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Per- and polyfluoroalkyl substances (PFAS) are widely used in many industrial and food processes. Their discharge into the environment shows a serious threat because of their toxicity, non-biodegradability and high mobility in water and soil. Photocatalytic reaction is confirmed an effective way for the degradation of PFOA. Photocatalytic materials with multifunctional properties can boost the generation of oxidizing materials, enhance the degradation efficiency of target pollutants. Herein, we report an easy-synthesis of ZIF67@C 3 N 4 and MIL-100(Fe)@C 3 N 4 by in-situ hydrothermal growth route for the photocatalytic degradation of perfluorooctanoic acid (PFOA). Unlike bare g-C 3 N 4 , ZIF67@C 3 N 4 and MIL-100(Fe)@C 3 N 4 composites exhibit higher specific surface areas which enhanced the adsorption properties. Moreover, the formed heterojunction systems boost the visible light responsive and the separation of photo-induced electrons, allowing excellent degradation of PFOA. Besides the same response to spectrum below 420 nm as C 3 N 4 , ZIF67@C 3 N 4 holds a certain light absorption capacity between 500 and 600 nm, proving that ZIF67@C 3 N 4 -X has better light utilization capacity than ZIF67 and C 3 N 4. With the increase of MIL-100(Fe) addition, the red-shift becomes significant. Through the preliminary photocatalytic tests using methylene blue as a representative organic pollutant, the results showed that ZIF67@C 3 N 4 -24.4% and MIL-100(Fe)@C 3 N 4 -70% are the most effective. When ZIF67@C 3 N 4 -24.4% and MIL-100(Fe)@C 3 N 4 -70% were applied comparatively towards the photocatalytic oxidation of PFOA, the results showed that the removal rates reached 79.2% and 60.5%, respectively, which is much higher than bare C 3 N 4. The quenching tests indicated that photo-induced h+ played a major role in the photocatalytic degradation of PFOA by ZIF67@C 3 N 4 -24.4%, while O 2- and h+ participated equality towards the PFOA degradation in MIL-100(Fe)@C 3 N 4 -70% system. Besides the photonic effects, it was suggested that the adsorption and electron shuttle effect also played significant role on the excellent removal of PFOA, wherein the adsorption e behavior of catalysts help the accumulation of PFOA nearby the photoactive C 3 N 4 area. In addition, this process promoted further mineralization of generated intermediate products, making the system more sustainable. [Display omitted] • C 3 N 4 modified by ZIF67 and MIL-100(Fe) were synthesized. • Photo-induced h+ played a major role in the photocatalytic degradation of PFOA by ZIF67 @C 3 N 4. • Adsorb and Shuttle process was main reason behind the excellent removal of PFOA by the photocatalysts. • The formed heterojunction systems boost the separation of photoproduced charges, allowing excellent oxidation of PFOA. [ABSTRACT FROM AUTHOR]

In this present work, a commercial coffee waste was treated using cationic surfactants cetyltrimethyl ammonium bromide (CTAB) or cetylpyridinium chloride (CPC) to enhance its adsorption capacity for the removal of methyl orange dye (MO, anionic dye) from aqueous solutions. A series of experiments were undertaken in an agitated batch to assess the effect of key parameters such as pH, contact time, adsorbent dose and ionic strength. Maximum methyl orange dye adsorption onto modified commercial coffee waste (MCWs) was observed at pH 3.5 with 0.1 g/50 ml of adsorbent dose. Modeling study shows that pseudo-second-order kinetic model and Langmuir adsorption isotherm model provide better fitness to the experimental data. The maximum adsorption capacity (62.5 mg/g at 25 °C) was obtained with CPC modified commercial coffee waste. Calculated thermodynamic parameters ∆ G 0 , ∆ H 0 and ∆ S 0 showed that adsorption is spontaneous and exothermic. The FT-IR analysis showed that possible mechanisms controlling MO adsorption on the MCWs included electrostatic interactions and hydrophobic interaction. [ABSTRACT FROM AUTHOR]

