腐植酸在含酚废水处理中的实验研究

对腐植酸吸附剂处理含酚废水进行了实验研究,考察了吸附时间、温度、pH值对吸附率的影响,通过改变腐植酸用量与化学耗氧量(CODCr)的关系探讨了其在工业应用的可能性。结果表明,腐植酸对含酚废水有较好的处理效果,在pH=1.0时,室温下吸附12h,吸附率可达95%以上;腐植酸用量为0.5g/10mL废水时,CODCr值可降至50mg/L以下。     

Adsorptive Removal of Cobalt from Aqueous Solutions by Utilizing Industrial Waste and its Cement Fixation

Abstract

In the present study, the adsorption potential of battery industry waste as adsorbent has been investigated for the removal of cobalt from aqueous solutions. The results have shown that the prepared adsorbent adsorbs cobalt to a sufficient extent (35 mg/g). The adsorption of cobalt has been studied on this battery industry waste as a function of contact time, concentration, and temperature by the batch method. The adsorption has been found to be endothermic and the data conform to the Langmuir equation. The analysis of kinetic data indicates that adsorption is a first order process and pore‐diffusion controlled.

Further, the metal‐laden adsorbent was immobilized into cement for ultimate disposal and no significant leaching was observed from the stabilized products. Thus, the present study clearly reveals that battery industry waste can be fruitfully employed in treating industrial effluents containing toxic metal ions. The proposed technology (utilization of industrial wastes for effluent treatment and then ultimate disposal of adsorbents laden with pollutants in cementitious materials by fixation) provides a twofold aim of wastewater treatment and solid waste management.     

Continuous Adsorption of a Cationic Dye on Surface Modified Rice Husk: Statistical Optimization and Dynamic Models

The continuous adsorption of a cationic dye (Methylene Blue, MB) on surface-modified rice husk was investigated. First, rice husk was submitted to ultrasound-assisted, supercritical CO₂ and NaOH treatments. The adsorbents were characterized. Then, the continuous adsorption was optimized by response surface methodology (RSM), using raw rice husk as the adsorbent. Finally, under the optimal conditions, breakthrough curves were obtained using all adsorbents and the models were used to interpret these curves. The optimal bed performance was reached at a flow rate of 5?mL?min^?1 and an initial MB concentration of 10?mg?L^?1. Under these conditions, the breakthrough time was 109?min, the length of the mass transfer zone was 20.1?cm, and the maximum capacity of the column was 1.55?mg?g^?1. All surface modifications were able to improve the rice husk characteristics in relation to the MB adsorption. Consequently, the bed performance was significantly improved when the surface-modified adsorbents were used. The breakthrough times were 109, 240, 155, and 385?min, respectively, when raw rice husk, UA–rice husk, SCO₂–rice husk, and NaOH–rice husk were used. The length of the mass transfer zone was 20.1, 7.9, 15.9, and 9.3?cm for raw rice husk, UA–rice husk, SCO₂–rice husk, and NaOH–rice husk, respectively. The dynamic models were able to fit the adsorption data and provided physically consistent parameters.     

Biotechnology group meeting. Biochemistry and genetics for increasing productivities of industrial fermentation

Biosorption of heavy metals by microbial cells has been recognized as a potential alternative to existing technologies for removing heavy metals from industrial waste waters. Many aquatic microorganisms, such as algae, can take up dissolved metals from their surroundings to their cells. In this study, the adsorption of lead(II) ions was investigated in a single-staged batch reactor. Chlorella vulgaris, a green alga, was used as the sorbent. The sorption phenomenon was expressed by the Freundlich adsorption isotherm and this expression was used for the calculation of residual or adsorbed metal ion concentration at equilibrium (C_eq or C_x,eq) at a given ‘volume of waste water containing heavy metal ion/quantity of alga (V₀/X₀)’ ratio in a single-staged batch reactor. Experimental C_eq and C_x,eq values were compared to calculated ones. Applications in waste water treatment for lead(II) removal have been suggested.     

