铁盐共沉淀泡沫浮选法去除废水中Cr（Ⅵ）的应用研究

采用铁盐共沉淀泡沫浮选法去除废水中Cr（Ⅵ）,用FeSO4将六价铬还原成三价状态,考察了还原剂用量、捕捉剂品种及pH对总铬去除率的影响。结果表明,对浓度为10mg／L的含Cr（Ⅵ）模拟废水,使用FeSO4作还原剂,LAS作捕捉剂,铁铬摩尔比为7：1,pH：10,鼓泡10min的条件下,Cr（Ⅵ）去除率可达99．1％。     

铁盐共沉淀泡沫分离法去除水中铬离子

采用铁盐共沉淀泡沫分离法对水中的铬离子去除进行了研究,考察了pH值、Fe^2＋/Cr（Ⅵ）摩尔比、十二烷基苯磺酸钠（LAS）浓度、气液比等因素的影响.实验结果表明：当水中的铬离子含量为8 mg·L^-1时,去除率可达97.1%.根据泡沫分离过程与化学反应过程在物理行为上的类似性,引入等效的化学反应常数,对采用共沉淀泡沫分离法去除水中的铬离子进行宏观动力学研究.结果表明该泡沫分离过程可等效为一级反应,结合停留时间分布测定对该过程的数学模型进行了分析讨论.     

间歇式泡沫分离法去除废水中Cr(Ⅵ)的研究

采用间歇式泡沫分离法分离废水中的Cr(Ⅵ),系统地考察了废水pH、表面活性剂烷基糖苷(APG)的质量浓度和空气流量对Cr(Ⅵ)脱除效果的影响.实验结果表明:当废水Cr(Ⅵ)质量浓度为20 mg/L、处理量为3 L时,其最佳工艺条件为pH=5.5、空气流量400 mL/min、表面活性剂质量浓度200 mg/L和反应时间...     

连续式泡沫分离法去除废水中铬(Ⅲ)离子的动力学

采用铁盐共沉淀连续式泡沫分离法脱除废水中的铬(Ⅲ)离子,实验考察了pH值、Fe2+/Cr(Ⅵ)摩尔比、十二烷基苯磺酸钠(SDBS)浓度、空气流量、分离时间等因素的影响.结果表明,最佳分离工艺条件为,Fe2+/Cr(Ⅵ)摩尔比5∶1,pH值9.0,空气流量450 mL/min,SDBS浓度60 mg/L,分离时间30 m...     

麸皮去除废水中Cr(VI)的实验研究

以麸皮为生物吸附剂,考察麸皮用量、废水pH、时间、Cr(Ⅵ)初始浓度对废水中Cr(Ⅵ)去除率的影响。结果表明,麸皮作为生物吸附剂可有效去除废水中的Cr(Ⅵ),麸皮用量200 g/L,pH=2、Cr(Ⅵ)初始浓度为5 mg/L,吸附240 min时,Cr(Ⅵ)去除率为99.31%。麸皮对Cr(Ⅵ)离子的吸附过程接近准二级动力学方程,吸附符合Freundlich等温模型,饱和吸附量为55.44 mg/kg。     

泡沫浮选法处理含氰废水

本文研究了在含氰废水中按化学计量比加入Fe~(2+)和Fe~(3+)离子以生成无毒的亚铁氰化铁絮状物沉淀,然后采用泡沫浮选进行分离的除氰方法。操作过程中拟加入一定量的阳离子表面活性剂,采用5~#烧结玻璃板作气体分布器,在pH值为4.0～6.5之间,能获得较高的分离效率。操作宜在阳光直射不到的阳暗处进行以避免亚铁氰化铁沉淀的光解反应发生。     

泡沫浮选法处理含铬废水的试验研究

本实验采用泡沫浮选技术脱除废水中的Cr^3 ，用十二烷基硫酸钠(SDS)作表面活性剂，Fe(OH)3作絮凝剂，得到间歇操作流程适宜的操作参数为：溶液pH值为5．5左右，SDS为180mg／L，气体流量800mL/min。在此操作条件下，Cr^3 的脱除率可达97％左右。     

内循环式泡沫浮选塔处理含铬废水

采用自制的内循环泡沫浮选塔处理含铬废水,考察pH值、Fe(NO3)3浓度、十二烷基硫酸钠(SDS)浓度、气体流量、分离时间等因素对分离效率的影响,并与常规泡沫塔比较. 结果表明,在12~35 min内,内循环式浮选塔分离效率更高,35 min时塔内铬离子浓度为0.6 mg/L,常规泡沫塔内铬离子浓度为10 mg/L. 内循环浮选塔最佳分离工艺条件为,对初始铬浓度为20 mg/L的废水,在pH 5.5、SDS 100 mg/L、Fe(NO3)3 60 mg/L、气体流量800 mL/min条件下处理效果最好,泡沫夹带率约为10%,Cr(III)脱除率可达97%以上.     

