Palygorskite Research Articles

Preparing an ATP/P (n‐BuMA‐St)/Fe3O4 Oil‐Absorbing Resin Composite via a Double Pickering Emulsion Template Method and Elucidation of Its Properties

AbstractNumerous methods have been used for preparing porous materials; however, these techniques can not uniformly incorporate inorganic additives into the pore structure. Therefore, a novel method has been presented to fabricate an oil‐absorbing resin composite with three‐dimensional porous structure by using a double Pickering emulsion template. First, an oil‐in‐water‐in‐oil double Pickering emulsion was prepared using attapulgite (ATP) and modified Fe3O4. Second, the Pickering emulsion was employed as a template to synthesize the ATP/P(n‐BuMA‐St)/Fe3O4 oil‐absorbing resin composite by utilizing butyl methacrylate (n‐BuMA) and styrene (St) as comonomers, divinylbenzene as the crosslinking agent, and benzoyl peroxide as the initiator. Finally, the oil absorption performance of the resin composite was explored. The oil absorption ratio of the resin goes up to 754.75 %, while its oil retention rate approximately equals 84 %; when the mass ratio of St and poly (butyl methacrylate) is 2 : 1, the mass percentages of crosslinking agent, initiator, emulsifier, and ATP are observed to be 2 %, 0.4 %, 3 %, and 0.6 %, respectively. Overall, this work provides a novel strategy for preparing an oil‐absorbing composite resin, which is expected to be popularized and utilized for oil spill remediation and oily wastewater treatment.

Attapulgite as a cost-effective catalyst for low-energy consumption amine-based CO2 capture

The extensive heat duty of solvent regeneration has significantly hampered the industrial application of amine-based CO2 capture technology. Catalytic CO2 desorption with solid acid catalysts has recently emerged as a promising and competitive strategy for improving solvent regeneration performance. The reported catalysts have exhibited poor activities and are relatively expensive, which has slowed the large-scale implementation of this technique. In this work, three low-cost and environmentally friendly clay catalysts, namely, attapulgite (ATP), activated bentonite (K-10), and sepiolite (SEP), were used to catalyze the CO2 desorption in the CO2-loaded 5 M monoethanolamine (MEA) solution at 88 °C. The findings revealed that ATP, K-10, and SEP catalysts accelerated CO2 desorption, and the ATP demonstrated better catalytic activity in the early stage of the desorption process. In particular, the introduction of ATP significantly increased the CO2 desorption rate by 54–57% and reduced the relative heat duty by about 32%, compared to the blank test. The superior catalytic performance of ATP might be attributed to its favorable surface area and medium acid sites. The catalytic effect of ATP was confirmed using FT-IR and Raman techniques, and a potential catalytic desorption mechanism was proposed. Furthermore, the stability of activated ATP was demonstrated using 15 CO2 absorption-desorption cycles. These results demonstrated that ATP significantly contributes to the advancement of the amine-based CO2 capture process and has significant potential for large-scale deployment. This work may pave the avenue for developing abundant and inexpensive clay-based solid acid catalysts for low-energy consuming CO2 capture technology.

Degradation of 4-chlorophenol through activating oxidants byzero-valent Al/Fe-saturated attapulgite composites

