Investigation of phosphate adsorption from an aqueous solution using spent fluid catalytic cracking catalyst containing lanthanum

A spent fluid catalytic cracking (FCC) catalyst containing lanthanum (La) was used as a novel adsorbent for phosphorus (P) in simulated wastewater. The experiments were conducted in a batch system to optimize the operation variables, including pH, calcination temperature, shaking time, solid-liquid ratio, and reaction temperature under three initial P-concentrations (C₀ = 0.5, 1.0, and 5.0 mg/L). Orthogonal analysis was used to determine that the initial P-concentration was the most important parameter for P removal. The P-removal rate exceeded 99% and the spent FCC catalyst was more suitable for use in low P-concentration wastewater (C₀ <5.0 mg/L). Isotherms, thermodynamics and dynamics of adsorption are used to analyze the mechanism of phosphorus removal. The results show that the adsorption is an endothermic reaction with high affinity and poor reversibility, which indicates a low risk of second releasing of phosphate. Moreover, chemical and physical adsorption coexist in this adsorption process with LaPO₄ and KH₂PO₄ formed on the spent FCC catalyst as the adsorption product. These results demonstrate that the spent FCC catalyst containing La is a potential adsorbent for P-removal from wastewater, which allows recycling of the spent FCC catalyst to improve the quality of water body.

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磷酸盐改性方解石去除水中磷酸盐研究

使用磷酸盐溶液和方解石之间的反应得到方解石去除水中磷酸盐后的产物,即磷酸盐改性方解石,通过实验对比分析了方解石和磷酸盐改性方解石对水中磷酸盐的去除动力学,并考察了磷酸盐改性方解石去除水中磷酸盐的各种影响因素。磷酸盐改性方解石对水中磷酸盐的去除能力明显优于方解石。当反应时间为2h时,实验条件下磷酸盐改性方解石对水中磷的去除率达到72%,而方解石对磷的去除率仅为35%。当pH为5~7时,磷酸盐改性方解石对水中磷酸盐的去除能力较高;当pH由7增加到10 h,对磷酸盐的去除能力略微下降;当pH由10增加到12 h,对磷酸盐的去除能力急剧下降。磷酸盐改性方解石对水中磷酸盐的单位去除量随初始磷质量浓度的增加而增加。过高的初始磷质量浓度会导致磷酸盐改性方解石对水中磷酸盐的去除率过低。磷酸盐改性方解石对水中磷酸盐的去除能力随反应温度的升高而增加。磷酸盐改性方解石对水中磷酸盐的去除动力学可以较好地采用准二级动力学模型加以描述。水中共存的钙离子有利于磷酸盐改性方解石对磷酸盐的去除,而水中共存的碳酸氢根离子抑制了磷酸盐改性方解石对磷酸盐的去除。磷酸盐改性方解石去除水中磷酸盐的主要机制是磷酸钙沉淀作用。磷酸盐改性方解石不仅会为磷酸钙沉淀反应的异质成核提供核心,促进磷酸钙沉淀的形成,而且当水处于对方解石不饱和状态时会溶解释放出可溶性钙,为磷酸钙沉淀的形成提供钙源。上述结果表明,方解石去除水中磷酸盐后的产物可以被再次用于水中磷酸盐的去除,并且对磷酸盐的去除效果优于原始的方解石。     

Adsorption and removal of antimony from aqueous solution by an activated Alumina

The adsorption of Sb(V) ions from aqueous solutions onto commercially available activated alumina (AA) was investigated. AA has a much higher adsorption capacity than presently used adsorbents. Sb(V) ions are likely adsorbed through electrostatic attraction and/or specific adsorption mechanism, while the optimum pH is found in the range of 2.8–4.3. The Sb(V) ions adsorption capacities increase with increasing temperature. The addition of nitrate, acetate, arsenite, chloride, and silicate ions affected Sb(V) ions adsorption only slightly, while the coexisting ascorbate, arsenate, phosphate, sulfate, EDTA, tartrate, and citrate ions substantially depressed Sb(V) ions adsorption.     

