重金属杂质对磷酸铵镁结晶法处理制药废水的影响

磷酸铵镁沉淀法处理废水时常受众多因素影响,其中重金属类杂质对该过程影响较大。实验研究了Mn²⁺、Cu²⁺杂质存在条件下,用该法去除制药废水中PO₄^3-、NH₄⁺污染物,同时,用XRD、XRF、SEM等手段研究了所得鸟粪石晶体特征。结果表明,pH为9.5时,Mn²⁺、Cu²⁺杂质存在条件下,PO₄^3-去除率分别为88%和85%,投加晶种有利于回收特定晶形鸟粪石,Cu²⁺对磷酸铵镁结晶过程的影响较Mn²⁺存在时显著。     

Kinetics and the mass transfer mechanism of hydrogen sulfide removal by biochar derived from rice hull

The biochar derived from rice hull was evaluated for its abilities to remove hydrogen sulfide (H₂S) from gas phase. The surface area and pH of the biochar were compared. The biochar derived from rice hull was evaluated for its abilities to remove hydrogen sulfide (H₂S) from gas phase. The surface area and pH of the biochar were compared. The different pyrolysis temperature has great influence on the adsorption of H₂S. At the different pyrolysis temperature, the H₂S removal efficiency of rice hull-derived biochar was different. The adsorption capacities of biochar were 2.09 mg·g^–1, 2.65 mg·g^–1, 16.30 mg·g^–1, 20.80 mg·g^–1, and 382.70 mg·g^–1, which their pyrolysis temperatures were 100 °C, 200 °C, 300 °C, 400 °C and 500 °C respectively. Based on the Yoon-Nelson model, it analyzed the mass transfer mechanism of hydrogen sulfide adsorption by biochar.

Implications: The paper focuses on the biochar derived from rice hull–removed hydrogen sulfide (H₂S) from gas phase. The surface area and pH of the biochar were compared. The different pyrolysis temperatures have great influence on the adsorption of H₂S. At the different pyrolysis temperatures, the H₂S removal efficiency of rice hull–derived biohar was different. The adsorption capacities of biochar were 2.09, 2.65, 16.30, 20.80, and 382.70 mg·g^?1, and their pyrolysis temperatures were 100, 200, 300, 400, and 500 °C, respectively. Based on the Yoon-Nelson model, the mass transfer mechanism of hydrogen sulfide adsorption by biochar was analyzed.     

Cadmium (Cd2+) removal by nano zerovalent iron: surface analysis, effects of solution chemistry and surface complexation modeling

Nano zerovalent iron (nZVI) is an effective remediant for removing various organic and inorganic pollutants from contaminated water sources. Batch experiments were conducted to characterize the nZVI surface and to investigate the effects of various solution properties such as pH, initial cadmium concentration, sorbent dosage, ionic strength, and competitive ions on cadmium removal by nZVI. Energy-dispersive X-ray and X-ray photoelectron spectroscopy results confirmed removal of Cd²⁺ ions by nZVI through adsorption. Cd²⁺ adsorption decreased in the presence of competitive cations in the order: Zn²⁺?>?Co²⁺?>?Mg²⁺?>?Mn²⁺?=?Cu²⁺?>?Ca²⁺?>?Na²⁺?=?K⁺. Higher concentrations of Cl^? significantly decreased the adsorption. Cadmium removal increased with solution pH and reached a maximum at pH 8.0. The effects of various solution properties indicated Cd²⁺ adsorption on nZVI to be a chemisorption (inner-sphere complexation) process. The three surface complexation models (diffuse layer model, constant capacitance model, and triple layer model) fitted well to the adsorption edge experimental data indicating the formation of nZVI–Cd bidentate inner-sphere surface complexes. Our results suggest that nZVI can be effectively used for the removal of cadmium from contaminated water sources with varying chemical conditions.     