Removal of copper,cadmium, and chromium from wastewater by modified wheat bran using Box–Behnken design: Kinetics and isotherm

In this work, copper, cadmium, and chromium were removed using hydrochloric acid-treated wheat bran as an adsorbent. Experiments were carried out in batch adsorption mode. Box–Behnken design of response surface methodology was used to determine the effect of initial metal concentration, pH, temperature, and adsorbent dose on removal efficiency of copper, cadmium, and chromium. Analysis of variance results are shown for all the three heavy metal, and the effect of the parameters is discussed. The optimum initial metal concentration, pH, temperature, and adsorbent dose were found to be 90.58 mg/L, 6, 35.9°C, and 2.39 g, respectively. Pseudo-second-order kinetic model was found to be the best suitable model for adsorption rate. The isotherms of adsorption data were analysed using various adsorption isotherm models such as Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherms. It was found that Langmuir and Temkin isotherms represent the equilibrium data for these heavy metal removals.     

Adsorption of Pb(II) Ions Using Humic Acid Coated Chitosan-Tripolyphosphate (HA-CTPP) Beads

A new humic acid (HA) based adsorbent was prepared by coating humic acid on chitosan tripolyphosphate (CTPP) beads. Humic acid-chitosan tripolyphosphate (HA-CTPP) beads thus obtained were characterized using Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. Swelling capacity studies of CTPP and HA-CTPP beads conducted in the pH range, pH = 1–10 showed that HA-CTPP beads are more stable against swelling than CTPP beads. Equilibration of HA-CTPP beads in water for different pH showed that leaching of HA from the beads is negligible and the beads are stable for adsorption applications. Adsorption of Pb(II) ions onto HA-CTPP beads were studied as a function of various operational parameters such as initial pH, metal ion concentration, and contact time. The results showed that HA-CTPP beads are suitable for Pb(II) ions adsorption and the kinetics of sorption very well fit into pseudo-second order model. The Langmuir model was found to be more suitable for explaining the observed adsorption data, giving a theoretical maximum adsorption capacity of 223.7 mg/g. HA-CTPP beads could possibly find application in the treatment of waste water contaminated with other toxic and/or heavy metals.     

C/W emulsion-templated macroporous anionic monolith: Application for dye removal

A clean, sulfonated, highly adsorptive macroporous monolith was constructed using a carbon dioxide-in-water (C/W) high internal phase emulsion template. The random copolymerization of N-hydroxyethyl acrylamide and sodium styrene sulfonate in the water phase was initiated with persulfate. The chemical composition of the novel sulfonated monolith was confirmed by Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy, and the interconnected pore structure was confirmed by scanning electron microscopy (SEM). Results showed that the void sizes were 47–92 μm and that the interconnected pore throats were approximately 10–30 μm. Such a hydrophilic, anionic macroporous material exhibited excellent adsorption properties for cationic dyes. The maximum adsorption capacity of the monolith for methylene blue (MB) and malachite green (MG) reached 1,316 and 2,624 mg/g, respectively, in 500–800 mg/L dye solution at 25°C. Furthermore, the kinetics and thermodynamic parameters of the adsorption process were examined. Experimental data exhibited that adsorption kinetically followed the pseudo-second-order model. The removal rates of MG and MB both exceeded 90% after six regenerations. The adsorption mechanism of the adsorbent was demonstrated preliminarily. The dynamic adsorption operation of MB was conducted in a fixed column, and the breakthrough curve data were fitted using the Thomas and bed depth service time models. All these findings indicated the potential industrial applications of adsorptive sulfonated macroporous monolith.     

Removal of Cd2+, Cu2+, Ni2+, and Pb2+ ions from aqueous solutions using tururi fibers as an adsorbent

This work investigates the removal of Cd²⁺, Cu²⁺, Ni²⁺, and Pb²⁺ ions from aqueous solutions using tururi fibers as an adsorbent under both batchwise and fixed‐bed conditions. It was found that modification of the tururi fibers with sodium hydroxide increased the adsorption efficiencies of all metal ions studied. The fractional factorial design showed that pH, adsorbent mass, agitation rate, and initial metal concentration influenced each metal adsorption differently. The kinetics showed that multi‐element adsorption equilibria were reached after 15 min following pseudo‐second‐order kinetics. The Langmuir, Freundlich, and Redlich–Peterson models were used to evaluate the adsorption capacities by tururi fibers. The Langmuir model was found to be suitable for all metal ions. Breakthrough curves revealed that saturation of the bed was reached in 160.0 mL with Cd²⁺ and Cu²⁺, and 52.0 mL with Ni²⁺ and Pb²⁺. The Thomas model was applied to the experimental data of breakthrough curves and represented the data well. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40883.     

