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The narrow light-response range and high electron/hole recombination rate greatly restrict the widespread use of photocatalytic technology. The integration of exposing dominant facet of semiconductor and Z-scheme heterostructures designing is expected to break those barriers. Herein，In this work, hydrothermal and ultrasonic stirring methods were used to selectively exposed the (001) and (110) facet of BiOI to construct the BiOI/CdS heterostructures. The obtained BiOI(001)/CdS material shown the maximum degradation for tetracycline-based antibiotics (Oxytetracycline, Tetracycline and Doxycycline), and excellent reduction of hexavalent chromium. Combining the electron spin resonance and scavenger experiments, the superior photocatalytic capacity was attributed to the generation of superoxide and hydroxyl radicals. DFT calculation results shown BiOI(001)/CdS performed high binding energy and adsorption energy for hexavalent chromium, and the different work function between BiOI(001) and CdS confirmed the building of internal electric field, thereby increased the charge separation. Finally, the Gaussian 09 and HPLC-MS program investigated the attack sites of free radicals and degradation pathways in the degradation of antibiotics. This study not only provides a potential photocatalyst, also gives an in-depth understanding of the photocatalytic properties of heterojunctions constructed by different exposed crystal facets., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

It is challenging work to develop a low-cost, efficient, and environmentally friendly Cr(VI) adsorbent for waste water treatment. In this paper, we used hemicelluloses from chemical fiber factory waste as the raw material, and prepared two kinds of carbon materials by the green hydrothermal method as adsorbent for Cr(VI). The results showed that hemicelluloses hydrothermally treated with citric acid (HTC) presented spherical shapes, and hemicelluloses hydrothermally treated with ammonia solution (HTC-NH 2 ) provided spongy structures. The adsorption capacity of the samples can be obtained by the Langmuir model, and the adsorption kinetics could be described by the pseudo-second-order model at pH 1.0. The maximum adsorption capacity of HTC-NH 2 in the Langmuir model is 74.60 mg/g, much higher than that of HTC (61.25 mg/g). The green hydrothermal treatment of biomass with ammonia solution will provide a simple and feasible way to prepare adsorbent for Cr(VI) in waste water treatment.