亚铁盐在碱性条件下还原六价铬的研究

从理论上分析了亚铁盐在碱性条件下还原六价铬的可能性,并在实验和实践中得到证实,从而提出“一步法”治理电镀混合废水的新工艺。     

麸皮去除废水中Cr(Ⅵ)的实验研究

以麸皮为生物吸附剂,考察麸皮用量、废水pH、时间、Cr(Ⅵ)初始浓度对废水中Cr(Ⅵ)去除率的影响.结果表明,麸皮作为生物吸附剂可有效去除废水中的Cr(Ⅵ),麸皮用量200 g/L,pH=2、Cr(Ⅵ)初始浓度为5 mg/L,吸附240 min时,Cr(Ⅵ)去除率为99.31％.麸皮对Cr(Ⅵ)离子的吸附过程接近准二级...     

光催化法处理含Cr(VI)废水的研究

采用P 25 TiO2作为光催化剂,研究了废水的pH值、Cr(VI)的初始浓度、气氛及有机物等因素对含铬废水中Cr(VI)去解率的影响。结果表明,在pH值为3.0时,光催化反应速率最大;反应气氛对该体系中Cr(VI)的光催化还原无明显影响;苯酚、葡萄糖等有机物的存在能有效地促进Cr(VI)的光催化还原,当加入与Cr(VI)等物质的量的苯酚或葡萄糖时,150 mL反应液[Cr(VI)浓度为0.96 mmol/L],0.15 g光催化剂,经12 W紫外灯照射反应120 m in,Cr(VI)完全被去除,相对于在反应体系中不加有机物时,Cr(VI)光催化还原效率提高了近100%;Cr(VI)的光催化还原符合L-H动力学规律。     

Studies on the removal of Cr(VI) from waste-water by feldspar

The efficacy of feldspar in the removal of Cr(VI) from representative waste-water from a plating industry has been investigated in a completely mixed batch reactor at different concentrations, rate of agitation and particle size. The data obey the Langmuir isotherm for the present system and the process of uptake follows first-order kinetics. The maximum removal (91%) was observed at 40°C and pH 2.5 with initial concentration of 19.23 μmol dm^?3 Cr(VI) and 40 g dm^?3 feldspar. The process involves both film and pore diffusion to different extents. Column studies have also been carried out using a certain concentration of waste-water. More than 92% recovery has been achieved and the column can be used for 10 cycles before regeneration. The present technique seems to be quite attractive.     

Enhanced adsorptive removal of Cr(VI) in aqueous solution by polyethyleneimine modified palygorskite

Polyethyleneimine (PEI) modified palygorskite (Pal) was used for the adsorption of Cr(VI) in aqueous solution. The absorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). Characterized results confirmed that the Pal has been successfully modified by PEI. The modification of PEI increased the Cr(VI) adsorption performance of the Pal by the adsorption combined reduction mechanism, and amino groups of the adsorbent play the main role in the enhanced Cr(VI) adsorption. The maximum adsorption capacity was 51.10 mg·g⁻¹ at pH 4.0 and 25 °C. The adsorption kinetics of Cr(VI) on the adsorbent conforms to the Langmuir isotherm model. The maximum adsorption occurs at pH 3, and then the adsorption capacity of PEI-Pal was decreased with the increase of pH values. The adsorption kinetics of Cr(VI) on PEI-Pal was modeled with pseudo-second-order model. The addition of Cl⁻, SO₄²⁻ and PO₄³⁻ reduced the Cr(VI) adsorption by competition with Cr(VI) for the active sites of PEI-Pal. The Cr(VI) saturated PEI-Pal can be regenerated in alkaline solution, and the adsorption capacity can still be maintained at 30.44 mg·g⁻¹ after 4 cycles. The results demonstrate that PEI-Pal can be used as a potential adsorbent of Cr(VI) in aqueous solutions.     