<p indent="0mm">Zero-valent aluminum (ZVAl) is a promising heterogeneous catalyst in advanced oxidation technologies. However, the natural dense oxide layer of ZVAl impedes electron transfer from the core metal. Herein, a commercial clay, that is, attapulgite (ATP), with the advantages of abundant yield and low cost, was treated with FeCl₃ through saturated ion-exchange to enhance its Fe content, and was further mixed with micro-sized ZVAl (mZVAl) to obtain a mZVAl/Fe-saturated ATP composite (mZVAl-FeATP). It was explored to activate three oxidants, namely, H₂O₂, persulfate (PS), and peroxymonosulfate (PMS), for 4-chlorophenol (4-CP) degradation. The mZVAl-FeATP presented better activation ability to PMS than to PS and H₂O₂. The synergistic oxidative degradation performance and mechanisms of the mZVAl-FeATP/PMS system were systematically explored. The results showed that the mZVAl-FeATP/PMS system can quickly degrade 4-CP at pH ranging from 3.00 to 9.00. The main reactive species were <inline-formula id="INLINE37"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msubsup other="0"><mml:mrow other="0"><mml:mtext other="0">SO</mml:mtext></mml:mrow><mml:mn other="1">4</mml:mn><mml:mrow other="1"><mml:mo other="1">•</mml:mo><mml:mo other="1">−</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula>, •OH and ¹O₂. During the reaction process, mZVAl, acted as an electron donor, could not only reduce the adsorbed Fe(III) to Fe(II) on the surface of mZVAl-FeATP for PMS activation, but also promote Fe(III)/Fe(II) cycle. mZVAl-FeATP/PMS system with a good general applicability could effectively degrade various organic contaminants in different water sources, in addition to 4-CP. Moreover, the catalytic reactivity of mZVAl-FeATP can be restored by a second ball milling process. In short, this work provided a simple and environmentally-friendly modification strategy, which can overcome the obstacle of electron transferring caused by ZVAl’s oxide film and make full use of interlayer structure of clay minerals, thereby broadening the applications of zero-valent aluminum and clay minerals in the field of water environmental remediation.

Interface mechanism of peroxymonosulfate activation by cobalt-copper-ferrite nanoparticles mediated by palygorskite for bisphenol S degradation: A dual-path activation mechanism

Peroxymonosulfate (PMS)-based advanced oxidation processes are perceived as a novel strategy for water purification. However, designing an efficient catalyst with a low metal leaching rate remains challenging. Here, under palygorskite (PAL) mediation, 16%-CoCu0.4Fe1.6O4@PAL (16%-CCFO@PAL) was constructed, exhibiting ample oxygen vacancies (VO) and low metal leakage. The VO was confirmed by systematic characterizations and theoretical calculations. The catalyst showed the efficient catalytic capacity for PMS by dual-path (i.e., metal sites and VO) activation. Large amounts of SO4•-, •OH, and 1O2 were produced, greatly destroying bisphenol S (BPS). BPS removal was greater than 99% within 25 min in the 16%-CCFO@PAL/PMS system. At the metal sites, PMS was activated under the synergistic effects of Co(II)/Co(III), Fe(II)/Fe(III), and Cu(I)/Cu(II) pairs and electron transfer. In addition to metal sites, the VO was also an activation center for PMS, which mainly captured the OI atom in [H-OI-OII-SO3]-, donating an electron to OI and promoting SO4•- generation. The interfacial reaction mechanism was explored by in situ tests, and a dual-path activation mechanism was proposed. This work provides a new perspective for VO-assisted PMS activation for water treatment.

Tobacco Waste Liquid-Based Organic Fertilizer Particle for Controlled-Release Fulvic Acid and Immobilization of Heavy Metals in Soil

Every year, a large amount of tobacco waste liquid (TWL) is discharged into the environment, resulting in serious pollution for the environment. In this work, a TWL-based particle (OACT) was fabricated by CaO, attapulgite (ATP), and TWL, and, then, OACT was coated by amino silicon oil (ASO) to form OACT@ASO. Therein, OACT@ASO had high controlled-release ability for fulvic acid (FA), because of the nanonetworks structure for ATP and the high content of FA in TWL. The release ratio (RR) of FA from OACT@ASO reached 94% at 75 h in deionized water, and 23% at 32 d in silica sand. Furthermore, the release mechanism of FA from OACT@ASO was consistent with the First-order law. Additionally, OACT@ASO also possessed high immobilization capacity for Cu(II), Cd(II), and Pb(II) (CCP) in soil. Notably, a pot experiment indicated that OACT@ASO could facilitate the growth of pakchoi seedlings and decrease the absorption of CCP by pakchoi seedlings. Thus, this study provides a new kind of organic fertilizer which could not only release FA, but also immobilize CCP in soil.

