Enhancement of oil recovery using zirconium-chitosan hybrid composite by adsorptive method

Synthesis of bagasse nanocellulose-filled composite polyurethane xerogel for the efficient adsorption of Rhodamine-B dye from aqueous solution: investigation of adsorption parameters

In this study, polyurethane (PU)-based xerogels were synthesized by using the biobased polyol derived from chaulmoogra seed oil. These polyol was used for the preparation of PU xerogels using methylene diphenyl diisocyanate hard segment and polyethylene glycol (PEG6000) as soft segment with 1,4-diazabicyclo[2, 2, 2]octane as catalyst. Tetrahydrofuran, acetonitrile and dimethyl sulfoxide were used as the solvents. Nanocellulose (5 wt %) prepared from bagasse were added as filler, and the obtained composite xerogels were evaluated for chemical stability. The prepared samples were also characterized by using SEM and FTIR. Waste sugarcane bagasse nanocellulose proved as a cheap reinforcer in the xerogel synthesis and for the adsorption of Rhodamine-B dye from the aqueous solution. The factors that affect the adsorption process have been studied including the quantity of the adsorbent (0.02-0.06 g), pH (6-12), temperature (30-50) and time (30-90). Central composite design for four variables and three levels with response surface methodology has been used to get second-order polynomial equation for the percentage dye removal. RSM was confirmed by the measurement of analysis of variance. Increase in the pH and quantity of the adsorbent was found to increase the sorption capacities of the xerogel (NC-PUXe) towards rhodamine B, maximum adsorption.

The blending effect of natural polysaccharides with nano-zirconia towards the removal of fluoride and arsenate from water

Nano-zirconia (ZO) was synthesized using a microwave-assisted one-pot precipitation route. Two biopolymers, chitosan (CTS) and carboxymethyl cellulose were blended with ZO at different w/w ratios. The formulation with 30% w/w chitosan (ZO-CTS) was found to give enhanced uptake of F^- and As(V). ZO and the most effective ZO-CTS system were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. These confirmed the formation of a composite system containing nanoparticles of 50 nm in size, in which ZO was present in the amorphous form. It was observed that the combination of ZO with CTS improved the F^- and As(V) adsorption capacity most notably at pH 5.5. Fluoride adsorption by ZO-CTS followed the Freundlich isotherm model, with an adsorption capacity of 120 mg g^-1. Adsorption of As(V) by ZO-CTS could be fitted with both the Langmuir and Freundlich isotherm models and was found to have a capacity of 14.8 mg g^-1. Gravity filtration studies conducted for groundwater levels indicated the effectiveness of ZO-CTS in adsorbing As(V) and F^- at a pH of 5.5. The ability of the ZO-CTS in removing Cd(II) and Pb(II) was also investigated, and no such enhancement was observed, and found the neat ZO was the most potent sorbent here.

Wheat husk-based sorbent as an economical solution for removal of oil spills from sea water

Oil spills are a significant threat to the marine ecosystem that requires immediate removal from the oceanic environment. Many technologies have been employed to clean up oil spills. Of these, adsorption has scored a prominent success due to the high efficiency, economic viability, environmental friendship, and ease of application. The utilization of agricultural waste to produce biosorbents have been considered as an ecofriendly and efficient approach for removing oil. Thus, a new low-cost oil adsorbent was prepared via esterification of the wheat straw (Str) with a hydrophobic benzoyl group, the resulting copolymer (Str-co-Benz) was characterized by FTIR, TGA, DSC, and SEM and used at laboratory scale. The oil spill cleanup process was conducted using a crude oil-natural seawater system under different adsorption conditions such as oil concentration, adsorbent dose, agitation time and speed. Equilibrium studies were performed to determine the capacity of the prepared materials for crude oil adsorption. Langmuir and Freundlich adsorption models were used to describe the experimental isotherms. The reliability of the data was examined and evaluated via application of response surface methodology program. The results showed that oil adsorption followed a pseudo-second-order kinetic model and fitted well with Langmuir model with a maximum adsorption capacity of 10.989 and 12.786 g/g for Str and (Str-co-Benz), respectively. Overall, the modified wheat husk is an effective platform for removing oil from marine ecosystems due to low cost, biodegradability, simple synthesis and fast removal. Moreover, the resulted solid can be used as a fuel in some industrial processes such as steam boilers and brick production incinerators.

Low-grade sepiolite with low loading of Na/La salts for simultaneous removal of ammonia and phosphate from wastewater

Efficient treatment of wastewater is of paramount importance for protecting the ecosystem. In this work, we prepared a low-grade sepiolite with low Na/La salt loadings (Na/La-Sep) and employed it for the simultaneous removal of ammonia (N) and phosphate (P) species in the wastewater. The key factors influencing the nutrient removal efficiency of Na/La-Sep, such as the concentration of the La/Na salt solution, the co-existing ion type, and surface zero charges, were investigated. Na/La-Sep exhibits excellent N and P adsorption capability and reduced the N and P concentrations in the spiked and real-world wastewaters to below the allowable N and P discharge limits. Due to the extraordinarily low cost of low-grade sepiolite and the low loading of Na/La salts, Na/La-Sep has a substantially lower cost when compared to other reported clay mineral adsorbents. Furthermore, the N and P removal mechanisms by Na/La-Sep were unraveled by combining the kinetic studies, the molecular dynamics (MD) simulation, and the electron density difference. The present findings might shed light on a new way to develop cost-efficient and high-efficiency adsorbents for alleviating eutrophication and deepen the understanding of N and P removal at a molecular level.