[Display omitted] Worldwide, arsenic contamination has become a matter of extreme importance owing to its potential toxic, carcinogenic and mutagenic impact on human health and the environment. The magnetite-loaded biochar has received increasing attention for the removal of arsenic (As) in contaminated water and soil. The present study reports a facile synthesis, characterization and adsorption characteristics of a novel magnetite impregnated nitrogen-doped hybrid biochar (N/Fe 3 O 4 @BC) for efficient arsenate, As(V) and arsenite, As(III) removal from aqueous environment. The as-synthesized material (N/Fe 3 O 4 @BC) characterization via XRD, BET, FTIR, SEM/EDS clearly revealed magnetite (Fe 3 O 4) impregnation onto biochar matrix. Furthermore, the adsorbent (N/Fe 3 O 4 @BC) selectivity results showed that such a combination plays an important role in targeted molecule removal from aqueous environments and compensates for the reduced surface area. The maximum monolayer adsorption (Q max) of developed adsorbent (N/Fe 3 O 4 @BC) (18.15 mg/g and 9.87 mg/g) was significantly higher than that of pristine biochar (BC) (9.89 & 8.12 mg/g) and magnetite nano-particles (MNPs) [7.38 & 8.56 mg/g] for both As(III) and As(V), respectively. Isotherm and kinetic data were well fitted by Langmuir (R2 = 0.993) and Pseudo first order model (R2 = 0.992) thereby indicating physico-chemical sorption as a rate-limiting step. The co-anions (PO 4 3-) effect was more significant for both As(III) and As (V) removal owing to similar outer electronic structure. Mechanistic insights (pH and FTIR spectra) further demonstrated the remarkable contribution of surface groups (OH–, –NH 2 and –COOH), electrostatic attraction (via H- bonds), surface complexation and ion exchange followed by external mass transfer diffusion and As(III) oxidation into As(V) by (N/Fe 3 O 4 @BC) reactive oxygen species. Moreover, successful desorption was achieved at varying rates up to 7th regeneration cycle thereby showing (N/Fe 3 O 4 @BC) potential practical application. Thus, this work provides a novel insight for the fabrication of novel magnetic biochar for As removal from contaminated water in natural, engineering and environmental settings. [ABSTRACT FROM AUTHOR]

Coffee residue, a low-cost agricultural byproduct, was tested as a precursor for the production of porous carbons in a chemical scheme using phosphoric acid. The raw material was impregnated and then paralyzed respectively at 600 and 700°C for 1h. The resulting products were characterized by adsorption of phenol at room temperature. The impregnation ratios have shown a strong influence on the capacity adsorption and surface area. The adsorption equilibrium was reached after forty minutes. The appropriate isotherms of adsorption involved in this study were developed according to Langmuir and Freundlich models. [ABSTRACT FROM AUTHOR]

This study emphasized the efficiency of unconventional delignification treatment "Acetocell" as a basic pretreatment to isolate cellulose fiber from Tamarix aphylla 's stem. Chemical proprieties of obtained cellulose were determined and its efficiency for cadmium ions adsorption was evaluated subsequently. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis, thermogravimetric analysis (TGA), Scanning Electron Microscopy (SEM), fluorescence microscope and Morfi were used to analyze the thermochemical and morphological characteristics of the fibers before and after treatment. Cellulose was used as a biosorbent to remove cadmium ions from polluted water. The effects of many parameters on the efficiency removal of cadmium were investigated; the amount of cellulose, the contact time, pH and the initial concentration of cadmium ions. The optimum conditions were 45 mg of adsorbent, 45 mg L−1, 1200 min and pH 8 which provide best adsorption capacity equal to 44.21 mg g−1. The energy value E = 6.65 kJ mol−l which confirm the physical interaction between cellulose-cadmium ions. Then Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models were followed for modeling adsorption. Langmuir isotherm and the pseudo-second order model seems the most suitable which describe better the adsorption of cadmium ions with best R2 values which equal to 0.9937 and 0.9979, respectively. [ABSTRACT FROM AUTHOR]