Rubberized Geopolymer Composites: Value-Added Applications

Alginate/geopolymer hybrid beads as an innovative adsorbent applied to the removal of 5-fluorouracil from contaminated environmental water

Water contaminated by cytostatic drugs has many negative impacts on the ecosystems. In this work, cross-linked adsorbent beads based on alginate and a geopolymer (prepared from an illito-kaolinitic clay) were developed for a promising decontamination of the 5-fluorouracil (5-FU) cytostatic drug from water samples. The characterization of the prepared geopolymer and its hybrid derivative was performed by scanning electron microscopy, X-ray diffraction, Fourier transform infrared and termogravimetric analysis. Batch adsorption experiments indicated that alginate/geopolymer hybrid beads (AGHB) allow an excellent 5-FU removal efficiency of up to 80% for a dosage adsorbent/water of 0.002 g/mL and a concentration of 5-FU of 2.5 mg/L. The adsorption isotherms data follow well the Langmuir model. The kinetics data favor the pseudo-second-order model. The maximum adsorption capacity (q_max) was 6.2 mg/g. The optimal adsorption pH was 4. Besides pore filling sorption process, the carboxyl and hydroxyl groups from alginate immobilized onto the geopolymer matrix favored the retention of 5-FU ions by hydrogen bonds. Common competitors, such as dissolved organic matter, do not significantly affected the adsorption. In addition, this material has not only eco-friendly and cost-effective advantages but also excellent efficiency when applied to real environmental samples such as wastewater and surface water. This fact suggests that it could have a great application in the purification of contaminated water.

A comprehensive review on sustainable clay-based geopolymers for wastewater treatment: circular economy and future outlook

In the present era of significant industrial development, the presence and dispersal of countless water contaminants in water bodies worldwide have rendered them unsuitable for various forms of life. Recently, the awareness of environmental sustainability for wastewater treatment has increased rapidly in quest of meeting the global water demand. Despite numerous conventional adsorbents on deck, exploring low-cost and efficient adsorbents is interesting. Clays and clays-based geopolymers are intensively used as natural, alternative, and promising adsorbents to meet the goals for combating climate change and providing low carbon, heat, and power. In this narrative work, the present review highlights the persistence of some inorganic/organic water pollutants in aquatic bodies. Moreover, it comprehensively summarizes the advancement in the strategies associated with synthesizing clays and their based geopolymers, characterization techniques, and applications in water treatment. Furthermore, the critical challenges, opportunities, and future prospective regarding the circular economy are additionally outlined. This review expounded on the ongoing research studies for leveraging these eco-friendly materials to address water decontamination. The adsorption mechanisms of clays-based geopolymers are successfully presented. Therefore, the present review is believed to deepen insights into wastewater treatment using clays and clays-based geopolymers as a groundbreaking aspect in accord with the waste-to-wealth concept toward broader sustainable development goals.

A Comprehensive Review on Fly Ash-Based Geopolymer

The discovery of an innovative category of inorganic geopolymer composites has generated extensive scientific attention and the kaleidoscopic development of their applications. The escalating concerns over global warming owing to emissions of carbon dioxide (CO2), a primary greenhouse gas, from the ordinary Portland cement industry, may hopefully be mitigated by the development of geopolymer construction composites with a lower carbon footprint. The current manuscript comprehensively reviews the rheological, strength and durability properties of geopolymer composites, along with shedding light on their recent key advancements viz., micro-structures, state-of-the-art applications such as the immobilization of toxic or radioactive wastes, digital geopolymer concrete, 3D-printed fly ash-based geopolymers, hot-pressed and foam geopolymers, etc. They have a crystal-clear role to play in offering a sustainable prospect to the construction industry, as part of the accessible toolkit of building materials—binders, cements, mortars, concretes, etc. Consequently, the present scientometric review manuscript is grist for the mill and aims to contribute as a single key note document assessing exhaustive research findings for establishing the viability of fly ash-based geopolymer composites as the most promising, durable, sustainable, affordable, user and eco-benevolent building materials for the future.