Degradation of bisphenol A in aqueous solution by persulfate activated with ferrous ion

Degradation of bisphenol A (BPA) in aqueous solution was studied with high-efficiency sulfate radical (SO₄ ^?·), which was generated by the activation of persulfate (S₂O₈ ^2?) with ferrous ion (Fe²⁺). S₂O₈ ^2? was activated by Fe²⁺ to produce SO₄ ^?·, and iron powder (Fe⁰) was used as a slow-releasing source of dissolved Fe²⁺. The major oxidation products of BPA were determined by liquid chromatography-mass spectrometer. The mineralization efficiency of BPA was monitored by total organic carbon (TOC) analyzer. BPA removal efficiency was improved by the increase of initial S₂O₈ ^2? or Fe²⁺ concentrations and then decreased with excess Fe²⁺ concentration. The adding mode of Fe²⁺ had significant impact on BPA degradation and mineralization. BPA removal rates increased from 49 to 97 % with sequential addition of Fe²⁺, while complete degradation was observed with continuous diffusion of Fe²⁺, and the latter achieved higher TOC removal rate. When Fe⁰ was employed as a slow-releasing source of dissolved Fe²⁺, 100 % of BPA degradation efficiency was achieved, and the highest removal rate of TOC (85 %) was obtained within 2 h. In the Fe⁰–S₂O₈ ^2? system, Fe⁰ as the activator of S₂O₈ ^2? could offer sustainable oxidation for BPA, and higher TOC removal rate was achieved. It was proved that Fe⁰–S₂O₈ ^2? system has perspective for future works.     

Multi-component adsorption of copper,nickel and zinc from aqueous solutions onto activated carbon prepared from date stones

The removal of Cu²⁺, Ni²⁺, and Zn²⁺ ions from their multi-component aqueous mixture by sorption on activated carbon prepared from date stones was investigated. In the batch tests, experimental parameters were studied, including solution pH, contact time, initial metal ions concentration, and temperature. Adsorption efficiency of the heavy metals was pH-dependent and the maximum adsorption was found to occur at around 5.5 for Cu, Zn, and Ni. The maximum sorption capacities calculated by applying the Langmuir isotherm were 18.68 mg/g for Cu, 16.12 mg/g for Ni, and 12.19 mg/g for Zn. The competitive adsorption studies showed that the adsorption affinity order of the three heavy metals was Cu²⁺?>?Ni²⁺?>?Zn²⁺. The test results using real wastewater indicated that the prepared activated carbon could be used as a cheap adsorbent for the removal of heavy metals in aqueous solutions.     

The effects and the toxicity increases caused by bicarbonate,chloride, and other water components during the UV/TiO<Subscript>2</Subscript> degradation of oxazaphosphorine drugs

The influences of HCO₃ ^?, Cl^?, and other components on the UV/TiO₂ degradation of the antineoplastic agents ifosfamide (IFO) and cyclophosphamide (CP) were studied in this work. The results indicated that the presence of HCO₃ ^?, Cl^?, NO₃ ^?, and SO₄ ^2? in water bodies resulted in lower degradation efficiencies. The half-lives of IFO and CP were 1.2 and 1.1 min and increased 2.3–7.3 and 3.2–6.3 times, respectively, in the presence of the four anions (initial compound concentration = 100 μg/L, TiO₂ loading =100 mg/L, anion concentration = 1000 mg/L, and pH = 8). Although the presence of HCO₃ ^? in the UV/TiO₂/HCO₃ ^? system resulted in a lower degradation rate and less byproduct formation for IFO and CP, two newly identified byproducts, P11 (M.W. = 197) and P12 (M.W. = 101), were formed and detected, suggesting that additional pathways occurred during the reaction of ?CO₃ ^? in the system. The results also showed that ?CO₃ ^? likely induces a preferred ketonization pathway. Besides the inorganic anions HCO₃ ^?, Cl^?, NO₃ ^?, and SO₄ ^2?, the existence of dissolved organic matter in the water has a significant effect and inhibits CP degradation. Toxicity tests showed that higher toxicity occurred in the presence of HCO₃ ^? or Cl^? during UV/TiO₂ treatment and within 6 h of reaction time, implying that the effects of these two anions should not be ignored when photocatalytic treatment is applied to treat real wastewater.     