Adsorption studies of Cr(VI) and Cu(II) metal ions from aqueous solutions by synthesized Ag and Mg co-doped TiO2 nanoparticles

ABSTRACT

This communication provides the eliminating of heavy metals from water resources using Ag-Mg/TiO₂ nanoparticles. The nanoparticles with a size of 15 nm were prepared using sol-gel technique and used for the removal of Cr(VI) and Cu(II) from waste waters. Batch sorption studies were carried out to investigate the adsorption of the above metal ions for a concentration range of 0.1–10 mg/L. The maximum sorption capacity values were found to be 2.42 mg/g for Cr(VI) and 2.03 mg/g for Cu(II) at a concentration of 0.1 ppm. The mechanism of adsorption was also investigated. The results showed that both Freundlich and Dubinin–Radushkevitch isotherms were found to be the best fit for the adsorption of metals. The results from kinetic data reveal that the pseudo-second-order and Reichenberg film diffusion models were found to be well fit for the experimental data. The value of the thermodynamic parameter ΔH° revealed the endothermic adsorption process and negative value of ΔG° shows the feasibility and spontaneity of material–anion interaction. In addition, the method is considered to be simple and cost-effective, and shows excellent adsorption removal properties on heavy metals for industrial applications.     

Fast Removal of Sr(II) From Water by Graphene Oxide and Chitosan Modified Graphene Oxide

Graphene oxide is a unique material that can be used for adsorption of radioactive waste because it contains various function groups such as epoxide, carbonyl, carboxyl and hydroxyl in addition to its high specific surface area. The as-prepared GO and the modified one (GO-chitosan composite) have been prepared then characterized and used as adsorbent for radioactive metal ions [Strontium, Sr(II)]. The results showed that the prepared materials are efficient adsorbents for removal of Sr(II) from water. The effect of contact time, pH and temperature on adsorption have been studied. The results indicated that the maximum adsorption capacity was about 140 and 179.6 mg/g for GO and GO-chitosan composite respectively. It was found that pH?~?6 and temperature?~?40 °C are the best condition for removal of Sr(II) from water. Two isotherm models (Langmuir and Freundlich) and three kinetic models (Pseudo-first-order, pseudo-second-order, and intra-particle particle diffusion model) have been applied. Based on the calculated isotherm parameters (R²), it can be concluded that Langmuir model fits the adsorption equilibrium data better than Freundlich model, the results also indicated that the second order kinetic model is the best representative for adsorption of Sr(II) on GO, Chitosan and GO-Chitosan. Based on the regressions of intraparticle diffusion model, experimental data showed that the adsorption process involved intraparticle diffusion, which was not the only rate-controlling step.     

乙醇-水体系在马铃薯粉吸附剂上的气相吸附过程研究

利用固定床吸附柱(φ25 mm×900 mm)对乙醇-水体系在马铃薯粉吸附剂中的气相吸附过程进行了研究,研究了不同条件下乙醇-水体系在马铃薯粉中吸附的透过曲线。结果表明,在本试验条件下,生产能力和透过时间随温度降低、粒径变小、进料流量降低和床层高度增加而增大。在乙醇-水体系进料流量为3 mL/min左右、床层温度80℃、吸附剂粒径245～350μm、床层高度700 mm和进料乙醇体积分数94.5%条件下,每1 000 g马铃薯粉吸附剂可脱水得到无水乙醇205.1 g。马铃薯粉吸附性能良好,再生容易,具备作为生物质吸附剂制备无水乙醇的潜力。     

粉煤灰吸附与Fenton氧化联合处理焦化废水的研究

利用粉煤灰作为吸附剂,分别对生化处理前焦化废水和生化处理后焦化废水进行了吸附处理,并将处理效果进行了对比,考察了pH值,药剂投加量,吸附时间,吸附温度等因素对处理效果的影响,得出最佳处理条件为:废水pH值为5左右时,每100 mL废水中加入6 g粉煤灰,吸附时间为40 min,处理后焦化废水的COD和色度可达污水综合排放标准(GB8978—96)中二级排放标准。对吸附处理后的焦化废水利用Fenton试剂进一步氧化处理,每升废水中投加1.40 g FeSO_4,1 mL质量分数为30%双氧水,氧化30 min后,废水中COD、色度以及含油量均达到污水综合排放标准(GB8978—96)中一级排放标准,并且此种处理方法比单独用Fenton氧化法处理,每升废水可节约3 mL双氧水和4.2 g FeSO_4,大大减少了药剂使用量,减少了废水处理的成本。     

