Search

This study focuses on the comprehensive recycling and utilization of zinc ferrite, a by-product of wet zinc refining, for the treatment of azo dye wastewater. It explores the adsorption performance of various materials on Amido Black 10B and analyzes the factors that influence the adsorption process. Zinc ferrite derived from the by-products of wet zinc refining, zinc ferrite synthesized via calcination, and titanium dioxide prepared using the sol–gel method are utilized as adsorbents, specifically targeting Amido Black 10B. By adjusting factors such as calcination temperature, mixing ratio, initial pH, adsorbent dosage, adsorption time, initial concentration, and reaction temperature, the effects on the adsorption of Amido Black 10B are studied. Additionally, the performance of composite materials consisting of different crystalline forms of titanium dioxide and purified zinc ferrite is examined. Furthermore, the adsorption process of Amido Black 10B by purified zinc ferrite/titanium dioxide is analyzed in terms of kinetics and thermodynamics. The results show that titanium dioxide and purified zinc ferrite, prepared at temperatures of 300 °C to 550 °C, achieve over 90% removal efficiency when co-adsorbing Amido Black 10B. The best performance is observed at a ratio of 4:6 for purified zinc ferrite to titanium dioxide, with removal efficiency exceeding 80%. The second-order kinetic model fits the adsorption data well, and higher initial solution concentrations lead to decreased adsorption rates. The adsorption process of purified zinc ferrite/titanium dioxide on Amido Black 10B is spontaneous, exothermic, and reduces system disorder. Higher temperatures negatively impact the adsorption process. [ABSTRACT FROM AUTHOR]

In this study, methyl orange, methylene blue, and amido black 10B were removed as target dyes using purified, synthetic, and purchased zinc ferrite as adsorbents and photocatalysts. The highest removal rates of amido black 10B by these adsorbents ranged from 81.62% to 88.33%. The removal rate of methyl orange was approximately 1%, and the removal rate of methylene blue was approximately 2%. Hence, an investigation was conducted to elucidate the factors that influence the removal efficacy of purified zinc ferrite on amido black 10B. Titanium dioxide prepared at different calcination temperatures was unsuccessful in removing amido black 10B, but the physical mixing of titanium dioxide prepared at suitable calcination temperatures with purified zinc ferrite had a positive effect on amido black 10B removal. Since zinc ferrite could not be used as an adsorbent to remove methyl orange and methylene blue, the photocatalytic degradation properties of zinc ferrite and its influencing factors were studied. The optimal conditions for the photocatalytic degradation of methylene blue and methyl orange by zinc ferrite are as follows: a zinc ferrite catalyst dosage of 0.15 g, an initial solution concentration of 20 mg/L, and a pH of 6.0. The dosage of the zinc ferrite/titanium dioxide composite catalyst is 0.15 g, the initial solution concentration is 20 mg/L, and the pH is 6.5. [ABSTRACT FROM AUTHOR]

Utilising waste amine-oxime (WAO) resin through microwave semi-carbonization, a carbon adsorbent (CA) was obtained to remove Pb(II). After microwave treatment, the pore size of the skeleton structure, three-dimensional porous network, and lamellar pore structure of WAO was improved. The distribution coefficient (Kd) of Pb(II) onto CA is 620 mL/g, and the maximum adsorption capacity of Pb(II) is 82.67 mg/g after 20 min of WAO microwave treatment. The adsorption kinetics and adsorption isotherms conform to the quasi-second-order kinetic equation and Langmuir adsorption isotherm model, respectively. The surface of MT-WAO is negatively charged and the adsorption mechanism is mainly electrostatic interaction. Pb(II) elution in hydrochloric acid solution is more than 98%, and its recovery is high at 318 K and for 1 h. [ABSTRACT FROM AUTHOR]

[Display omitted] • Integration of reduction of dusts and preparation of porous carbon material. • Coupling mechanism between the coal and Zn-bearing dusts was clarified. • K, Na-embedded porous carbon material exhibited good NO adsorption capacity. • K and Na on porous carbon material promoted the chemisorption process of NO. • The solid waste was utilized to treat the NO-bearing flue gas. The increasingly generation of NO-containing flue gases and zinc-bearing dusts has posed huge pressure to the environment. A green process of integration of reduction of zinc-bearing dusts and preparation of porous carbon material with high NO adsorption capacity was developed and its mechanism was clarified in this paper. The reduced dusts with high content of iron (70.52 %) and low contents of harmful elements (0.017 % Zn, 0.015 % K and 0.026 % Na) could be used as high-quality raw material for ironmaking while the K, Na-embedded porous carbon material (APC) with surface area of 390.38 m2/g can be used as effective adsorbent for NO pollution control. The adsorption property and mechanism of NO on APC was investigated. It was found that the maximal removal rate of NO could reach 96.15 %, and the K, Na on porous carbon material could promote the chemisorption process of NO and increase the NO adsorption efficiency of APC. The hazardous waste was successfully utilized to treat the flue gas in this work. [ABSTRACT FROM AUTHOR]