We report an ingenious technique to prepare magnetic alkaline lignin-dopamine nanoparticles (AL-DA/Fe 3 O 4 NPs). Alkaline lignin, a kind of abundant waste from agriculture, pulping and bio-energy industry, was functionalized by the conjugation with DA molecules and nano-precipitation method. Benefiting from the three-dimensional network of lignin and mussel-inspired DA molecules, chromium(III) can be effectively removed by physisorption and chemisorption. The maximum Cr(III) adsorption capacity of AL-DA/Fe 3 O 4 NPs was found to be 44.56 mg/g, which was among the highest of previously reported biomass-based Cr(III) adsorbents. Moreover, sensitive magnetic responsiveness (24.6 emu/g) of AL-DA/Fe 3 O 4 NPs can be more helpful in recycling (over 90% recycled within 2 min) and multiple reusing. The preparation of this low-cost, high adsorptive capacity and good ecofriendly lignin-based nano-adsorbent is expected to become a sustainable technology to simultaneously achieve the wastewater reutilization from pulping and bio-energy industry and purification of other modern industries., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A novel cationic biosorbent was synthesized by grafting organosolv lignin with GT (also named (2-hydrazinyl-2-oxoethyl)-trimethylazanium chloride, abbreviated as GT) and formaldehyde in an aqueous solution by an eco-friendly way (named QA-g-OL). QA-g-OL was employed as biosorbent to remediate hexavalent chromium polluted water. Research found Cr(VI) removal is a pH-dependence process. It was also found that part of the Cr(VI) was reduced to Cr(III) during the process of adsorption in the range of pH was 2.0 to 7.0. Furthermore, QA-g-OL possess strong absorbability for Cr (VI) in a broad concentration range (from 10 to 100 mg/L). The removal efficiencies of Cr (VI) were 93.40%, 96.70%, 98.78% and 97.84% when initial concentration was 10, 20, 50, 80 and 100 mg/L under optimum pH, respectively. On the other side, the adsorption process exhibited swift equilibrium characteristics, the adsorption equilibrium can be achieved within 10 min. The mechanism of hexavalent chromium removed by QA-g-OL were also discussed, results can be benefit for the application of biomass-based adsorbents in the treatment of hexavalent chromium polluted wastewater., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this study, Fe 0 and mixed anaerobic culture were integrated in one column to investigate the coupled abiotic and biotic effects on hexa-valent chromium (Cr(VI)) removal and column longevity with an abiotic Fe 0 column in the control experiments. According to the breakthrough study, a slower Cr(VI) breakthrough rate of 0.19 cm/PV was observed in the biotic Fe 0 column whereas the value in the abiotic Fe 0 column was 0.30 cm/PV, resulting in 64% longer life-span and 62% higher Cr(VI) removal capacity in the biotic Fe 0 column than the abiotic one. The solid phase characterization by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) confirmed that this enhancement was attributed to the higher consumption of iron and greater production of diverse reactive minerals (e.g., green rust, magnetite and lepidocrocite) induced by the synergistic interaction of Fe 0 and anaerobic culture, providing more reactive sites for Cr(VI) adsorption, reduction and co-precipitation. Furthermore, the decreasing breakthrough rates and growing iron corrosion along the biotic Fe 0 column demonstrated an inhomogeneous distribution of reactive zones in the column and its latter 3/5 section was considered to be the most reactive area for Cr(VI) removal. These results indicate that the inoculation of microorganisms in Fe 0 -based permeable reactive barriers will enable this technology a higher removal capacity and longer life-span for the remediation of Cr(VI)-contaminated groundwater., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A one-pot bio-iron system was established to investigate synergetic abiotic and biotic effects between iron and microorganisms on Cr(VI) removal. More diverse iron corrosion and reactive solids, such as green rusts, lepidocrocite and magnetite were found in the bio-iron system than in the Fe 0 -H 2 O system, leading to 4.3 times higher Cr(VI) removal efficiency in the bio-iron system than in the Fe 0 -H 2 O system. The cycling experiment also showed that the Cr(VI) removal capacity of Fe 0 in the bio-iron system was 12.4 times higher than that in the Fe 0 -H 2 O system. A 62days of life-span could be achieved in the bio-iron system, while the Fe 0 -H 2 O system lost its efficacy after 30days. Enhanced effects of extra Fe 2+ on Cr(VI) removal was observed, largely contributed to the adsorbed Fe 2+ on iron surface, which could function as an extra reductant for Cr(VI) and promote the electron transfer on the solid phase. The results also showed that the reduction of Cr(VI) by microorganisms was insignificant, indicating the adsorption/co-precipitation of Cr by iron oxides on iron surface was responsible for the overall Cr(VI) removal. Our study demonstrated that the bio-amended iron corrosion could improve the performance of Fe 0 for Cr(VI) removal from groundwater., (Copyright © 2017 Elsevier B.V. All rights reserved.)

At present, there are many methods for Cr(VI) concentration determination in diluted samples, however, these methods have their own inherent drawbacks, such as long response time, complicated pretreatment, expensive equipment etc. In this paper, a paper-based test strip method specific for determination of diluted Cr(VI) samples was developed. In this method, Aliquat 336, as an anion exchanger was loaded into filter paper to form a test strip. This test strip was used to pre-concentrate Cr(VI) when contacting with the diluted Cr(VI)-containing solution. The Cr(VI)-containing test strip was then immersed into a diphenylcarbazide (DPC) solution (a color forming solution), and the color intensity was correlated to the Cr(VI) concentration. The detection range of the present method was found to be 0.02-1.50 mg/L. The results also showed that the method gave a high selectivity for Cr(VI) in the diluted samples to be tested. The method was applied to synthesized samples and the results, which were compared to those from a reference method, showed that the developed method is an effective, reliable way for Cr(VI) determination in diluted samples.