Application of nitrogen-enriched nanobiopolymer for the effective removal of Cr(VI) from tannery effluent

Nitrogen-enriched nanobiopolymer has been fabricated using (2,3-epoxypropyl) trimethylammonium chloride (EPTMAC) and explored for the removal of Cr(VI) from tannery effluent. The removal efficiency of nanobiopolymer was found to be 23.99 mg g^?1 (95.94%) under optimized conditions. The sorption data agrees well with the Langmuir and pseudo-second-order model. Equilibrium parameter (R_L) and sorption energy show the favorability and physical binding of Cr(VI) on the nanobiopolymer’s backbone. The values of ?G° (?7.84 kJ mol^?1), ?S° (65.97 J mol^?1K^?1) and ?H° (11.82 kJ mol^?1) reflect the feasible nature of the sorption process. Reusability study was also conducted to state the performance of the nanobiopolymer.     

Efficient removal of Cr(VI) and Pb(II) from aqueous solution by magnetic nitrogen-doped carbon

The magnetic nitrogen-doped carbon (MNC) was prepared from polypyrrole by a simple high temperature calcination process in this paper. The structure and properties of MNC were analyzed by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, Brunner-Emmet-Teller, vibrating sample magnetometer, and X-ray photoelectron spectroscopy. The capacity of MNC to adsorb Cr(VI) and Pb(II) was evaluated. The effects of the initial pH, dosage, concentration and temperature on the adsorption capacity of MNC were measured. MNC had a large specific surface area and a special porous structure. Its nitrogen and carbon sources were rich, and the ratio of carbon to nitrogen was fixed. The maximum Cr(VI)-adsorption capacity and maximum Pb(II) adsorption capacity of MNC could reach 456.63 and 507.13 mg∙g⁻¹ at 318 K, respectively. The pseudo-second-order model was used to describe the adsorption kinetics of MNC, and the Freundlich model was employed to discuss its isotherms. The adsorption process was affected by the electrostatic force, the reducing reaction, pores and chelation. The results of this study suggest that MNC is a material with superior performance, and is very easily regenerated, reused, and separated in the adsorption process.     

A Study in the Adsorption Behaviors of Cr (VI) on Crosslinked Cationic Starches

The adsorption behaviors between Cr (VI) and crosslinked cationic starch with quaternary ammonium group were investigated in various conditions. The adsorption processes are found to be dependent on the initial pH of the solution, the dose of the absorbents, initial concentration of Cr (VI), and adsorption temperature. The adsorption reaches equilibrium in a short time, and follows the Langmuir isotherm. The adsorption capacity increases with the increasing cationic groups. The adsorption thermodynamics study shows that adsorption processes are exothermic, and lower temperature is favorable to the adsorption of Cr (VI).     

啤酒酵母吸附Cr（VI）的动力学及热力学研究

研究啤酒酵母对溶液中铬(VI)的吸附效果和机理,通过红外对吸附前后菌体表面特征分析,表明Cr (VI)与菌体表面基团发生配位络合反应.结果表明,在温度为35 ℃,pH=2,Cr(VI)初始浓度为20 mg/L时达到最大吸附量,最大吸附量为4.19 mg/g.酵母菌对Cr(VI)的吸附行为基本符合Langmuir方程,并且在 25,30和35 ℃条件下的理论最大吸附量qmax分别为4.472,4.533,4.702 mg/g.动力学研究表明,反应在240 min吸附基本达到平衡状态,准二级动力学模型能够更好的描述吸附过程.不同温度下的吸附热力学显示,该吸附过程为自发的吸热反应.     

Studies of adsorption behavior of crosslinked chitosan for Cr(VI), Se(VI)

In this work, it was found that crosslinked chitosan (CCTS) had strong adsorption ability for some anions under certain conditions. Cr(VI) and Se(VI) existed in anion forms in aqueous solution, and their adsorption rates by CCTS were 97% for Cr(VI) at pH 3.0 and 95% for Se(VI) at pH 4.0. In addition, the adsorption balance time and isotherm of CCTS for Cr(VI) and Se (VI) were discussed and adsorption mechanism was explained. This research will be useful for designing CCTS‐based adsorption for metallic toxin removal and preconcentrating Cr(VI) and Se(VI) in their trace analysis. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3216–3219, 2000     

Removal of Cr(VI) from Model Solutions by a Combined Electrocoagulation Sorption Process

The elimination of hexavalent chromium from synthetic effluents in a batch stirred electrocoagulation cell with aluminum electrodes coupled with a sorption process using red onion skin adsorbent is addressed. The effect of process variables such as medium pH and adsorbent concentration was investigated in an attempt to optimize the removal capacity. Adsorption and electrocoagulation were first considered separately, with maximum Cr(VI) removal yields of 47 % and 78 %, respectively, at pH 2. When combining the two processes, a removal of 97 % of the total Cr(VI) in a pH range of 3–6 was achieved. The almost total elimination observed for the considered pollutant demonstrated the feasibility and the synergistic effect of the coupled process.