Influence of Fe and mn ions on the incorporation of radioactive 35SO2 by sulfate aerosols

The rate of incorporation of radiolabeled sulfur dioxide has been determined in submicron sized ammonium sulfate droplet aerosols with and without catalytic metal ions (Fe³⁺, Mn²⁺). The sulfate droplets were generated by nebulizing solutions with a multiple jet Collison nebulizer and aged up to 30 min in a 10 m³ plug-flow reaction duct. Radiolabeled ³⁵SO₂ was metered into purified air to provide a concentration of 5 ppm.Three different atmospheres were studied: SO₂ in purified air, SO₂ in the presence of ammonium sulfate aerosol (1 mg m⁻³, 1 μm MMAD), and SO₂ in the presence of ammonium sulfate aerosol containing Fe³⁺ and Mn²⁺ ions. No measurable SO₂ conversion was detected in samples from atmospheres without the catalytic metal ions. A net SO₂ conversion rate equivalent to 0.02 % h⁻¹ was observed in the presence of Fe³⁺ and Mn²⁺ ions.     

一体式A/O反应器中不同碳硫比对除碳脱臭效率的影响

在污水处理领域同步除碳脱臭研究一直是个难题,本实验开发了一种新型同步除碳脱臭一体式A/O反应器,研究了该一体式A/O反应器处理不同碳硫比有机废水时的同步除碳脱臭功能。结果表明,碳硫比为30∶1时,即进水SO24-浓度为133 mg/L,该反应器总COD去除率可达到95%。在进水SO24-浓度不大于400 mg/L时,中间产物臭气硫化氢气可以完全去除,实现了同步除碳脱臭的功能,减少了在有机废水处理过程中的大量臭气的排放。微生物学角度分析,表明污泥中含有大量的硫细菌。     

Adsorption of ammonium on biochar prepared from giant reed

Giant reed was used as precursor for making biochar in order for the adsorption of NH₄ ⁺–N from aqueous solution. And the adsorption of the product to NH₄ ⁺–N was examined. The surface features of biochar were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy/energy dispersive spectrometer (SEM-EDS), and X-ray diffraction (XRD). XRD patterns showed several peaks and correspond to the high amount of crystalline material. The crystals contain KCl, K₂O, CaO, MgO, and SiO and possess high surface area which enhances adsorption. The influence of different parameters such as initial concentration, adsorption time, pH, and ionic strength has been carried out. The adsorption could reach equilibrium through 24 h reaction and had the best adsorption amount at the solution pH values from 7 to 9. The cation has great influence on the adsorption of NH₄ ⁺–N, whereas the anion exerted a weaker effect. The adsorption followed pseudo-first-order and pseudo-second-order models. And the intraparticle diffusion and desorption studies further elucidated that the mechanism of adsorption on the product was ion exchange. The product equilibrium data was well described by the Langmuir and Freundlich model. The maximum adsorption capacities were 1.490 mg/g. Biochar derived from giant reed at 500 °C was suggested as a promising adsorbent for the removal of NH₄ ⁺–N from slightly polluted wastewater.     

Rapid dye degradation with reactive oxidants generated by chloride-induced peroxymonosulfate activation

Transition-metal is known to catalyze peroxymonosulfate (PMS) decomposition to produce sulfate radicals. Here we report reactions between PMS and chloride, without a need of transition metals, also can be used to degrade organic dye pollutant (Rhodamine B, (RhB)). Some important operating parameters, such as dosages of PMS and Cl^?, pH of solution, temperature, ionic strength, and several common cations, were systematically investigated. Almost complete decoloration of RhB was achieved within 5 min ([PMS]?=?0.5 mM, [Cl^?]?=?120 mM, and pH 3.0), and RhB bleaching rate increased with the increased dosages of both PMS and chloride ion, following the pseudo-first-order kinetic model. However, the total organic carbon (TOC) removal results demonstrated that the decoloration of RhB was due to the destruction of chromophore rather than complete degradation. RhB decoloration could be significantly accelerated due to the high ionic strength. Increasing of the reaction temperature from 273 K to 333 K was beneficial to the RhB degradation, and the activation energy was determined to be 32.996 kJ/mol. Bleaching rate of RhB with the examined cations increased with the order of NH₄ ⁺?<?Na⁺?<?K⁺?<?Al³⁺?<?Ca²⁺?<?Mg²⁺. Some major degradation products of RhB were identified by GC-MS. The present study may have active technical implications for the treatment of dyestuff wastewater in practice.     

