Submerged Membrane Photo Reactor (SMPR) with Simultaneous Photo Degradation and TiO2 Catalyst Recovery for Efficient Dyes Removal

In this study, a polyvinylidene difluoride (PVDF) hollow fiber membrane module incorporated with TiO2 was submerged into a photocatalytic reactor to create a hybrid photocatalysis with membrane separation process (a submerged membrane photoreactor, SMPR), for advanced dyes wastewater treatment. The SMPR performance was assessed by the degradation of single component Rhodamine B (RhB) and degradation of mixed dyes (RhB and Methyl orange (MO)) in a binary solution. Several operational parameters such as the amount of catalyst loading, permeate flux, and the effect of aeration were studied. Fouling tendency on the membrane was also investigated to determine the optimum operating conditions. The results show that the synergetic effect of the low catalyst loading and permeate flux creates the environment for optimum light penetration for high photocatalytic activity as the hybrid system with low catalyst loading (0.5 g/L) and 66 L/m2h of flux with aeration at 1.3 L/min has proven to increase the photocatalysis performance by 20% with additional catalyst recovery. In addition, applying the low catalyst loading and flux permeate with aeration brings minimal fouling problems.

Competitive coordination of iron(III) and copper(II) ions with amidoximated polyacrylonitrile nanofiber and the catalytic performance of the complex

This present work describes the competitive coordination of iron (III) and copper (II) ions with amidoximated polyacrylonitrile nanofiber and the catalytic performance of the resulting complex (Fe-Cu-AO- n-PAN). The coordination results showed that the increase of the initial concentration of metal ions was beneficial to the increase of the coordination amount. There were both competition and synergistic effects between the two metal ions. But AO- n-PAN was more inclined to coordinate with Fe3+ ions. The promotion effect of Cu2+ ions on iron coordination due to weak positive electric property and small ion radius increased with its initial concentration in the solution. The Langmuir-Freundlich isotherm model among of four selected isotherm models for binary system showed the best fit to the co-coordination reaction between AO- n-PAN and Fe3+-Cu2+ binary solution. Fe-Cu-AO- n-PAN as heterogeneous Fenton catalyst displayed improved catalytic performance than mono-metal complexes due to its better dye adsorption and the synergistic effect between Cu2+ and Fe3+ ions during degradation process, and both the alkali-resistant and the reusability of it were improved at the same time.

A novel fluorometric chemosensor based on imidazo[4,5-b]phenazine-2-thione for ultrasensitive detection and separation of Hg2+ in aqueous solution

We synthesize and develop 1,3-dihydro-2H-imidazo[4,5-b]phenazine-2-thione as a ratiometric chemosensor for recognition of Hg²⁺ in DMSO/H₂O (v/v = 9:1) binary solution. We rationally introduce the phenazine imidazole group as fluorophore and the thione moiety as recognition site to bind Hg²⁺. Interestingly, the chemosensor shows ultrasensitive response for Hg²⁺ and the lowest limit of detection is 0.167 nM. In addition, it can also separate Hg²⁺ from aqueous solution with excellent ingestion capacity, and the adsorption ratio is up to 96%. Furthermore, ion test strips based on the chemosensor are fabricated to conveniently and efficiently detect Hg²⁺.

Kinetics of Adsorption Competition of Pb-Cu and Pb-Methylene Blue in Aqueous Solution using Silica Gels from Coal Fly Ash

The present study investigates the removal of Pb2+ using silica gel (SG) in the presence of the Cu2+ (Pb-Cu) and methylene blue (Pb-MB) ion competitor. These pollutants are toxic and harmful to the ecosystem. The presence of the multicomponent pollutants causes more complications to remove from the water system. The adsorptions were examined in a batch system under certain experimental conditions (pH solution system and contact time). Meanwhile, the FTIR spectrophotometer determines the differences adsorption interaction in silica functional groups before and after adsorption. The results showed that the silanol group of silica gel acted as an adsorption site. In the single systems, the adsorption capacity of silica gel follows the order MB > Cu2+ > Pb2+ of around 84.03; 64.81; and 56.88 mg.L−1, respectively. The kinetic adsorptions of both single and binary systems were best fitted to pseudo-second-order models. In the binary solution systems, both adsorption capacity and adsorption rate of each component decreased compared to the single system. The results indicated that the cationic competitors influenced the Pb2+ adsorption, or vice versa, depending on the amount of charge and adsorption affinity.

