Enhanced adsorption of Methylene Blue from aqueous solution by chitosan-g-poly(acrylic acid)/vermiculite hydrogel composites

A series of chitosan-g-poly （acrylic acid）/vermiculite hydrogel composites were synthesized and used as adsorbents for the investigation of the effect of process parameters such as vermiculite content, pH of dye solution, contact time, initial concentration of dye solution, temperature, ionic strength and concentration of surfactant sodium dodecyl sulfate on the removal of Methylene Blue （MB） from aqueous solution. The results showed that the adsorption capacity for dye increased with increasing pH, contact time and initial dye concentration, but decreased with increasing temperature, ionic strength and sodium dodecyl sulfate concentration in the present of the surfactant. The adsorption kinetics of MB onto the hydrogel composite followed pseudo second-order kinetics and the adsorption equilibrium data obeyed Langmuir isotherm. By introducing 10 wt.% vermiculite into chitosan-g-poly （acrylic acid） polymeric network, the obtaining hydrogel composite showed the highest adsorption capacity for MB, and then could be regarded as a potential adsorbent for cationic dye removal in a wastewater treatment process.

Removal of Methyl Violet from aqueous solutions using poly (acrylic acid-co-acrylamide)/attapulgite composite

The adsorption of Methyl Violet （MV） cationic dye from aqueous solution was carried out by using crosslinked poly （acrylic acid-coacrylamide）/attapulgite （Poly（AA-co-AM）/ATP） composite as adsorbent. The factors influencing adsorption capacity of the composite such as pH, concentration of the dye, temperature, contact time, adsorbent dosage, ionic strength and surfactant were systematically investigated. The equilibrium data fitted very well to the Langmuir isotherm and the maximum adsorption capacity reached 1194 mg/g at 30℃. The thermodynamic parameters including △G0, △H0 and △S0 for the adsorption processes of MV on the composite were also calculated, and the negative △H0 and △G0 confirmed that the adsorption process was exothermicand spontaneous. The kinetic studies showed that the adsorption process was consistent with the pseudo second-order kinetic model and the desorption studies revealed that the regeneration of the composite adsorbent can be easily achieved.

Fabrication of porous adsorbents from eco-friendly aqueous foam for high-efficient removal of cationic dyes and sustainable utilization assessment

Porous materials applied in environmental remediation have received researchers'extensive attention recently,but the related green and convenient preparation method is rarely reported.Here,we recommended a green and convenient strategy for the fabrication of porous material via aqueous foam templates,which was synergistically stabilized by Codonopsis pilosula(CP)and clay minerals of attapulgite(APT).The characterization results revealed that the APT was modified by organic molecules leached from CP and anchored at the air-water interface,which improved the foam stability significantly.The novel porous material of polyacrylamide/Codonopsis pilosula/attapulgite(PAM/CP/APT)templated from the aqueous foam via a polymerization reaction had excellent adsorption capacity for the cationic dyes methyl violet(MV)and methylene blue(MB),and the adsorption capacity can reach 755.85 mg/g and557.64 mg/g,respectively.More importantly,the adsorption capacity of spent adsorbent material was still over 200 mg/g after being recycled five times through a simple carbonization process,and then it was added to the plant pot,the total biomass was increased by about86.42%.This study provided a green and sustainable pathway for the preparation,application and subsequent processing of porous materials.

Fabrication porous adsorbents templated from aqueous foams using astragalus membranaceus and attapulgite as stabilizer for efficient removal of cationic dyes

The water-based foam stabilized by the natural surfactant applied in the fabrication of porous materials has attracted extensive attention,as the advantages of cleanness,convenience and low cost.Particularly,the development of a green preparation method has became themain research focus and frontier.In thiswork,a green liquid foamwith high stability was prepared by synergistic stabilization of natural plant astragalus membranaceus(AMS)and attapulgite(APT),and then a novel porous material with sufficient hierarchical pore structure was templated from the foam via a simple free radical polymerization of acrylamide(AM).The characterization results revealed that the amphiphilic molecules from AMS adsorbed onto thewater-air interface and formed a protective shell to prevent the bubble breakup,and APT gathered in the plateau border and formed a three-dimensional network structure,which greatly slowed down the drainage rate.The porous material polyacrylamide/astragalus membranaceus/attapulgite(PAM/AMS/APT)showed the excellent adsorption performance for cationic dyes of Methyl Violet(MV)and Methylene Blue(MB)in water,and the maximum adsorption capacity could reach to 709.13 and 703.30 mg/g,respectively.Furthermore,the polymer material enabled to regenerate and cycle via a convenient calcination process,and the adsorption capacitywas still higher than 200 mg/g after five cycles.In short,this research provided a new idea for the green preparation of porous materials and the treatment of water pollution.

