Micellar enhanced ultrafiltration and activated carbon fibre hybrid processes for copper removal from wastewater

Several series of experiments were conducted to investigate copper removal from artificial suspension in micellar enhanced ultrafiltration (MEUF) and activated carbon fibre (ACF) hybrid processes. Sodium dodecyl sulphate (SDS) was used as a surfactant. Copper removal increased with the increase of molar ratio of copper to SDS, operating retentate pressure and initial permeate flux. Permeate flux decreased with the increase of molar ratio of copper to SDS. Specific and relative fluxes declined, respectively, with the increase of retentate pressure and initial permeate flux. Based on removal efficiency and permeate flux, initial permeate flux of 1.05 m³/m²/day, copper to SDS molar ratio of 1:30 (9.44 mM of SDS), and operating retentate pressure of 1.4 bar were found to be the optimum operating parameters for 0.5 mM or less initial copper concentration. Average copper removal at the optimised condition was 98% and the corresponding permeate copper concentration was less than 1 mg/L. Adsorptive capacity of activated carbon fibre (ACF) for SDS was 170 mg/g. Langmuir isotherm equation gives a better fit with the experimental results compared to the Freundlich isotherm equation. Overall SDS removal efficiency of two sets of ACF unit in series was 85%.     

铁氧体法去除废水中的镍、铬、锌、铜离子

采用铁氧体法处理含镍、铬、锌、铜的废水,研究了pH及硫酸亚铁投加量对重金属离子去除效果的影响.对于镍、锌、铜离子,最佳絮凝pH分别为8.00～9.80、8.00～10.50和10.00,投加的亚铁离子与其摩尔比均为2～8;六价铬的最佳还原pH为4.00～5.50,最佳絮凝pH则为8.00～10.50,最佳投料比为20....     

改性活性炭脱除模拟烟气中气态汞的实验研究

以椰壳活性炭为原料,经硝酸活化再采用NaCl或NaBr溶液化学浸渍改性制备燃煤烟气脱汞吸附剂。通过N_2吸附-脱附(BET),扫描电子显微镜(SEM),X射线光电子能谱(XPS)对制备的吸附剂进行表征,并且采用模拟烟气在管道喷射装置内考察汞吸附脱除性能。结果表明:与原始椰壳活性炭相比,经硝酸活化后的椰壳活性炭汞吸附能力得到提高;而采用NaBr改性后的椰壳活性炭脱汞效果最好。在管道喷射实验装置内,经过1 mol/L NaBr改性后的椰壳活性炭,在模拟烟气温度120℃,碳汞质量比8 000,停留时间2 s条件下,脱汞率达到92.7%。改性后的椰壳活性炭是一种具有潜在应用价值的优良脱汞吸附剂。     

Regeneration and reuse of spent NaOH-treated oil palm frond for copper and zinc removal from wastewater

The use of NaOH-treated oil palm frond (OPF) sorbent for Cu and Zn removal and its subsequent regeneration process are reported. The regeneration of the spent sorbent was achieved by desorbing the metals in 0.1 M of sodium hydroxide (NaOH), ethylene diamine tetraacetic acid (EDTA), hydrochloric acid (HCl) and nitric acid (HNO₃) solutions. The reusability study of the sorbent was conducted using 100 mg/l of Cu and Zn at a pH of 4.5 and 5.5, respectively for 1 h. The results were to be correlated with the mechanism of the metal uptake. Freundlich isotherm fitted the data to indicate the presence of heterogeneous metal sorption sites. Zn showed better regeneration efficiency of up to 88% and HCl was the best regeneration agent. The results confirmed that ion exchange was the main mechanism for the metal uptake. The desorption efficiency dropped by merely about 20% while the sorption capacity experienced a drastic drop after reuse for the fourth cycle. The damage occurred on the heavy metal binding sites by the strong acid was responsible for this drop.     

Preparation and characterizations of activated carbon from kenaf fiber for equilibrium adsorption studies of copper from wastewater

The potential of activated carbon prepared from kenaf fiber (KF) to remove copper (II) from aqueous effluents was investigated. The fibers were first semi-carbonized, then impregnated with potassium hydroxide (KOH) and finally activated by using carbon dioxide (CO₂) gas to produce activated carbon. Pore structure and physical characteristics of the prepared kenaf fiber activated carbon (KFAC) were determined. Adsorption studies for divalent copper (Cu) ions were carried out to delineate the effect of contact time, temperature, pH and initial metal ion concentration on equilibrium adsorption capacity. The experimental data followed pseudo-second-order kinetics and Elovich Model than pseudo-first-order. Langmuir, Freundlich and Temkin models were implemented to analyze the parameters for adsorption at 30 °C, 50 °C and 70 °C. Thermodynamic parameters such as ??G ^o , ??H ^o and ??S ^o which represent Gibbs free energy, enthalpy and entropy, respectively, were evaluated. It was concluded that activated carbon from kenaf fiber (KFAC) can be used as an efficient adsorbent for removal of Cu (II) from synthetic wastewater.     

