环境•农林最新文献

Water sources is contaminated with different types of impurities. Several technologies and materials are used for purification of contaminated water. Most of the reported technologies costly and produce secondary contaminants. Nowa day, researchers are used hydrogels for water purification. Hydrogels are applied drug delivery, catalysis, tissue engineering, sensing and removal of environmental pollutants, applications, and energy storage. Hydrogels have specific functional groups as –COOH, -SO₃H, -OH, CONH₂, -NH₂, -SH and other groups which are responsible for applications. Hydrogels were removes impurities from water through physio-adsorption, chemo-adsorption, sorption and secondary forces. The aim of this review is to explore the preparation method, conceptualization of hydrogels and their uses in water purification. It describes details of toxicants in water, different types of hydrogels and their synthesis methods. These hydrogels were used for water purification and evaluated for removal capacity with respect to toxicants in water. Nowadays hydrogels are modified based on their applications to create specific functionality on hydrogel. Specific hydrogel will be emerging tool for specific applications.

Nowadays, the use of antibiotics is widespread which is causing great pressure on the ecological environment. Incorporation of nitrogen source in biochar can improve its adsorption performance, which is widely used as an adsorbent due to its high efficiency and low-cost. In this study, municipal sludge and red mud were used as raw materials, urea as nitrogen source and KOH and ammonium oxalate as activators to prepare N-doped sludge-based magnetic biochar (NBC) by co-pyrolysis for adsorption of norfloxacin (NOR) in wastewater. The experiment was conducted using 50 mL of NOR wastewater with a concentration of 100 mg/L. The optimal adsorption conditions were identified as 1.6 g/L dosage, pH 5, and temperature 25 °C. The actual adsorption capacity of NBC reached a maximum of 160.25 mg/g. The maximum adsorption capacity of NBC was 388.82 mg/g, which was measured by Langmuir isothermal modelling. The adsorption kinetics are consistent with a pseudo-second order model, while the adsorption isotherms are consistent with the Langmuir and Freundlich models. The characterization demonstrates that NBC is a rough and porous material, with a specific surface area of 192.8397 m2/g and a surface functional group composition including -OH/NH, C = C, C = N, C-O. The main mechanisms of this research include pore filling, π-π interactions, H-bonding and electrostatic interactions. The introduction of a nitrogen source to sludge-based magnetic biochar (BC) has improved its performance in various aspects of adsorption. This paper demonstrates the excellence of NBC by comparing the adsorption performance of NOR with that of BC, which has great potential for future practical applications.

Graphical Abstract

Soil aggregation plays a critical role in the maintenance of soil nutrient storage and supply. After five years of crop biomass management, field samples from a sandy loam mountain hilly soil were examined for aggregate distribution, physical subfractions within aggregates, and organic nitrogen (N) fractions, such as nonhydrolyzable N (NHN), hydrolysable ammonium N (HAN), amino-sugar N (ASN), amino-acid N (AAN), and hydrolysable unidentified N (HUN). The total N pool and theoretically mineralizable N were used to calculate the soil N storage and supply capacity, respectively. The total N, mineralizable N, and coefficient of mineralisation rate were all considerably raised by crop biomass incorporation. Analysis of covariance structures showed that the organic N fractions had an impact on the supply and storage of N in the soil, with HUN and AAN contributing the most to the potentially mineralizable N and; also HUN and AAN making up the largest portion of the total soil N pool. In comparison to bulk soils that had not had biomass removed, the amounts of organic N components HAN, ASN, AAN, HUN, and NHN were higher by 98.2%, 87.2%, 71.47%, 38.91%, and 43.27%, respectively. Compared to microaggregates, biomass incorporation enhanced soil macroaggregates by 9.37% and had higher organic N percentages and accumulation efficiency. The mineralizable N was significantly correlated with all fractions of N. The inorganic nitrogen and total nitrogen (TN) were higher in 100% biomass inclusion-T₅ (60.01 and 841.58) and lowest in total removal of biomass-T₁ (24.92 and 479.74). The > 2 mm aggregate size significantly contributed more in organic N fractions rather than 2–0.25 mm or less.

Freshwater resources are limited on the earth, and we have highly contaminated it with various pollutants. Reuse and recycle of wastewater is the need of the hour in the present Anthropocene. Removal of heavy metals from the wastewater is one of the prerequisites for further reuse of the water. Evidence shows that heavy metal contamination can disrupt ecosystem functioning and human health. Several researchers have reported the bio-sorption process using waste material as alternative adsorbents to remove heavy metal from aqueous medium. Despite the advantages of the bio-sorption process, there are still several research need to be included like evaluation of bisorbent against industrial wastewater and its economic assessmment for its commercialization. This review synthesizes the contemporary information on heavy metal (Cd, Pb, Ni, Cr, As, Hg) removal from various biomaterials (plant-based, algae-based, animal/bacteria/fungi/protozoa) from the literature published between 2007 and 2020.