Enzymatic preparation of hydrophobic biomass with one-pot synthesis and the oil removal performance

Oil pollution is causing deleterious damage to aquatic ecosystems and human health.The utilization of agricultural waste such as corn stalk(CS)to produce biosorbents has been considered an ecofriendly and efficient approach for removing oil.However,most previous studies focused on the modification of the whole CS,which is inefficient due to the heterogeneity of CS.In this study,corn stalk pith(CP),which has excellent amphipathic characteristics,was selected to prepare a high-efficiency oil sorbent by grafting dodecyl gallate(DG,a long-chain alkyl)onto CP surface lignin via laccase mediation.The modified biomass(DGCP)shows high hydrophobicity(water contact angle=140.2°)and superoleophilicity(oil contact angle=0°)and exhibits a high oil sorption capacity(46.43 g/g).In addition,DGCP has good stability and reusability for adsorbing oil from the aqueous phase.Kinetic and isotherm models and two-dimensional correlation spectroscopy integrated with FTIR analyses revealed that the main sorption mechanism involves the H-bond effect,hydrophobic effect and van der Waals force.This work provides an ecofriendly method to prepare oil sorbents and new insights into the mechanisms underlying the removal of spilled oil from wastewater.

Identification of sources,characteristics and photochemical transformations of dissolved organic matter with EEM-PARAFAC in the Wei River of China

Dissolved organic matter(DOM)in rivers is a critical regulator of the cycling and toxicity of pollutants and the behavior of DOM is a key indicator for the health of the environment.We investigated the sources and characteristics of DOM in surface water and sediment samples of the Wei River,China.Dissolved organic carbon(DOC)concentration and ultraviolet absorbance at 254 nm(UV254)increased in the surface water and were decreased in the sediment downstream,indicating that the source of DOM in the water differed from the sediment.Parallel factor(PARAFAC)analysis of the excitation-emission matrices(EEM)revealed the presence of terrestrial humus-like,microbial humus-like and tryptophan-like proteins in the surface water,whereas the sediment contained UVA humic-like,UVC humic-like and fulvic-like in the sediment.The DOM in the surface water and sediment were mainly derived from microbial metabolic activity and the surrounding soil.Surface water DOM displayed greater photodegradation potential than sediment DOM.PARAFAC analysis indicated that the terrestrial humic-like substance in the water and the fulvic-like component in the sediment decomposed more rapidly.These data describe the characteristics of DOM in the Wei River and are crucial to understanding the fluctuations in environmental patterns.

Sorption of tylosin and sulfamethazine on solid humic acid

Tylosin（TYL） and sulfamethazine（SMT） are ionizable and polar antimicrobial compounds,which have seeped into the environment in substantial amounts via fertilizing land with manure or sewage. Sorption of TYL and SMT onto humic acid（HA） may affect their environmental fate. In this study, the sorption of TYL and SMT on HA at different conditions（pH, ionic strength） was investigated. All sorption isotherms fitted well to the Henry and Freundlich models and they were highly nonlinear with values of n between 0.5 and 0.8, which suggested that the HA had high heterogeneity. The sorption of TYL and SMT on HA decreased with increasing p H（2.0–7.5）, implying that the primary sorption mechanism could be due to cation exchange interactions between TYL~＋/SMT~＋ species and the functional groups of HA.Increasing ionic strength resulted in a considerable reduction in the K_d values of TYL and SMT,hinting that interactions between H bonds and π–π EDA might be an important factor in the sorption of TYL and SMT on HA. Results of Fourier transform infrared（FT-IR） and ~13C-nuclear magnetic resonance（NMR） analysis further demonstrated that carboxyl groups and O-alkyl structures in the HA could interact with TYL and SMT via ionic interactions and H bonds,respectively. Overall, this work gives new insights into the mechanisms of sorption of TYL and SMT on HA and hence aids us in assessing the environmental risk of TYL and SMT under diverse conditions.