Mesoporous carbon structure impregnated with 2D engineered zirconium: A sustainable adsorbent for the removal of dyes from the aqueous solution

The key designing of new breeds of the adsorbents aimed to improve the physical, chemical and textural morphology along with surface functionalization, selectivity toward the contaminants, and regenerations efficiency. In this aspect, two adsorbents named wet oxidative and ultrasonicated zirconium impregnated composite, have been synthesized through two routes, i.e., wet oxidation and ultrasonication. In wet oxidation method, carbon-based materials are oxidized using an oxidant followed by impregnation, while in ultrasonication assisted route, the impregnation is carried out using acoustic phenomenon. The characterization study revealed that the wet oxidation process is more competent in impregnating zirconium and developing diverse porosity and functionalities. The maximum adsorption capacity of wet oxidative adsorbent was 812 mg/g for Reactive Blue 19 and 203.18 mg/g for Methylene Blue, that accentuated the efficiency of the adsorbent over raw activated carbon. The electrostatic interaction, hydrogen-bonding and ligand exchange phenomenon are the involved adsorption mechanism for dyes. The regeneration study finally asserts that the wet oxidative adsorbent shows an insignificant decrease in its capacity up to the 5^th-cycle (i.e., 87.67% removal at 5^th cycle) as compared to raw AC (46.71% removal at 5th cycle). Further, a continuous fixed-bed column study revealed a significant correlation between experimental breakthrough data and kinetic data. Thus, the developed adsorbent has a sedulous adsorption capacity to remove the most stubborn toxic dyes and can be used in industrial-scale applications.

Chitosan based adsorbents for the removal of phosphate and nitrate: A critical review

The tremendous development in the industrial sector leads to discharging of the several types of effluents containing detrimental contaminants into water sources. Lately, the proliferation of toxic anions particularly phosphates and nitrates onto aquatic systems certainly depreciates the ecological system and causes a deadly serious problem. Chitosan (Cs) is one of the most auspicious biopolymer adsorbents that are being daily developed for removing of various contaminants from polluted water. This is due to its unparalleled benefits involving biocompatibility, non-toxicity, facile modifications and low-cost production. Nevertheless, chitosan displays considerable drawbacks including low adsorption capacity, low surface area and lack of reusability. Therefore, few findings have been established regarding the aptitude of modified chitosan-based adsorbents towards phosphate and nitrate anions. This review elaborates an overview for the current advances of modified chitosan based-adsorbent for phosphate and nitrate removal, in specific multivalent metals-modified chitosan, clays and zeolite-modified chitosan, magnetic chitosan and carbon materials-modified chitosan. The efforts that have been executed for enriching their adsorption characteristics as well as their possible adsorption mechanisms and reusability were well addressed. Besides, the research conclusions for the optimum adsorption conditions were also discussed, along with emphasizing the foremost research gaps and future potential trends that could motivate further research and innovation to find best solutions for water treatment problems facing the world.

A comprehensive review on the applications of functionalized chitosan in petroleum industry

The biomaterials have gained the attention for utilization as sustainable alternatives for petroleum-derived products due to the rapid depletion of petroleum resources and environmental issues. Chitosan is an economical, renewable and abundant polysaccharide having unique molecular characteristics. Chitosan is derived by deacetylation of chitin, a natural polysaccharide existing in insects' exoskeleton, outer shells of crustaceans, and some fungi cell walls. Chitosan is widely used in numerous domains like agriculture, food, water treatment, medicine, cosmetics, fisheries, packaging, and chemical industry. This review aims to account for all the efforts made towards chitosan and its derivatives for utilization in the petroleum industry and related processes including exploration, extraction, refining, transporting oil spillages, and wastewater treatment. This review includes a compilation of various chemical modifications of chitosan to enhance the petroleum field's performance and applicability.