脉冲电源电解处理含氰含银电镀废水

利用脉冲电源从含氰含银电镀废水中回收银和去除氰,对比了脉冲电源与直流电源对含氰镀银废水的处理效果,系统研究了脉冲电源的电解电压、占空比和脉冲频率等参数对电能消耗、银回收率和除氰率的影响。结果表明,脉冲电源较直流电源能更加有效降低阳极的超电位,减少电极的极化,从而降低槽电压,进而有效地降低电能消耗。脉冲电源的优化参数是：脉冲电压2.0 V,脉冲频率1200 Hz,占空比50%。在循环流速100 ml·min^-1,pH值10～11,曝气速率1.0 L·min^-1的实验条件下,通入电解电压2.0 V、脉冲频率1200 Hz以及占空比50%的脉冲电源,电解2.0 h后,银回收率高达99%,除氰率达到86%。     

Comparing the efficacy of a novel waste-based adsorbent with PAC for the simultaneous removal of chromium (VI) and cyanide from electroplating wastewater

The potential of powdered pistachio hull (PHP) for the co-adsorption of Cr(VI) and cyanide from electroplating wastewater was compared to that of powdered activated carbon (PAC). The results of dynamic adsorption experiments indicated that the complete and simultaneous removal of Cr(VI) and cyanide from wastewater was achieved with 2 g/L of PHP after 60 min of contact. Alternatively, with PAC, 69.2 and 77.8% of Cr(VI) and cyanide, respectively, were removed under the same conditions. Adsorption of Cr(VI) and cyanide by PHP and PAC followed pseudo-second order kinetics, and the equilibrium adsorption data best fit the Langmuir isotherm. The maximum capacity of PHP for the co-adsorption of Cr(VI) and cyanide was 117.6 and 151.5 mg/g, respectively, and the maximum capacity of PAC for the adsorption of Cr(VI) and cyanide was 47.6 and 39.4 mg/g, respectively. It was found that which intraparticle diffusion controlled the adsorption of Cr(VI) and cyanide onto PHP and PAC under the selected conditions. Overall, PHP efficiently adsorbed Cr(VI) and cyanide from industrial effluents; thus, PHP is an affordable and cost-effective system for the treatment of wastewater.     

含铬废水的电化学法处理技术及研究进展

相比于六价铬,三价铬毒性更低且易形成不溶性沉淀物,将六价铬去除或还原为低毒的三价铬是废水除铬的关键过程。电化学技术因其通用性和环境相容性被广泛用于污水处理中,可通过"清洁试剂"——电子来实现Cr(Ⅵ)去除或分离。分别对电化学除铬技术如电絮凝、电化学还原/燃料电池、电渗析/电去离子/反向电渗析等技术的除铬机理及研究进展进行了回顾,并对电化学除铬技术的发展进行了总结和展望,作者认为电极材料的优化改性,集成反应器的开发与调控以及实现能源同步回收是今后电化学除铬技术的研究方向。     

蔗渣活性炭去除糖蜜酒精废水COD的实验研究

通过单因素与正交实验,研究了蔗渣活性炭处理糖蜜酒精废水的工艺条件及其影响因素.结果表明,最佳工艺条件为蔗渣活性炭投加质量0.30 g、吸附时间120 min、溶液的pH=7.3(中性)和温度为30℃(常温),在此条件下糖蜜酒精废水COD去除率达74.3%.     

