Waste-to-wealth application of wastewater treatment algae-derived hydrochar for Pb(II) adsorption

Investigation of adsorption and biosorption features of bio-functionalized poly(GMA-Co-EGDMA) polymer beads in the treatment of nicotine from tobacco industry

The investigation of multifunctional materials for modern enzyme immobilization is an attractive subject in advanced adsorption and biosorption applications. In the present study, the feasibility of immobilization of Lipozyme TL 100L (LPZM) on 3-aminopropyltriethoxysilane (APTES) modified poly-(GMA-co-EGDMA) (PEGDMA) was investigated for adsorption and biosorption of nicotine from aqueous solution. Characterization tests confirmed successful immobilization of lipozyme which significantly altered thermal behavior, surface characteristics, and surface morphology of PEGDMA and PEGDMA/APTES. In addition, the immobilization yields were calculated as 85.0% and 72.0% onto PEGDMA/APTES using physical adsorption and covalent immobilization methods, respectively. The nicotine removal efficiencies were calculated to be 66.4%, 79.0%, 98.9%, and 85.7%, using raw PEGDMA, PEGDMA/APTES, PEGDMA/APTES@LPZM, and PEGDMA/APTES/GU@LPZM, respectively. For the raw PEGDMA, the Langmuir isotherm was best fitted to the adsorption data, while Langmuir-Freundich model described well the adsorption process on PEGDMA/APTES and PEGDMA/APTES@LPZM. The maximum adsorption capacities of Langmuir-Freundlich model increased from 8.118 to 17.32 mg/g after enzyme immobilization. The negative enthalpy value, ΔH° (- 10.37 kJ/mol), revealed that the nicotine adsorption on PEGDMA/APTES@LPZM was exothermic in nature, which was corroborated by the decrease observed in the number of adsorbed molecules with increasing temperature. In the kinetic experiments, the adsorption on PEGDMA and PEGDMA/APTES@LPZM reached equilibrium with the removal percentages as 66.4% and 98.9% at the end of 3 h, respectively. The nicotine adsorption performances in real water matrices were also investigated, and PEGDMA/APTES@LPZM showed satisfactory reusability with removal percentage decreased from 98.9% (1st cycle) to 83.0% (6th cycle).

Hydrochar: A Review on Its Production Technologies and Applications

Recently, due to the escalating usage of non-renewable fossil fuels such as coal, natural gas and petroleum coke in electricity and power generation, and associated issues with pollution and global warming, more attention is being paid to finding alternative renewable fuel sources. Thermochemical and hydrothermal conversion processes have been used to produce biochar and hydrochar, respectively, from waste renewable biomass. Char produced from the thermochemical and hydrothermal decomposition of biomass is considered an environmentally friendly replacement for solid hydrocarbon materials such as coal and petroleum coke. Unlike thermochemically derived biochar, hydrochar has received little attention due to the lack of literature on its production technologies, physicochemical characterization, and applications. This review paper aims to fulfill these objectives and fill the knowledge gaps in the literature relating to hydrochar. Therefore, this review discusses the most recent studies on hydrochar characteristics, reaction mechanisms for char production technology such as hydrothermal carbonization, as well as hydrochar activation and functionalization. In addition, the applications of hydrochar, mainly in the fields of agriculture, pollutant adsorption, catalyst support, bioenergy, carbon sequestration, and electrochemistry are reviewed. With advancements in hydrothermal technologies and other environmentally friendly conversion technologies, hydrochar appears to be an appealing bioresource for a wide variety of energy, environmental, industrial, and commercial applications.