Metal-containing organic compounds for memory and data storage applications.

With the upcoming trend of Big Data era, some new types of memory technologies have emerged as substitutes for the traditional Si-based semiconductor memory devices, which are encountering severe scaling down technical obstacles. In particular, the resistance random access memory (RRAM) and magnetic random access memory (MRAM) hold great promise for the in-memory computing, which are regarded as the optimal strategy and pathway to solve the von Neumann bottleneck by high-throughput in situ data processing. As far as the active materials in RRAM and MRAM are concerned, organic semiconducting materials have shown increasing application perspectives in memory devices due to their rich structural diversity and solution processability. With the introduction of metal elements into the backbone of molecules, some new properties and phenomena will emerge accordingly. Consequently, the RRAM and MRAM devices based on metal-containing organic compounds (including the small molecular metal complexes, metallopolymers, metal-organic frameworks (MOFs) and organic-inorganic-hybrid perovskites (OIHPs)) have been widely explored and attracted intense attention. In this review, we highlight the fundamentals of RRAM and MRAM, as well as the research progress of the applications of metal-containing organic compounds in both RRAM and MRAM. Finally, we discuss the challenges and future directions for the research of organic RRAM and MRAM.

Highly efficient P uptake by Fe3O4 loaded amorphous Zr-La (carbonate) oxides: Electrostatic attraction, inner-sphere complexation and oxygen vacancies acceleration effect.

Bimetallic oxides composites have received an increasing attention as promising adsorbents for aqueous phosphate (P) removal in recent years. In this study, a novel magnetic composite MZLCO was prepared by hybridizing amorphous Zr-La (carbonate) oxides (ZLCO) with nano-Fe3O4 through a one-pot solvothermal method for efficient phosphate adsorption. Our optimum sample of MZLCO-45 exhibited a high Langmuir maximum adsorption capacity of 96.16 mg P/g and performed well even at low phosphate concentration. The phosphate adsorption kinetics by MZLCO-45 fitted well with the pseudo-second-order model, and the adsorption capacity could reach 79% of the ultimate value within the first 60 min. The phosphate adsorption process was highly pH-dependent, and MZLCO-45 performed well over a wide pH range of 2.0-8.0. Moreover, MZLCO-45 showed a strong selectivity to phosphate in the presence of competing ions (Cl-, NO3-, SO42-, HCO3-, Ca2+, and Mg2+) and a good reusability using the eluent of NaOH/NaCl mixture, then 64% adsorption capacity remained after ten recycles. The initial 2.0 mg P/L in municipal wastewater and surface water could be efficiently reduced to below 0.1mg P/L by 0.07 g/L MZLCO-45, and the phosphate removal efficiencies were 95.7% and 96.21%, respectively. Phosphate adsorption mechanisms by MZLCO-45 could be attributed to electrostatic attraction and the inner-sphere complexation via ligand exchange forming Zr/La-O-P, -OH and CO32- groups on MZLCO-45 surface played important roles in the ligand exchange process. The existence of oxygen vacancies could accelerate the phosphate absorption rate of the MZLCO-45 composites.

Phosphate removal by a La(OH)3 loaded magnetic MAPTAC-based cationic hydrogel: Enhanced surface charge density and Donnan membrane effect.

Cationic hydrogels have received great attention to control eutrophication and recycle phosphate. In this study, a type of La(OH)3 loaded magnetic MAPTAC-based cationic hydrogel (La(OH)3@MMCH) was developed as a potential adsorbent for enhanced phosphate removal from aqueous environment. La(OH)3@MMCH exhibited high adsorption capacity of 105.72±5.99 mg P/g, and reached equilibrium within 2 hr. La(OH)3@MMCH could perform effectively in a wide pH range from 3.0 to 9.0 and in the presence of coexisting ions (including SO42-, Cl-, NO3-, HCO3-, SiO44- and HA). The adsorption-desorption experiment indicated that La(OH)3@MMCH could be easily regenerated by using NaOH-NaCl as the desorption agent, and 73.3% adsorption capacity remained after five cycles. Moreover, La(OH)3@MMCH was employed to treat surface water with phosphate concentration of 1.90  mg/L and showed great removal efficiency of 95.21%. Actually, MMCH showed high surface charge density of 34.38-59.38 meq/kg in the pH range from 3.0 to 11.0 and great swelling ratio of 3014.57% within 24 h, indicating that MMCH could produce the enhanced Donnan membrane effect to pre-permeate phosphate. Furthermore, the bifunctional structure of La(OH)3@MMCH enabled it to capture phosphate through electrostatic attraction and ligand exchange. All the results prove that La(OH)3@MMCH is a promising adsorbent for eutrophication control and phosphate recovery.

