DEGRADATION OF REACTIVE DYES USING IMMOBILIZED PEROXIDASE PURIFIED FROM NIGELLA SATIVA

The present study was aimed to exploit the free and immobilized peroxidase from Nigella sativa seeds to degradation of textile dyes polluting the environment and water. The optimum conditions for extracting the enzyme from the Nigella seeds were determined and the highest specific activity of the enzyme was obtained 1750 units / mg protein when extracting the enzyme from the ground seeds at a ratio of 1:20 (w: v) with sodium acetate buffer at 0.2 M and pH 5.0 for 15 minutes. The enzyme was purified using two steps including the concentration by sucrose and gel filtration by using Sephadex G-150. The results shown an increase in final purification folds 2.8 time with an enzyme yield of 35%. The immobilization of peroxidase were done by entrapment method using Ca- alginate and the immobilization ratio was reached to 49%. The removal efficiency of dyes by crude enzyme (free, immobilized) and partial purified peroxidase were studied with textile dyes such as yellow, red, black and blue dyes at optimum conditions pH 5, temperature 37oC after 3 hr. Maximum removal efficiency of dyes observed with crude peroxidase and reached (76.9, 88.7, 91 and 88) % respectively. These results were close to the efficiency of the purified enzyme in removing the four dyes, while the efficiency of the crude immobilized enzyme in removing the dyes was about (70, 81, 72 and 56.4)%, respectively.

Co-Treatment with Single and Ternary Mixture Gas of Dimethyl Sulfide, Propanethiol, and Toluene by a Macrokinetic Analysis in a Biotrickling Filter Seeded with Alcaligenes sp. SY1 and Pseudomonas Putida S1

The biotrickling filter (BTF) treatment is an effective way of dealing with air pollution caused by volatile organic compounds (VOCs). However, this approach is typically used for single VOCs treatment but not for the mixtures of VOC and volatile organic sulfur compounds (VOSCs), even if they are often encountered in industrial applications. Therefore, we investigated the performance of BTF for single and ternary mixture gas of dimethyl sulfide (DMS), propanethiol, and toluene, respectively. Results showed that the co-treatment enhanced the removal efficiency of toluene, but not of dimethyl sulfide or propanethiol. Maximum removal rates (rmax) of DMS, propanethiol and toluene were calculated to be 256.41 g·m−3·h−1, 204.08 g·m−3·h−1 and 90.91 g·m−3·h−1, respectively. For a gas mixture of these three constituents, rmax was measured to be 114.94 g·m−3·h−1, 104.17 g·m−3·h−1 and 99.01 g·m−3·h−1, separately. Illumina MiSeq sequencing analysis further indicated that Proteobacteria and Bacteroidetes were the major bacterial groups in BTF packing materials. A shift of bacterial community structure was observed during the biodegradation process.

Photocatalysis and flocculation processes for recycling aquaculture effluent into nutrient-rich irrigation water

This research aimed to create a novel technique for recovering fertilizers from aquaculture effluent to overcome potential non-renewable fertilizers shortages. There are two steps: Photocatalyst technique for nutrient mobilization, succeeded by solids precipitating with two natural and one synthetic flocculant. The photocatalytic degradation of organonitrogen compounds in batch experiments started under the irradiation of sunlight. Following that, photocatalytic breakdown of organonitrogen compounds produces inorganic nitrogen constituents like NH4+, NO2−, and NO3−, which could be used as manure. It was found that, after 12 h of circulating, the concentration of inorganic nitrogen become as NH4+ = 17.2 g/L, NO2− = 18.1 mg/L, and NO3− = 15.9 mg/L. The jar test was adopted to assess the capacity of two natural compounds (tamarind kernel polysaccharide (TKP) and tannin-based product (TBS)) and synthetic water-soluble polymer cationic polyacrylamide (SWP) to reduce turbidity, total suspended solids (TSS), COD and colour. The findings reveal that with a dose of 20 mg/L of TBS, 20 mg/L of TKP, and 50 mg/L of SWP, the maximum turbidity reductions were 95, 93, and 94%, respectively. The TBS was slightly better than TKP and highly better than SWP in terms of coagulation activities with TSS, COD and colour maximum removal efficiencies.