Preparation of porous adsorbent via Pickering emulsion template for water treatment: A review

Porous materials as emerging potential adsorbents have received much more attention because they are capable of capturing various pollutants with fast adsorption rate, high adsorption capacity, good selectivity and excellent reusability.In order to prepare porous materials with decent porous structure, Pickering emulsion template method has been proved to be one of the most effective technologies to create pore structure.This paper reviewed comprehensively the latest research progress on the preparation of porous materials from various Pickering emulsions and their applications in the decontamination of pollutants(e.g., heavy metal ions, organic pollutants) and in the oil/water separation.It was expected that the summaries and discussions in this review will provide insights into the design and fabrication of new efficient porous adsorbents, and also give us a better understanding of the subject.

From waste hot-pot oil as carbon precursor to development of recyclable attapulgite/carbon composites for wastewater treatment

The utilization of waste products as valuable materials was a technical imperative for waste management. In this study, the cost-effective attapulgite/carbon(APT/C) composite was developed for wastewater treatment using waste hot-pot oil as a carbon precursor through a facile one-step calcination process. The APT/C composite prepared at 300°C exhibited the excellent adsorption capacity and rapid equilibrium rate over a broad p H range for the removal of various pollutants. More importantly, the removal ratios of the composites toward Methyl Violet and tetracycline still remained 77.6% and 60.2% of the initial adsorption capacity after ten adsorption–regeneration cycles via a facile thermal regeneration strategy, respectively.Beyond all doubt, this research provided a feasible and economical way for the sustainable utilization of waste hot-pot oil in wastewater treatment, achieving the concept of disposal waste with waste and recycling.

Investigation of acetylated kapok fibers on the sorption of oil in water

Kapok fibers have been acetylated for oil spill cleanup in the aqueous environment. The structures of raw and acetylated kapok fiber were characterized using Fourier transform infrared （FT-IR） spectroscopy and scanning electron microscopy （SEM）. Without severe damage to the lumen structures, the kapok fibers were successfully acetylated and the resulting fibers exhibited a better oil sorption capacity than raw fibers for diesel and soybean oil. Compared with high viscosity soybean oil, low viscosity diesel shows a better affinity to the surface of acetylated fibers. Sorption kinetics is fitted well by the pseudo second-order model, and the equilibrium data can be described by the Freundlich isotherm model. The results implied that acetylated kapok fiber can be used as the substitute for non-biodegradable oil sorption materials.

Removal of antibiotics from aqueous solution by using porous adsorbent templated from eco-friendly Pickering aqueous foams

The aqueous foam template without any solvent and only using the particles stabilizer has attracted much attention for preparation of the porous adsorbents.Herein,a novel porous adsorbent was fabricated via thermal-initiated polymerization of Pickering aqueous foams,which was stabilized by the natural sepiolite(Sep)and pine pollen,and utilized for the removal of antibiotic from aqueous solution.The stabilizing mechanism of Pickering aqueous foam of that the Sep was modified with the leaching substance from pine pollen and arranged orderly around the bubble to form a dense"shell"structure was revealed.The adsorbents possessed the hierarchical porous structure and excellent adsorption performance for antibiotic of chlorotetracycline hydrochloride(CTC)and tetracycline hydrochloride(TC).The equilibrium adsorption capacities of CTC and TC were achieved with 465.59 and 330.59 mg/g within 60 min at 25℃,respectively.The adsorption process obeyed Langmuir model and pseudo-second-order adsorption kinetic model.This work provided eco-friendly approach for fabricate porous adsorbents for wastewater treatment.