Synthesis of α-Fe2O3 nanofibers for applications in removal and recovery of Cr(VI) from wastewater

Purpose

Nanomaterials such as iron oxides and ferrites have been intensively investigated for water treatment and environmental remediation applications. The purpose of this work is to synthesize α-Fe₂O₃ nanofibers for potential applications in removal and recovery of noxious Cr(VI) from wastewater.

Methods

α-Fe₂O₃ nanofibers were synthesized via a simple hydrothermal route followed by calcination. The crystallographic structure and the morphology of the as-prepared α-Fe₂O₃ nanofibers were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope. Batch adsorption experiments were conducted, and Fourier transform infrared spectra were recorded before and after adsorption to investigate the Cr(VI) removal performance and adsorption mechanism. Langmuir and Freundlich modes were employed to analyze the adsorption behavior of Cr(VI) on the α-Fe₂O₃ nanofibers.

Results

Very thin and porous α-Fe₂O₃ nanofibers have been successfully synthesized for investigation of Cr(VI) removal capability from synthetic wastewater. Batch experiments revealed that the as-prepared α-Fe₂O₃ nanofibers exhibited excellent Cr(VI) removal performance with a maximum adsorption capacity of 16.17 mg g^?1. Furthermore, the adsorption capacity almost kept unchanged after recycling and reusing. The Cr(VI) adsorption process was found to follow the pseudo-second-order kinetics model, and the corresponding thermodynamic parameters ΔG°, ΔH°, and ΔS° at 298 K were calculated to be ?26.60 kJ?mol^?1, ?3.32 kJ?mol^?1, and 78.12 J?mol^?1 K^?1, respectively.

Conclusions

The as-prepared α-Fe₂O₃ nanofibers can be utilized as efficient low-cost nano-absorbents for removal and recovery of Cr(VI) from wastewater.     

Removal mechanisms and kinetics of trace tetracycline by two types of activated sludge treating freshwater sewage and saline sewage

Understanding the removal mechanisms and kinetics of trace tetracycline by activated sludge is critical to both evaluation of tetracycline elimination in sewage treatment plants and risk assessment/management of tetracycline released to soil environment due to the application of biosolids as fertilizer. Adsorption is found to be the primary removal mechanism while biodegradation, volatilization, and hydrolysis can be ignored in this study. Adsorption kinetics was well described by pseudo-second-order model. Faster adsorption rate (k ₂?=?2.04?×?10^?2?g?min^?1?μg^?1) and greater adsorption capacity (q _e?=?38.8 μg?g^?1) were found in activated sludge treating freshwater sewage. Different adsorption rate and adsorption capacity resulted from chemical properties of sewage matrix rather than activated sludge surface characteristics. The decrease of tetracycline adsorption in saline sewage was mainly due to Mg²⁺ which significantly reduced adsorption distribution coefficient (K _d) from 12,990?±?260 to 4,690?±?180 L?kg^?1. Species-specific adsorption distribution coefficients followed the order of $ K_{\mathrm{d}}^{{ + 00}} \gg K_{\mathrm{d}}^{{ + - 0}} > K_{\mathrm{d}}^{{ + - - }} $ . Contribution of zwitterionic tetracycline to the overall adsorption was >90 % in the actual pH range in aeration tank. Adsorption of tetracycline in a wide range of temperature (10 to 35 °C) followed the Freundlich adsorption isotherm well.     

