A review on carbon-based biowaste and organic polymer materials for sustainable treatment of sulfonamides from pharmaceutical wastewater.

Frequent detection of sulfonamides (SAs) pharmaceuticals in wastewater has necessitated the discovery of suitable technology for their sustainable remediation. Adsorption has been widely investigated due to its effectiveness, simplicity, and availability of various adsorbent materials from natural and artificial sources. This review highlighted the potentials of carbon-based adsorbents derived from agricultural wastes such as lignocellulose, biochar, activated carbon, carbon nanotubes graphene materials as well as organic polymers such as chitosan, molecularly imprinted polymers, metal, and covalent frameworks for SAs removal from wastewater. The promising features of these materials including higher porosity, rich carbon-content, robustness, good stability as well as ease of modification have been emphasized. Thus, the materials have demonstrated excellent performance towards the SAs removal, attributed to their porous nature that provided sufficient active sites for the adsorption of SAs molecules. The modification of physico-chemical features of the materials have been discussed as efficient means for enhancing their adsorption and reusable performance. The article also proposed various interactive mechanisms for the SAs adsorption. Lastly, the prospects and challenges have been highlighted to expand the knowledge gap on the application of the materials for the sustainable removal of the SAs.

A review on superior advanced oxidation and photocatalytic degradation techniques for perfluorooctanoic acid (PFOA) elimination from wastewater.

Perfluorooctanoic acid (PFOA) has been identified as the most toxic specie of the family of perfluorinated carboxylic acids (PFCAs). It has been widely distributed and frequently detected in environmental wastewater. The compound's unique features such as inherent stability, rigidity, and resistance to harsh chemical and thermal conditions, due to its multiple and strong C-F bonds have resulted in its resistance to conventional wastewater remediations. Photolysis and bioremediation methods have been proven to be inefficient in their elimination, hence this article presents intensive literature studies and summarized findings reported on the application of advanced oxidation processes (AOPs) and photocatalytic degradation techniques as the best alternatives for the PFOA elimination from wastewater. Techniques of persulfate, photo-Fenton, electrochemical, photoelectrochemical and photocatalytic degradation have been explored and their mechanisms for the degradation and defluorination of the PFOA have been demonstrated. The major advantage of AOPs techniques has been centralized on the generation of active radicals such as sulfate (SO4•-) hydroxyl (•OH). While for the photocatalytic process, photogenerated species (electron (e) and holes (h + vb)) initiated the process. These active radicals and photogenerated species possessed potentiality to attack the PFOA molecule and caused the cleavage of the C-C and C-F bonds, resulting in its efficient degradation. Shorter-chain PFCAs have been identified as the major intermediates detected and the final stage entails its complete mineralization to carbon dioxide (CO2) and fluoride ion (F-). The prospects and challenges associated with the outlined techniques have been highlighted for better understanding of the subject matter for the PFOA elimination from real wastewaters.

Correlating black soldier fly larvae growths with soluble nutrients derived from thermally pre-treated waste activated sludge.

Black soldier fly larvae (BSFL) have been deployed to valorize various organic wastes. Nonetheless, its growth rate whilst being offered with waste activated sludge (WAS) is not promising, likely by virtue of the presence of extracellular polymeric substances' structure in WAS. In this work, the WAS were first thermally pre-treated under different treatment temperatures and durations before being administered as the feeding substrates for BSFL. The results showed the thermal pre-treatment could improve WAS palatability and subsequently, enhance the growth of BSFL especially after the pre-treatments at 75 °C and above. The highest larva weight gained was recorded at 2.16 mg/larva for the WAS sample being pre-treated at 90 °C and 16 h. Furthermore, the samples pre-treated above 75 °C also achieved higher degradation rates, indicating that the 75 °C was a threshold temperature to effectively hydrolyze the WAS. The changes of WAS characteristics, namely, (i) soluble chemical oxygen demand (SCOD), (ii) soluble carbohydrate, (iii) soluble protein, (iv) humic substances and (v) total soluble protein and humic substances, after the thermal pre-treatments were also studied in correlating with the BSFL growth. Accordingly, a model was successfully developed with the highest R2 value attained at 0.95, evidencing the SCOD was the most suitable WAS characteristic to accurately predict the BSFL growth behavior.

Tunable band structure of synthesized carbon dots modified graphitic carbon nitride/bismuth oxychlorobromide heterojunction for photocatalytic degradation of tetracycline in water.