Removal of cyanide in aqueous solution by oxidation with hydrogen peroxide in presence of activated alumina

This work is dedicated to the removal of free cyanide from aqueous solution by oxidation with hydrogen peroxide H₂O₂ catalyzed by neutral activated alumina. Effects of initial molar ratio [H₂O₂]₀/[CN^?]₀, catalyst amount, pH, and temperature on cyanide removal have been examined. The presence of activated alumina has increased the reaction rate showing thus, a catalytic activity. The rate of removal of cyanides increases with rising initial molar ratio [H₂O₂]₀/[CN^?]₀ but decreases at pH 10 to 12. Increasing the alumina amount from 1.0 to 30 g/L has a beneficial effect, and increasing the temperature from 20 °C to 35 °C improves cyanide removal. The kinetics of cyanide removal has been found to be of pseudo-first-order with respect to cyanide and the rate constants have been determined.     

Removal of Janus Green dye from aqueous solutions using oxidized multi-walled carbon nanotubes

Multi-walled carbon nanotubes (MWCNTs) were oxidized and characterized by Fourier transform infrared spectroscopy. The adsorption characteristics of the oxidized MWCNT adsorbent were examined using Janus Green (JG) as adsorbate. In batch tests, the effects of pH, adsorbent dose, contact time, and temperature were studied. The maximum adsorption capacity was found to be 56 mg g^?1. The experimental data were fitted to the Langmuir, Freundlich, and Tempkin isotherm models, the first one being the most appropriate. Kinetic analysis showed that adsorption was most accurately represented by a pseudo-second-order model.     

Comparative adsorption of Pb(II) and Cd(II) ions on chestnut shell in aqueous system

In this study, high capacity Chestnut shell, a waste product from the chestnut sugar production industry, was successfully applied to remove Pb (II) and Cd (II) ions from aqueous solutions. Maximum adsorption capacities were found as 541.25?mg/g and 75.86?mg/g for Pb(II), and Cd(II) respectively. Several important parameters influencing the adsorption of Pb(II) and Cd(II) ions such as contact time, pH, temperature and effect of metal concentration were investigated systematically by batch experiments. Langmuir and Freundlich adsorption models were used to describe adsorption isotherms and constants. The thermodynamic parameters, such as standard free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°), of the adsorption process were calculated. The adsorbents were characterised by scanning electron microscopy. It has been observed from the experimental results that in case of both Cd (II) and Pb (II), pseudo 2nd order kinetic model. From the results, Chestnut Shell are considered as an effective, low cost and environmental friendly adsorbent for the removal of Pb (II) and Cd (II) from wastewater.     

Biosorption of Direct Yellow 12 from aqueous solution using green alga Ulva lactuca

The potential of commonly available green alga Ulva lactuca was investigated as viable biomaterials for removal of synthetic azo dye (Direct Yellow 12, DY-12) from aqueous solution. The results obtained from the batch experiments revealed that the ability of the U. lactuca to remove DY-12 from its aqueous solution was dependent on the dye concentration, pH, and algal biomass but less dependent on the particle size of the U. lactuca. The equilibrium conditions and kinetics of adsorption were investigated, and the adsorption kinetic was consistent with the pseudo-second-order model (R²=1). The adsorption isotherm followed only the Freundlich model with a correlation coefficient R²=0.99. This study demonstrated that the U. lactuca could be used as an effective biosorbent for the removal of DY-12 from its aqueous solution.     

Biosorption of Direct Yellow 12 from aqueous solution using green alga Ulva lactuca

The potential of commonly available green alga Ulva lactuca was investigated as viable biomaterials for removal of synthetic azo dye (Direct Yellow 12, DY-12) from aqueous solution. The results obtained from the batch experiments revealed that the ability of the U. lactuca to remove DY-12 from its aqueous solution was dependent on the dye concentration, pH, and algal biomass but less dependent on the particle size of the U. lactuca. The equilibrium conditions and kinetics of adsorption were investigated, and the adsorption kinetic was consistent with the pseudo-second-order model (R ²=1). The adsorption isotherm followed only the Freundlich model with a correlation coefficient R ²=0.99. This study demonstrated that the U. lactuca could be used as an effective biosorbent for the removal of DY-12 from its aqueous solution.     