中和-活性炭催化过氧化氢氧化法预处理脱墨废水的实验研究

采用中和-活性炭催化过氧化氢氧化法对旧报纸脱墨废水进行了预处理实验研究。探讨了中和实验、催化实验的各种因素对实验结果的影响,结果表明,20mL的CODcr值为31000mg/L、色度15000倍的脱墨废水,先用稀硫酸进行中和至pH=4,再用质量分数为30%的0.8mLH2O2和0.8g活性炭粉末在pH=3的条件下催化氧化19min,CODcr值降为2300mg/L,COD去除率达90%以上,色度降低为0倍,去除率为100%。     

The use of a combination of activated carbon and nickel microfibers in the removal of hydrogen cyanide from air

A hybrid material consisting of an activated carbon powder (50-80 mesh) trapped in 8 μm Ni-microfibers was prepared using standard wet layer paper-making/sintering and impregnation procedures. This was used together with a granular Cu-Zn-Mo-Ag-triethylenediamine impregnated carbon to purify air contaminated with hydrogen cyanide (HCN). This combination of materials improves HCN removal efficiency from air compared with that obtained using granular impregnated carbon alone. The HCN vapor breakthrough behavior for this combination of materials was examined theoretically.     

含碱性表面基团活性炭去除Cr(Ⅵ)的研究

介绍了用氧化剂和高温处理制取含碱性表面基团活性炭的方法，测定了它们的离子交换空量。研究了溶液pH和Cr(Ⅵ）的初始浓度对Cr（Ⅵ）去除率的影响。讨论了含碱性表面基团活性炭对溶液中Cr(Ⅵ）的去除机理。     

Use of activated carbon for the recovery of chromium from industrial wastewaters

A technique for the removal and recycling of hexavalent chromium from electroplating industries was developed. It involves a two-phase process which consists of (1) the use of an activated carbon bed for the accumulation of chromium onto the surface of activated carbon followed by (2) the regeneration of the carbon leading to a concentrated chromium solution with potential for reclamation or reuse within the plating operation. Results from continuous flow experiments showed that in excess of 99% chromium removal efficiency can be achieved. It was also revealed that regeneration of the exhausted carbon under acidic conditions recovered chromium in the trivalent state with concentrations as high as 3 g dm⁻³, more than 12 times the influent concentration. The adsorption capacity of the activated carbon was found to increase with successive cycles of adsorption/regeneration. However, when regeneration was achieved under alkaline conditions, the chromium was recovered in the hexavalent state with concentrations as high as 8·4 g dm⁻³, in excess of 33 times the chromium influent concentration. In addition, under caustic regeneration conditions, the data showed that the adsorption capacity in this case decreases with the increased number of exhaustion cycles. Mass balance calculation for both acid and caustic regeneration indicated that in both cases the regeneration process was incomplete with a recovery efficiency averaging around 50%. In an attempt to maximise the recovery efficiency, a combination of caustic followed by acid regeneration was applied to the exhausted activated carbon and the results led to a drastic improvement in the total recovery process (85–98%). These results clearly show that activated carbon is a viable candidate for the removal and recovery of chromium from electroplating industries. The critical advantage in the use of activated carbon is (1) the ability to regenerate and thus prepare a concentrated chromium solution for potential reclamation or recycle to the plating operation, and (2) the potential of avoiding the generation of hazardous sludge for land disposal. ©1997 SCI     

Palladium,silver, and zinc oxide nanoparticles loaded on activated carbon as adsorbent for removal of bromophenol red from aqueous solution

The adsorption of bromophenol red (BPR) onto three adsorbents including palladium, silver and zinc oxide nanoparticles loaded on activated carbon (Pd-NP-AC, Ag-NP-AC and ZnO-NP-AC) in a batch system has been studied and the influence of various parameters has been optimized. The influence of time on removal of BPR on all adsorbent was investigated and experimental data were analyzed by four kinetic models including pseudo first and second-order, Elovich and the intraparticle diffusion equations. Following fitting the experimental data to these models, the respective parameters of each model such as rate constants, equilibrium adsorption capacities and correlation coefficients for each model were investigated and based on well known criterion their applicability was judged. It was seen that the adsorption of BPR onto all adsorbents sufficiently described by the pseudo second-order equation in addition to interparticle diffusion model. The adsorption of BPR on all adsorbent was investigated at various concentration of dye and the experimental equilibrium data were analyzed and fitted to the Langmuir, Freundlich, Tempkin, Dubinin, and Radushkevich equations. A single stage in batch process was efficient and suitable for all adsorbents using the Langmuir isotherm with maximum adsorption of 143 mg g^?1 for Pd-NP-AC, 250 mg g^?1 for Ag-NP-AC and 200 mg g^?1 for ZnO-NR-AC. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° for Pd-NP-AC adsorbent were calculated.     

