title: Synthesis and characterisation of low-cost biopolymeric/mineral composite systems and evaluation of their potential application for heavy metal removal

authors: Zia, Zahida

subjects: Water treatment

abstract: Heavy metal pollution and waste management are two major environmental problems faced in the world today. Anthropogenic sources of heavy metals, especially effluent from industries, are serious environmental and health concerns by polluting surface and ground waters. Similarly, on a global scale, thousands of tonnes of industrial and agricultural waste are discarded into the environment annually. There are several conventional methods to treat industrial effluents, including reverse osmosis, oxidation, filtration, flotation, chemical precipitation, ion exchange resins and adsorption. Among them, adsorption and ion exchange are known to be effective mechanisms for removing heavy metal pollution, especially if low-cost materials can be used. 
This thesis was a study into materials that can be used to remove heavy metals from water using low-cost feedstock materials. The synthesis of low-cost composite matrices from agricultural and industrial by-products and low-cost organic and mineral sources was carried out. The feedstock materials being considered include chitosan (generated from industrial seafood waste), coir fibre (an agricultural by-product), spent coffee grounds (a by-product from coffee machines), hydroxyapatite (from bovine bone), and naturally sourced aluminosilicate minerals such as zeolite. 
The novel composite adsorbents were prepared using commercially sourced HAp and bovine sourced HAp, with two types of adsorbents being synthesized, including two- and three-component composites. Standard synthetic methods such as precipitation were developed to synthesize these materials, followed by characterization of their structural, physical, and chemical properties (by using FTIR, TGA, SEM, EDX and XRD). 
The synthesized materials were then evaluated for their ability to remove metal ions from solutions of heavy metals using single-metal ion type and two-metal ion type solution systems, using the model ion solutions, with quantification of their removal efficiency. It was followed by experimentation using the synthesized adsorbents for metal ion removal in complex systems such as an industrial input stream solution system obtained from a local timber treatment company. 
Two-component composites were considered as control composites to compare the removal efficiency of the three-component composites against.  The heavy metal removal experiments were conducted under a range of experimental conditions (e.g., pH, sorbent dose, initial metal ion concentration, time of contact). Of the four metal ion systems considered in this study (Cd²⁺, Pb²⁺, Cu²⁺ and Cr as chromate ions), Pb²⁺ ion removal by the composites was found to be the highest in single-metal and two-metal ion type solution systems, while chromate ion removal was found to be the lowest. The bovine bone-based hydroxyapatite (bHAp) composites were more efficient at removing the metal cations than composites formed from a commercially sourced hydroxyapatite (cHAp). 
In industrial input stream solution systems (containing Cu, Cr and As), the Cu²⁺ ion removal was the highest, which aligned with the observations recorded in the single and two-metal ion type solution systems. Arsenate ion was removed to a higher extent than chromate ion using the three-component composites, while the removal of chromate ion was found to be higher than arsenate ion when using the two-component composites (i.e., the control system). 
The project also aimed to elucidate the removal mechanisms of these synthesized composite materials by using appropriate adsorption and kinetic models. The adsorption of metal ions exhibited a range of adsorption behaviours as both the models (Langmuir and Freundlich) were found to fit most of the data recorded in different adsorption systems studied. The pseudo-second-order model was found to be the best fitted to describe the kinetics of heavy metal ion adsorption in all the composite adsorbent systems studied, in single-metal ion type and two-metal ion type solution systems. The ion-exchange mechanism was considered as one of the dominant mechanisms for the removal of cations (in single-metal and two-metal ion type solution systems) and arsenate ions (in industrial input stream solution systems) along with other adsorption mechanisms.  In contrast, electrostatic attractions were considered to be the dominant mechanism of removal for chromate ions.