Evaluation of various preparation methods of oil palm fiber (OPF) biochar for ammonia-nitrogen (NH3-N) removal

The aim of this study is to develop a oil palm based biochar for the selective removal of NH3-N in low concentration from aquaculture wastewater. In this study, three different preparation methods of biochar were evaluated for the adsorption of NH3-N from synthetic aquaculture wastewater. The three methods are pyrolysis, activation with acid before pyrolysis and activation after pyrolysis with numerous oxidizing agents. In the 1st method, various biochars have been prepared at different pyrolysis temperatures (300 – 500 °C) and holding time (0.5 – 2 hr). The maximum removal efficiency of 50 % was achieved at preparation condition of 300 °C and 2 hr. In the 2nd method, the acid activated raw OPF was pyrolyze at 300 °C, 1 hr. The maximum removal was lower compared to the 1st method without acid treatment. In the 3rd Method, the optimized biochar from the 1st method was activated with different activating agents such as, HNO3, HCl, H3PO4, H2SO4, CH3COOH and H2O2 at 100 °C for 2 hr. It was noticed that activation after pyrolysis did not show any improvement in the removal of NH3-N from synthetic aquaculture wastewater. Characterization of optimized samples were carried out to investigate the adsorption mechanism process of NH3-N. The 1st method (pyrolysis) was the best which reported the highest (50 %) removal of NH3-N. Pyrolyzed OPF is a potential adsorbent for NH3-N.

Removal of Heavy Metals from Wastewater Using Novel Polydopamine-Modified CNTs-Based Composite Membranes

The presence of major heavy metals including Pb2+, Cu2+, Co2+, Ni2+, Hg2+, Cr6+, Cd2+, and Zn2+ in water is of great concern because they cannot degrade or be destroyed. They are toxic even at very low concentrations. Therefore, it is necessary to remove such toxicants from water. In the current study, polydopamine carbon nanotubes (PD-CNTs) and polysulfone (PS) composite membranes were prepared. The structural and morphological features of the prepared PDCN composite membranes were studied using FTIR, XRD, SEM, and EDS. The potential application of PDCNs for heavy metal removal was studied for the removal of Pb2+, Cr6+, and Cd2+ from wastewater. The maximum removal efficiency of 96.1% was obtained for Cr6+ at 2.6 pH using a composite membrane containing 1.0% PD-CNTs. The removal efficiencies decreased by 64.1 and 73.4, respectively, by enhancing the pressure from 0.50 up to 0.85 MPa. Under the same circumstances, the percentages of Pb+2 removal at 0.49 bar by the PDCNS membranes containing 0.5% and 1.0% PD-CNT were 70 and 90.3, respectively, and decreased to 54.3 and 57.0, respectively, upon increasing the pressure to 0.85 MPa. The results showed that PDCNS membranes have immense potential for the removal of heavy metals from water.

Removal of Various Hazardous Materials Using a Multifunctional Biomass-Derived Hydroxyapatite (HAP) Catalyst and Its Antibacterial Effects

In the present study, oyster shells, a cause of environmental pollution, were employed effectively to synthesize hydroxyapatite (HAP) by facile oxidation and phosphorylation. The ability of HAP to adsorb various metal cations and inhibit bacterial growth was validated. The biomass-derived HAP catalyst exhibited high metal cation adsorption in water at room temperature and under various acidic conditions (M = Cr, Mn, Ni, Cu, Cd, Ba, and Pb). HAP was demonstrated to have a maximum removal efficiency of 92.8% for the heavy metal Pb. Even under different pH conditions, HAP was demonstrated to be effective for the removal of three harmful heavy metals, Cr, Cd, and Pb, with a particularly high removal efficiency demonstrated for Pb under all conditions (average removal efficiency of Cr: 63.0%, Cd: 59.9%, and Pb: 91.6%). In addition, HAP had a significant influence on phosphate ion adsorption in aqueous solution, eliminating 98.1% after 3 min. Furthermore, biomass-derived HAP was demonstrated to have significant antibacterial activity against E. coli and S. aureus (5 mM: 74% and 78.1%, 10 mM: 89.6% and 96.0%, respectively).