In this study, a novel dual-cation organomontmorillonites (OMt) nanocomposite was synthesized by two kinds of modifiers cetyltrimethylammonium chloride and cysteamine hydrochloride, and the adsorption behavior of modifiers into montmorillonite (Mt) has been investigated. The OMt were characterized by techniques, such as X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, and thermogravimetric and differential thermal (TG-DTA) analyses. The effects of temperature, contact time, the order of addition and the concentration of organic modifiers on the amounts of organics adsorbed were investigated. The adsorption amount of cetyltrimethylammonium chloride (CTAC) and cysteamine hydrochloride (CSH) increased with the increase of the added CTAC amount and contact time, while the addition order of modifiers and modification temperature had no significant effect on the actual adsorption amount of CTAC and CSH on Mt, as confirmed by the XRD patterns. The experimentally determined isotherms showed a good fit with the Langmuir adsorption models. The adsorption kinetics demonstrated that the adsorption of CTAC and CSH by Mt followed the pseudo-second-order model, and CTAC adsorption rate on Mt was faster than that of CSH. FTIR spectrum clearly revealed the incorporation of surfactant ions into the interlayer region. The TG-DTA analyses showed that the total mass losses of OMt strongly depended on the molecular volume of modifiers. [ABSTRACT FROM AUTHOR]

Montmorillonite (Mt) is proposed as a promising adsorbent for removing contaminants from water, yet it is unclear whether and how the layer charge density (LCD) of Mt. affects its hydration properties, especially for the capturing performance of anions by polyelectrolyte modified Mt. Here, the feasibility and performance of perchlorate uptake by poly-(diallydimethylammonium chloride) (PDDA) functionalized Mt. (PDDA-Mt x) with different LCD were investigated. PDDA species were loaded via partial intercalation or adsorption on the surface/end sites of Mt. The CEC of Ca-Mt x increased with increasing LCD, while on the contrary for colloidal valence. The perchlorate uptake by Ca-Mt x can be significantly improved by introducing PDDA species. As expected, the PDDA-Mt 0.3 showed superior perchlorate capture of up to 0.80 mmol/g due to the relatively high positive zeta potential and loading of un-ionized PDDA. The perchlorate uptake by PDDA-Mt x still maintained largely despite a slight decrease in the presence of co-competing anions NO-3, SO2–4 and PO3–4. The capture behaviors were well characterized by the pseudo-second-order and Langmuir isotherm models, and the natures of spontaneous and endothermic were demonstrated by thermodynamic analysis. Anion exchange and electrostatic were the dominant ways in which perchlorate was captured onto PDDA-Mt x. [Display omitted] • PDDA modified montmorillonites (PDDA-Mt x) are prepared for ClO− 4 capture. • Hydration property and PDDA loading are affected by layer charge density of Ca Mt. • A maximum ClO− 4 uptake capacity of 0.80 mmol/g was achieved by PDDA-Mt 0.3. • Ion exchange between ClO− 4 and PDDA-Cl species drives adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyelectrolytes were successfully loaded on Mt with a positive surface potential. • PDDA+ intercalation speed was fast (<0.1 h) and desorption ratio was < 10 % after 48 h. • The adsorption performance was as follow: PDDA x -Mt > CH-Mt > PAM-Mt > PQ28-Mt. • PMt showed a superior adsorption selectivity to ClO 4 -. • Anion exchange played a crucial role in the ClO 4 - adsorption processing onto PMt. Polyelectrolyte (with different unit structure or molecular weight) modified montmorillonite (PMt) was synthesized for perchlorate (ClO 4 -) removal. It was found polyelectrolytes were successfully loaded on montmorillonite (Mt), and the surface potential of most PMt changed from negative to positive. Polyelectrolyte desorption on Mt was < 10 % after 48 h. Poly(diallyldimethylammonium chloride) species modified montmorillonite (PDDA x -Mt) showed excellent adsorption performance for ClO 4 - with maximum adsorption amount over 2.78 mmol/g and equilibrium time within 10 min. The adsorption performance of PMt toward ClO 4 - followed this order: PDDA x -Mt > CH-Mt > PAM-Mt > PQ28-Mt. Moreover, PDDA x -Mt and CH-Mt showed a superior adsorption selectivity to ClO 4 - among competitive oxyanions in the quaternary-adsorbate system (ClO 4 - > PO 4 3- > SO 4 2- > NO 3 –). The enhanced ClO 4 - adsorption could be mainly attributed to the presence of anion exchange sites (−R 4 N+-Cl− or –NH 3 +-Cl−) provided by PDDA or CH, followed by electrostatic gravitation and weak hydrogen bonding interaction. Density functional theory (DFT) calculation revealed that ClO 4 - adsorbed on PMt is a process of electrons transferring from O atoms in ClO 4 - to H atoms on C in PDDA+ or N in CH+, PAM+ and PQ28+. The preparation method of PMt is simple with excellent adsorption performance and selectivity toward ClO 4 -, suggesting promising applications in anion wastewater treatment. [ABSTRACT FROM AUTHOR]