text: Synthesis and characterisation of low-cost biopolymeric/mineral composite systems and evaluation of their potential application for heavy metal removal Heavy metal pollution and waste management are two major environmental problems faced in the world today. Anthropogenic sources of heavy metals, especially effluent from industries, are serious environmental and health concerns by polluting surface and ground waters. Similarly, on a global scale, thousands of tonnes of industrial and agricultural waste are discarded into the environment annually. There are several conventional methods to treat industrial effluents, including reverse osmosis, oxidation, filtration, flotation, chemical precipitation, ion exchange resins and adsorption. Among them, adsorption and ion exchange are known to be effective mechanisms for removing heavy metal pollution, especially if low-cost materials can be used. 
This thesis was a study into materials that can be used to remove heavy metals from water using low-cost feedstock materials. The synthesis of low-cost composite matrices from agricultural and industrial by-products and low-cost organic and mineral sources was carried out. The feedstock materials being considered include chitosan (generated from industrial seafood waste), coir fibre (an agricultural by-product), spent coffee grounds (a by-product from coffee machines), hydroxyapatite (from bovine bone), and naturally sourced aluminosilicate minerals such as zeolite. 
The novel composite adsorbents were prepared using commercially sourced HAp and bovine sourced HAp, with two types of adsorbents being synthesized, including two- and three-component composites. Standard synthetic methods such as precipitation were developed to synthesize these materials, followed by characterization of their structural, physical, and chemical properties (by using FTIR, TGA, SEM, EDX and XRD). 
The synthesized materials were then evaluated for their ability to remove metal ions from solutions of heavy metals using single-metal ion type and two-metal ion type solution systems, using the model ion solutions, with quantification of their removal efficiency. It was followed by experimentation using the synthesized adsorbents for metal ion removal in complex systems such as an industrial input stream solution system obtained from a local timber treatment company. 
Two-component composites were considered as control composites to compare the removal efficiency of the three-component composites against.  The heavy metal removal experiments were conducted under a range of experimental conditions (e.g., pH, sorbent dose, initial metal ion concentration, time of contact). Of the four metal ion systems considered in this study (Cd²⁺, Pb²⁺, Cu²⁺ and Cr as chromate ions), Pb²⁺ ion removal by the composites was found to be the highest in single-metal and two-metal ion type solution systems, while chromate ion removal was found to be the lowest. The bovine bone-based hydroxyapatite (bHAp) composites were more efficient at removing the metal cations than composites formed from a commercially sourced hydroxyapatite (cHAp). 
In industrial input stream solution systems (containing Cu, Cr and As), the Cu²⁺ ion removal was the highest, which aligned with the observations recorded in the single and two-metal ion type solution systems. Arsenate ion was removed to a higher extent than chromate ion using the three-component composites, while the removal of chromate ion was found to be higher than arsenate ion when using the two-component composites (i.e., the control system). 
The project also aimed to elucidate the removal mechanisms of these synthesized composite materials by using appropriate adsorption and kinetic models. The adsorption of metal ions exhibited a range of adsorption behaviours as both the models (Langmuir and Freundlich) were found to fit most of the data recorded in different adsorption systems studied. The pseudo-second-order model was found to be the best fitted to describe the kinetics of heavy metal ion adsorption in all the composite adsorbent systems studied, in single-metal ion type and two-metal ion type solution systems. The ion-exchange mechanism was considered as one of the dominant mechanisms for the removal of cations (in single-metal and two-metal ion type solution systems) and arsenate ions (in industrial input stream solution systems) along with other adsorption mechanisms.  In contrast, electrostatic attractions were considered to be the dominant mechanism of removal for chromate ions.

year: 2022

title: CatchIt: Capturing Cues of Bookmarked Moment to Feed Digital Parrot

authors: Alyamani, Hasan Jamal

subjects: Augmented memory system

abstract: CatchIt is a mobile application which aims to capture information about moments in a user’s life in a semi-automatic way. The captured moments are then ready to be fed into an augmented memory system for later retrieval.