The influence of sorption material preparation on the removal of metal ions from the aqueous solution

ABSTRACT

Very important in adsorption processes is the preparation of material sorbents and from this reason, the impact of washing agent of raw sorbent was analysed. The adsorption capacity was studied in relation to the function of the equilibrium time, the amount of biosorbent and the initial metal(II) ions concentration. In this research for the sake of comparison, the sorptive properties of out-of-date coffee were compared to coffee washed with different agents (mineral acids and water). The scanning electron microscopy and Fourier transform infrared spectroscopy were used to characterise the biosorbents and to identify the functional groups that participated in metal(II) ions bonding. The obtained results clearly indicate that the out-of-date coffee are effective biosorbent for cadmium(II) and nickel(II) ions from aqueous solution. However, for metal(II) ions removal efficiency could influence sorbent preparation and nickel(II) ions were best adsorbed on coffee washed with water, but cadmium(II) ions on raw biosorbent (out-of-date coffee). The best results of sorption were achieved after the contact time of 30 and 60?min, respectively for cadmium(II) and nickel(II) ions.     

不同部位梧桐生物质炭对水溶液中镉吸附的机理

为了探究梧桐不同部位废弃物所制备的生物质炭(皮、枝、叶)对Cd²⁺的吸附效率和稳定修复的机理,以此为园林废弃物炭化利用在重金属污染修复方面的应用提供科学依据.利用实验室模拟法,通过高温煅烧法制备梧桐不同部位生物质炭,采用元素分析仪、比表面积及孔隙分析(BET)、X射线衍射仪(XRD)、扫描电镜/能谱(SEM/EDS)及衰减全反射红外光谱(ATR-IR)等技术研究不同反应时间、重金属浓度和溶液初始pH条件下生物质炭对Cd²⁺吸附效果的影响,并运用四步萃取法和脱附实验分析生物质炭上Cd²⁺的吸附形态和稳定性.3种生物质炭都在8 h左右达到吸附平衡,最终吸附量依次为树皮炭>枝条炭>叶片炭;溶液初始浓度为0.5—2 g·L^-1时Cd²⁺的吸附量呈增长趋势,在2.5—3g·L^-1时逐渐平缓;生物质炭Cd²⁺吸附量均随着pH的升高而升高,但在pH值为5—8时,吸附的趋势逐渐平稳;树皮炭的酸溶态和非生物利用态的稳定Cd形态要高于枝条炭和叶片炭;比表面积不是影响梧桐生物质炭吸附Cd²⁺的主要影响因素,吸附动力学,ATR,XRD和重金属形态萃取均证实Cd碳酸盐类矿物生成是主导吸附机理;3种生物质炭的脱附量在4 h后逐渐趋于平衡,其中脱附量最大为叶片炭,最小为树皮炭.梧桐不同部位的初始性质对生物质炭吸附Cd²⁺具有明显的影响,其中梧桐皮具备更高的吸附量和重金属稳定形态,并且相比其他种类生物质炭有明显优势.因此,从吸附效果和生产成本的角度,本研究建议以梧桐皮为主,枝条和叶片为辅的生物质炭对重金属Cd进行修复治理.     

Removal of Methylene Blue from aqueous solution by marine green alga Ulva lactuca

Biosorption of colours is an important technology for treatment of different types of industrial wastewaters containing dyes. The objective of this study was to convert green alga Ulva lactuca to dye adsorbents for wastewater treatment. The importance of commonly available green alga Ulva lactuca was investigated as viable biomaterials for the biological treatment of synthetic basic blue 9 (5-ch1oro-N,N,N^',N^'-tetramethyl-5λ⁴-phenothiazine-3,7-diamine) effluents. The results obtained from the batch experiments revealed the ability of the green algae to remove the basic blue 9, and this was dependent on the dye concentration, pH, and algal biomass. We investigated the equilibrium and kinetics of adsorption, and the Langmuir and Freundlich equations were used to fit the equilibrium isotherm. The adsorption isotherm of basic blue 9 followed both the Langmuir and Freundlich models with a correlation coefficient of ∼0.96-0.99, and the adsorption kinetics followed the pseudo-second-order model (R²=1.0). The maximum adsorption capacity was about 40.2 mg of dye per gram of dry green algae at pH 10, 25 g l^-1 dye and 2.5 g l^-1 alga concentrations. This study demonstrated that the green algae could be used as an effective biosorbent for the treatment of dye-containing wastewater streams.     