Nitrate removal from aqueous solutions by magnetic cationic hydrogel: Effect of electrostatic adsorption and mechanism.

Excessive nitrate (NO3-) is among the most problematic surface water and groundwater pollutants. In this study, a type of magnetic cationic hydrogel (MCH) is employed for NO3- adsorption and well characterized herein. Its adsorption capacity is considerably pH-dependent and achieves the optimal adsorption (maximum NO3--adsorption capacity is 95.88 ± 1.24 mg/g) when the pH level is 5.2-8.8. The fitting result using the homogeneous surface diffusion model indicates that the surface/film diffusion controls the adsorption rate, and NO3- approaches the center of MCH particles within 30 min. The diffusion coefficient (Ds) and external mass transfer coefficient (kF) in the liquid phase are 1.15 × 10-6 cm2/min and 4.5 × 10-6 cm/min, respectively. The MCH is employed to treat surface water that contains 10 mg/L of NO3-, and it is found that the optimal magnetic separation time is 1.6 min. The high-efficiency mass transfer and magnetic separation of MCH during the adsorption-regeneration process favors its application in surface water treatment. Furthermore, the study of the mechanism involved reveals that both -N+(CH3)3 groups and NO3- are convoluted in adsorption via electrostatic interactions. It is further found that ion exchange between NO3- and chlorine occurs.

Brilliant red X-3B uptake by a novel polycyclodextrin-modified magnetic cationic hydrogel: Performance, kinetics and mechanism.

A novel polycyclodextrin-modified magnetic cationic hydrogel (PCD-MCH) was developed and its performance, kinetics and mechanism for the removal of reactive brilliant red X-3B (X-3B) were studied. The results showed that the zeta-potential of PCD-MCH was 32.8 to 16.7mV at pH3.0-10.5. The maximum X-3B adsorption capacity of PCD-MCH was 2792.3mg/g. The adsorption kinetics could be well-described by the Weber-Morris model and the homogeneous surface diffusion model (HSDM). Diffusion stages corresponding to surface or film diffusion, intra-particle or wide mesopore diffusion, and narrow mesopore/micropore diffusion occurred at 0-120, 120-480 and 480-1200min, respectively. The latter two diffusion stages were rate-controlling for X-3B adsorption kinetics. At the initial X-3B concentration of 600mg/L, the diffusion coefficient (Ds) and external mass transfer coefficient in the liquid phase (kF) were 3×10-11cm2/min and 4.68×10-6cm/min, respectively. X-3B approaching the center of PCD-MCH particles could be observed at 360min. At the end of the third diffusion stage, the Cp at q/qe=0 was 45.20mg/L, which was close to the homogeneous Cp value of 46mg/L along the radius of PCD-MCH particles. At pH3.0-10.0, PCD-MCH showed stable X-3B adsorption capacities. After five regeneration-reuse cycles, the residual adsorption capacity of regenerated PCD-MCH was higher than 892.7mg/g. The corresponding adsorption mechanism was identified as involving electrostatic interactions, cyclodextrin cavities and hydrogen bonds, of which cyclodextrin cavities showed prominent capture performance towards dye molecules through the formation of inclusion complexes.

Dye removal by eco-friendly physically cross-linked double network polymer hydrogel beads and their functionalized composites.