Assessing the Performance of Environmentally Friendly-Produced Zerovalent Iron Nanoparticles to Remove Pharmaceuticals from Water

Nano zerovalent iron (nZVI), produced from green tea extracts, was incorporated in a cation exchange resin (R-nFe) to investigate its performance regarding the removal of four non-steroidal anti-inflammatory drugs (NSAIDs): ibuprofen (IBU), naproxen (NPX), ketoprofen (KTP) and diclofenac (DCF). The effect of contact time, NaCl pretreatment, pH, R-nFe dose, the role of the supporting material, the initial concentration of pollutants, and the combined effect of nZVI with oxidative reagents was assessed through a series of batch experiments. According to the results, the best removal efficiencies obtained for DCF and KTP were 86% and 73%, respectively, at 48 h of contact time with NaCl pretreated R-nFe at a dose of 15 g L−1 and a pH of 4. The maximum removal efficiency for NPX was 90% for a contact time of 60 min with PS 1 mM and a pH of 3, which was quite similar to the experiment with a greater contact time of 48 h without PS addition. The maximum IBU removal was 70%; this was reached at pH 3, with a contact time of 30 min and R-nFe 15 g L−1. To the authors’ best knowledge, this is the first study investigating the utilization of nZVI, produced from leaf extracts and incorporated into a cationic exchange resin, to remove NSAIDs from water.

SYNTHESIS OF MIXED-METAL MIL(Ti-Fe) FROM VIETNAM ILMENITE ORE AND ITS APPLICATION FOR DEGRADATION OF DYE

In this work, the mixed-metal metal-organic frameworks MIL(Ti-Fe) were synthesized by the hydrothermal method. MIL(Ti-Fe) hybrid material was fabricated from ilmenite ore and 1,3,5-benzene tricarboxylic acid at a temperature of 130 oC for 24 hours. The prepared material was characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (IR), and Brunauer-Emmett-Teller (BET) surface area. The obtained MIL(Ti-Fe) particles have a diameter of from 0.2-1.0 µm with a BET surface area of 85.482 m2 g-1. The influence of various vital parameters such as pH of the dye solution, initial dye concentration, adsorption time, and amount of the catalyst on the dye removal efficiency was investigated. The photocatalytic degradation rate of Rhodamine B was found to be 0.0074 min-1 at pH 7. The maximum removal of Rhodamine B was obtained at the catalyst dose of 1.0 g L-1. Under simulated sunlight irradiation, the resultant mixed-metals MOFs showed high photodegradation toward Rhodamine with degradation efficiency of approximately 99,97% after 6 hours. Furthermore, the resultant materials also showed remarkable absorption behavior toward Rhodamine B with the adsorption capacity of 70 mg g-1.

Comparison of sorption efficiency of natural and MnO2 coated zeolite for copper removal from model solutions

Removal of heavy metals from the environment is important for living beings. The present work investigates the applicability of the natural and MnO2 - coated zeolite as sorbent for the removal of copper from synthetic solutions. Batch experiments were carried out to identify the influence of initial pH and concentration in the process of adsorption. A maximum removal efficiency of Cu(II) was observed in 10 mg/L for natural (95.6%) and modified (96.4%) zeolite, where the values was almost identical, but at concentration of 500 mg/L was the removal efficiency of modified zeolite three times higher. Based on the correlation factors R2, the Langmuir isotherms better describe the decontamination process than Freundlich. The optimum pH value was set at 5.0.

Magnetic-Based Coreshell Nanoparticles as Potential Adsorbents for the Removal of Cu2+ Under Ultraviolet (UV) Light

The magnetite (Fe3O4) and maghemite (γFe2O3) nanopartides, magnetite-silica-silver chloride (Fe3O4-SiO2-AgCl) and maghemite-silica-silver chloride (γFe2O3-SiO2-AgCl) coreshell structures have successfully been synthesized by using a simple wet chemistry method. The efficiency of these particles as the adsorbents for the removal of copper ion, Cu2+ in aqueous solution under UV light was investigated. Two different parameters were studied, namely the adsorbents contact time (60, 120, 180, 240 and 300s) and the solution-stirring rate (100, 200 and 300 rpm). From the results, the removal percentage of the copper ions from the solution were above 90% after 5 hours of adsorption process at 300 rpm by using Fe3O4 (94%) and γFe2O3 (92%) nanoparticles. The maximum removal of copper ions was nearly 100% when yFe2O3-SiO2-AgCl & Fe3O4-SiO2-AgCl coreshell particles were used. The samples that were prepared without magnetic core such as AgCl-SiO2, AgCl and SiO2 particles, showed lower percentage of the copper ions removal (78%, 60% and 20%, respectively). This situation shows that the magnetic nanoparticles plays and important role during the adsorption process due to their large active sites for the adsorption to occur.