Surfactant-assisted adsorption of uranyl ions in aqueous solution on TiO2/polythiophene nanocomposite

In this work, hexadecyltrimethylammonium-bromide (HTAB)-modified polythiophene (PTh)/TiO₂ nanocomposite (HTAB/PTh/TiO₂) was applied to remove uranyl ions (UO₂²⁺). FT-IR, XRD, ζ potential, TGA, SEM, and XPS were utilized to obtain the chemical and physical properties of HTAB/PTh/TiO₂. The effects of HTAB content, preparation temperature, and adsorption conditions on UO₂²⁺ removal were investigated comprehensively. And the UO₂²⁺ adsorption process on HTAB/PTh/TiO₂ was fitted to the Sips model with a saturated adsorption capacity of 234.74 mg/g, which was 6 times over TiO₂. The results suggested that the surfactant of HTAB can significantly improve the adsorption ability of TiO₂ for UO₂²⁺ ions. This work provides a strategy of surfactant modification for enhancing the separation and recovery ability of adsorbent toward UO₂²⁺ in the radioactive wastewater.

     

工业废水中多金属离子的吸附净化

以含有Si、Al、Ca、C元素的矿物材料作为基质,经特定条件处理后造粒成型加工成轻质多孔Si-Al-Ca-C结构的吸附材料。研究了该吸附材料对工业废水中多种金属离子的吸附性能,探讨了影响吸附性能的因素。研究结果表明,在一定条件下,Si-Al-Ca-C吸附材料对工业废水中Al3+、Ca2+、Mn2+、Cu2+、Fe3+、Mg2+、As3+和Zn2+的净化率分别高达99.34%、99.82%、98.26%、98.16%、97.76%、97.01%、100%和89.09%。金属离子残留浓度分别为0.152、0.07、0.012、0.02、0.119、0.311、0和0.259 mg/L,均低于国家污水综合排放标准(GB8978-1996)一级标准。     

微电解-Fenton深度处理制药废水影响因素与参数控制

采用铁炭微电解-Fenton联合工艺深度处理制药废水生化出水,探讨了初始pH、曝气量、反应时间等因素对微电解出水Fe2+和Fe3+变化规律、COD降解速率以及后续Fenton氧化效果的影响,为优化微电解-Fenton氧化联合工艺提出了微电解间歇加酸的理论。间歇加酸可提高微电解系统中COD降解速率和Fe2+含量,使后续Fenton氧化无需投加FeSO4·7H2O即可达到较好的COD去除效果。结果表明,当初始pH=2.5,曝气量为0.6 m3/h,间歇加酸30 min/次,微电解反应2 h,出水投加1 mL/L的H2O2进行Fenton氧化2 h,COD总去除率可达81.33%;间歇加酸30 min/次可将微电解反应2 h出水Fe2+浓度从50 mg/L提高至151 mg/L,COD降解速率从10.6 mg COD/(L·h)提高至22.2 mg COD/(L·h)。     

Post-treatment of bio-treated acrylonitrile wastewater using UV/Fenton process: degradation kinetics of target compounds

In this study, post-treatment of bio-treated acrylonitrile wastewater was performed using the UV/Fenton process. Five target compounds (furmaronitrile, 3-pyridinecarbonitrile, 1,3-dicyanobenzene, 5-methyl-1H-benzotriazole, and 7-azaindole) were selected as target compounds and their degradation kinetics were examined. Under optimal reaction conditions (H₂O₂ dosage 3.0 mM, Fe²⁺ dosage 0.3 mM, and initial pH 3.0), more than 85% of total organic carbon (TOC) was eliminated in 30 min when a 10-W UV lamp was employed, and the electrical energy per order of magnitude for TOC removal was as low as 2.96 kWh m^?3. Furthermore, the target compounds and the toxicity were largely removed from the bio-treated effluent. Size exclusion chromatography with organic carbon detector analysis revealed that organic components with a wide range of molecular weights were greatly reduced after the UV/Fenton process. A simplified pseudo steady-state (SPSS) model was applied to predict the degradation of target compounds during the UV/Fenton process. The concentrations of generated hydroxyl radicals were estimated to be 3.06 × 10^?12 M, 6.37 × 10^?12 M, and 10.9 × 10^?12 M under 5-, 10-, and 15-W UV lamps, respectively. These results demonstrate that the proposed SPSS model fitted well with experimental data on the post-treatment of real wastewater, and consequently indicate that this model can be a useful tool in the prediction of degradation of target compounds during the UV/Fenton process.

