Environmental contamination by heavy metals has continued to be a source of serious concerns to researchers because of its far-reaching implications on the earth as we know it. This is because environmental pollution occasioned by heavy metals (HMs) which are non-biodegradable pose direct or indirect negative effects on environmental health, including that of plants, animals, and humans owing to their increased bioaccumulation in environmental matrices. Wastewater from industries producing chemicals is disposed of directly without proper treatment into the environment. However, HMs enter the food chains and food webs via the air, water, and soil, thereby inducing several diseases and disorders in both humans and animals. The features of rice husk (RH) as novel adsorbent are because it is chemically stable as well as being insoluble in water in addition to its large surface area relative to other agricultural waste products. There is an increasingly high awareness of the roles played by RH in environmental uses or applications for the sequestration of environmentally harmful chemical substances This review summarizes some recent developments in the use of RH and its derivatives as an environmentally friendly adsorbent that is highly suitable for the removal of heavy metal.

Potentially toxic elements (PTEs) are metallic chemicals with densities that are higher than that of water. Water pollution by PTEs due to the discharge of untreated pharmaceutical industrial effluents is a risk to human health and ecological integrity. The present review paper provides an overview of the threats to human health due to water contamination by PTEs such as lead, cobalt, cadmium, nickel, and arsenic originating from pharmaceutical industrial wastewater. This review reveals the associated advantages and shortcomings of the outmoded and the modern methods and the challenges involved in addressing the shortcomings. Additionally, due to the increasing amount of uncontrollable pharmaceutical effluents entering the ecosystem, this paper reviewed the management approach supported by the World Health Organization and the Environmental Protection Agency. Studies revealed that PTEs find their way into human bodies through different pathways, which include drinking water, edibles, and dermal vulnerability at intervals. This paper focuses on how pharmaceutical effluents can be handled and how regulations and strategies can be reinforced step by step. To preserve public health and the environment, a comprehensive study on the environmental evaluation of carcinogenic substances, particularly toxic elements and metalloids, should be supported and advocated. To protect living organisms and the welfare of consumers, efforts should be made to reduce the presence of potentially hazardous elements on land and water.

This review study is dealing with the recent advances and developments in the metal–organic framework (MOF) materials especially in the aspect of environmental remediation of heavy metals. Its application in some area of technological and mechanical advancement was also considered. The process of its synthesis and characterization was also put into consideration. Metal-organic frameworks can be said to be an exciting new class of nanoporous crystalline materials containing a metal as its central ion surrounded by organic ligands. An overwhelming characteristic of MOFs lies in its surface area which is amazingly large, exceeding those of known best activated carbons and zeolites. There is an increasingly high demand in the application of MOFs for a multitude of environmental uses or application to be used for capturing and separating various unwanted or even environmentally harmful chemicals, elements or materials. The advantage of MOFs over other known adsorbent materials, such as zeolites and carbon black, is that it possesses a far greater surface area along with amazingly great pore properties. In this review the synthesis and characterization of MOFs, the fate of heavy metals, the application of MOFs in heavy metals remediation and other means of heavy metals remediation are well discussed.

The spatio-temporal variation of two organotin compounds (OTCs) of tributyltin and triphenyltin in the seawater and sediment of Cape Town harbour was investigated. The organotin compounds were determined by GC-FPD following prior extraction with 0.02% tropolone. The concentration of OTCs varies for locations in Cape Town harbour. The concentration of OTCs in seawater ranges from 0.067±0.01 to 111.290±32.20×10−3μg/l for TBT while that of TPT ranges between between ND±SD and 23008.0±0.03×10−3μg/l respectively between locations. Relatively higher concentrations were measured for TBT and TPT during summer than in winter and spring seasons (p⩽0.05). Apparently, the observed high or low values recorded for TBT in Cape Town harbour could be the result of an increase or decrease in the traffic of ships and boats. TBT was detected in all the sediment samples analysed except for location 9 (entrance to harbour), the two control sites (which are located far away from the inner harbour where boating activities are taking place), and location 12 (Robinson dry dock 2) where the samples were not at all found. For the control sites, antifouling compounds TBT and TPT were not detected throughout except for TBT that was found in control A during summer. The seasonal variation of OTC abundance in sediment was also investigated. The results indicated that TBT is present throughout the seasons but is predominantly present in this order summer>winter>spring