石油焦基高比表面积活性炭处理含铬废水的研究

以石油焦为原料,采用KOH活化法制取高比表面积活性炭。考察了高比表面积活性炭吸附废水中Cr（VI）时,pH值、Cr（VI)浓度、吸附时间和活性炭用量等因素对Cr(VI）吸附量和废水中Cr(VI）残余浓度的影响。实验结果表明高比表面积活性炭在适宜条件下对Cr(VI）具有较大的吸附量和良好的再生效果。     

壳聚糖/活性炭纤维复合膜的制备及对甲基橙的吸附研究

通过化学交联法制备了纯壳聚糖膜和壳聚糖/活性炭纤维复合膜(质量比为1∶1.1);探讨时间、pH值、温度、甲基橙溶液初始浓度以及吸附剂用量对吸附甲基橙的影响。研究结果表明,最佳吸附时间为120 min,在pH为6.0,甲基橙初始浓度10 mg/L,温度为10℃时,膜对甲基橙的吸附效果最好,去除率达99.54%。     

交联壳聚糖树脂的制备及对Cr（Ⅵ）的吸附研究

以壳聚糖为原料,通过反相悬浮交联法制备交联壳聚糖树脂,将其用于吸附Cr（Ⅵ）,考察了吸附时间、溶液pH、树脂用量、Cr（Ⅵ）的初始浓度和介质等因素对吸附的影响。实验结果表明,吸附平衡时间为20 min,最佳吸附pH为6.0,最佳用量为10 mg,Cr（Ⅵ）起始浓度为6 mg/mL,介质对吸附的影响大小顺序：Cu2＋〉Na＋。重复使用3次,再生性能好。     

竹炭壳聚糖吸附剂的制备及对Cr(Ⅵ)的吸附性能

采用竹炭与壳聚糖复配的方法,并以海藻酸钠作为交联剂制备竹炭壳聚糖吸附剂,考察了制备过程中的交联剂种类、原料配比、操作条件及吸附过程中的吸附时间、溶液酸度等对Cr(Ⅵ)吸附性能的影响。结果表明,竹炭壳聚糖比活性炭壳聚糖具有更好的吸附性能;壳聚糖的交联剂对吸附性能的影响不大;当m(竹炭)∶m(壳聚糖)为1∶2,吸附t为30 min,溶液pH为5~7时,竹炭壳聚糖吸附剂对Cr(Ⅵ)有较好的吸附性能。     

Red mud (aluminum industrial waste): An eco-friendly treatment of electroplating effluent

In this work, aluminum industrial waste, red mud (RM), was activated to verify its potential in the management of electroplating wastewater containing hexavalent chromium (Cr(VI)). A comparison between the adsorption capabilities of RM and activated red mud (ARM) towards Cr(VI) from aqueous solutions was made. The effects of several parameters were evaluated. The adsorbents were characterized by field emission scanning electron microscopy (FESEM), Fourier transmission infrared spectroscopy (FTIR), x-ray diffraction (XRD), zeta potential, and thermogravimetric analysis (TGA). The particle size was observed as 23.59 nm. The ARM demonstrated an acceptable adsorption capacity of 25.641 mg/g at a pH of 2, adsorbent dosage of 2 g/L, initial Cr(VI) concentration of 100 mg/L, at 25°C. The experimental data is in good agreement with Langmuir adsorption isotherm. The kinetic study was performed to verify that the adsorption follows pseudo-second-order kinetics. In addition, the ARM showed decent recyclability for adsorbing Cr(VI) as even after three adsorption cycles, and the adsorption capacity was reduced by ~30%. The results recommend ARM to be an efficient and cost-effective adsorbent for Cr(VI) removal from industrial wastewater.     

Synthesis and characterization of carbon/AlOOH composite for adsorption of chromium(VI) from synthetic wastewater

In this work, flake like carbon/AlOOH composite has been synthesized and evaluated as a new adsorbent for the removal of Cr(VI) from synthetic wastewater. Different characterization tools such as, SEM, EDAX, XRD and XPS were performed to characterize the composite material. Batch adsorption studies for Cr(VI) removal were performed under the influence of various operational parameters such as solution pH, contact time, initial solution concentration and temperature. Results obtained revealed that adsorption of Cr(VI) onto carbon/AlOOH composite followed the pseudo-second order kinetics and Freundlich isotherm model. Thermodynamic results suggests that adsorption of Cr(VI) onto carbon/AlOOH composite was spontaneous and endothermic in nature.     