聚羟基丁酸酯(PHB)对水中微量多环芳烃的仿生吸附

基于生物体组织可对水体中低浓度有机污染物的高倍富集现象,以一种微生物细胞内广泛合成的聚羟基丁酸酯(PHB)为吸附剂,对水溶液中微量的多环芳烃(PAHs)进行仿生吸附研究.实验选取萘、菲和芘为模型污染物,考察了温度、时间、溶液pH和吸附剂用量等因素对吸附效果的影响,并分别以经典的吸附动力学模型、等温吸附模型和吸附热力学模型对吸附过程的机理进行了分析.结果表明,PHB对微量的萘(<1500μg.L-1)、菲(<1000μg.L-1)和芘(<130μg.L-1)具有较高的吸附速率,分别在60、120、80 min即可基本达到平衡,吸附动力学符合拟二级动力学模型;3种多环芳烃的等温吸附曲线用Henry、Langmuir和Freundlich方程进行拟合,线性关系良好,反映出PHB仿生吸附剂与PAHs之间存在着"吸溶"作用而非通常的位点吸附;考察分配系数Kd与Kow、温度的关系,发现Kd与Kow呈正相关,与温度呈负相关;低温有利于吸附,PHB对菲和芘的吸附为自发过程,而对萘的吸附为非自发过程.上述仿生吸附原理的阐明对微污染水处理技术的研究具有重要指导作用.     

Immobilization of NZVI in polydopamine surface-modified biochar for adsorption and degradation of tetracycline in aqueous solution

Polydopamine/NZVI@biochar composite (PDA/NZVI@BC) with high removal efficiency of tetracycline (TC) in aqueous solutions was successfully synthesized. The resultant composite demonstrated high reactivity, excellent stability and reusability over the reaction course. Such excellent performance can be attributed to the presence of the huge surface area on biochar (BC), which could enhance NZVI dispersion and prolong its longevity. The carbonyl group contained on the surface of biochar could combine with the amino group on polydopamine(PDA). The hydroxyl groups in PDA is able to enhance the dispersion and loading of NZVI on BC. Being modified by PDA, the hydrophilicity of biochar was improved. Among BC, pristine NZVI and PDA/NZVI@BC, PDA/ NZVI@BC exhibited the highest activity for removal of TC. Compared with NZVI, the removal efficiency of TC could be increased by 55.9% by using PDA/NZVI@BC under the same conditions. The optimal modification time of PDA was 8h, and the ratio of NZVI to BC was 1:2. In addition, the possible degradation mechanism of TC was proposed, which was based on the analysis of degraded products by LC-MS. Different important factors impacting on TC removal (including mass ratio of NZVI to BC/PDA, initial concentration, pH value and the initial temperature of the solution) were investigated as well. Overall, this study provides a promising alternative material and environmental pollution management option for antibiotic wastewater treatment.

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Adsorption of cadmium from aqueous solution using Rooibos shoots as adsorbent

The use of Rooibos shoots, a natural adsorbent, for cadmium removal from wastewater is proposed. The effects of initial pH, adsorbent dosage, contact time, and initial concentration were investigated in the batch adsorption mode. The optimum pH was found to be 5.5. Isotherm and kinetic data were modeled; the data fitted best to the Freundlich model, and, kinetically, the adsorption was of pseudo-second order as shown by the high R² value of 0.9928 along with close agreement between the experimental q_e (13.9 mg g^?1) and calculated q_e (14.24 mg g^?1) values. The studied biomass material was found to be effectively used for removal of cadmium from contaminated mine wastewater.     