Hydrogels have attracted large attention in wastewater treatment fields due to their low-cost and good interaction with pollutants, among which novel double network hydrogel is an outstanding class. To expand the application of double network hydrogel in water treatment, in this study, eco-friendly physically cross-linked double network polymer hydrogel beads (DAP) are prepared and studied in depth on the mechanism of Methylene Blue (MB) adsorption; and then the polymer hydrogels are further functionalized by inorganic materials. MB adsorption on DAP favors alkaline condition which is due to the increase of electrostatic attraction and adsorption site, and it reaches equilibrium within 10 hr, which is faster than that of the single network hydrogel beads (SAP). Through thermodynamics study, the process shows to be an exothermic and spontaneous process. The adsorption isotherms are well fitted by Langmuir model, with a maximum monolayer adsorption capacity of 1437.48 mg/g, which is larger than SAP (1255.75 mg/g). After being functionalized with common inorganic materials including activated carbon, Fe3O4 and graphene oxide (GO), the composites show to have larger pore sizes and have obvious increases in adsorption capacity especially the one contains GO. Then the composites contains Fe3O4 are used as heterogeneous Fenton catalyst which shows to have excellent performance in MB degradation. The results indicate the potential of polymer double network to be functionalized in environmental areas.

Strong enhancement of methylene blue removal from binary wastewater by in-situ ferrite process.

Dye wastewater containing heavy metal ions is a common industrial effluent with complex physicochemical properties. The treatment of metal-dye binary wastewater is difficult. In this work, a novel in-situ ferrite process (IFP) was applied to treat Methylene Blue (MB)-Cu(II) binary wastewater, and the operational parameters were optimized for MB removal. Results showed that the optimum operating conditions were OH/M of 1.72, Cu2+/Fe2+ ratio of 1/2.5, reaction time of 90min, aeration intensity of 320mL/min, and reaction temperature of 40°C. Moreover, the presence of Ca2+ and Mg2+ moderately influenced the MB removal. Physical characterization results indicated that the precipitates yielded in IFP presented high surface area (232.50m2/g) and a multi-porous structure. Based on the Langmuir model, the maximum adsorption capacity toward MB was 347.82mg/g for the precipitates produced in IFP, which outperformed most other adsorbents. Furthermore, IFP rapidly sequestered MB with removal efficiency 5 to 10 times greater than that by general ferrite adsorption, which suggested a strong enhancement of MB removal by IFP. The MB removal process by IFP showed two different high removal stages, each with a corresponding removal mechanism. In the first brief stage (<5min), the initial high MB removal (~95%) was achieved by predominantly electrostatic interactions. Then the sweep effect and encapsulation were dominant in the second longer stage.

Boron-Doped Engineering for Carbon Quantum Dots-Based Memristors with Controllable Memristance Stability.

Carbon quantum dots-based memristors (CQDMs) have emerged as a rising star in data storage and computing. The key constraint to their commercialization is memristance variability, which mainly arises from the disordered conductive paths. Doping methodology can optimize electron and ion transport to help construct a stable conductive mode. Herein, based on boron (B)-doped engineering strategy, three kinds of comparable quantum dots are synthesized, including carbon quantum dots (CQDs), a series of boron-doped CQDs (BCQDs) with different B contents, and boron quantum dots. The corresponding device performances highlight the superiority of BCQDs-based memristors, exhibiting a ternary flash-type memory behavior with longer retention time and more controllable memristance stability. The comprehensive analysis results, including device performance, functional layer morphology, and material simulated calculation, illustrate that the doped B elements can directionally guide the migration of aluminum ions by enhancing the capture of free electrons, resulting in ordered conductive filaments and stable ternary memory behavior. Finally, the conceptual applications of logic display and logic gate are discussed, indicating a bright prospect for BCQDs-based memristors. This work proves that modest B doping can optimize memristance property, establishing a theoretical foundation and template scheme for developing effective and stable CQDMs.

Occurrence of metals, phthalate esters, and perfluoroalkyl substances in cellar water and their relationship with bacterial community in rural areas of China.