Valorisation of Waste Glasses for the Development of Geopolymer Mortar—Properties and Applications: An Appraisal

The current review paper studies the most noteworthy points in the fabrication of inorganic, eco-benign geopolymer mortar stressing the valorisation of Waste of Glasses (WG) about its properties and applications. Only a few studies are so far accessible on the topic, and therefore, more advanced studies in this respect will be valuable to construction industries and the research scientist, too. Mostly, the centre of attention on its valorisation with WG points a finger to its attitude to embrace the “conversion of wastes into best” strategy. Up until now, their character is neither well understood nor as embraced as OPC mortars. That is why this article reviews its confined literature with an aim to comprehend the valorisation of WG incorporation with geopolymer mortar, and it also reviews studies on its properties and applications, establishing it as a forthcoming constructive, productive, cost-effective, and sustainable large-scale construction material. The recommendations of this paper will be helpful for potential researchers on the topic. However, there are some challenges, such as curing impediments, occasionally practical antagonises of use, a restrained chain of supply, and a precondition for a sharp-eyed command of mixing design for preparing it for use in roadways to replace OPC counterparts in industry. When fabricated by employing abundantly available precursors, activators, and WG up to the standard superior control of varied properties, chiefly strength, durability, and the low-carbon footprints of alkali activators, GP mortars supplemented with WG are ground-breaking approaches to part of the prospect toolbox of sustainable and reasonably inexpensive construction materials. Finally, the paper identifies research work challenges, endorsement of utilisation, and most essentially the features of its properties and pertinent discussions for this promising new kind of valorised construction material.

A State-of-the-Art Review on Innovative Geopolymer Composites Designed for Water and Wastewater Treatment

There is nothing more fundamental than clean potable water for living beings next to air. On the other hand, wastewater management is cropping up as a challenging task day-by-day due to lots of new additions of novel pollutants as well as the development of infrastructures and regulations that could not maintain its pace with the burgeoning escalation of populace and urbanizations. Therefore, momentous approaches must be sought-after to reclaim fresh water from wastewaters in order to address this great societal challenge. One of the routes is to clean wastewater through treatment processes using diverse adsorbents. However, most of them are unsustainable and quite costly e.g. activated carbon adsorbents, etc. Quite recently, innovative, sustainable, durable, affordable, user and eco-benevolent Geopolymer composites have been brought into play to serve the purpose as a pretty novel subject matter since they can be manufactured by a simple process of Geopolymerization at low temperature, lower energy with mitigated carbon footprints and marvellously, exhibit outstanding properties of physical and chemical stability, ion-exchange, dielectric characteristics, etc., with a porous structure and of course lucrative too because of the incorporation of wastes with them, which is in harmony with the goal to transit from linear to circular economy, i.e., "one's waste is the treasure for another". For these reasons, nowadays, this ground-breaking inorganic class of amorphous alumina-silicate materials are drawing the attention of the world researchers for designing them as adsorbents for water and wastewater treatment where the chemical nature and structure of the materials have a great impact on their adsorption competence. The aim of the current most recent state-of-the-art and scientometric review is to comprehend and assess thoroughly the advancements in geo-synthesis, properties and applications of geopolymer composites designed for the elimination of hazardous contaminants viz., heavy metal ions, dyes, etc. The adsorption mechanisms and effects of various environmental conditions on adsorption efficiency are also taken into account for review of the importance of Geopolymers as most recent adsorbents to get rid of the death-defying and toxic pollutants from wastewater with a view to obtaining reclaimed potable and sparkling water for reuse offering to trim down the massive crisis of scarcity of water promoting sustainable water and wastewater treatment for greener environments. The appraisal is made on the performance estimation of Geopolymers for water and wastewater treatment along with the three-dimensional printed components are characterized for mechanical, physical and chemical attributes, permeability and Ammonium (NH4+) ion removal competence of Geopolymer composites as alternative adsorbents for sequestration of an assortment of contaminants during wastewater treatment.