Designing attapulgite-based self-healing superhydrophobic coatings for efficient corrosion protection of magnesium alloys

Magnesium (Mg) and its alloys are susceptible to corrosion, which affects their large-scale applications. The traditional superhydrophobic coatings for corrosion protection of Mg substrates are particularly fragile and easily damaged after prolonged exposure to harsh conditions. Herein, a superhydrophobic ODA/PDA/APT-Ce3+ (OPA-Ce3+) coating with corrosion inhibition and self-healing properties was proposed to prevent corrosion of Mg alloy via combining the cerium nitrate loaded attapulgite (APT), polydopamine (PDA) and octadecylamine (ODA). Once the OPA-Ce3+ coating was corroded, the Ce3+ adsorbed by the APT were released to form insoluble cerium oxide and hydroxides, thereby inhibiting the penetration of the corrosive substance and preventing further occurrence of corrosion. Furthermore, the OPA-Ce3+ coating exhibited favorable self-healing ability against chemical damage, which could recover its superhydrophobicity under solar exposure after O2 plasma etching. The impedance modulus (|Z|0.01 Hz) of OPA-Ce3+ coating was about 3 orders of magnitude higher than that of Mg substrate after being exposed to 3.5 wt% NaCl solution for 15 days, showing outstanding long-lasting anticorrosion performance. Moreover, the abrasion resistance and chemical stability of the as-fabricated coating were also excellent. This work is expected to provide a new perspective for preparing cost-effective and durable anticorrosion coating on metal substrates.

Remediation of Cd-contaminated acid soil with shell powder-based nanocomposite

Soil acidification has negative effects on the sustainability of agricultural systems. In this present work, an acid soil amendment termed ASR was prepared with a nanocomposite consist of attapulgite (ATP), shell powder (SP), and red mud (RM), wherein ATP served as a nanocarrier. ASR could self-assembly to form a nanonetwork film around crop roots and hinder the input of H + and bivalent cadmium (Cd(II)) and the output of base cations (Ca 2+ and Mg 2+ and so on). Thus, ASR could effectively improve the pH of acid soil and meanwhile control the migration and spatial distribution of Cd(II), which reduced the bioavailable Cd(II) amount in the soil around crop roots. Note that pot experiment also indicated that ASR showed a positive effect on the growth of edible amaranths and significantly inhibited the uptake of Cd.

Interfacial ionic transport in natural palygorskite-Na0.60CoO2 nanocomposite mineral materials

Natural clay minerals have been applied to various energy fields due to their low cost, good stability, and abundance of resources, but few of them have been investigated for fuel cell application. Proton ceramic fuel cell, one of the most promising sustainable-energy-conversion technologies, has attracted a lot of attentions because it possesses high ionic conductivity at relatively low temperatures (<600 °C). However, the characteristics of expensive construction cost and high temperature operation hinder the development and industrialization of fuel cell. In this paper, natural clay minerals palygorskite (PAL) and Na0.60CoO2 (NCO) nanosheets composite were synthesized via an electrostatic adsorption method, and used as the electrolyte of fuel cell. NCO/PAL demonstrated a high conductivity of 0.27 S∙cm−1 at 550 °C and the maximum power output of 641 mW cm−2 was achieved for NCO/PAL cell. The mechanism of proton transport at the interface of NCO/PAL semiconductor-insulator composite was discussed.

Effects of rod-like attapulgite and lamellar kaolin reinforcement on the tribological behavior of PBO textile-resin composite liner

Textile-resin composite liners play an important role in aerospace industry owing to the self-lubrication and reinforcement. Herein, PBO (poly(p-phenylene benzobisoxazole) textile-phenolic resin composite liners reinforced with clay were prepared. Results indicated that the addition of kaolin and APL (attapulgite) have improved the wear-resistance of composites owing to the tribofilm and tribo-oxidatio layer (characterized by FIB-TEM). Clay is held together by van der Waals interactions and hydrogen bonds. During rubbing process, clay were exposed, broken and exfoliated releasing plenty of active oxygen atoms and the Si–O dangling bonds, which was contributed to the occurrence of tribo-oxidatio. Besides, ribbon-like APL performed better behavior than kaolin due to the higher specific surface area, more easy exfoliation and rolling bearing effect.