Biosorption of cationic Hg2+ and Remazol brilliant blue anionic dye from binary solution using Gelidium corneum biomass

Remazol brilliant blue (RBB) is an anthraquinone anionic dye that has several commercial uses, especially in the textile industries and is well-known for its detrimental impacts on marine life and the surrounding ecosystem. Mercury (Hg2+) is also one of the most severe hazardous environmental contaminants due to its bioaccumulation through the food chain and high toxicity to the human embryo and fetus. The biosorption potential of Gelidium corneum biomass for bioremoval of Hg2+ and RBB dye simultaneously from binary mixture was assessed. The effects of initial pH, contact time, Hg2+, RBB, and biomass concentrations on the biosorption process were investigated in 50 batch experiments using a Face-centered central composite design. The maximum removal percentage of Hg2+ (98.25%) was achieved in the run no. 14, under optimum experimental conditions: 200 mg/L Hg2+, 75 mg/L RBB, pH 5. At 30 °C, 4 g/L algal biomass was used, with a contact time of 180 min. Whereas, the maximum removal percentage of RBB (89.18%) was obtained in the run no. 49 using 200 mg/L Hg2+, 100 mg/L RBB, pH 5, 4 g/L algal biomass and 180 min of contact time. FTIR analysis of Gelidium corneum biomass surface demonstrated the presence of many functional groups that are important binding sites responsible for Hg2+ and RBB biosorption. SEM analysis showed apparent morphological alterations including surface shrinkage and the appearance of new shiny adsorbate ion particles on the Gelidium corneum biomass surface after the biosorption process. The EDX study reveals an additional optical absorption peak for Hg2+, confirming the role of Gelidium corneum biomass in Hg2+ biosorption. In conclusion, Gelidium corneum biomass has been shown to be an eco-friendly, sustainable, promising, cost-effective and biodegradable biosorbent to simultaneously biosorb Hg2+ and RBB dye from aquatic ecosystems.

Binary adsorption of [Pb(II) + Co(II)] from aqueous solution using thiolated saw dust

Technology advancement contributed to an increase in industrial activities, resulting in the introduction of metal ions into water resources at concentrations well above the WHO limits. Heavy metals are highly toxic and carcinogenic; usually occur as multicomponent mixtures in aquatic environment. In present study, batch experiments have been conducted to study the dependence of varying concentration, time, pH and temperature on the uptake of Pb(II) as pure component under equilibrium conditions using thiolated saw dust. Saw dust has been chemically modified with thioglycolic acid and characterised using proximate and FTIR analyses, degree of thiolation has also been determined. To determine the effect of presence of Co(II) ions on the uptake of Pb(II) ions, batch experiments for [Pb(II) + Co(II)] mixture have been carried out for concentration ratios of 1:0, 1:1, 1:2, 1:3, 1:4 of Pb:Co at pH 5 and data has been interpreted using Langmuir competitive isotherm shows that adsorption of Pb(II) has been suppressed by the presence of Co(II) ions in the binary solution, hence the adsorption process is antagonistic in nature. Study also indicates the possibility of simultaneous removal of both metal ions using low cost bioadsorbent, which is economical specially for application in small scale industries.

Protein Hydration in a Bioprotecting Mixture

We combined broad-band depolarized light scattering and infrared spectroscopies to study the properties of hydration water in a lysozyme-trehalose aqueous solution, where trehalose is present above the concentration threshold (30% in weight) relevant for biopreservation. The joint use of the two different techniques, which were sensitive to inter-and intra-molecular degrees of freedom, shed new light on the molecular mechanism underlying the interaction between the three species in the mixture. Thanks to the comparison with the binary solution cases, we were able to show that, under the investigated conditions, the protein, through preferential hydration, remains strongly hydrated even in the ternary mixture. This supported the water entrapment scenario, for which a certain amount of water between protein and sugar protects the biomolecule from damage caused by external agents.