In this study, graphitic carbon nitride (CN) decorated with carbon quantum dot (CQD) and bismuth oxychlorobromide (BiOClxBr1-x) was fabricated by calcination and hydrothermal methods. The morphology characterization of the synthesized photocatalyst revealed that CQD and BiOClxBr1-x solid solution were deposited on the CN surface. CQD served as the electron reservoir, which could reduce the recombination of electron-hole pairs, thus improving the overall photocatalytic performance. The synergistic effect of 1 wt% CQDs and BiOCl0.75Br0.25 markedly improved the interfacial charge transfer efficiency and light-harvesting capacity of the composite. The degradation rate of tetracycline (TC) over CN/CQD/BiOCl0.75Br0.25 was 83.4 % after 30 min and favorable stability with near-initial capacity under visible light irradiation. Meanwhile, the reaction mechanism of the photocatalytic performance was demonstrated by the analysis of the surface adsorption sites, efficient utilization of visible light, and charge carrier transfer. The degradation by-products and potential degradation pathways were also analyzed using liquid chromatography-mass spectrometry. Finally, the toxicity estimation software tool (T.E.S.T) analysis indicated that the toxicity of most intermediates was lower than TC. This work provideed a strategy for fabricating visible light (VL) photocatalyst with excellent photocatalytic activity, furnishing a new insight for interface charge transfer.

Current perspectives, future challenges and key technologies of biohydrogen production for building a carbon-neutral future: A review.

The ever-increasing quantity of greenhouse gases in the atmosphere can be attributed to the rapid increase in the world population as well as the expansion of globalization. Hence, achieving carbon neutrality by 2050 stands as a challenging task to accomplish. Global industrialization had necessitated the need to enhance the current production systems to reduce greenhouse gases emission, whilst promoting the capture of carbon dioxide from atmosphere. Hydrogen is often touted as the fuel of future via substituting fossil-based fuels. In this regard, renewable hydrogen happens to be a niche sector of novel technologies in achieving carbon neutrality. Microalgae-based biohydrogen technologies could be a sustainable and economical approach to produce hydrogen from a renewable source, while simultaneously promoting the absorption of carbon dioxide. This review highlights the current perspectives of biohydrogen production as an alternate source of energy. In addition, future challenges associated with biohydrogen production at large-scale application, storage and transportation are included. Key technologies in producing biohydrogen are finally described in building a carbon-neutral future.

Porous hexagonal nanoplate cobalt oxide derived from a coordination polymer as an effective catalyst for activating Oxone in water.

As cobalt (Co) represents an effective transition metal for activating Oxone to degrade contaminants, tricobalt tetraoxide (Co3O4) is extensively employed as a heterogeneous phase of Co for Oxone activation. Since Co3O4 can be manipulated to exhibit various shapes, 2-dimensional plate-like morphology of Co3O4 can offer large contact surfaces. If the large plate-like surfaces can be even porous, forming porous nanoplate Co3O4 (PNC), such a PNC should be a promising catalyst for Oxone activation. Therefore, a facile but straightforward method is proposed to prepare such a PNC for activating Oxone to degrade pollutants. In particular, a cobaltic coordination polymer with a morphology of hexagonal nanoplate, which is synthesized through coordination between Co2+ and thiocyanuric acid (TCA), is adopted as a precursor. Through calcination, CoTCA could be transformed into hexagonal nanoplate-like Co3O4 with pores to become PNC. This PNC also shows different characteristics from the commercial Co3O4 nanoparticle (NP) in terms of surficial reactivity and textural properties. Thus, PNC exhibits a much higher catalytic activity than the commercial Co3O4 NP towards activation of Oxone to degrade a model contaminant, salicylic acid (SA). Specifically, SA was 100% degraded by PNC activating Oxone within 120 min, and the Ea of SA degradation by PNC-activated Oxone is 70.2 kJ/mol. PNC can also remain stable and effective for SA degradation even in the presence of other anions, and PNC could be reused over multiple cycles without significant loss of catalytic activity. These features validate that PNC is a promising and useful Co-based catalyst for Oxone activation.

Development of 3-dimensional Co3O4 catalysts with various morphologies for activation of Oxone to degrade 5-sulfosalicylic acid in water.

Since 5-sulfosalicylic acid (SFA) has been increasingly released to the environment, SO4--based oxidation processes using Oxone have been considered as useful methods to eliminate SFA. As Co3O4 has been a promising material for OX activation, the four 3D Co3O4 catalysts with distinct morphologies, including Co3O4-C (with cubes), Co3O4-P (with plates), Co3O4-N (with needles) and Co3O4-F (with floral structures), are fabricated for activating OX to degrade SFA. In particular, Co3O4-F not only exhibits the highest surface area but also possesses the abundant Co2+ and more reactive surface, making Co3O4-F the most advantageous 3D Co3O4 catalyst for OX activation to degrade SFA. The mechanism of SFA by this 3D Co3O4/OX is also investigated and the corresponding SFA degradation pathway has been elucidated. The catalytic activities of Co3O4 catalysts can be correlated to physical and chemical properties which were associated with particular morphologies to provide insights into design of 3D Co3O4-based catalysts for OX-based technology to degrade emerging contaminants, such as SFA.