Achieving high loading inhibitor carriers with pH-response for active corrosion protection using attapulgite

A new pH-response inhibitor self-healing anticorrosion coating containing attapulgite (ATP) that inhibits 1-allyl-3-octylimidazolium bromide (expressed as ATP@IL) has been developed. This inhibitor carrier can store 28.6 wt% weight of inhibitor. When ATP@IL was added into 0.5 M H2SO4 solution, the inhibition efficiency reached 99.8% (steel corrosion rate is reduced to 0.2%). The Rct of ATP@IL increased by 59.5% compared with pure IL and increased by 99.97% compared with pure ATP, evidence of an excellent inhibition efficiency. Furthermore, this material was added to a water-based epoxy resin (EP) to synthesize a self-healing coating (ATP@IL/EP), resulting in excellent anti-corrosion performance due to the pH-response releasing of inhibitive material. The inhibitors are adsorbed on the surface of the steel substrate, forming a sustainable protective film to prevent the contact of metal and corrosive medium. Electrochemical tests indicated that this new coating with pH-triggered self-healing property possessed a much longer time protective ability compared to the common epoxy resin coatings with ATP. The EIS data illustrated that the impedance of ATP@IL/EP coating was above 108 Ω cm2 after 40 days, which was two orders of magnitude higher than the EP coating. This meant ATP@IL could further improve the protective ability compared to the ATP.

Performance, Reaction Pathway and Kinetics of the Enhanced Dechlorination Degradation of 2,4-Dichlorophenol by Fe/Ni Nanoparticles Supported on Attapulgite Disaggregated by a Ball Milling-Freezing Process.

Attapulgite (ATP) disaggregated by a ball milling–freezing process was used to support Fe/Ni bimetallic nanoparticles (nFe/Ni) to obtain a composite material of D-ATP-nFe/Ni for the dechlorination degradation of 2,4-dichlorophenol (2,4-DCP), thus improving the problem of agglomeration and oxidation passivation of nanoscale zero-valent iron (nFe) in the dechlorination degradation of chlorinated organic compounds. The results show that Fe/Ni nanoparticle clusters were dispersed into single spherical particles by the ball milling–freezing-disaggregated attapulgite, in which the average particle size decreased from 423.94 nm to 54.51 nm, and the specific surface area of D-ATP-nFe /Ni (97.10 m2/g) was 6.9 times greater than that of nFe/Ni (14.15 m2/g). Therefore, the degradation rate of 2,4-DCP increased from 81.9% during ATP-nFe/Ni application to 96.8% during D-ATP-nFe/Ni application within 120 min, and the yield of phenol increased from 57.2% to 86.1%. Meanwhile, the reaction rate Kobs of the degradation of 2,4-DCP by D-ATP-nFe/Ni was 0.0277 min−1, which was higher than that of ATP-nFe/Ni (0.0135 min−1). In the dechlorination process of 2,4-DCP by D-ATP-nFe/Ni, the reaction rate for the direct dechlorination of 2,4-DCP of phenol (k5 = 0.0156 min−1) was much higher than that of 4-chlorophenol (4-CP, k2 = 0.0052 min−1) and 2-chlorophenol (2-CP, k1 = 0.0070 min−1), which suggests that the main dechlorination degradation pathway for the removal of 2,4-DCP by D-ATP-nFe/Ni was directly reduced to phenol by the removal of two chlorine atoms. In the secondary pathway, the removal of one chlorine atom from 2,4-DCP to generate 2-CP or 4-CP as intermediate was the rate controlling step. The final dechlorination product (phenol) was obtained when the dechlorination rate accelerated with the progress of the reaction. This study contributes to the broad topic of organic pollutant treatment by the application of clay minerals.

