adsorption–desorption, SEM, TEM, and EDX. In the next step, the hydrothermal method was applied to deposition LDH on the spherical graphene oxide. The synthesized spherical graphene modified by LDH was used to remove As(Ⅲ) as a toxic heavy metal ion. The effect of influenced variables including p H, contact time, amount of sorbent, and type eluent studied and the optimum values were as 8, 30, 50, and HCl(0.5 mol·L^(-1)), respectively. After optimization, the studied sorbent was shown a high adsorption capacity(149.3 mg·g^(-1)). The adsorption mechanism and kinetic models exhibited good agreement with the Langmuir isotherm and pseudo-second-order trends, respectively. Besides, the synthesized product was tested for seven times without significant loss in its sorption efficiency.

Tailoring the separation performance of a carbon nanotube-based mixed matrix membrane decorated with metal–organic framework

Synthesis of mixed matrix membranes(MMM)using carbon nanotubes(CNTs)has shown great prospects for achieving excellent selective separation because of its special structure.Nevertheless,the preparation of highly selective MMM faces challenges,which is attributed to the obstacles encountered by CNTs dispersion in polymer matrix and elimination of interface defects.A novel CNT-based composite decorated with metal–organic framework(MOF)was synthesized and applied to the preparation of MMM.MOF was post modified,and then carboxyl groups were inserted on the outer surface of CNTs.The synthetic MMM(Cu-MOF-en@MWCNT)not only has selective adsorption on dyes,but also has selective photodegradation on dyes.The method of using CNTs to wrap the outside of MOF has great potential in dye separation.The performance of MMM was further improved by decorating MOF on the filler to improve the selectivity to the designated dye.

Role of intrinsic defects on carbon adsorbent for enhanced removal of Hg^(2+)in aqueous solution

Carbon is a normally used adsorbent for removal of heavy metal ion in aqueous solutions,but the efficient adsorbent needs intensive modification by heteroatom doped or supported noble metals that cause severe pollution and easy leaching of active components during use.In this paper,the role of intrinsic defects on Hg^(2+)adsorption for carbon adsorbent was investigated.The maximum adsorbing capacity of defectrich carbon has been improved up to 433 mg·g^(-1)which is comparable to most of the modified carbon adsorbents via supported metal chloride or noble metal components.The basicity is increased with the content of defective sites and the strong chemical bonding can be formed via electron transformation between the defect sites with adsorbed Hg^(2+).The present study gives a direction to explore cheap and easily scale-up high-performance mercury adsorbents by simply tuning the intrinsic defective structure of carbon without the necessity to support metal or other organic compounds.