Occurrence, Properties and Utilization of Natural Zeolites

Herein, Saccharum munja (SM) plant biomass and its novel composites with 0.5%, 1% and 2% functionalized carbon nanotube (CNT) were innovatively proposed as a versatile biosorbent for the removal of safranine O (SO) and methylene blue (MB) dyes from the single and binary systems. The morphology, structure and physicochemical properties of the as-fabricated adsorbents were characterized using various techniques such as X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscope (FESEM) and Differential Scanning Calorimetry (DSC). Batch adsorption studies revealed maximum removal of dyes at neutral pH and equilibrium was reached within 10 min of contact time for both the dyes. The adsorption process was modelled by the pseudo-second-order kinetics and Langmuir isotherm, where the maximum adsorption capacity of the 1%CNT+SM composite was enhanced by 336.29% and 35.49% as compared to raw SM, in the case of SO and MB dye respectively. Interestingly, the raw SM and its composites showed a higher affinity in the binary system towards the removal of SO (82.56-95.67%) as compared to MB (80.67-94.24%) dye. Regeneration studies depicted excellent reusability even after the tenth sequential adsorption–desorption cycle, which makes these adsorbents a promising material for wastewater remediation.

Adsorptive studies on the removal of dyes from single and binary systems using Saccharum munja plant-based novel functionalized CNT composites

In-situ fabrication of surfactant modified CNT-based novel bio-composite and its performance evaluation for simultaneous removal of anionic dyes: Optimization by Box-Behnken design

The present work consists in studying the adsorption of phenol onto zeolites Y modified by silylation, in order to increase their hydrophobic character. The operation was carried out by chemical liquid deposition with trimethylchlorosilane (TMCS). Study of the effect of certain parameters like initial concentration, pH and ionic strength were conducted. Experimental data were fitted by the models of Langmuir, Freundlich and Dubinin-Raduskevich calculated by non-linear regression. Results obtained show that the adsorption of phenol on samples is very fast and supported at acidic values of pH. We also found that phenol uptake increases with Si/Al ratio and modification by silylation improves the percentage of adsorption by approximately 30%.

Iconography : Adsorption of phenol from aqueous solution onto zeolites Y modified by silylation

The escalating problems of antibiotic resistance coupled with its growing environmental pollution as a result of rapid release of antibiotics demands the development of new and efficient antibacterial agents. To overcome this problem, antibacterial compounds are immobilized on a carrier system such as zeolite. In this study, zeolite A was successfully synthesized from natural kaolinite using alkaline hydrothermal method with sizes ranging from 0.5 to 0.9 µm. The product was used as a carrier system by loading it with three concentrations of streptomycin (50 mg/L, 100 mg/L and 200 mg/L). To characterize and validate the production of the zeolite A, the samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy with energy dispersive X-ray (FESEM-EDX), transmission electron microscope (TEM) and dispersion behaviour. The XRD and FTIR results proved that zeolite A framework was maintained even after loading with streptomycin denoting its successful adsorption with minimal release. FESEM-EDX micrographs clearly indicated the presence of streptomycin particles on the cubic surface of zeolite A. In term of its dispersion behaviour, streptomycin-zeolite showed hydrophobic as compared to hydrophilic parent zeolite and thus, could attract bacterial cell wall. The antibacterial assay of the samples was conducted against Gram-negative bacteria (Escherichia coli ATCC 11229) and Gram-positive bacteria (Staphylococcus aureus ATCC 6538) through disk diffusion technique (DDT) and minimum inhibition concentration (MIC). The DDT results indicated that the streptomycin released into the media because the inhibition zone values increased proportional to the increasing amount of streptomycin adsorbed onto zeolite A. Both types of bacteria were susceptible to the modified zeolite with the lowest MIC value for Gram negative bacteria at 3.0 g/L in distilled water. In conclusion, the synthesized zeolite A from raw kaolinite is a good adsorbent for antibiotic streptomycin, generating a broad spectrum antibacterial activity.

Characterization and antibacterial activity of synthesized zeolite from natural kaolinite loaded with streptomycin

In this study, the simultaneous action of surfactant modified clinoptilolite (SMC) as adsorbent for dyes and its antibacterial activity was investigated. Methylene blue (MB) and acid orange 7 (AO7) represent cationic and anionic dyes, respectively were used as adsorbate in this study and the antibacterial activity was studied against Gram-negative ( Escherichia coli ATCC 11229) and Gram-positive bacteria ( Staphylococcus aureus ATCC 6538 and Enterococcus faecalis ATCC 2921). Initially, natural zeolite clinoptilolite was modified with 3 different concentrations (0.1, 1.0 and 4.0 mM) of cationic surfactant hexadecyltrimethyl ammonium bromide (HDTMA-Br). The SMC samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), amount of HDTMA adsorbed and dispersion behaviour. Result from XRD shows that the HDTMA-Br molecules caused no effect on primary structure of the clinoptilolite since the clinoptilolite structure remained the same after modification with HDTMA-Br. Compared to the unmodified clinoptilolite, FTIR spectra of the SMC shows peak corresponds to C-H stretches which proved the attachment of HDTMA onto the clinoptilolite surfaces. In the dispersion behaviour study, SMC samples were located at the adjacent phase between the water and oil mixture. The amount of HDTMA-Br adsorbed onto the clinoptilolite increased with the increasing concentrations of the surfactant. The use of SMC as adsorbent and antibacterial agent were further studied against the ionic dyes and bacteria simultaneously. The results show that the adsorption capacity of SMC towards both ionic dyes increase with the increasing HDTMA-Br concentration. While for the antibacterial activity, the number of colony forming unit of bacteria seem to be highly reduced at the highest concentration of the HDTMA (4.0 mM) attached on the clinoptilolite. Hence, this study had shown that SMC has high adsorption capacity towards the ionic dyes at the same time reducing the growth of both Gram positive and negative bacteria in aquoes solution.

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Muhammad Syafiq Abd Aziz

Papers

Simultaneous action of surfactant modified clinoptilolite: adsorbent of dyes and antibacterial agent