Gallagherrosendahl6912

In recent times, research interest into the development of biodegradable, cost-effective and environmental friendly adsorbents with favourable properties for adsorption of pollutants is a challenge. Modification of chitosan via different physical and chemical methods have gained attention as a promising approach for removing organic (such as dyes and pharmaceuticals) and inorganic (such as metal/metal ions) pollutants from aqueous medium. In this regard, researchers have reported grafting and cross-linking approach among others as a potentially useful method for chitosan's modification for improved adsorption efficiency with respect to pollutant uptake. This article reviews the trend in chitosan modification, with regards to the summary of some recently published works on modification of chitosan and their adsorption application in pollutants (metal ion, dyes and pharmaceuticals) removal from aqueous medium. The review uniquely highlights some common cross-linkers and grafting procedures for chitosan modification, their influence on structure and adsorption capacity of modified-chitosan with respect to pollutants removal. Findings revealed that the performance of modified chitosan for adsorption of pollutants depends largely on the modification method adopted, materials used for the modification and adsorption experimental conditions. Cross-linking is commonly utilized for improving the chemical and mechanical stabilities of chitosan but usually decreases adsorption capacity of chitosan/modified-chitosan for adsorption of pollutants. However, literature survey revealed that adsorption capacity of cross-linked chitosan based materials have been enhanced in recently published works either by grafting, incorporation of solid adsorbents (e.g metals, clays and activated carbon) or combination of both prior to cross-linking.Photocatalytic activation of persulfate (PAPS) is considered an efficient and green approach for the mitigation of organic pollutants because of its advantages in low energy consumption and high reusability of photocatalysts. Herein, direct Z-scheme CeO2@LDH heterojunction photocatalyst with a core-shell structure is constructed. We reveal that CeO2@LDH exhibits excellent persulfate (PS) activation performance and high degradation efficiency of RhB under visible light irradiation. Control experiments by quenching catalytically active radicals and analysis of electron paramagnetic resonance (ESR) spectra suggest that the sulfate radical (SO4·-) generated by photocatalytic activation of PS, together with superoxide radical (·O2-) and hydroxyl radical (·OH), degrade pollutants synergistically. Density functional theory (DFT) calculations indicate that the built-in electric field across the surface of CeO2 and LDH is the intrinsic driving force for the efficient transfer of hot carriers in the Z-scheme heterojunction. The construction of this transfer path can effectively engineer the interfacial band structure and inhibit the recombination of photogenerated electron-hole pairs and promote their transportation. Meanwhile, electrons were found to accumulate at the conduction band (CB) of LDHs and holes populate at valence band (VB) of CeO2, generating more active species for photodegradation of RhB. We demonstrate that the Z-scheme heterojunction photocatalyst activated PS system (Z-scheme/PS) is a promising method to degrade RhB and potentially organic pollutants in general.Adsorption of 18 neutral organic compounds (OCs) on polar (polybutylene succinate (PBS) and polycaprolactone (PCL)) and nonpolar (low-density polyethylene (LDPE) and polystyrene (PS)) microplastics (MPs) were investigated. The adsorption coefficients (Kd) varied with ranges of 130-42,002, 124-27,768, 6.40-10,713, and 1.52-10,332 L kg-1 for adsorption on PCL, PBS, LDPE, and PS MPs, respectively. The polar MPs showed greater adsorption capacities than nonpolar MPs. Non-specific interaction, i.e. hydrophobic partition played a crucial role in the adsorption of OCs on all MPs, while polar interactions also contributed significantly to the greater adsorption on polar MPs. Poly-parameter linear free energy relationships (pp-LFERs) with multiple linear regression (MLR) and feedforward network (FN) were then employed to model the adsorption of OCs on MPs so as to obtain deep insights into adsorption mechanisms. The MLR models achieved Radj2 of 0.90-0.97 and root mean square error (RMSE) of 0.13-0.38 log units, while the FN models achieved Radj2 of 0.85-0.90 and RMSE of 0.21-0.60 log units. The MLR models are more accurate under selected equilibrium concentrations while FN models are capable of making predictions under varying equilibrium concentrations. Lastly, both MLR and FN models showed good prediction on literature adsorption data on nonpolar MPs.A pot study was performed to evaluate the influence of O3 stress with different biochar treatments on a wheat cultivar (HD 2967). Plants were subjected to ambient and elevated (ambient+20 ppb) O3 along with three doses of biochar (0%, 2.5%, and 5%). Elevated ozone alone reduced most of the growth parameters, negatively affecting the test cultivar's physiology. Although enzymatic antioxidants were up-regulated by elevated O3, damage to the membrane integrity was evident by higher MDA content in the wheat leaves. Besides, the uptake of nutrients was observed to be reduced under elevated O3 due to the reduced phyto-availability of the soil's nutrients and cation exchange capacity. Such limitation of assimilates and nutrients marked a trade-off between growth and defence, translating to grain yield loss. However, applying biochar as a soil