余热制冷吸附床的一个新传热传质模型

在既考虑吸附剂颗粒内部的传质阻力,又考虑吸附剂颗粒之间的外部传质阻力的前提下,建立了余热吸附制冷系统中吸附床的三维非平衡传热传质数学模型,它包括加热/冷却流体传热模型、换热管传热模型、肋片传热模型、吸附剂颗粒床传热传质模型4部分;通过对模型的数值求解,获得了吸附床内部的温度演变曲线和性能指标,与实验结果基本吻合。     

改性粉煤灰处理含磷废水的研究

采用浓硫酸固相反应法对粉煤灰进行改性用于含磷废水的净化,考察了pH值,吸附剂用量,磷初始浓度,反应时间对净化过程的影响。通过实验发现溶液pH值在4-10范围内对磷的吸附过程影响不显著,改性粉煤灰可以在较宽的pH值范围内进行脱磷处理;随着粉煤灰加入量的增加和初始溶液中磷酸根浓度的降低,磷的净化率逐渐增加。对于含磷50 mg/L的溶液,当粉煤灰的投加量为1.5%时,磷的吸附效率可达99.66%,净化后水中含磷量为0.17 mg/L。改性粉煤灰对水中磷的净化过程速度较快,5 min可达到最大净化率。改性粉煤灰对磷的吸附等温线符合Freudlich方程。     

EQUILIBRIUM,KINETICS, AND BREAKTHROUGH STUDIES FOR ADSORPTION OF Cr(VI) ON CHITOSAN

Wastewater containing low levels of pollutants can be effectively treated by the adsorption technique. In the present work, an adsorption study was carried out using chitosan as adsorbent in a fixed-bed column for the removal of Cr(VI) from wastewater solutions. The column performance of Cr(VI) adsorption onto chitosan was studied at different bed heights (3–9 cm), flow rates (50–200 mL/min), initial metal concentrations (2–10 mg/L), pH values (2–7), and temperatures (30°–60°C). The equilibrium data for the batch adsorption of Cr(VI) on chitosan were tested using the Langmuir, Freundlich, and BET isotherm models. The Langmuir model was found to be the most suitable, with a maximum adsorption capacity of 35.7 mg/g and a correlation coefficient (R ²) = 0.952. The experimental data were found to fit well with the pseudo-second-order kinetic model, with R ² = 0.999. The dynamics of the adsorption process was modeled using the Adams-Bohart, Thomas, and mass transfer models. The models were used to predict the breakthrough curves of adsorption systems and to determine the characteristic design parameters of the column. The adsorption data were observed to fit well with all three models. The model parameters were derived using MATLAB software. In order to compare quantitatively the applicability of adsorption dynamic models in fitting to experimental data, the percentage relative deviation (P) was calculated and found to be less than 5, confirming that the fit is good for all three models.     

改性羟基磷灰石对水体中五价钒的吸附

随着工业的发展,水体重金属污染逐渐成为环境污染的重要组成部分,寻求环境友好型材料来治理水体重金属污染已成为当今环境科学研究的热点之一.以Ca(NO3)2· 4H2O和(NH4)2HPO4为原料,利用溶液共沉淀法制备羟基磷灰石,并采用聚乙二醇对其改性,得到改性羟基磷灰石,并用其对水体中的钒污染物进行吸附研究.单因素吸附实验表明,溶液pH值、吸附剂投加量、吸附时间和环境温度均会对吸附产生影响.在钒浓度为100 mg· L-1,溶液pH值为5.00的条件下,当改性羟基磷灰石投加量为10 g· L-1时,吸附趋于平衡,得到最大吸附率95.2%.在一定条件下,聚乙二醇改性羟基磷灰石可用于水体钒污染的修复.     