     

Facile, effective, and environment-friendly degradation of sulfamonomethoxine in aqueous solution with the aid of a UV/Oxone oxidative process

The degradation of sulfamonomethoxine (SMM) in the aqueous environment by the combination of UV illumination and Oxone has been studied. Experimental results indicated that the UV illumination can effectively activate Oxone to produce sulfate-free radicals (SO₄ ^??). When 10 mmol L^?1 Oxone was added, 96.78 % removal of SMM (5 mg L^?1) was achieved within 90 min. Mineralization of SMM was investigated by measuring the total organic carbon, which decreased by 89.01 % after 90 min reaction. Six intermediate compounds generated during the SMM degradation were identified with the aid of liquid chromatography and mass spectroscopy, combined with proton nuclear magnetic resonance spectroscopy. A general reaction pathway for the degradation of SMM was proposed, where the presence of SO₄ ^?? remained crucial during the degradation process.     

Oxidation of ofloxacin by Oxone/Co2+: identification of reaction products and pathways

Oxidative degradation of ofloxacin (OFX) by sulfate free radicals (SO₄ ^??) in the UV/Oxone/Co²⁺oxidation process was investigated for the first time, with a special focus upon identifying the transformation products as well as understanding the reaction pathways. Thirteen main compounds were identified after the initial transformation of OFX; the detailed structural information of which were characterized by high-performance liquid chromatography–high resolution mass spectrometry and MS fragmentation analysis. The degradation pathways mainly encompassed ring openings at both the piperazinyl substituent and the quinolone moiety, indicating that the usage of SO₄ ^?? aided the oxidative degradation of OFX to undergo more facile routes compared to those in previous reports by using OH^?/h⁺ as the oxidant, where the initial transformation attacks were mainly confined to the piperazine moiety. Moreover, in this study, smart control over the pH conditions of the oxidation system via different modes of Oxone dosage resulted in the selective degradation of the functional sites of OFX molecule, where it was shown that the SO₄ ^??-driven destruction of the quinolone moiety of OFX molecule favored the neutral pH conditions. This would be beneficial for the reduction of bacterial resistance against quinolones in the aqueous environment.     

Preparation of calcium oxalate—bromopyrogallol red inclusion sorbent and application to treatment of cationic dye and heavy metal wastewaters