Chitosan-Ni/Fe layered double hydroxide composites as an efficient solid phase extraction sorbent for HPLC-PDA monitoring of parabens in personal care products

There is a dire need for development of efficient and sensitive methods to efficiently screen parabens. In this research, we focused on quantification of four parabens (i.e., methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butyl paraben (BP)) using chitosan intercalated nickel/iron layered double hydroxide (CS-Ni/Fe-LDH) composites as solid phase extraction sorbent prior to HPLC-PDA analysis. CS-Ni/Fe LDH composites with a heterogeneous, porous texture, and coral reef-like structure exhibit appealing extraction efficiency for the target parabens due to the enhanced possibility for the formation of hydrogen bonding and hydrophobic interactions. The performance of the composites was assessed and optimized for solid phase extraction of parabens from standard samples and real samples (rose water, cream, toothpaste, hair serum, and sunscreen). The LDH-SPE-HPLC method exhibited a wide linear range (e.g., 100-50,000 ng L^-1), good linearity (R² ≥ 0.999), and good precision (relative standard deviation (RSD) < 3%). This method successfully enriched selected parabens with remarkable recovery above 85.95% and a good RSD (0.01-2.90%). The quantitation of MP, EP, PP, and BP was made at detection range (and limits of detection (LOD)) of 5-15 (9.8), 11-21 (16.2), 6-18 (12.4), and 10-20 (15.6) ng L^-1, respectively. The prepared composites also displayed excellent performance with enhanced reusability/durability (n = 30 cycles) and reproducibility (n = 5).

Synthesis, characterization and sorption studies of a zirconium(iv) impregnated highly functionalized mesoporous activated carbons

This study aimed to develop a highly functionalized adsorbent material for the removal of persistent anionic reactive dye. The modification process was commenced via a wet oxidation method by using zirconium salt as an impregnating material. The process led to an increase in the overall porosity, thermal stability and its oxidative functionality. The newly synthesised material was named ZrAC. The morphological and textural images revealed the irregular and eroded structures with an increase in porosity of the modified adsorbent. The results of chemical and spectral analysis disclosed that the material had successfully gained the oxidative functionality over the surface that will favour the removal of anionic dye. Equilibrium isotherms and adsorption kinetics studies insinuate that the overall process of adsorption follows the Sips isotherm and pseudo-second order kinetic model, respectively. The monolayer adsorption capacity of ZrAC was found to be superior (506 mg g⁻¹) to AC at 500 mg L⁻¹ concentration of persistent reactive dye. Moreover, the desorption capabilities of ZrAC were found to be more prominent, which finally affirms its potential use in a continuous flow system as a reusable adsorbent. Additionally, the stability of zirconium, corroborated from ICP-MS and XPS data, revealed the stability of zirconium after adsorption cycles thus verified its reusability. Thus, the characterization and experimental results of ZrAC strongly advocated its potential as a future adsorbent for removal of reactive dyes.

The present work focuses to develop a varied meso-microporous sorbent by using Zr(iv) as an impregnated metal. The modification develops the oxidative functionalities and porosity of the sorbent that enhances its efficiency for the removal of RB19.

In-situ fabrication of zirconium entrenched biopolymeric hybrid membrane for the removal of toxic anions from aqueous medium

The eutrophication of water bodies resulting from the excessive amounts of phosphate and nitrate ions in the water systems will cause serious environmental problems. This study deals with the adsorptive removal of toxic anions from aqueous medium using zirconium entrenched chitosan-starch membrane (Zr-CS-ST). The optimization of several influencing key factors like adsorbent dosage, shaking time, solution pH, aggressive ions, zero point charge and temperature were examined by batch mode adsorption experiments. In addition, Freundlich isotherm model showed an outstanding fit with the experimental data's, yielding the maximum adsorption capacities of 86.28 and 70.88 mg/g for phosphate and nitrate, respectively. Thermodynamic parameters, including the Gibbs free energy, entropy and enthalpy change indicated that the removal of both anions by Zr-CS-ST membrane was feasible, spontaneity and endothermic in nature. The diffusion and reaction based kinetic models were exposed to study about the kinetics and adsorption process were followed by pseudo-second-order and intra-particle diffusion kinetic models. The removal mechanism involved by different types of interactions such as complexation, ion exchange and electrostatic interaction, which were adopted for the removal mechanisms. We exposed that, Zr-CS-ST was successfully developed and will be effectively employed for the remediation of phosphate and nitrate ions in field/practical applications.

Synthesis of Honeycomb-Like Carbon Foam from Larch Sawdust as Efficient Absorbents for Oil Spills Cleanup and Recovery

Hydrophobic oil absorbents with interconnected porous structure have been widely used in dealing with the pervasive environmental issue of oil spills. In this work, hydrophobic foams with 3D interconnected porous honeycomb structures of liquefied-larch-based polymer foam (LLB-PF) and its carbonized product liquefied-larch-based carbon foam (LLB-CF) was prepared from larch sawdust waste and used for oil and organics separation. The results revealed that the 3D interconnected and open-cell honeycomb structure of LLB-PF was formed simultaneously during self-foaming, which remained intact even after carbonization. The two ultralight foams, especially LLB-PF, exhibited remarkable oil/water selectivity. The foams exhibited efficient and rapid absorption capacities, not only for oils but also for organic solvents. LLB-PF and LLB-CF could absorb tetrachloromethane and epoxidized soybean oil up to 88 and 153 times their own weight, respectively. The recycle tests showed that LLB-PF and LLB-CF exhibited excellent absorption capacities even after five cycles, demonstrating an excellent cyclability. The high oil and organic solvent absorption performance along with the renewable and low-cost starting materials positions LLB-PF and LLB-CF foams as promising candidates with great potential for oil and organics cleanup.