锰氧化物-阳离子交换树脂复合材料的制备及其对水中重金属的吸附性能

采用原位沉淀-空气氧化法将锰氧化物负载于大孔强酸性阳离子交换树脂D001上,制备出一种新型锰氧化物-阳离子交换树脂复合材料Mn-D001,并对该材料吸附水中Pb2+、Cd2+、Cu2+的性能进行了深入研究.TEM、XRD以及XPS的分析结果表明,负载的锰氧化物以MnO2的形态存在.基于单一金属离子静态吸附的一元体系实验表明,Mn-D001比D001对Pb2+、Cd2+、Cu2+具有更高的吸附选择性,在高浓度竞争离子Ca2+、Mg2+、Na+共存的情况下,仍能保持较高的重金属去除率;Mn-D001对Pb2+、Cd2+、Cu2+的吸附行为符合准一级动力学模型(R2>0.99)和Langmuir吸附等温线模型(R2>0.99).在温度为303 K时,Mn-D001对3种重金属的饱和吸附容量可分别达到476.19 mg.g-1、243.90 mg.g-1及196.08 mg.g-1,优于原有树脂D001.基于复合重金属离子竞争吸附的二元、三元体系的实验表明,Mn-D001对3种重金属的吸附能力顺序为Pb2+>Cu2+>Cd2+,吸附能力由原有树脂D001以及负载的锰氧化物的性质共同决定.     

Adsorption of fatty acids on fine mineral particles as a purification method of industrial wastewaters

The problem of fines disposal and utilization that has to be faced from most of the mineral processing plants, in relation with the removal of fatty acids (reagents that constitute usual anionic collectors and could be possibly found in flotation plant waters) led to the study of the adsorption of later on fine particles, being in this case magnesite and dolomite. Another main application of this work is in the separation of fines (at sub‐sieve size range) by flotation. Sodium oleate and a commercial tall oil fatty acid were selected in the present. Common parameters and their effect on adsorption were carefully looked at, including the pH of solution and concentration. The presence of modifying reagents (as sodium hexametaphosphate, pyrophosphate and carboxymethyl cellulose) was also examined.     

Preparation and characterization of calcium alginate-based composite adsorbents for the removal of Cd,Hg, and Pb ions from aqueous solution

Composite adsorbent materials containing calcium alginate, clinoptilolite, and coal-derived humic acid were prepared. Humic acid (HA), clinoptilolite (CL), alginate (AL), alginate-entrapped humic acid (AL/HA), clinoptilolite (AL/CL), and humic acid/clinoptilolite (AL/HA/CL) samples were characterized. The effectiveness of the samples as adsorbents for the removal of cadmium (Cd), mercury (Hg), and lead (Pb) were studied in a series of batch-adsorption experiments. For the AL, AL/HA, AL/CL, and AL/HA/CL adsorbents, uptake versus time data were evaluated using two kinetic models, a linear and a non-linear pseudo-first-order and a pseudo-second-order model. The data for each metal ion on all adsorbents showed good correspondence with the pseudo-second-order kinetic model. The equilibrium data were fitted to Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherm models. The results show that a non-linear method seems more appropriate for obtaining isotherm parameters. The non-linear Freundlich and Langmuir models for Pb and Hg produced a best fit with high R ² value (0.99). For HA adsorbent, the equilibrium data for Cd removal better fit to the non-linear Dubinin–Radushkevich isotherm.     

Removal of pesticides from water samples by adsorption with fatty acids supported on barium sulphate

Oleic or linoleic acid supported on barium sulphate was used to remove atrazine and terbuthylazine in the range of 0.1–2.0 μg/L using spiked water samples. The sorption of atrazine depends on the stirring time and the best value is 150 min. Terbuthylazine is removed well with a stirring time of 60 min and its adsorption is about 90%. Detection of the residual pesticide in treated waters, after solid phase extraction (SPE), was carried out by GC‐MS operating in selected ion monitoring (SIM) using a calibration curve by direct injection of standard solutions of herbicide.