Application of Polyacrylamide for Methylene Blue Removal from Aqueous Solutions

In this study the removal of methylene blue (MB) dye from aqueous solutions by polyacrylamide (PAA) as a potential adsorbent was reported. PAA was characterized using SEM and FTIR measurements. Batch adsorption experiments were performed as a function of the solution pH, contact time, solute concentration and temperature. Evaluation of the obtained data with isotherm studies indicated that the adsorption process was matched well with the Langmuir model. The maximum capacity of adsorbent for MB was 111.1 mg g−1. Kinetic studies were carried out on various kinetic models and the pseudo-second order kinetic model was fitted very well with experimental data. Moreover, the thermodynamic parameters indicated that the adsorption reaction was endothermic and spontaneous process

Ultrasonic assisted removal of Ni(II) and Co(II) ions from aqueous solutions by carboxylated nanoporous graphene

The present study was focused on the simultaneous removal of Ni(II) and Co(II) ions from aqueous solutions by ultrasound-assisted adsorption onto carboxylated nanoporous graphene (G-COOH). Nanoporous graphene was synthesized by chemical vapor deposition method then functionalized by carboxyl groups and finally characterized using SEM, XRD, EDX, BET and FT-IR techniques. The effects of variables such as pH, sonication time, adsorbent dosage, and temperature on simultaneous removal of Ni(II) and Co(II) ions were studied and optimized. The kinetic and isotherm experiment data could be well described with the pseudo-second order kinetic model and the Langmuir isotherm model. The maximum adsorption capacity of G-COOH for Ni(II) and Co(II) ions was 94.34 mg g−1 and 87.72  mg g−1, respectively. Thermodynamic studies indicated that the adsorption process was spontaneous and endothermic in nature

Kinetic and Thermodynamic study of Cd (II), Co (II), Zn (II) removal from aqueous solution by Kiwi Tree Leaves

In this study, a perfect adsorbent presented for removal of the heavy metals Co2+, Cd2+ and Zn2+ from aqueous solution and waste water by using activated carbon prepared from agricultural waste, kiwi tree leaves. Studies agree with, Langmuir adsorption isotherm. The values of constants for the Thermodynamic and kinetic isotherms were obtained. The kinetic isotherm experiment data could be well described with the pseudo-second order kinetic model and, Thermodynamic studies indicated that the adsorption processes were exothermic and spontaneous in nature. The result of experiments showed that Cd2+, Co2+ and Zn2+ metal ions removal increased with increasing pH, amount of adsorbent and, decreased with increasing the temperature and initial concentration of solutions. It was demonstrated that the developed method based on Kiwi tree leaves is safe, easy, inexpensive, fast and trusty for eliminate of toxic metal ions from wastewater

Nitrogen-modified nanoporous activated carbon from eucalyptus leaves for ultrasound-assisted removal of basic dyes using derivative spectrophotometric method

The nanoporous activated carbon (AC) was prepared from the eucalyptus leaves via chemical activation with KOH, then treated with nitric acid/ /urea (NOAC) and finally used as a new adsorbent for simultaneous ultrasound- assisted removal of basic red 46 (BR46) and basic yellow 13 (BY13) dyes from binary aqueous solutions. The NOAC nano-adsorbent was characterized with SEM, TEM, Raman, BET, FTIR, CHN, pHpzc and Boehm titration analysis. Both of the AC and NOAC samples had superior BET surface area of 2222 and 1572 m2 g-1 with average micropore volume of 0.81 and 0.50 cm3 g-1, respectively. First order derivative spectrophotometric method was used for analysis of BY13 in binary mixtures. Small amount of the adsorbent (30 mg) was capable to remove high percentage of dyes (>99 %) in a very short time (8 min). The adsorption of dyes follows the Langmuir isotherm and the pseudo- -second-order kinetics. The adsorption capacities of NOAC for single solutions of BR46 and BY13 were 1111 and 1250 mg g-1 as well as for binary solutions were 769 and 909 mg g-1, respectively. The adsorption thermodynamics were also explored. Exhausted NOAC was regenerated using HCl (2 M) and reused for five adsorption-desorption cycles with high performance

Graphene oxide-packed micro-column solid-phase extraction combined with flame atomic absorption spectrometry for determination of lead (II) and nickel (II) in water samples

<div><p>A sensitive and simple method has been established for simultaneous preconcentration of trace amounts of Pb (II) and Ni (II) ions in water samples prior to their determination by flame atomic absorption spectrometry. This method was based on the using of a micro-column filled with graphene oxide as an adsorbent. The influences of various analytical parameters such as solution pH, adsorbent amount, eluent type and volume, flow rates of sample and eluent, and matrix ions on the recoveries of the metal ions were investigated. Using the optimum conditions, the calibration graphs were linear in the range of 7–260 and 5–85 μg L⁻¹ with detection limits (3<i>S</i>_b) of 2.1 and 1.4 μg L⁻¹ for lead and nickel ions, respectively. The relative standard deviation for 10 replicate determinations of 50 μg L⁻¹ of lead and nickel ions were 4.1% and 3.8%, respectively. The preconcentration factors were 102.5 and 95 for lead and nickel ions, respectively. The adsorption capacity of the adsorbent was also determined. The method was successfully applied to determine the trace amounts of Pb (II) and Ni (II) ions in real water samples. The validation of the method was also performed by the standard reference material.</p></div

Fabrication of nanowalled catalytically self-threaded supramolecular polyrotaxane microcapsules using droplet microfluidics

Abstract Micrometer-scale monodisperse droplets are produced to generate nanowalled supramolecular microcapsules using microfluidics for high reproducibility and high-throughput manipulation, efficient material consumption, and control over hierarchical structure, shape, and size. In this study, an optimized microfluidic droplet generation technique and a unique liquid–liquid interfacial polymerization method were applied to fabricate the monodisperse polyrotaxane–based supramolecular microcapsules in a fast and simple way. To minimize the uncertainty due to droplet volume variation, the inlet pressures were supplied from the same source while lowering the interfacial tension and the main channel hydrodynamic resistance, which are critical for high monodispersity. The target polyrotaxane network (PN) was simply formed at the interface of the water and oil phases in ultra-monodisperse microdroplets via the cucurbit[6]uril (CB6)-catalyzed azide–alkyne cycloaddition (CB6-AAC) reaction between azido- and alkyne-functionalized tetraphenylporphyrin monomers (TPP-4AZ and TPP-4AL). The thickness of the interfacially assembled PN microcapsules was 20 nm as analyzed by cross-sectional TEM and TEM-EDX techniques. The resultant water-in-oil PN microcapsules were highly monodisperse in size and able to retain target molecules. Here, rhodamine 6G (Rh6G)-loaded PN microcapsules were fabricated, and the release rate of the Rh6G cargo was investigated over time for controlled drug release applications