Mussel‐inspired magnetic adsorbent: Adsorption/reduction treatment for the toxic Cr(VI) from simulated wastewater

A novel magnetic adsorbent, poly(catechol‐1,4‐butanediamine)‐coated Fe₃O₄ composite (Fe₃O₄@PCBA), was successfully fabricated via an easy and gentle method according to the mussel‐inspired adhesion property of polydopamine. Effects of many factors on the adsorption performance of Fe₃O₄@PCBA for Cr(VI) were investigated, including temperature, pH value, contacting time, adsorbent dosage, and initial Cr(VI) concentration. The thermodynamics, adsorption isotherm, kinetics, and intraparticle diffusion of adsorption were also studied systematically. Results indicated that the removal rate of Cr(VI) was approximately close to 100% when the initial concentration was less than 120 mg/L, and the maximum uptake capacity of Fe₃O₄@PCBA for Cr(VI) was 280.11 mg/g complied with Langmuir isotherm model. Accordingly, the nocuous Cr(VI) could be partially reduced to Cr(III) during the adsorption period. Hopefully, this strategy could be extended to prepare series of magnetic Fe₃O₄@catechol–amine adsorbents with different amino and phenolic hydroxyl groups for Cr(VI) removal. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46530.     

Adsorption of Pb2+ and Cd2+ onto a Novel Activated Carbon‐Chitosan Complex

A novel activated carbon‐chitosan complex adsorbent (ACCA) was prepared via the crosslinking of glutaraldehyde and activated carbon‐(NH₂‐protected) chitosan complex under microwave irradiation. The surface morphology of this adsorbent was characterized. The adsorption of ACCA for Pb²⁺ and Cd²⁺ was investigated. The results demonstrate that ACCA has higher adsorption capacity than chitosan. The adsorption follows pseudo first‐order kinetics. The isotherm adsorption equilibria are better described by Freundlich and Dubinin‐Radushkevich isotherms than by the Langmuir isotherm. The adsorbent can be recycled. These results have important implications for the design of low‐cost and effective adsorbents in the removal of heavy metal ions from wastewaters.     

Adsorption behaviors of the aminated chitosan adsorbent

Using inverse suspension technology, a novel aminated chitosan adsorbent with higher adsorption ability for metal cations and metal anions was prepared. Through cross-linking amination reaction, the content of amidocyanogen of aminated chitosan adsorbent was enhanced four times than that of chitosan cross-linked adsorbent. As can be seen from the results, the adsorption ability of the novel aminated chitosan adsorbent for (Nicit)⁻ and Cr(VI) was enhanced remarkably. When the initial concentration of metallic ion was 1,000 mg/L, the adsorption capacity of the novel aminated chitosan adsorbent for nickel citrate and Cr(VI) was up to 30.2 mg/g and 28.7 mg/g, respectively. And the adsorption capacity of the novel aminated chitosan adsorbent for Ni²⁺ was still higher. So the new aminated chitosan adsorbent offers not only a higher uptake for metal cations but also a better adsorption capacity for metal anions.     

膨润土-壳聚糖复合吸附剂处理水中Cr(Ⅵ)的研究

将壳聚糖与膨润土结合,制备出复合吸附剂,研究了其对Cr(VI)的吸附,详细探讨了复合吸附剂吸附Cr(VI)的最佳工艺条件。结果表明,复合吸附剂对Cr(VI)具有较好的吸附性能,吸附的最佳工艺条件是:pH值为4～6,废水中Cr(VI)质量浓度不大于10mg/L,吸附平衡时间为40min左右,吸附剂用量为8.0g/L,壳聚糖与膨润土质量比为0.04。与单一的膨润土或壳聚糖相比,该吸附剂对Cr(VI)离子的吸附速度快、吸附能力强,并且具有成本低、应用范围广等优点。     

A high Cr (VI) absorption efficiency and easy recovery adsorbent: Electrospun polyethersulfone/polydopamine nanofibers

Cr (VI) is a highly toxic pollutant to humans, to achieve high adsorption capacity, easy recovery, and good reusability, polyethersulfone/polydopamine (PES/PDA) ultrafine fibers were prepared successfully. A series of preparing effect factors were investigated systematically and the optimum one is 8.5 pH value at room temperature and 2 g/L dopamine concentration. And then they were used as an adsorbent for the removal of Cr (VI) ions from wastewater. The effect factors pH, the adsorbent dosage, and time were discussed on Cr (VI) adsorption process and the Cr (VI) adsorption behavior was investigated. It is found that the maximum Cr (VI) adsorption capacity is 115.2 ± 4.8 mg/g at pH = 3 using 0.06 g PES/PDA with 80 mins. The Cr (VI) adsorption process followed the pseudo-second-order model (r² ≥ 0.99) and adsorption isotherms were fitted to the Langmuir model (R² ≥ 0.999). Furthermore, the Cr (VI) adsorption mechanism was supposed according to the X-ray photoelectron spectroscopic results. Finally, PES/PDA ultrafine fibers were considered to be a promising adsorbent with good stability (decomposing temperature, 356°C), high adsorption efficiency (112.1 ± 2.5 mg/g), and good reusability (three times) on the coexistence of anions and the actual industry wastewater environment.     