Water cellars are traditional rainwater harvesting facilities that have been widely used in rural areas of northwest China. However, there are few reports about the water quality and health risk caused by the cellar water, especially phthalate esters (PAEs) and perfluoroalkyl substances (PFASs). This study investigated and assessed the health risks caused by the metals, PAEs, PFASs and bacterial communities in cellar water. The results showed that the turbidity and total number of bacterial colonies ranged from 4.7 to 58.5 NTU and 5-557 CFU/mL, respectively. The turbidity and total number of bacterial colonies were the main water quality problems. Due to high concentration of Tl (0.005-0.171 µg/L), the samples reached a high level of metal pollution. PAEs showed no non-carcinogenic and carcinogenic risk. The perfluorobutanoic acid (PFBA), perfluorobutanesulfonic acid (PFBS), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS) were the main components of PFASs. PFOA and PFOS reached a moderate risk level in many cellar water samples. Moreover, Tl, Pb, As, PFBA and PFBS could change the bacterial community composition and induce the enrichment of bacterial functions related to human diseases. Besides these parameters, dissolved oxygen (DO) also affected the bacterial functions related to human diseases. Therefore, more attention should be paid to turbidity, DO, Tl, Pb, As, PFOA, PFOS, PFBA and PFBS in the cellar water. These results are meaningful for the water quality guarantee and health protection in rural areas of China.

Rapid and selective harvest of low-concentration phosphate by La(OH)3 loaded magnetic cationic hydrogel from aqueous solution: Surface migration of phosphate from -N+(CH3)3 to La(OH)3.

Phosphate is an important factor for the occurrence of surface water eutrophication, and is also a non-renewable resource which faces a potential depletion crisis. In this study, La(OH)3 loaded magnetic cationic hydrogel composite MCH-La(OH)3-EW was used to absorb low strength phosphate in simulated water and real water. The adsorption amount of MCH-La(OH)3-EW was 39.14 ± 0.31 mg P/g and the equilibrium time was 120 min at the initial phosphate concentration of 2.0 mg P/L. The adsorption process was a spontaneous endothermic reaction. MCH-La(OH)3-EW exhibited a high selectivity towards phosphate within pH of 4.0-10.0 or in the presence of co-existing ions (including Cl-, SO42-, NO3-, HCO3-, SiO32-) and humic acid. After 10 cycles of adsorption-desorption, the adsorption amount of regenerated MCH-La(OH)3-EW still remained at 63.4% of its maximum value. For the real water sample with phosphate concentration of 2.0 mg P/L, the phosphate removal efficiency could achieve 97.65-98.90% and the effluent turbidity was 2.10-4.27 NTU at the MCH-La(OH)3-EW dosage of 0.04 g/L. The adsorption mechanism analysis showed that both quaternary amine groups (-N+(CH3)3) and La(OH)3 of MCH-La(OH)3-EW were involved in the process of phosphate adsorption. The electrostatic interaction between phosphate and -N+(CH3)3 rapidly occurred at the initial stage of adsorption process, then the electrostatic absorbed phosphate migrated to La(OH)3 on the surface of MCH-La(OH)3-EW via ligand exchange to form inner-sphere complex. This phenomenon was conducive to phosphate adsorption kinetics by MCH-La(OH)3-EW.

Rapid prediction of the activated carbon adsorption ratio by a regression model.

Regression analysis of micropore volume and particle size of powdered activated carbon (PAC) is applied to develop a model to predict the adsorption ratio of a non-polar compound, 2-methylisorneol (2-MIB), onto PACs. This model likewise predicts the adsorption ratio of the same PACs and other PACs in background water containing similar natural organic matter (NOM). When this model is used to predict the same PACs adsorption ratios at 30 and 50 mg L-1, the respective percent sample deviations standard error (SDEV) is of 30% SDEV and 12% were obtained. Further, the model is also employed for the prediction of 2-MIB adsorption capacities for 12 different PACs in water with similar NOM at the same dosages, with average SDEV values of 44% and 28%, respectively. Results indicate that 2-MIB adsorption occurrs mainly through the micropore filling mechanism. Nevertheless, when this model is expanded to predict PAC adsorption of NOM with different properties in water, the results exhibited rather large errors. Though this model cannot be applied to waters containing NOM with different properties, it provides information for water utilities themselves or the ones using similar source water to predict the PAC dosage without any adsorption experiment when change of PAC is needed.

Identifying the function of activated carbon surface chemical properties in the removability of two common odor compounds.