Adsorption studies on copper,cadmium, and zinc ion removal from aqueous solution using magnetite/carbon nanocomposites

Magnetite/carbon nanocomposites were tested as adsorbents for removal of metal ions from aqueous solutions. The effect of adsorption parameters such as solutions pH (ranging between 2 and 9), the nature and the quantity of the sorbent (10, 20, 40, and 60 mg), initial concentration of metal ions (10, 30, 50, 100, and 150 mg/L), and temperature (25, 45, and 65°C) was evaluated. The removal efficiency of metal ions depends on solution pH and increases with increasing carbon content, the dose of magnetite/carbon nanocomposites, and the temperature and decrease with initial concentration of the metal ions. The adsorption kinetics was described by pseudo-second-order model, and the equilibrium experimental data were well fitted to the Sips isotherm, yielding a maximum adsorption capacity of 41.11, 76.67, and 48.45 mg/g for copper, cadmium, and zinc, respectively. The thermodynamic parameter Gibbs free energy was determined to be negative, which indicated that the adsorption process is spontaneous. The optimum conditions (1 g/L adsorbent, 25°C, and pH 6) were selected for removal of metal ions from real wastewaters, with good results indicating that investigated nanocomposites could be used for the application in real systems.     

活性炭-珍珠岩复合材料处理含铬废水的研究

采用活性炭-珍珠岩复合材料处理含铬废水,分别试验了复合材料的投加量、吸附时间、pH值、温度、含铬废水初始浓度等因素对Cr（Ⅵ）去除率的影响.结果表明,当活性炭与珍珠岩质量比为10∶1,活性炭投加量为0.5 g/mL,珍珠岩为0.05 g/mL,pH为4,吸附时间为130 min,温度为25℃时,铬的去除率最佳,可以达到96％.     

类活性炭材料强化去除焦化废水中有机污染物的研究

选取焦粉和活性焦两种类活性炭材料,采用HNO_3氧化、HNO_3-N_2联用和负载TiO_2对其进行改性。通过对焦化废水去除效果的比较,确定最佳改性方法。并采用SEM-EDS、XRD和FTIR对改性前后类活性炭材料的组成、晶体结构和表面官能团的变化进行分析。结果显示,焦粉采用HNO_3-N_2联用活化不仅可以增加其表面官能团,还能够增加内部孔隙率;活性焦采用负载具有催化氧化作用的TiO_2可以有效提高对有机物的去除效果。     

Pretreatment with fine bubbles for effective zinc ion precipitation and removal from zinc electroplating wastewater

Heavy metals such as zinc are widely used in plating plants for the processing of material surfaces; therefore, an adequate wastewater treatment is required afterwards to comply with wastewater regulations. However, the presence of chemicals such as degreasing agents in the wastewater generated from the plating process inhibits the formation of hydroxides, thereby making treatment of wastewater and compliance with the stipulated regulations difficult. Herein, the effects of fine bubbles on oil cleaning and wastewater treatment were investigated for developing an alternative cleaning technology to degreasing agents. The concentration of fine bubbles significantly affected the oil cleaning. The fine bubbles demonstrated remarkable cleaning of highly viscous oil, which was difficult to remove using pure water. The high cleaning effect of fine bubbles on oil was achieved because of the hydrophobic interaction of the bubbles. Furthermore, a decrease in cleaning effect was observed for samples with uneven shapes, which was attributed to the difficulty in penetration of fine bubbles in materials with irregularities. Furthermore, fine bubble cleaning exhibited better efficiency for wastewater treatment than degreaser cleaning. Therefore, fine bubble cleaning is speculated to be an excellent cleaning technology with high oil cleaning effectiveness and improved wastewater treatability.     

Adsorption of chromium by activated carbon from aqueous solution

Adsorption isotherms of Cr(III) and Cr(VI) ions on two samples of activated carbon fibres and two samples of granulated activated carbons from aqueous solutions in the concentration range 20–1000 mg/l have been studied. The adsorption isotherms have been determined after modifying the activated carbon surfaces by oxidation with nitric acid, ammonium persulphate, hydrogen peroxide and oxygen gas at 350°C and after degassing at different temperatures. The adsorption of Cr(III) ions increases on oxidation and decreases on degassing. On the other hand, the adsorption of Cr(VI) ions decreases on oxidation and increases on degassing. The increase of Cr(III) and the decrease of Cr(VI) on oxidation and the decrease of Cr(III) and the increase of Cr(VI) on degassing have been attributed to the fact that the oxidation of the carbon surface enhances the amount of acidic carbon–oxygen surface groups while degassing eliminates these surface groups. Thus while the presence of acidic surface groups enhances the adsorption of Cr(III) cations, it suppresses the adsorption of Cr(VI) anions.