In CatchIt, the time and location contexts of the captured moment will be saved automatically from the system and GPS respectively once the user bookmarks the moment with the ability of modifying them later; whereas the desired other context, people, will be saved manually. The user of CatchIt also can capture further details (contents) of the moments by different ways: taking notes (textual information), taking photo, recording video, and recording audio. Additionally, the user can revise an earlier moment if the user wishes to. Later on, the user can transfer the selective bookmarked moments into the augmented memory system called the Digital Parrot.
The implementation of CatchIt is the central focus of this study. To do so, the requirements of CatchIt are specified based on results of a previous study and from a scenario. The conceptual architecture and the user interface of CatchIt are designed according to the CatchIt requirements. The user interface is implemented in addition to the database where is the captured information from the user interface will be stored in and retrieved from.
Evaluating the usability of CatchIt will come next. In the evaluation, the study will involve three sessions: (1) initial questionnaire to know more about the preferred capturing ways of different scenarios, (2) testing the applications where an existing mobile application, Hansel, will be tested for the same length of testing CatchIt (one week for each) and (3) a guided interview which will extract the usability of CatchIt comparing with Hansel on one hand and adding a new contact to the phone using the application Contacts. An additional goal of the last session of the study will be to extract the feeling and the interests of using CatchIt.
The results of this study indicated the user interface of CatchIt needs to be even easier to use. The findings of the study form the foundation for further work to improve the user interface of CatchIt and to understand more of the user needs of such mobile capturing application.

text: CatchIt: Capturing Cues of Bookmarked Moment to Feed Digital Parrot CatchIt is a mobile application which aims to capture information about moments in a user’s life in a semi-automatic way. The captured moments are then ready to be fed into an augmented memory system for later retrieval.

In CatchIt, the time and location contexts of the captured moment will be saved automatically from the system and GPS respectively once the user bookmarks the moment with the ability of modifying them later; whereas the desired other context, people, will be saved manually. The user of CatchIt also can capture further details (contents) of the moments by different ways: taking notes (textual information), taking photo, recording video, and recording audio. Additionally, the user can revise an earlier moment if the user wishes to. Later on, the user can transfer the selective bookmarked moments into the augmented memory system called the Digital Parrot.
The implementation of CatchIt is the central focus of this study. To do so, the requirements of CatchIt are specified based on results of a previous study and from a scenario. The conceptual architecture and the user interface of CatchIt are designed according to the CatchIt requirements. The user interface is implemented in addition to the database where is the captured information from the user interface will be stored in and retrieved from.
Evaluating the usability of CatchIt will come next. In the evaluation, the study will involve three sessions: (1) initial questionnaire to know more about the preferred capturing ways of different scenarios, (2) testing the applications where an existing mobile application, Hansel, will be tested for the same length of testing CatchIt (one week for each) and (3) a guided interview which will extract the usability of CatchIt comparing with Hansel on one hand and adding a new contact to the phone using the application Contacts. An additional goal of the last session of the study will be to extract the feeling and the interests of using CatchIt.
The results of this study indicated the user interface of CatchIt needs to be even easier to use. The findings of the study form the foundation for further work to improve the user interface of CatchIt and to understand more of the user needs of such mobile capturing application.

year: 2012

title: Kia whakatōmuri te haere whakamua: ‘I walk backwards into the future with my eyes fixed on my past’

authors: Rameka, Lesley Kay

subjects: Māori

abstract: This whakataukī or ‘proverb’ speaks to Māori perspectives of time, where the past, the present and the future are viewed as intertwined, and life as a continuous cosmic process. Within this continuous cosmic movement, time has no restrictions – it is both past and present. The past is central to and shapes both present and future identity. From this perspective, the individual carries their past into the future. The strength of carrying one’s past into the future is that ancestors are ever present, existing both within the spiritual realm and in the physical, alongside the living as well as within the living. This article explores Māori perspectives of the past and the models and inspiration they offer. In this way, it provides a critique of the practices in early childhood education, highlighting the importance of cultural concepts and practices, and discusses implications for both teaching and academic practice.

text: Kia whakatōmuri te haere whakamua: ‘I walk backwards into the future with my eyes fixed on my past’ This whakataukī or ‘proverb’ speaks to Māori perspectives of time, where the past, the present and the future are viewed as intertwined, and life as a continuous cosmic process. Within this continuous cosmic movement, time has no restrictions – it is both past and present. The past is central to and shapes both present and future identity. From this perspective, the individual carries their past into the future. The strength of carrying one’s past into the future is that ancestors are ever present, existing both within the spiritual realm and in the physical, alongside the living as well as within the living. This article explores Māori perspectives of the past and the models and inspiration they offer. In this way, it provides a critique of the practices in early childhood education, highlighting the importance of cultural concepts and practices, and discusses implications for both teaching and academic practice.

year: 2017