Novel eco-friendly spherical porous adsorbent fabricated from Pickering middle internal phase emulsions for removal of Pb(Ⅱ) and Cd(Ⅱ)

Spherical porous materials prepared from the emulsion template used in the water treatment have displayed a vast prospect, as the high surface area, abundant porous structure, convenient operation and excellent adsorption performance. But the tedious fabrication process, high consumption of organic solvent and surfactant limited the application widely. Herein, a facile and eco-friendly spherical porous adsorbent(SPA) is fabricated from the green surfactant-free(corn oil)-in-water Pickering medium internal phase emulsions(Pickering MIPEs) via the convenient ion crosslinking procedure. The Pickering MIPEs synergistically stabilized with the semi-coke(SC), which is the natural particle produced from the shale oil distillation, and sodium alginate(SA) has excellent storage and anti-coalescence stability. The as-prepared porous adsorbent possessed the abundant pore structure, which provided favorable conditions for effective mass transfer in adsorption, and could be tuned by varying the SA dosage. The saturation adsorption capacities of Pb(II) and Cd(II) can be achieved with 460.54 and 278.77 mg/g within 45 min at 25 ℃, respectively. Overall, this study supplied a viable and eco-friendly route for fabricating the spherical porous adsorbent with a tunable porous structure for heavy metal ion wastewater.

Evaluation of Ce(Ⅲ) and Gd(Ⅲ) adsorption from aqueous solution using CTS-g-(AA-co-SS)/ISC hybrid hydrogel adsorbent

CTS-g-（AA-co-SS）/ISC hybrid hydrogel adsorbent with crosslinked network structure and superior adsorption performance for rare-earth metal ions was successfully synthesized in aqueous solution by a simple one-step free-radical grafting polymerization reaction among acrylic acid（AA）, sodium p-styrenesulfonate（SS） and chitosan（CTS） using illite/smectite clay（ISC） as the inorganic additive. The structure of the as-prepared CTS-g-（AA-co-SS）/ISC hydrogel adsorbent was characterized, and the reaction parameters such as AA/SS molar ratio and ISC content were optimized, and the effects of pH values, initial concentration and contact time on the adsorption performance for Ce（Ⅲ） and Gd（Ⅲ） were systematically evaluated. It was found that the maximum adsorption capacities of the hydrogel adsorbent toward Ce（Ⅲ） and Gd（Ⅲ） reached 174.05 and 223.79 mg/g, respectively, and the adsorption quickly achieved equilibrium within 15–20 min. The adsorbed Ce（Ⅲ） and Gd（Ⅲ） could be easily desorbed for recovery, and the used adsorbent was able to be regenerated for reuse. After five adsorption-desorption cycles, the regenerated adsorbent could still retain the adsorption capacities that were close to the initial value. The adsorption process was well described by pseudo-second-order kinetic mode and the Langmuir isotherm model, and the chemical complexation between ions and –COO~–was mainly responsible for the high adsorption capacity. As a whole, the hybrid hydrogel adsorbent was potential to be used for the adsorption and recovery of Ce（Ⅲ） and Gd（Ⅲ） from water.

Facile fabrication of the porous adsorbent from natural plant Angelica Sinensis stabilized liquid foam for dye removal

Porous materials as emerging high-efficiency adsorbents have attracted increasing attention in recent years,due to the high specific surface area,fast adsorption rate,favorable adsorption capacity to heavy metal,dyes,and other pollutants,etc.Among various approaches,the foam template method with the advantage of flexible operation and controllable pores structure is proposed to prepare net type of porous adsorbents with superior adsorption capacity and rapid adsorption rate.In this process,natural plant Angelica Sinensis(AS)was treated with a simple alkalineheat process,and the resultant product was used firstly to prepare foam with high stability,and the positive effect of the cellulose dissociation and the conversion of ligustilide into amphiphilic moleculars on improving the stability of Pickering foam was revealed.The liquid foam can serve as pore-foaming template and precursor of polymerization for synthesizing porous adsorbent by one-step integrated process of free radical polymerization and silane hydrolysis.The porous adsorbent showed the sufficient porous structure and excellent adsorption performance for cationic dye,with maximum adsorption capacities of 386.13 mg g^(-1) and 284.20 mg g^(-1) for methyl violet(MV)and malachite green(MG).In a word,the novel approach can provide an important reference for green synthesis of high stable foam and the superporous material,and the adsorbent showed great application potential in the field of water treatment.