Single- or dual-cation organomontmorillonites (OMt) modified by one or two cationic surfactants, respectively and/or cysteamine hydrochloride (CSH) were used to remove Zn 2 + and/or phenol from aqueous solutions. The OMt were characterized by XRD, FTIR spectroscopy and N 2 adsorption-desorption isotherm analyses. The adsorption results of Zn 2 + and phenol showed that OMt had much larger adsorption capacities of phenol than that of Na + -Mt or CSH-Mt in the presence of Zn 2 + . Experiments with the simultaneous presence of both the contaminants showed that one did not affect the adsorption of the other with all the adsorbents. The uptakes of Zn 2 + and phenol onto dual-cation OMt increased with increasing solution pH, contact time, temperature and initial concentration of Zn 2 + and phenol. The adsorption equilibrium time was 10 min for both contaminants and the maximum adsorption capacities of Zn 2 + and phenol were found under alkaline environment. The adsorption of both Zn 2 + and phenol can be better described by Freundlich model than Langmuir isotherm. Phenol adsorption onto OMt was caused primarily by partitioning into an organic phase in the interlayers, and the uptakes of phenol increased with increasing alkyl chain length and loading amount of surfactant in single-cation OMt. Zn 2 + adsorption onto dual-cation OMt was due to ion exchange, formation of complexes and/or precipitation mechanism depending on the solution pH. [ABSTRACT FROM AUTHOR]

Hydroxy-Al pillaring agent was prepared and used to modify montmorillonite (Mt), and the effects of temperature, initial Al 3 + concentration and contact time were investigated by using a batch technique. The results showed that the uptake of Al 13 by Mt increased with increasing temperature, initial Al 3 + concentration and contact time. The adsorption equilibrium was achieved in 12 h as determined by kinetics. The adsorption kinetics demonstrated that the adsorption of Al 13 by Mt followed the pseudo-second-order kinetic model. The adsorption isotherms at the temperatures of 40, 60, 80 and 90 °C were determined and simulated using Langmuir, Freundlich and Redlich-Peterson models. The three kinds of isotherms could represent the experimental data well. The specific surface areas and pillar density increased while the total porous volumes slightly decreased with increasing Al 3 + concentrations. The XRD result showed that adsorbed Al 13 ions were located in the Mt interlayer spaces through monolayer adsorption. Thermodynamic analysis of adsorption process showed that the adsorption of Al 13 by Mt was spontaneous, endothermic with increasing disorder during the adsorption process and mainly physical in nature. [ABSTRACT FROM AUTHOR]

Various montmorillonite (Mt) nanocomposite adsorbents were prepared with Al 13 cations, dodecyl trimethyl ammonium chloride (DTAC) or dodecyl amine (DA) and characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and BET surface area and pore size analyses. The adsorption of hexavalent chromium, Cr(VI) onto various Mt nanocomposites as a function of adsorbent dosage, initial Cr(VI) concentration, contact time and solution pH was investigated. The results showed that the obtained nanocomposites had large basal spacing and good porous structure, and the specific surface areas followed the order: OH-Al-Mt > DA-Al-Mt > DTAC-Al-Mt > Na + -Mt > DTAC-Mt > DA-Mt. The removal efficiency of Cr(VI) ions increased with increasing the adsorbent dosage and contact time, but decreased with increasing initial Cr(VI) concentration, as expected. The adsorption of Cr(VI) was highly pH-dependent and the maximum removal efficiency of Cr(VI) was found in the acid environment. The adsorption equilibrium time was 2 h and the adsorption kinetic data of Cr(VI) on various adsorbents were well described by the pseudo-second-order kinetics model, which indicated that the adsorption reaction of Cr(VI) ions with the adsorbents was mainly due to chemical adsorption. Both the Langmuir model and Freundlich model fitted the equilibrium data well, which suggested that the Cr(VI) adsorption onto various adsorbents was both as monolayer and on heterogeneous surface conditions. The adsorption results indicated that among all the adsorbents used in this experiment, the dodecyl amine and Al 13 cations composited with Mt (DA-Al-Mt) was the most effective for removing Cr(VI) from wastewater. [ABSTRACT FROM AUTHOR]