In this study, the adsorption capacities of two common odor compounds, 2-methylisoborneol (2-MIB) and dimethyl disulfide (DMDS), onto nine common types of powdered activated carbon (PAC) were comprehensively compared to screen the critical surface chemical properties affecting the adsorption performance. The results showed that the adsorption capacities of all the PACs for DMDS were generally lower than those for 2-MIB. The Spearman's rank correlation analysis indicated that the adsorption capacity for 2-MIB did not have any correlation with the PAC surface sites, while the DMDS adsorption capacity was positively related to the number of basic sites. The effect of the PAC basic sites on the DMDS adsorption was further verified by density functional theory (DFT) calculation in two adsorption modes (facial mode and edge mode). The graphene structure in the edge mode was the most favorable for DMDS adsorption with the lowest adsorption enthalpy, followed by the ketone-doped structure under the facial mode. An independent gradient model indicated that van der Waals forces were dominant in the DMDS adsorption. Moreover, thermal modification was conducted to further prove the relationship between the basic sites and the DMDS adsorption. After thermal modification, the PAC with more basic sites and graphene structures was found to be more effective for DMDS adsorption. Overall, this study could offer guidance for water treatment plants with respect to the selection of PAC to solve the odor problems caused by various compounds (e.g., DMDS or 2-MIB), and the modification of PAC, aiming at more efficient odor removal.

NaLa(CO3)2 hybridized with Fe3O4 for efficient phosphate removal: Synthesis and adsorption mechanistic study.

Effectively eutrophication control and phosphate recovery have received increasing attention in recent years. In this study, a regenerable magnetic NaLa(CO3)2/Fe3O4 composites (MLC) which includes a novel phosphate-binding lanthanum species NaLa(CO3)2 hybridized with Fe3O4 nanoparticle was developed through a modified solvothermal method for phosphate removal from contaminated water. Based upon preliminary screening of synthesized MLC with different La-to-Fe molar ratios in terms of phosphate adsorption capacity and synthetic product yield, a MLC composite with a La-to-Fe molar ratio of 2:1 (MLC-21) was selected for further characterization and evaluation. MLC-21 exhibits a high magnetic separation efficiency of 97%, high phosphate adsorption capacity of 77.85 mg P/g, wide applicable scope of pH ranging from 4 to 11, excellent selectivity for phosphate in the presence of competing ions (Cl-, NO3-, HCO3-, SO42-, Ca2+, and Mg2+), good reusability with above 98% desorption efficiency using NaOHNaCl mixture and 83% adsorption capacity remained during five recycles. Furthermore, a real effluent wastewater with phosphate concentration of 1.96 mg P/L was used to verify the performance of MLC-21 through a magnetic separation integrated system (AMSS). By using the response surface methodology (RSM), the optimum parameters were determined to be 0.26 g/L of adsorbent dosage, 26.28 h of adsorption time and 24.12 min of magnetic separation time for meeting the phosphate emission standard of 0.5 mg P/L. The phosphorus in three representative eutrophic water bodies can be efficiently reduced to below 0.1 mg P/L by MLC-21 adsorption at different dosages. Electrostatic attraction and the inner-sphere complexation between La(HCO3)2+/La(CO3)2- and P via ligand exchange forming LaPO4 were responsible for the phosphate adsorption mechanisms of MLC.

Powdered activated carbon enhanced Manganese(II) removal by chlorine oxidation.

