Adsorbent Derived from Pinus pinaster Tannin for Cationic Surfactant Removal

Abstract

Pinus tannin gel (PTG) has proven to be an effective adsorbent for removing various cationic pollutants including heavy metals, dyes, and surfactants. The form of obtaining these condensed tannins from Pinus pinaster bark was conventional aqueous extraction using 5.0% ethanol as additive. The present study focused on the removal of the surfactant hexadecyltrimethylammonium bromide (CTAB) from aqueous solutions using PTG. Kinetic studies showed that the Lagergren, Ho, and Elovich models all adequately explained the kinetics of CTAB adsorption onto PTG, with r² correlation coefficients of around 0.98. The influences of pH and temperature were found not to be critical, and the CTAB-PTG system was modeled theoretically according to the Langmuir hypothesis using linear, nonlinear, and multiparametric forms, obtaining the values of the activation energies and such system constants as k _l .     

磺酰基桥联杯［4］芳烃多孔配位笼对海水中U(Ⅵ)的快速吸附

设计合成具有较强铀酰离子结合能力、较快吸附动力学的多孔框架配合物对于海水中铀吸附具有重大的意义。利用对叔丁基磺酰基桥联杯［4］芳烃（H4TC4A SO2）、六水氯化钴和1,3 二（2H 四氮唑 5 基）苯（H2L）在溶剂热的条件下构筑了一例长方体状杯芳烃基多孔配位笼（Co16）,并用于对海水中铀酰离子的吸附。对Co16吸附剂进行U(Ⅵ)吸附实验发现,Co16吸附剂在较宽的pH范围内对U(Ⅵ)具有优异的吸附能力,并在90 min内达到吸附平衡,且符合准二级动力学模型。吸附等温线较好地符合Langmuir模型,表明Co16吸附剂对U(Ⅵ)的吸附属于单层吸附,且对U(Ⅵ)的吸附容量高达54731 mg/g。热力学实验表明,Co16吸附剂对U(Ⅵ)的吸附属于自发吸热的行为。把该材料置于真实海水中20 d后,其在真实海水中的吸附容量可达488 mg/g。以上结果表明,Co16吸附剂在海水铀吸附方面具有巨大的应用潜力。     

煤基活性炭及活性炭纤维对甲烷吸附性研究

Inlfuence of ammonium salt treatment and alkali treatment of the coal based activated carbon （AC） and activated carbon ifber （ACF） adsorbents on methane adsorption capacity was studied via high-pressure adsorption experiment. Sur-face functional groups and pore structure of two types of adsorbents were characterized by the application of infrared ab-sorption spectroscopy （IR） and low temperature liquid nitrogen adsorption method. The results show that both ammonium salt treatment and alkali treatment have obvious effect on changing BET, pore volume as well as pore size distribution of adsorbents; and methane adsorption capacity of the activated carbon ifber is the maximum after the ammonium salt treatment.     

Computer Simulation of Dissociative Adsorption of Water on the Surfaces of Spinel MgAl2O4

Atomistic simulation techniques have been used to model the dissociative adsorption of water onto the low-index {100}, {110}, and {111} surfaces of spinel MgAl₂O₄. The Born model of solids and the shell model for oxygen polarization have been used. The resulting structures and chemical bonding on the clean and hydrated surfaces are described. The calculations show that the dissociative adsorption of water on the low-index surfaces is generally energetically favorable. For the {110} and {111} orientations, the surfaces cleaved between oxygen layers show high absorption and stability. The calculations also show that, for the {111} orientation, the surfaces may absorb chemically water molecules up to ∼90% coverage and have the highest stability. It is suggested that, during fracture, only partial hydration occurs, leading to cleavage preferentially along the {100} orientation.     

The effect of carotene extraction system on crude palm oil quality, carotene composition, and carotene stability during storage

Palm carotene was successfully concentrated from crude palm oil (CPO) by an adsorption process using a synthetic adsorbent followed by solvent extraction. Evaluation of feed CPO and CPO which underwent the carotene extraction process was conducted. The quality of CPO after the extraction process was slightly deteriorated in terms of free fatty acid, moisture content, impurities, peroxide value, anisidine value, discriminant function, and deterioration of bleachability index. However, the CPO still can be refined to produce refined, bleached, deodorized palm oil that meets the Palm Oil Refiners Association of Malaysia specifications. No extra cost was incurred by refining this CPO as the dosage of bleaching earth used was very similar to the refining of standard CPO. The triglyceride carbon number and fatty acid composition of CPO after going through the carotene extraction process were almost the same as CPO data. The major components of the carotene fraction were similar to CPO, which contains mainly α- and β-carotene. The carotene could be stored for at least 3 mon.     