conditioner ameliorated the detrimental effects of O3 with respect to the economic yield of wheat. Biochar alone improved soil properties and nutrient phyto-availability, which translated to better plant growth, stronger physiological capacity, and higher crop productivity. Thus, the study inferred that altered nutrient phyto-availablity and its uptake, likely associated with biochar-induced improved soil properties, relayed stronger plant physiology and antioxidative defence system to combat O3 induced oxidative stress.Direct or indirect exposure to inorganic arsenic (iAs) in the forms of AsIII (arsenite) and AsV (arsenate) through consumption of As-contaminated food materials and drinking water leads to arsenic poisoning. learn more Rice (Oryza sativa L.) plant potentially accumulates a high amount of iAs from paddy fields than any other cereal crops. This makes it to be a major source of iAs especially among the population that uses it as their dominant source of diet. The accumulation of As in human bodies poses a serious global health risk to the human population. Various conventional methods have been applied to reduce the arsenic accumulation in rice plant. However, the success rate of these techniques is low. Therefore, the development of efficient and effective methods aimed at lowering iAs toxicity is a very crucial public concern. With the current advancement in technology, new strategies aimed at addressing this concern are being developed and utilized in various parts of the world. In this review, we discuss the recent advances in the management of iAs in rice plants emphasizing the use of nanotechnology and biotechnology approaches. Also, the prospects and challenges facing these approaches are described.The production of fine particles from extremely high supersaturation has challenged the application of sulfide precipitation in treating heavy metal wastewater due to the difficulty of solid-liquid separation. To this end, a gas-liquid sulfide precipitation reactor for the removal of Cu2+ was designed by controlling the mass transfer and supersaturation levels during sulfidation processes. Particularly, a computational fluid dynamics (CFD) model of the reactor, integrating sulfidation reaction kinetics with two-phase flow hydrodynamics, was first built, followed by examining the effects of H2S(g) bubble diameter and flow rate. Based on the CFD simulation, the rate-limiting step of the gas-liquid sulfide precipitation reaction is the gas-liquid mass transfer process. Either reducing H2S(g) bubble diameter or increasing H2S(g) flow rate can result in the control of reaction rate and supersaturation level in the system. In order to validate the CFD simulations, we measured Cu2+ concentrations during the sulfidation process with the batch experiments. The agreement between computational and experimental results indicated that our mechanistic model can provide a protocol for the design and optimization of the reaction system, allowing one to visualize the time-dependent reaction process and evaluate the performance of a reactor.Temporary rivers become dependent on wastewater effluent for base flows, which severely impacts river ecosystems through exposure to elevated levels of nutrients, dissolved organic matter, and organic micropollutants. However, biodegradation processes occurring in these rivers can be enhanced by wastewater bacteria/biofilms. Here, we evaluated the attenuation of pharmaceuticals and their human metabolites performing retrospective analysis of 120 compounds (drugs, their metabolites and transformation products) in mesocosm channels loaded with wastewater effluents twice a week for a period of 31 days. Eighteen human metabolites and seven biotransformation products were identified with high level of confidence. Compounds were classified into five categories. Type-A recalcitrant drugs and metabolites (diclofenac, carbamazepine and venlafaxine); Type-B degradable drugs forming transformation products (TPs) (atenolol, sitagliptin, and valsartan); Type-C drugs for which no known human metabolites or TPs were detected (atorvastatin, azithromycin, citalopram, clarithromycin, diltiazem, eprosartan, fluconazole, ketoprofen, lamotrigine, lormetazepam, metformin, telmisartan, and trimethoprim); Type-D recalcitrant drug metabolites (4-hydroxy omeprazole sulfide, erythro/threo-hydrobupropion, and zolpidem carboxylic acid); Type-E unstable metabolites whose parent drug was not detectable (norcocaine, benzolylecgonine, and erythromycin A enol ether). Noteworthy was the valsartan acid formation from valsartan with transient formation of TP-336.The activation of carbon atoms in biochar is an important approach for realizing the reuse of discarded woody biomass resources. In this work, a strategy for the construction of carbon-based catalysts was proposed with Magnoliaceae root biomass as a carbon source, doped by SnS2 and further decorated with heteropoly acid. The introduction of SnS2 can activate the carbon atom and destroy the electronic inertness of the disordered biochar with 002 planes. In addition, the synergy between the Keggin unit of phosphotungstic acid and biochar/SnS2 can suppress recombination of e--h+ carriers. The adsorption and photocatalysis experiments results showed that the efficiency of removing As(III) by biochar/SnS2/phosphotungstic acid (biochar/SnS2/PTA) systems was 1.5 times that of biochar/SnS2 systems, and the concentration of total arsenic in the biochar/SnS2/PTA composite system gradually decreased during the photocatalysis process. The formation of As-POMs can simultaneously realize As(III) photooxidation and As(V) coprecipitation.