Background, aim, and scope  Dye pollutants are a major class of environmental contaminants. Over 100,000 dyes have been synthesized worldwide and more than 700,000 tons are produced annually and over 5% are discharged into aquatic environments. The adsorption or sorption is one of the most efficient methods to remove dye and heavy metal pollutants from wastewater. However, most of the present sorbents often bear some disadvantages, e.g. low sorption capacity, difficult separation of spoil, complex reproduction, or secondary pollution. Development of novel sorbents that can overcome these limitations is desirable. Materials and methods  On the basis of the chemical coprecipitation of calcium oxalate (CaC₂O₄), bromopyrogallol red (BPR) was embedded during the growing of CaC₂O₄ particles. The ternary C₂O₄ ^2––BPR–Ca²⁺ sorbent was yielded by the centrifugation. Its composition was determined by spectrophotometry and AAS, and its structure and morphology were characterized by powder X-ray diffraction (XRD), laser particle-size analysis, and scanning electron microscopy (SEM). The adsorption of ethyl violet (EV) and heavy metals, e.g. Cu(II), Cd(II), Ni(II), Zn(II), and Pb(II) were carried out and their removal rate determined by spectrophotometry and ICP-OES. The adsorption performance of the sorbent was compared with powder activated carbon. The Langmuir isothermal model was applied to fit the embedment of BPR and adsorption of EV. Results  The saturation number of BPR binding to CaC₂O₄ reached 0.0105 mol/mol and the adsorption constant of the complex was 4.70 × 10⁵ M^–1. Over 80% of the sorbent particles are between 0.7 and 1.02 μm, formed by the aggregation of the global CaC₂O₄/BPR inclusion grains of 30–50 nm size. Such a material was found to adsorb cationic dyes selectively and sensitively. Ethyl violet (EV) was used to investigate the adsorption mechanism of the material. One BPR molecule may just bind with one EV molecule. The CaC₂O₄/BPR inclusion material adsorbed EV over two times more efficiently than the activated carbon. The adsorption of EV on the CaC₂O₄/BPR inclusion sorbent was complete in only 5 min and the sedimentation complete in 1 h. However, those of EV onto activated carbon took more than 1.5 and 5 h, respectively. The treatment of methylene blue and malachite green dye wastewaters indicated that only 0.4% of the sorbent adsorbed over 80% of color substances. Besides, the material can also adsorb heavy metals by complexation with BPR. Over 90% of Pb²⁺, and approximately 50% of Cd²⁺ and Cu²⁺, were removed in a high Zn²⁺-electroplating wastewater when 3% of the material was added. Eighty-six percent of Cu²⁺, and 60% of Ni²⁺ and Cd²⁺, were removed in a high Cd²⁺-electroplating wastewater. Discussion  The embedment of BPR into CaC₂O₄ particles responded to the Langmuir isothermal adsorption. As the affinity ligand of Ca²⁺, BPR with sulfonic groups may be adsorbed into the temporary electric double layer during the growing of CaC₂O₄ particles. Immediately, C₂O₄ ^2– captured the Ca²⁺ to form the CaC₂O₄ outer enclosed sphere. Thus, BPR may be released and embedded as a sandwich between CaC₂O₄ layers. The adsorption of EV on the sorbent obeyed the Langmuir isothermal equation and adsorption is mainly due to the ion-pair attraction between EV and BPR. Different from the inclusion sorbent, the activated carbon depended on the specific surface area to adsorb organic substances. Therefore, the adsorption capacity, equilibrium, and sedimentation time of the sorbent are much better than activated carbon. The interaction of heavy metals with the inclusion sorbent responded to their coordination. Conclusions  By characterizing the C₂O₄ ^2––BPR–Ca²⁺ inclusion material using various modern instruments, the ternary in situ embedment particle, [(CaC₂O₄)₉₅(BPR)] _n ^2n–, an electronegative, micron-sized adsorbent was synthesized. It is selective, rapid, and highly effective for adsorbing cationic dyes and heavy metals. Moreover, the adsorption is hardly subject to the impact of electrolytes. Recommendations and perspectives  The present work provides a simple and valuable method for preparing the highly effective adsorbent. If a concentrated BPR wastewater was reused as the inclusion reactant, the sorbent will be low cost. By selecting the inclusion ligand with a special structure, we may prepare some particular functional materials to recover the valuable substances from seriously polluted wastewaters. The recommended method will play a significant role in development of advanced adsorption materials. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Dynamic and equilibrium studies of the RDX removal from soil using CMC-coated zerovalent iron nanoparticles

Rapid chemical degradation of toxic RDX explosive in soil can be accomplished using zerovalent nanoiron suspension stabilized in dilute carboxymethyl cellulose solution (CMC-ZVINs). The effect of operating conditions (redox-potential, Fe/RDX molar ratio) was studied on batchwise removal of RDX in contaminated soil. While anaerobic conditions resulted in 98% RDX removal in 3 h, only slightly over 60% RDX removal could be attained under aerobic conditions. The molar ratio did not have any influence on the intermediate and final RDX degradation products (methylenedinitramine, nitroso derivative, N₂, N₂O, NO₂^?), however, their distribution changed. Dynamic studies were conducted using a flow-through short column packed with RDX-contaminated soil and fed with CMC-ZVINs. The column was operated at two interstitial velocities (2.2 and 1.6 cm min^?1), resulting in the 76.6% and 95% removal of the initial RDX soil contamination load (60 mg kg^?1), respectively. While the column operating conditions could be further optimized, 95% of the RDX initially present in the contaminated soil packed in the column was degraded when flushed with a CMC-ZVINs suspension in this work.