Chlorine is not effective in the oxidative removal of soluble manganese(II) ions at neutral pH. Powdered activated carbon (PAC) also has a very limited capacity for Mn(II) removal through adsorption in drinking water treatment practice. This study explored the combined use of PAC and chlorine for Mn(II) removal and found that PAC dramatically catalyzed Mn(II) oxidation by chlorine under diverse conditions. At a dose as low as 5.0 mg/L, two different commercial PACs increased Mn(II) oxidation rate by two orders of magnitude respectively and reduced Mn(II) concentration from 200 µg/L to < 10 µg/L in tens of minutes. First-order kinetics with respect to aqueous Mn(II) concentration were observed. Typically, homogeneous Mn(II) oxidation by chlorine depends strongly on alkaline pH. In the presence of PAC, however, the reaction was still rather fast at pH 6.0. Increasing PAC doses linearly increased Mn(II) oxidation rate, indicating that the reaction was highly PAC surface active sites dependent. The efficacy of PAC was further corroborated in removing Mn(II) from natural water. SEM-EDS and XPS demonstrated that a MnO2 coating was formed on PAC surface after reaction, which resulted from heterogeneous oxidation of Mn(II) on PAC surface rather than the precipitation of Mn oxides formed through homogeneous oxidation in solution. Adsorption of free Mn(II) ions onto PAC surface was proved to directly correlate with Mn(II) oxidation rate. Two kinds of electron transfer pathways from adsorbed Mn(II) species to chlorine, enhanced by surface-complexation and electrically-conductive carbon surface respectively, were hypothesized.

Reduction of organic matter and disinfection byproducts formation potential by titanium, aluminum and ferric salts coagulation for micro-polluted source water treatment.

Typical Chinese source water has high content of low molecular weight and aromatic protein-like organic matter which is difficult to remove and poses a great challenge to conventional coagulation/flocculation. To investigate coagulation performance of this typical water, this research focused on organic matter removal characteristics and the associated disinfection byproducts formation potentials (DBPFPs) during the coagulation process by titanium salts compared with traditional aluminum and ferric salts. Results showed that based on the dissolved organic matter (DOM) removal, the optimal coagulant dosages of AlCl3, FeCl3 and TiCl4 were 0.5 mM and the optimal initial pH values were 8, indicating that the DOM in the typical Chinese water could be effectively removed through sweeping and adsorption by metal hydroxides rather than the complexation and charge neutralization effect under acidic conditions. Compared these three coagulants, the highest ultra violet absorbance at 254 nm removal rate of 72.9% was achieved by TiCl4. The three-dimensional excitation emission matrix results showed that the removal ability of humic acids by AlCl3 was poorer than FeCl3 and TiCl4. The removal rate of low molecular weight components (1600 Da) by TiCl4 was 20% higher than using AlCl3 and 14% higher than FeCl3. Comparing with AlCl3 and FeCl3, TiCl4 had a better performance on the control of DBPFPs, especially for chloroform and dichloroacetic acid, due to its higher removal ability of aromatic organics. The trihalomethane formation potentials removal rate by TiCl4 was three times higher than that by AlCl3 and twice by FeCl3, by which could be inferred that titanium salts achieved better removal of low molecular weight organic matter than aluminum and ferric salts.

Simultaneous cationic Cu (II)‒anionic Sb (III) removal by NH2-Fe3O4-NTA core-shell magnetic nanoparticle sorbents synthesized via a facile one-pot approach.

In this study, a regenerable magnetic core-shell nanoparticles NH2-Fe3O4-NTA which include 3-aminopropyltriethoxysilane (APTES) and nitrilotriacetic acid (NTA) crosslinked to Fe3O4 was developed by one-pot method for simultaneous removal of cationic and anionic metals. Another nanocomposite NH2-Fe3O4-NTAII was prepared by multi-step method for comparison. NH2-Fe3O4-NTA had positive zeta potential values of 35.1-0.8 mV at pH 1.8-11.0, with the saturation magnetization and surface area up to 40.56 emu/g and 56.94 m2/g, respectively. The maximum sorption capacities of NH2-Fe3O4-NTA for cationic Cu (II) and anionic Sb (III) were 55.56 and 51.07 mg/L, respectively, which were superior to that of NH2-Fe3O4-NTAII. Based on screening in terms of characterization and metal sorption capacity, NH2-Fe3O4-NTA with a feasible synthesis scheme was chosen for further evaluation. The Cu (II) removal by NH2-Fe3O4-NTA was favored with increasing pH, while the Sb (III) removal preferred low pH (2-3). Simultaneous sorption of Cu (II) and Sb (III) exhibited same removal performance with the sole sorption under high dosage (>1 g/L). In real wastewater applications of NH2-Fe3O4-NTA, multiple metals in actual wastewater could be removed to well below the regulation levels. Nonspecific electrostatic interactions, inner-sphere complexation, ligand exchange, chelation and coordination complexation were responsible for Cu (II) and Sb (III) removal.