In-depth study of synergism between torrefaction and catalyst for balanced production of bio-oil from rice husk pyrolysis based on hydrocarbons production, energy yield and deoxygenation degree

Previous studies concerning biomass to bio-oil mainly focused on hydrocarbons production, and how to balance the bio-oil production in terms of hydrocarbons production, energy yield and deoxygenation degree is a challenging issue. After the pretreatment of torrefaction, catalytic fast pyrolysis (CFP) was performed at two-zone fixed-bed reactor. The synergism between torrefaction and catalyst during torrefaction-catalytic fast pyrolysis (T-CFP) was investigated for the balanced production of bio-oil from rice husk. Firstly, the results of two catalysts（ZrO2/n-ZSM-5 and ZrO2/n-ZSM-5/attapulgite) indicated that the catalyst with the incorporation of attapulgite (ATP) could realize the balance between the acid and basic sites, which resulted in deeper deoxygenation. Then, the results of torrefaction-catalytic pyrolysis showed that, among three torrefaction temperatures adopted, mild torrefaction (210 °C) had better synergistic effects with both catalysts. Specifically, catalytic pyrolysis of biomass after mild torrefaction over both catalysts realized the enhancement of deoxygenation degree and energy yield. Moreover, with the pretreatment of mild torrefaction, the performance of ZrO2/n-ZSM-5/ATP turned out to be obviously superior to ZrO2/n-ZSM-5 in terms of hydrocarbons production (7.5%＞0.8%) and deoxygenation mode. Therefore, the combination of ZrO2/n-ZSM-5/ATP and mild torrefaction could achieve more balanced production of bio-oil from T-CFP process.

Insight into adsorption process and mechanisms of Cr(III) using carboxymethyl cellulose-g-poly(acrylic acid-co-acrylamide)/attapulgite composite hydrogel

ABSTRACT Cr(III) as one of the most concerned potentially toxic elements, is discharged from relevant industries and Cr(VI) reduction. Hydrogel-based adsorption could be one of the promising approaches for Cr(III) removal. Featured with environmental friendliness and low cost, carboxymethyl cellulose (CMC) was employed for the hydrogel synthesis, and attapulgite (APT) could be used to strengthen its stability. However, the adsorption performance and mechanisms need to be examined. In the present study, carboxymethyl cellulose-g-poly(acrylic acid-co-acrylamide)/ attapulgite (CMC-g-p(AA-co-AM)/APT) was synthesised via in situ copolymerisation. Its efficacy for removing Cr(III) from an aqueous solution was investigated using batch adsorption experiments. Results showed that the introduction of APT enhanced the thermal stability but decreased the swelling performance of the hydrogel. The prepared hydrogel could strongly adsorb Cr(III) at a wide pH range of 3.0–7.0. Cr(III) can be efficiently removed by the composite hydrogel within 1–2 h. At low concentration, CMC-g-p(AA-co-AM)/APT could slightly adsorbed more Cr(III) than CMC-g-p(AA-co-AM). The maximum absorption of CMC-g-p(AA-co-AM) and CMC-g-p(AA-co-AM)/APT were 74.8 and 47.7 mg/g at 298 K, respectively. The negative value of ΔHo and ΔGo indicated the adsorption of Cr(III) onto the two studied hydrogels is an exothermic and spontaneous process. Ion exchange and complexation, as implied by EDS, FT-IR and XPS, combining with electrostatic attraction are the possible adsorption mechanisms for Cr(III) onto the prepared hydrogels. All the results above suggests that the composite hydrogel CMC-g-p(AA-co-AM)/APT can be a promising candidate for the removal of Cr(III) from waste water.

Ceramic nanofiber membrane anchoring nanosized Mn2O3 catalytic ozonation of sulfamethoxazole in water

Catalytic ceramic nanofiber membranes (Mn@CNMs) were prepared by anchoring Mn2O3 nanoparticles on the pits of attapulgite (APT) nanofibers via an impregnation and in-situ precipitation method. An integrated catalytic ozonation/membrane filtration process applying Mn@CNM was employed to degrade sulfamethoxazole (SMX) and the removal achieved up to 81.3% during a 7-h continuous filtration. The reactive oxygen species (ROS) quenching and radical detection experiments were conducted to determine the contribution of 1O2, ·OH and O2·- towards the catalytic degradation of SMX. Moreover, Mn@CNM exhibited wide applicability for real water matrix and the total removal of various kinds of emerging contaminants in real hospital wastewater reached up to 98.5%. The excellent performances of Mn@CNM were attributed to the nano-confinement effect in the membrane layer. First, anchoring Mn2O3 nanoparticles on the pits of the APT surface suppressed the growth and aggregation of nanosized Mn2O3, providing abundant reactive sites for catalytic ozonation. Second, the interlaced APT nanofibers formed nano-sized network structures, where ROS and SMX were confined in close vicinity and ROS have more chances to attack SMX. This work provides a promising strategy for the preparation of catalytic ceramic membrane with high catalytic efficiency for degradation of emerging contaminants in water.