Equilibrium and Kinetic Studies of Ni (II) Adsorption using Pineapple and Bamboo Stem Based Adsorbents

This work addresses the preparation and characterization of inexpensive adsorbents for the removal of Ni (II) from aqueous solutions. Activated carbon based adsorbents have been prepared from plant based biomass resources, namely Pineapple stem ( Ananas Comosus ) and Bamboo Stem ( Bambuseae ). Adopting phosphoric acid and heat treatment techniques, it has been observed that the bamboo stem activated charcoal (BSAC) and pineapple stem (PS) adsorbents had a BET surface area of 116 and 11.47 m ² /g, respectively. FTIR analysis indicated that various surface functional groups (such as C ≡ N stretching, stretching vibration of C = O, –CH₃ wagging and C–O stretching vibration) contribute towards Ni (II) adsorption. Batch mode adsorption experiments were conducted for these adsorbents in the range of 50–300 mg/L Ni (II) solution concentration, 2–10 pH, 15–300 min. contact time, and 0.02–0.1 g/50 mL dosage. The BSAC adsorbent has been characterized with a metal uptake and %removal of 121.72 mg/g and 92.47, respectively, which corresponds to 45% higher metal uptake than corresponding bamboo based adsorbents presented in the literature. Further experimentation with BSAC enabled to achieve activated charcoal with surface area values similar to that of the commercial activated carbon adsorbent. The bamboo adsorbent has also been evaluated to perform similar to the commercial activated carbon for the removal and recovery of Pd (II) from synthetic electroless plating solutions. Also, a conceptual cost analysis indicated and affirmed towards the potential of the BSAC adsorbents for waste water treatment applications.     

Kinetics and Equilibrium Studies for the Removal of Cobalt,Manganese, and Silver in Ethanol using Dowex 50W-x8 Cation Exchange Resin

Organic solvents such as ethanol, find a wide range of applications in fuel, pharmaceutical industries, food industries, and paint formulations, among others. The removal of Ag(I), Co(II), and Mn(II) ions in ethanol by cation exchange resin, Dowex 50W-x8, was investigated. The adsorption characteristics of metal ions onto Dowex 50W-x8 resin were described by Langmuir isotherms. The maximum sorption exchange capacities at 298 K were obtained as 47.4 mg g^?1, 52.6 mg g^?1, and 58.5 mg g^?1 for Ag(I), Co(II), and Mn(II), respectively. The data was also fitted to Temkin and Dubinin-Radushkevich adsorption isotherm models to evaluate other adsorption properties. The ion exchange of silver, cobalt, and manganese on cation exchange resin followed pseudo-second-order kinetics, and the intraparticle diffusion was rate-determining step. The thermodynamic parameters indicated that the sorption of metal ions onto Dowex 50W-x8 resin was spontaneous (negative ΔG°) and endothermic in nature (positive ΔH°) implying that the adsorption capacity increased with increasing temperature. The resin can be regenerated by eluting metal ions with 3.0 mol L^?1 HNO₃ followed by washing it with 10 mL of Millipore water and 10 mL of 2.0 M NaOH, respectively. The proposed method was applied for metal ion removal in real ethanol samples.     

Modeling of solid—liquid adsorption: Effects of adsorbent loads on model parameters

The adsorption of cobalt phthalocyanine dye onto activated carbon in a continuous stirred tank adsorber was studied. The variables investigated were: adsorbent mass, adsorbent particle size and fluid flowrate. Several models based on film, pore and surface diffusion were constructed and fitted to the experimental data. Experimental results showed: (i) the increasing importance of the film mass transfer resistance for increasing adsorbent loads; (ii) the increasing importance of the surface diffusion mechanism for increasing adsorbent loads; and (iii) the better discrimination among different models for higher adsorbent loads and lower flowrate.     

Biosorption of hexavalent chromium from aqueous solutions using raw coconut fiber as a natural adsorbent

Abstract

This work aims to evaluate the Cr(VI) removal efficiency and adsorption capacity of the raw coconut fiber from synthetic aqueous solutions through the operational parameters as well as to represent the mechanisms of removal by kinetic and isotherm models. The experimental study was conducted in batch system and the optimum conditions for the adsorption of this metal by the biomass were according to: pH 2, contact time of 270?min, and 10?g/L of adsorbent dosage concentration. The removal efficiency obtained for Cr(VI) solutions was 99.2% at concentrations of 25–50?mg/L. For the highest concentrations, the removal decreased from 96.3% to 74.4%, when Cr(VI) solutions ranged from 100?mg/L to 250?mg/L, respectively. The adsorption kinetics was applied and showed a good agreement for pseudo-second-order and Elovich models, which point out a chemisorption. For the adsorption capacity at equilibrium conditions, the best fit was for the Redlich–Peterson isotherm indicating favorable adsorption and monolayer coverage.