Removal of Cr(VI) from aqueous solution using amino‐modified Fe3O4–SiO2–chitosan magnetic microspheres with high acid resistance and adsorption capacity

A novel, bioadsorbent material of polyethylenimine‐modified magnetic chitosan microspheres enwrapping magnetic silica nanoparticles (Fe₃O₄–SiO₂–CTS‐PEI) was prepared under relatively mild conditions. The characterization results indicated that the adsorbent exhibited high acid resistance and magnetic responsiveness. The Fe₃O₄ loss of the adsorbent was measured as 0.09% after immersion in pH 2.0 water for 24 h, and the saturated magnetization was 11.7 emu/g. The introduction of PEI obviously improved the adsorption capacity of Cr(VI) onto the adsorbent by approximately 2.5 times. The adsorption isotherms and kinetics preferably fit the Langmuir model and the pseudo‐second‐order model. The maximum adsorption capacity was determined as 236.4 mg/g at 25°C, which was much improved compared to other magnetic chitosan materials, and the equilibrium was reached within 60 to 120 min. The obtained thermodynamic parameters revealed the spontaneous and endothermic nature of the adsorption process. Furthermore, the Cr(VI)‐adsorbed adsorbent could be effectively regenerated using a 0.1 mol/L NaOH solution, and the adsorbent showed a good reusability. Due to the properties of good acid resistance, strong magnetic responsiveness, high adsorption capacity, and relatively rapid adsorption rate, the Fe₃O₄–SiO₂–CTS‐PEI microspheres have a potential use in Cr(VI) removal from acidic wastewater. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43078.     

凹凸棒活性炭复合滤料对水中CODMn的吸附研究

以凹凸棒活性炭复合滤料处理原水中的CODMn,探讨了滤料投加量、吸附时间、温度、pH值及原水初始浓度等因素对CODMn去除处理效果的影响。结果表明,滤料的最佳投加量及吸附时间分别为40g／L和80min,吸附反应是放热反应,在pH约为8时CODMn的去除率可达到54．27％,滤料对CODMn的吸附符合Langmuir吸附模型,凹凸棒活性炭复合滤料在微污染饮用水处理领域有一定的实际应用价值。     

Single step modification of micrometer-sized polystyrene particles by electromagnetic polyaniline and sorption of chromium(VI) metal ions from water

This article describes a single-step reproducible approach for the surface modification of micrometer-sized polystyrene (PS) core particles to prepare electromagnetic PS/polyaniline–Fe₃O₄ (PS/PANi–Fe₃O₄) composite particles. The electromagnetic PANi–Fe₃O₄ shell was formed by simultaneous seeded chemical oxidative polymerization of aniline and precipitation of Fe₃O₄ nanoparticles. The weight ratio of PS to aniline was optimized to produce core–shell structure. PS/PANi–Fe₃O₄ composite particles were used as adsorbent for the removal of Cr(VI) via anion-exchange mechanism. The composite particles possessed enough magnetic property for magnetic separation. The adsorption was highly pH dependent. Adsorption efficiency reached 100% at pH 2 in 120 min when 0.05 g of composite particles was mixed with 30 mL 5 mg L⁻¹ Cr(VI) solution. The adsorption isotherm fitted best with Freundlich model and maximum adsorption capacity approached 20.289 mg g⁻¹ at 323 K. The prepared composite was found to be an useful adsorbent for the removal of soluble Cr(VI) ions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47524.     

Synthesis of graphene oxide nanoribbons/chitosan composite membranes for the removal of uranium from aqueous solutions

In this study, a graphene oxide nanoribbons/chitosan (GONRs/CTS) composite membrane was successfully prepared by encapsulating CTS into GONRs, which were unzipped from multi-walled carbon nanotubes. The GONRs/CTS composite membrane so prepared was characterized using scanning electron microscopy, X-Ray diffraction and Fourier transform infrared spectroscopy. The effects of the experimental conditions such as the pH (2‒7), adsorbent dosage (10‒50 mg), experimental time (5 min–32 h), uranium concentration (25‒300 mg∙L⁻¹), experimental temperature (298 K‒328 K) on the adsorption properties of the composite membrane for the removal of U(VI) were investigated. The results showed that the U(VI) adsorption process of the GONRs/CTS composite membrane was pH-dependent, rapid, spontaneous and endothermic. The adsorption process followed the pseudo-secondary kinetics and Langmuir models. The maximum U(VI) adsorption capacity of the GONRs/CTS composite membrane was calculated to be 320 mg∙g⁻¹. Hence, the GONRs/CTS composite membrane prepared in this study was found to be suitable for separating and recovering uranium from wastewater.     