Antitumor Efficacy of Doxorubicin-Loaded Electrospun Attapulgite-Poly(lactic-co-glycolic acid) Composite Nanofibers.

Currently, cancer chemotherapeutic drugs still have the defects of high toxicity and low bioavailability, so it is critical to design novel drug release systems for cancer chemotherapy. Here, we report a method to fabricate electrospun drug-loaded organic/inorganic hybrid nanofibrous system for antitumor therapy applications. In this work, rod-like attapulgite (ATT) was utilized to load a model anticancer drug doxorubicin (DOX), and mixed with poly(lactic-co-glycolic acid) (PLGA) to form electrospun hybrid nanofibers. The ATT/DOX/PLGA composite nanofibers were characterized through various techniques. It is feasible to load DOX onto ATT surfaces, and the ATT/DOX/PLGA nanofibers show a smooth and uniform morphology with improved mechanical durability. Under neutral and acidic pH conditions, the loaded DOX was released from ATT/DOX/PLGA nanofibers in a sustained manner. In addition, the released DOX from the nanofibers could significantly inhibit the growth of tumor cells. Owing to the significantly reduced burst release profile and increased mechanical durability of the ATT/DOX/PLGA nanofibers, the designed organic–inorganic hybrid nanofibers may hold great promise as a nanoplatform to encapsulate different drugs for enhanced local tumor therapy applications.

Underwater superoleophobic mesh with robust Anthurium andraeanum-like attapulgite coating layer for effective oil spill recovery

It is highly desired to develop an efficient and stable approach to recover water from oil-water mixtures. In this work, we reported the facile fabrication of superhydrophilic and underwater superoleophobic membranes by coating a layer of Anthurium andraeanum-like attapulgite (ARATP) on commercially available wire meshes via sintering. The ARATP was obtained through anchoring nano-Fe3O4 on attapulgite (ATP), and its micro nano-structures can be adjusted by varying Fe3O4 content. Molecular dynamic simulations revealed the benefits of Fe3O4 in constructing superwetting coating layer with oil droplet repulsion larger than 227 KJ·mol−1. The membrane exhibited underwater superoleophobicity (with underwater oil contact angle at 157°) and was proven to treat various oil-water mixtures effectively (with a water permeation flux above 3249 L·m−2·h−1 and oil content in filtrate less than 2 mg·L−1). Furthermore, the chemical, mechanical stability and easy-cleaning property of the as-prepared membrane was demonstrated by different tests.

High‐density polyethylene/attapulgite (ATP) nanocomposites: Effect of the organophilization of ATP on the structural, mechanical, and thermal properties

AbstractOrganic–inorganic nanocomposites have attracted great interest due to the remarkable improvement in mechanical properties when compared to neat polymers. The use of a low‐cost nanofiller added to good properties becomes attractive to the industry. Attapulgite (ATP) is a very interesting nanofiller alternative, especially when used with polyolefins, as in the case of high‐density polyethylene (HDPE). However, this system is not simple, as HDPE is a nonpolar polyolefin that can cause low dispersion of ATP. One way to increase the interaction between these phases is the surface modification of ATP. In this work, the surface of ATP was modified using trimethylamine hydrochloride. HDPE/ATP nanocomposites with 1 and 5 wt% of raw ATP (ATPr) or organophilic ATP (ATPo) were prepared by extrusion. The effectiveness of the organophilization process of ATP was evaluated by X‐ray diffraction, mechanical properties (Shore D hardness and tensile test), and thermal properties (thermogravimetric analysis and differential scanning calorimetry), contact angle, and scanning electron microscopy. In the HDPE/ATPo nanocomposites, it was possible to observe an improvement in mechanical and thermal properties when compared to HDPE/ATPr nanocomposites. The organophilization of ATP promoted a greater interaction between the phases, contributing to a better dispersion of ATP in the HDPE matrix.