Evaluation of the treatability of various odor compounds by powdered activated carbon.

This study focused on evaluating the use of powdered activated carbon (PAC) adsorption for the treatability of various odor compounds with different structures. The adsorption performance of 14 odor compounds under various PAC dosages were fitted with two isotherm models (the Langmuir and Freundlich models) to evaluate the adsorption ability. The results indicated that the adsorption capacities estimated from isotherm model predictions were not suitable for the evaluation of treatability of the odor compound due to the neglection of odor threshold. A novel assessment method, through the comparison of the residual concentration at an inflection point (where the downward trend of the odor compound residual concentration and PAC dosage curve starts to flatten) and the corresponding threshold concentration, was employed. This assessment method considered the different thresholds of the various odor compounds and their absorbability by PAC as well as the cost. The results indicated that only the sulfur odor compounds, including dimethyl disulfide, diethyl disulfide and dimethyl trisulfide, were not suitable for PAC treatment. Other odor compounds could be treated by PAC with varying success. The correlations between the adsorption capacity and the treatability of various odor compounds and their properties, including the coefficient between octanol and water (LogKw), solubility, molar refractivity (MR), dipole and volume, were also evaluated using the Pearson and Spearman correlation analysis. The results indicated that there were not significant correlations between the adsorption capacity and the properties of the odor compounds, while there were significant correlations between the treatability and LogKw, MR and volume. The odor causing compound with a larger LogKw, MR and volume was more suitable to be treated by PAC.

[Adsorption of Methylene Blue and Cu(â ¡) by Activated Carbon/Macromolecule Composite Hydrogel].

Activated carbon/alginate/poly(vinyl alcohol) composite macromolecule hydrogels (CAP) were prepared as adsorbents to study their adsorption performance for methylene blue (MB) and Cu2+ in aqueous solution. The effect of dosage, pH, temperature, contact time, and initial concentrations of MB and Cu2+ on the adsorption process was investigated. SEM, FTIR, and BET analyses were conducted to identify the physicochemical properties of CAP. The results indicated that activated carbon was successfully loaded into the interconnected 3D porous network and CAP had rich -COOH and -OH groups. The surface area of the composite hydrogel was 112.7 m2·g-1. With the dosage and temperature increase, the adsorbed amount of MB and Cu2+ on CAP decreased, while with the increase in pH, the adsorbed amount increased. The adsorption isotherm was fitted to the Langmuir equation and the maximum monolayer adsorption capacities of MB and Cu2+ on CAP were 1940.75 and 190.48 mg·g-1, respectively. The adsorption was a fast process and 90% of the maximum adsorption capacity could be reached in 5 h. The kinetic data were fitted to the pseudo-second-order kinetic model reasonably well. CAP had excellent adsorption properties after five times of regeneration.

[Treating Simulated Dye Wastewater by an In Situ Copper Ferrite Process].

Four types of simulated dye wastewater containing methylene blue, tartrazine, Congo red, and crystal violet were treated by an in situ copper ferrite process, and the influencing factors of the operational parameters in this process were studied. The main mechanism of dye removal was suggested by reaction thermodynamics and solid products characterization for methylene blue removal. The results showed that an in situ copper ferrite process could effectively remove four kinds of simulated dyes by adjusting reaction conditions appropriately. The maximum capacities of the in situ copper ferrite process for methylene blue, crystal violet, tartrazine, and Congo red were 349.2, 382.2, 402.5 and 831.8 mg·g-1, respectively, under reaction condition of c(Cu2+) of 0.01 mol·L-1, c(Fe2+) of 0.025 mol·L-1, c(OH)/c(M)=1.7 (hydroxyl and metal molar ratio), reaction temperature of 40℃, and reaction time of 60 min. Comprehensive physical interactions, including a sweeping effect, encapsulation, and high active surface adsorption of the in situ Fe-Cu precipitates were the dominant mechanisms in dye removal by the process. Copper ferrite, as an effective magnetic adsorbent and a highly efficient environmental catalyst, was regenerated by magnetic separation, catalytic oxidation, and high temperature calcination.