Effect of rare earth addition on Cu-Fe/AC adsorbents for phosphine adsorption from yellow phosphorous tail gas

Phosphine(PH3) is a highly toxic air pollutant,commonly produced in phosphorous chemical industry.But it has received less research attention due to its handling difficultly.CO is the main content of the phosphorous chemical industry tail gas,the concentration of which is always more than 80 vol.%,and it can be the feed gas to produce various valuable products such as formate,oxalate,and methanol and so on.But,PH3 is one of the important barriers,which is harmful to the following chemical process.In order to make use of the tail gas,PH3 should be removed firstly,and CO should be covered in the whole purified procedure at the same time.In this work,the modified activated carbon(MAC) was used as the adsorbent to separate PH3 from the mixture tail gas.Series of MAC adsorbents were prepared for the adsorption of PH3,which loaded Cu-Fe and Ce(La),or separately.The PH3 adsorption capacities,chemical and physical properties of MAC were all investigated.The results showed that over 99% PH3 adsorption efficiency was achieved when used MAC adsorbents.The removal efficiency and PH3 adsorption capacity of the Cu-Fe-Ce/AC(20:1:0.4) were both much higher than those modified activated carbons.The maximum PH3 adsorption capacity was 71 mg of PH3/g of MAC on the Cu-Fe-Ce/AC,which were much higher than literature data using CuO only for adsorbing hydride gases.     

Synthesis of hybrid magnetic molecularly imprinted polymers for the selective adsorption of volatile fatty acids from anaerobic effluents

A novel magnetic, structured (with ordered pores) and hybrid imprinted polymer (HMMIP) was synthesized to selectively adsorb volatile fatty acids (VFAs) from aqueous matrices. Usual characterization techniques showed that a mesoporous adsorbent was obtained with relatively low specific areas but that could selectively (imprinting factor of 1.64) remove isovaleric acid (used as template) from aqueous solutions and effluents containing VFAs with a good capacity (Q_e ~ 50 mg g^?1). From kinetic studies a pseudo‐nth‐order model showed the best fit to the experimental data and resulted in k _{n = 3} equal to 8 × 10^?4 g mg^?1 min^?1 whereas thermodynamic studies indicated that the adsorption of isovaleric acid onto HMMIP was endothermic and entropically driven. Reuse studies indicated that HMMIP loaded with VFA could be efficiently regenerated with acetone–water solution which led to an adsorption loss of ca 10% after three regeneration/reuse cycles and that the magnetic and specific adsorbent could be removed from complex matrices with an efficiency of ca 77%. Biochemical methane production assays showed that the addition of HMMIP to anaerobic batch reactors increased by four times the methane production due to the selective adsorption of VFAs. © 2020 Society of Chemical Industry     

Polymer supports for the removal and degradation of hazardous organic pollutants: an overview

Over the last decades, the presence of highly organic pollutants has increased and become an environmental problem that affects all forms of life. To solve or reduce this problem, multiple strategies have been proposed for the elimination and degradation of organic compounds in aqueous media. This review aims to revise and critically discuss the most recent advances in polymer supports to be used for the adsorption and degradation of organic pollutants. However, the greatest challenge with respect to this issue is the industrial scale‐up of bioremediation processes that allow the removal and degradation of compounds in a continuous and large‐scale manner. © 2019 Society of Chemical Industry     

Tannin-based adsorbents from green tea for removal of monoaromatic hydrocarbons in water: Preliminary investigations

In this study, we report the adsorption of benzene and toluene from water using rarely reported tannin adsorbents. Tannin gel and tannin powder were synthesized by adding formaldehyde to green tea extract, while iron nanoparticles were synthesized by the addition of FeSO₄?·?7H₂O. The surface morphology of the synthesized adsorbents was determined using SEM and FTIR prior to application to contaminated water. The results show up to 88% removal of benzene and toluene in a batch system after 30?min of reaction time, with a higher rate of removal of toluene compared to benzene. A low pH value of 2 had an adverse effect on the tannin gel, reducing the total adsorption of benzene to approx. 37.5%. On the other hand, iron nanoparticles were least affected by the pH with an adsorption of 62.9% for benzene and 83.3% for toluene.