Fantastic properties of polydopamine boost photocatalytic activity of ATP@PDA@CdS for formaldehyde removal

Eco-friendly photocatalysts with full-spectrum light utilization and all-day-long photocatalytic activities are highly desired for formaldehyde (HCHO) removal. Polydopamine (PDA) is wrapped on the attapulgite (ATP) surface as a fantastic intermediate layer to construct ATP@PDA@CdS photocatalyst with Pt nanoparticles (NPs) as the cocatalyst. PDA is beneficial for homogeneous deposition and dispersion of CdS and Pt NPs and efficient in absorbing the energy beyond ultraviolet light (UV) to produce an excellent photothermal effect for photocatalysis. The reductive surface of PDA can also hinder the photocorrosion of CdS for long-term operation. The factors, such as relative humidity and particle size, affecting the photocatalytic activity and the all-day-long photocatalysis by Pt NPs are also discussed.

Immobilization of cadmium by mercapto-functionalized palygorskite under stimulated acid rain: Stability performance and micro-ecological response

The interaction of cadmium (Cd) pollution and acid rain stress has seriously threatened soil ecosystem and human health. However, there are still few effective amendments for the in-situ remediation in the Cd-contaminated acidified soil. In this study, the performance and mechanisms of palygorskite (PAL) and mercapto-functionalized PAL (MPAL) on Cd immobilization were investigated, and the stability as well as effects on soil micro-ecology under stimulated acid rain were also explored. Results showed that MPAL could react with Cd to form stable Cd-sulfhydryl and Cd–O complexes. The reduction of bioavailable Cd by MPAL was 121.19–164.86% higher than that by PAL. Notably, the Cd immobilization by MPAL remained stable within 90 days in which the concentrations of HOAc-extractable Cd were reduced by 18.28–25.12%, while the reducible and residual fractions were increased by 9.26–18.53% and 54.16%–479.01%, respectively. The sequential acid rain leaching demonstrated that soil after MPAL treatments had a strong H+ resistance, and the immobilized Cd showed prominent stability. In addition, activities of acid phosphatase, catalase and invertase in MPAL treated soil were significantly enhanced by 34.60%, 22.09% and 48.87%, respectively. After MPAL application, bacterial diversity was further improved with diversified sulfur metabolism biomarkers. The decreased abundance of Cd resistance genes including cadA, cadC, czcA, czcB, czcR and zipA also indicated that soil micro-ecology was improved by MPAL. These results showed that MPAL was an effective and eco-friendly amendment for the immobilization of Cd in contaminated soil.

Elevating the stability and adsorption performance of metal-organic frameworks by chitosan and attapulgite for capturing methylene blue in the water

Here we firstly report a novel adsorbent based on metal-organic frameworks (MOFs) which were modified by chitosan (CS) and attapulgite (ATP), including ZIF-8@ATP-CS, Zr-MOF@ATP-CS, and Al-MOF@ATP-CS. The preservative CS constructed a network framework for uniform diffusion of MOFs powder. The ATP not only strengthened the stability, but also improved the adsorption ability. Among these materials, Zr-MOF@ATP-CS had the most optimal adsorption capacity for methylene blue (MB), which could reach the equilibrium within 30 min and obtained the maximum adsorption of 442.86 mg g-1. Zr-MOF@ATP-CS went through five regenerations without significant reduction, which meant Zr-MOF@ATP-CS owned excellent stability. The ratio of ATP: CS in Zr-MOF@ATP-CS was also explored, and it was found that the best modification effect ratio was 0.75: 1. More importantly, the potential practical application was presented in this article. Finally, a possible mechanism was proposed. The novel materials were expected to further expand MOFs materials.