Preparation and characterization of higher degree‐deacetylated chitosan‐coated magnetic adsorbent for the removal of chromium(VI) from its aqueous mixture

Chitosan (90% deacetylated) coated magnetic adsorbent prepared by coprecipitation method to remove Cr(VI) from its aqueous solution. The experimental studies depicts that the predominant option for removal of Chromium by adsorption from its aqueous phase using Magnetic‐Chitosan (MC). The subsequent physical, chemical, and magnetic properties of MC were characterized by X‐ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectrometer, vibrating sample magnetometer. The influence of batch process parameters such as contact time, initial concentration, pH, and coexisting anions were investigated. The Box‐Behnken experimental design in response surface methodology was performed to design the experiment optimal operating conditions. The maximum percentage reduction of Cr(VI) is 96.3 that was obtained by magnetic chitosan with the optimal operating conditions of 149.53 mg/L at pH of 5.32 at the contact time of 80 min and at the temperature of 303 K. The average diameter of the magnetic chitosan was calculated from X‐ray diffractometer analysis as 24.5 nm. The equilibrium adsorption isotherm models such as Langmuir and Freundlich and the adsorption kinetics such as pseudo first order, pseudo second order and intra‐particle diffusion kinetic model were analyzed. The experimental data's suited for the best fit with the Langmuir isotherm model and pseudo first order kinetic model. It also revealed that Cr(VI) adsorption on MC is intrinsically exothermic and spontaneous. The magnetic chitosan was also used to investigate for the removal of Cr(VI) from the real water sources such as surface, underground, and tannery wastewater. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45878.     

Fabrication of a copolymer flocculant and application for Cr(VI) removal

A copolymer flocculant (CATCS) derived from starch and chitosan was fabricated and used as eco‐friendly adsorbent for removal of Cr(VI) from aqueous solution. The CATCS flocculant was characterized by scanning electron microscope, thermogravimetic analysis, and Fourier transform infrared spectroscopy. The effects of CATCS dosage, initial Cr(VI) concentration, pH, and reaction time on removal of Cr(VI) were discussed. The results showed CATCS removed Cr(VI) effectively and the adsorption isotherm agreed well with the Freundlich isotherm and R–P isotherm models. The enthalpy change (ΔH) of the process was 16.75 kJ/mol suggesting the existence of chemisorption and the reaction was endothermic. Moreover, the negative free energy change (ΔG) indicated the adsorption process was feasible and spontaneous. The positive entropy change (ΔS) showed there was an increase of disorder in the system during the adsorption process. The adsorption kinetics results showed that the adsorption could be described by the pseudo‐second‐order kinetics mechanism. The activation energy (E_a) of the adsorption reaction was 29.16 kJ/mol. POLYM. ENG. SCI., 56:1213–1220, 2016. © 2016 Society of Plastics Engineers     

Adsorption of Cr(VI) on Cross‐Linked Chitosan Beads

Abstract

A possibility of Cr(VI) removal by the adsorption method is discussed in the paper. An adsorbent were hydrogel chitosan beads are produced by the phase inversion method (by changing pH). The possibility of removing Cr(VI) ions by both pure chitosan hydrogel and its chelate compounds (chitosan cross‐linked with Cu(II) and Ag(I) ions) was investigated. The adsorption proceeded from the solutions of potassium dichromate and ammonium dichromate (NH₄)₂Cr₂O₇ and K₂Cr₂O₇. The process rates and adsorption isotherms were determined and described by relevant equations. The process rate was described by the pseudo‐ and second‐order equations, and adsorption equilibria by the Langmuir equations. A slight advantageous change in adsorption properties of chitosan beads was revealed after cross‐linking (for chromium concentration up to 10 g/dm³). A maximum adsorption was 1.1 g_Cr/g chitosan. Results of the studies show that chitosan hydrogel proves useful in the removal of Cr(VI) ions, additionally, cross‐linking with Cu(II) and Ag(I) ions has an advantageous effect in the case of low‐concentrated solutions.     

凹凸棒活性炭复合滤料对刚果红的吸附性能研究

文章以凹凸棒活性炭复合滤料处理原水中的刚果红,探讨了滤料投加量、吸附时间、温度、pH及原水初始浓度等因素对刚果红去除处理效果的影响。实验结果表明,25℃时,在中性50 mg/L的刚果红溶液中,振荡60 min,凹凸棒活性炭复合滤料对刚果红溶液的吸附可达平衡。凹凸棒活性炭复合滤料作为吸附剂处理含刚果红废水,是一种有效的方法。